CENTRAL SCIENCE LABORATORY
DEPARTMENT FOR ENVIRONMENT FOOD & RURAL AFFAIRS
Contingency planning for outbreaks of Thrips palmi
on protected cucumbers
Compiled by Lynne Matthews, Ray Cannon, Keith Walters and
Dominic Eyre
Central Science Laboratory, Sand Hutton, York, YO41 1LZ
With additional contributions from Rob Jacobson and Derek
Hargreaves
Cucumber Growers Association
23rd March 2005
CONTENTS
SUMMARY
1.
Introduction
2.
Prophylactic use of foliage and flower inhabiting natural enemies
2.1
Species currently available in the UK
2.2
Species available overseas (not yet registered in the UK)
3.
Prophylactic use of generalist natural enemies on the ground
3.1
UK products
4.
Remedial use of invertebrate natural enemies
4.1
UK products
4.2
Overseas products
5.
Remedial use of entomopathogenic fungi
5.1
UK products
6.
Chemical control
6.1
UK products
6.2
OVERSEAS PRODUCTS
7.
PHYSICAL CONTROL
8.
RECOMMENDATIONS (HIGH PRIORITY IN BOLD)
9.
REFERENCES
APPENDIX 1 - Cucumber Grower Association Proposed Strategy for the
Management of Thrips palmi in Cucumber Crops
APPENDIX 2 - A modular approach to integrated control of Thrips palmi
Karny: Concept note
2
Summary
Thrips palmi is not established anywhere in Europe, and although it has been
successfully eradicated from an ornamental crop in the UK, there are a dearth
of effective measures which could be utilised in the event of an outbreak in an
edible crop. Lessons learnt in an ornamental situation would not necessarily
apply to an edible crop, when Integrated Pest Management (IPM) is practised.
T. palmi is notoriously difficult to control by chemical means alone and
effective IPM measures need to be developed which can be utilised in a UK
situation. T. palmi occurs out-of-doors in many tropical and sub-tropical
countries, and a wide range of potential natural enemies have been identified,
in some cases providing highly effective control, suppressing the pest to low
population levels.
In the UK, the main economic threat is to protected edible crops such as
cucumbers, aubergines and sweet peppers, where current pest management
relies heavily on biological control. Although there have not been any
outbreaks of T. palmi on cucumbers in the EU, there was a finding of a single
adult on a cucumber nursery in the Beverley area, Yorkshire, in 1999. This,
together with a similar ‘trace’ find on cucumbers in the Netherlands, prompted
concern among UK growers and led to the Cucumber Growers Association
(CGA) approaching Plant Health Division (PHD) with a proposed strategy for
T. palmi. This then led on to meetings with CSL, which resulted in the present
document and recommendations for work in support of an improved
contingency plan for this species on cucumber. This modular strategic
approach to T. palmi control is reflected in the recommendations.
In equivalent cucumber growing situations where the pest is established –
such as Japan – biological control systems are in general less well-developed
than in Western Europe, and furthermore, utilise native biological control
agents (BCAs) which are both unavailable and unregistered in the UK. In
other words, they would be classified as non-native organisms in the UK, thus
requiring extensive testing and regulatory approval (via the Advisory
Committee on Releases to the Environment, ACRE) before they could be
released.
Thrips palmi is a highly cryptic pest, with a reputation for rapidly developing
resistance to a wide range of chemical insecticides. Although a number of
effective products are potentially available for T. palmi control, many of these
are not available in the UK. Of those that are registered, some are either not
approved for use in edible crop situations or would have the effect of
disrupting existing biological control measures for other pests. One notable
exception is spinosad, which is registered in cucumbers and which is
reportedly compatible with beneficials.
The aim of this work has been to review the range of existing control
measures for T. palmi, worldwide, and to select those with the potential for
further investigation. Recommendations are provided for the assessment of
3
both biological and chemical controls methods, categorised according to
whether or not they are currently available – i.e. registered – in the UK.
Assessments and selection of appropriate controls will have to be carried out
under quarantine conditions, which put a constraint on the level of
experimentation that can be carried out. Further work will also be necessary
to adapt the most efficacious methods selected, into IPM programmes, and to
consider how these can be best adapted to achieving the goal of eradication
of the pest, whilst minimising the impact on the Industry.
4
1.
Introduction
Thrips palmi Karny (Thysanoptera: Thripidae), the melon thrips, is widely
distributed in tropical and sub-tropical regions, including Southeast Asia, the
Pacific Islands, the Caribbean Islands and South America (Murai, 2001). In
1978, T. palmi was found in Japan for the first time and it rapidly became the
most serious pest of aubergine, cucumber and sweet pepper both in
greenhouses and out-of-doors. It has also invaded southern Florida and
Australia and is a serious threat to these protected crops in Europe, where it
is listed as a IAI pest in EC Plant Health Legislation (Directive 2000/29/EC).
To date, there have been 26 outbreaks of T. palmi in the EU - 25 in the
Netherlands and one in the UK - all of which were successfully eradicated by
a combination of crop destruction and intensive insecticide applications. In the
Netherlands, outbreaks occurred on Cactaceae and Ficus benjamina between
1988 and 1994. The UK outbreak was detected in April 2000 on an all-yearround (AYR) chrysanthemum crop on the south coast, although the outbreak
was well advanced and probably long established at this time. T. palmi was
declared eradicated in July 2001 after freedom from the pest occurred over
two complete cropping cycles (Cannon et al., in prep.). Although many
lessons on how to control T. palmi were learnt during this successful
eradication of T. palmi on an ornamental crop, they do not necessarily apply
to an outbreak on cucumbers. For example, biological control was not being
practised on the infested chrysanthemum crop, and the availability of
insecticides is much greater for ornamentals than for edible crops.
In addition to these high-profile outbreaks in the Netherlands and the UK,
which were on ornamentals, there were two ‘trace’ finds on cucumber crops
(one in the UK and the other one in the Netherlands) which prompted great
concern among growers, and were the spur to the formulation of a proposed
strategy for T. palmi on cucumber crops and to the formal approaches to the
Plant Health Division (PHD) by the Cucumber Growers Association (CGA).
The UK find was a single adult female T. palmi, which was detected on
cucumber plants at a large cucumber nursery in the Beverley area, Yorkshire
in 1999. Despite extensive re-sampling, no further specimens were detected;
thrips control on this site was to a high standard. Fortunately, the find
occurred towards the end of the cropping season, and a thorough clean-up
programme was implemented during the crop break. The following season,
the crop received an intensive biocontrol programme against the western
flower thrips, Frankliniella occidentalis (WFT), which might also have
prevented further establishment of T. palmi. In 1998, the year before this
‘trace’ find, the Netherlands reported to the European Commission, that a
single T. palmi larva had been found on cucumber at a nursery in the NoordBrabant region. Thus, cucumber (and other edible cops such as aubergine
and peppers) are at a very real risk from this invasive thrips.
T. palmi remains a major pest of several greenhouse crops in Japan,
including aubergine, sweet pepper and watermelon (Yano, 2004). However,
the highest reproductive rates and the maximum intrinsic rate of natural
increase of T. palmi populations occurs on cucumbers (Murai, 2001), so it is
5
this crop which is most at risk. T. palmi tends to live and feed on the leaves of
cucumber plants; the leaf edges curl downward after heavy thrips feeding and
serious damage often occurs during the early crop stages. Thrips feed by
bursting the cells of the host plants and sucking up the exposed cell sap,
resulting in discoloration of plant tissues leading to scarring and distortion of
plant and produce (Kirk, 1997). Given its tendency to feed on the foliage, T.
palmi is often reported to be less damaging to cucumber fruit than WFT
(Rosenheim et al. 1990). Nevertheless, fruits may also be damaged; scars,
deformities, and abortion are reported. Densities from one to ten T. palmi per
cucumber leaf have been considered to be the threshold for economic
damage in some Japanese studies (Capinera, 2000). However, studies in
Hawaii suggested a damage threshold of 94 thrips per leaf early in plant
growth (Welter et al. 1990). Although there have been no reported outbreaks
of T. palmi on cucumbers in the EU, the singleton finds, detailed above,
illustrate that there is a pathway for the introduction of T. palmi to UK
cucumber crops, although it is not clear how this occurred (Cannon et al., in
prep.).
T. palmi is a notoriously difficult pest to control, with many studies
demonstrating that the use of chemicals alone will not be effective (Kawai,
1990; 2001; Rosenheim et al., 1990; Young and Zhang, 1998). Equally,
successful biological control of T. palmi is not achievable at present (Website
2), partly because biological control using arthropods is not well developed in
countries such as Japan (Wada, 1999; Website 6), where the pest is present .
An integrated pest management (IPM) system has been suggested as the
way forward for the control of T. palmi (Kawai and Kitamura, 1987 in Walker,
1994) and this is likely to be the best option for eradicating outbreaks of T.
palmi in edible UK crops. IPM programmes combine a range of control
measures, including: the use of biological agents (BCAs); physical methods
such as trapping, and the use of plastic mulches and other barriers; cultural
measures such as rouging and manipulation of the crop environment; as well
as carefully targeted pesticides applied at critical times (Lenteren, 1995;
Jacobson, 1997; Loomans and Vierbergen, 1999).
The aims of this report are therefore to:
i)
identify and review the availability and efficacy of a range of
biological, chemical and physical products (or treatment options) for
use against T. palmi on cucumbers; comparing what is currently
registered in the UK with what is available elsewhere, worldwide;
and
ii)
develop an effective IPM treatment schedule and eradication
strategy for T. palmi, in the event of an outbreak on cucumbers in
the UK. Components of the strategy might also be applicable to
other protected salad crops in the UK.
6
2.
Prophylactic use of foliage and flower inhabiting natural enemies
2.1
Species currently available in the UK
The predatory mite, Amblyseius cucumeris (Mesostigmata: Phytoseiidae), is
currently used to control F. occidentalis in UK cucumber crops; it is
recommended that culture sachets be put on plants as early as possible and
replaced when they stop producing predators (approximately every 8 weeks)
(Jacobson et al., 2001b). A. cucumeris is also effective against T. palmi in
aubergines, strawberries and cucumbers under greenhouse conditions. One
mite can consume, on average, 65.3 first instar larvae of T. palmi and 18.7
second instars during its life cycle, and females consume more prey as the
thrips density increases (Cuellar et al., 2002). A. cucumeris was registered for
use as a BCA (‘Cucumeris’ ®) in Japan in April, 1998 (Wada, 1999). It is
produced by ‘Techno Green Company’, a subsidiary of ‘Nippon Kayaku’ and
distributed through the ‘Tomen Corporation’ (Website 3). The recommended
dose is 100 mites per cucumber plant sprinkled at the base of each plant at
the beginning of insect occurrence; at least 2-3 consecutive weekly releases
are recommended. A. cucumeris is also used to control T. palmi on pepper;
100 adults per plant, released three times at 1-week intervals (starting 3 days
after planting), reduced a population of T. palmi to between one third to one
fifth of its original size, for 6 weeks (Kurogi et al.,1997). A. cucumeris must be
applied to each cucumber plant, because a lack of overlapping foliage early in
the season hinders the dispersal of the mites within the crop (Website 3).
Amblyseius sachets are not used in Japan because the authorities do not
permit the importation of Tyrophagus mites, which are incorporated into the
sachets as a prey source for the Amblyseius; Tyrophagus mites may cause
slight damage to some crops, especially when growing conditions are humid
and they are present in large numbers (Website 5). In conjunction with this,
there has been no investment in the machinery required to produce the
culture packs (Rob Jacobson, Cucumber Growers Association, pers. comm.),
but the Amblyseius sachet system would be the standard method of
introducing A. cucumeris to an outbreak of T. palmi on cucumbers in the UK.
A rate of 1000 A. cucumeris per plant is used to control F. occidentalis and it
is suggested that at least this amount would be required to control T. palmi
(Rob Jacobson, pers. comm.).
Amblyseius spp. are relatively inexpensive in comparison with predatory
Hemiptera such as Orius spp. (see section 4) and populations can increase
more rapidly. However, as with some Orius spp., A. cucumeris is limited in its
early and late season uses by a tendency to enter diapause in response to
short daylengths, a state where the mites continue feeding but do not
reproduce (Chambers and Long, 1991), although some biocontrol companies
sell strains which are not susceptible to diapause, e.g. ‘Thripex’ by ‘Koppert’
(Website 5).
Koppert are developing a new BCA: the predatory mite Typhlodromips
swirskii. In trials it has given excellent thrips control in sweet pepper and
7
cucumber (Website 5), although as a non-native animal it will require a licence
for release in the UK (David Flory, Koppert, pers. comm.). Phytoseius spp.
(Mesostigmata: Phytoseiidae) mites are also known to prey on thrips,
including T. palmi; they are recorded feeding readily on first instar larvae of T.
palmi in Thailand (Hirose et al., 1993), but the only product registered for use
in the UK, P. persimilis, is almost completely dependent on spider mites and
is marketed for the control of spider mites only.
Some generalist predators, available for use in the UK, may also have some
potential for use in a T. palmi eradication programme: e.g. the bug, Anthocoris
nemoralis (Hemiptera: Anthocoridae), and larvae of the lacewing, Chrysoperla
carnea (Neuroptera: Chrysopidae). A. nemoralis is primarily sold for the
control of pear psyllid in orchards, but will feed on a range of small insects,
including thrips and mites. Diapause restricts its use to between March and
October in the UK (Clare Sampson, Biological Crop Protection, pers. comm.).
In trials, C. carnea had a medium consumption of 14.4 T. palmi nymphs in 24
hours (Alvarez et al., 2002).
2.2
Species available overseas (not yet registered in the UK)
Several non-indigenous mites are recorded feeding on T. palmi, including
some exotic Amblyseius spp. and Typhlodromalus aripo (Mesostigmata:
Phytoseiidae). Adult female A. mckenziei and A. okinawanus have been
detected preying on T. palmi on cucumbers in Japan; they prefer first instar T.
palmi to second instars and adult thrips (Kajita, 1986). In other tests, adult A.
maai and A. asetus consumed 80.2 and 90.2 T. palmi larvae, respectively,
and it was concluded that the latter had the potential to be used for the
biological control of thrips pests (ChyiChen and WenHua, 2001). A.
longispinosus (Hirose, 1989b) and A. tsugawai (CABI, 2004) have been
recorded in Japan. CABI (2004) also list A. bakeri amongst the natural
enemies of T. palmi. T. aripo can consume 72.9 first instar larvae of T. palmi
and 21.6 second instars during its life cycle and females respond positively to
higher densities of thrips (Cuellar et al., 2002). Recently, a new biocontrol
product has been developed containing A. montdorensis, which has higher
rates of prey consumption and a higher reproductive potential than A.
cucumeris when used in its optimum temperature range of 20-30°C. (Richard
GreatRex, Syngenta Bioline, pers. comm.). In trials, it has been found
predominantly on leaves or fruits and not in flowers. This apparent preference
for leaves makes the species of interest for the control of T. palmi, although
so far performance against this pest has not been tested (Cox et al.,
unpublished CSL document).
A range of other natural enemies of T. palmi have been reported; CABI (2004)
list 23 different species, including: Megaphragma (Hymenoptera:
Trichogrammatidae), a parasitoid of eggs in Thailand; Carayonocoris indicus
(Hemiptera: Anthocoridae), attacking larvae and adults in Japan, and
Propylea japonica (Coleoptera: Coccinellidae), attacking larvae in Japan.
However, the only other natural enemy to be sold commercially appears to be
the predatory thrips, Franklinothrips vespiformis (Thysanoptera: Thripidae). F.
8
vespiformis provides effective control of T. palmi in greenhouses in Okinawa
Prefecture, Japan (Yano, 2003), where it is registered for use in protected
aubergines and cucumbers (Yano, 2004). It can effectively locate and feed on
the eggs of T. palmi embedded within plant tissues (Loomans and Heijboer,
1999). Campylomma chinensis (Hemiptera: Miridae) is also recorded as a
predator of T. palmi in Japan (Hirose et al., 1999) and Taiwan (Parker et al.,
1995). Final instar larvae and adults of C. chinensis consume 20 and 27-29 T.
palmi per day, respectively (Parker et al., 1995), whilst the related species, C.
livida has been identified as an important natural enemy in Thailand and the
Philippines (Searca, 1991). Adult C. livida attack second instar larvae of T.
palmi (Hirose et al., 1993). Other predators of T. palmi reported in the
literature are the stilt bug, Yemma exilis (Heteroptera: Berytidae), which has
been observed feeding on adults and larvae of T. palmi on aubergine in a
plastic greenhouse. In experiments, the mean number of T. palmi consumed
by a female bug was 4-7 for the first 5 days (Kohno and Hirose, 1997) and in
Trinidad, the beetle, Coleomegilla maculata (Coleoptera: Coccinellidae), has
been found preying on T. palmi, although it is not indigenous to the country
(Cooper, 1990).
The literature also reports two larger-scale surveys (in Thailand and Vietnam)
carried out to identify potential BCAs for T. palmi. Of eight natural enemies
found in Thailand, the eulophid larval parasitoid, Ceranisus menes
(Hymenoptera: Eulophidae), was found to be the most effective; 40-60% of
larvae were parasitized in domestic gardens that were not sprayed with
insecticides (Hirose et al., 1993). In contrast, Castineiras et al. (1996a) found
parasitism by C. menes to range from c. 24-29% at 25-29ºC. The rate of
parasitism decreased to 11.5% at 21ºC. Ceranisus spp. are also effective
against T. palmi in Japan (Hirose, 1989a). The larval predator Bilia sp.
(Hemiptera: Anthocoridae) was the second most effective natural enemy in
the survey in Thailand; both adults and nymphs attack T. palmi larvae (Hirose
et al., 1993). Another anthocorid, Wollastoniella parvicuneis, also preys on T.
palmi in aubergine crops in northern Thailand (Yasunaga, 1995). Cage trials
in Japan in winter greenhouses showed that W. rotunda successfully
developed, reproduced and suppressed T. palmi populations, and it was
concluded that it had the potential to be an effective control agent for T. palmi
on aubergines (Nakashima et al., 2004). However, in an IPM programme,
interspecific competition may occur between anthocorid species. Finally, a
survey of indigenous natural enemies of T. palmi in Gia Lam Hanoi (Institute
for Fruit and Vegetables Research) in Vietnam found 14 species of
indigenous natural enemies – 13 predators and one parasitoid. Those not
mentioned previously are Xylocoris sp., Lyctocoris beneficus and Amphiareus
obscuriceps (Hemiptera: Anthocoridae); Isometopus japonicus and Orthotylus
sp. (Hemiptera: Miridae); Haplothrips sp. (Thysanoptera: Phlaeothripidae);
Aeolothrips sp. (Thysanoptera: Aeolothripidae); Scolothrips sexmaculatus
(Thysanoptera: Thripidae); Menochilus sexmaculatus, Micrapis discolor and
Oenopia sauzati (Coleoptera: Coccinellidae) (Try and Hung, 2003).
9
3.
Prophylactic use of generalist natural enemies on the ground
3.1
UK products
The soil predatory mite Hypoaspis miles (Mesostigmata: Laelapidae),
commercially produced for fungus gnat control in the UK, will feed on thrips
that drop to the ground to pupate (Brodsgaard et al., 1996; Gillespie and
Quiring, 1992). It is a useful predator of low-level pest populations, since
adults can live for up to 70 days in the absence of food, providing they have
fed previously. It is also very mobile and is tolerant of many insecticides
applied to the foliage of crops (Website 4), probably as a result of spatial
separation from these chemicals. Up to 30% reduction in damage caused by
F. occidentalis is seen where H. miles is used (Richard GreatRex, Syngenta,
pers. comm.). Recommended release rates vary from 100 per m 2
(‘preventative’) to 500 per m2 (‘curative heavy’) (Website 5). Atheta coriaria
(Coleoptera: Staphylinidae) is a soil-dwelling rove beetle native to the UK.
Laboratory trials in Canada have shown that it is capable of consuming pupae
and late larvae of F. occidentalis and it may have some potential for the
control of T. palmi (Richard GreatRex, Syngenta Bioline, pers. comm.).
However, hydroponic cucumber crops do not provide a favourable
environment for soil-dwelling predators, due to the plastic floor covering
(Derek Hargreaves, Cucumber Growers Association, pers. comm.). A mesh
covering might improve the environment, but further research on the efficacy
of H. miles and A. coriaria against T. palmi would be required before such
expense could be justified.
4.
Remedial use of invertebrate natural enemies
4.1
UK products
The predatory bugs, Orius majusculus and O. laevigatus (Hemiptera:
Anthocoridae), are used to control thrips in the UK; O. laevigatus is well
adapted to living in confined spaces, which could increase its chances of
coming into contact with T. palmi (Chambers et al., 1993). However, the
efficacy of these species against T. palmi is unknown and they enter diapause
in response to short daylengths, limiting their potential for use in UK crops.
Critical day length varies between species; for O. majusculus it is between 14
and 16 hrs, limiting establishment in UK crops between September and April
(Jacobson, 2003). O. laevigatus requires a minimum daylength of 10-11 hrs.
Supplementary lighting has been used to establish localised populations of O.
majusculus from early March (Jacobson, 1993), and releasing adults only
might bring forward the establishment of Orius spp. by 3-4 weeks (Jacobson,
1993), since there is evidence that it is the final nymphal stage that is
susceptible to diapause (Ruberson et al., 1991).
An alternative approach might be to use non-diapausing subtropical strains,
such as those that occur for O. laevigatus (Shipp and Ramakers, 2000).
However, it is likely that non-native strains would need to be licensed before
being released in the UK and there are additional, complicating factors that
10
limit the establishment of Orius spp. in cucumber crops. For example, large
populations of thrips are required to ensure settlement of O. laevigatus due to
the lack of pollen in cucumber crops (Chambers et al., 1993). In the absence
of suitable (or sufficient) food, or if released in hot conditions, adult Orius sp.
will fly and may leave the crop area. To overcome this problem, ‘Syngenta
Bioline’ have been trailing a product containing only first and second instar
Orius nymphs (Richard GreatRex, Syngenta, pers. comm.), but this again
raises the problem of diapause. In addition, the most common egg-laying sites
for O. majusculus are within the youngest 50 cm of growth. During routine
crop maintenance, lateral shoots are removed, which could result in the loss
of 30% unhatched eggs of O. majusculus. Furthermore, some eggs laid in the
short-lived flowers may not complete development (Jacobson, 1995). The
practice of re-planting cucumber crops in mid-summer to maintain fruit quality
also remains a potential obstacle to the establishment of Orius spp. (HDC,
2000a; Jacobson, 2003) due to their relatively long life-cycle: 3-4 weeks under
spring and summer conditions in cucumber and pepper crops (Jacobson,
2003).
Foliar applications of entomopathogenic nematodes, such as Steinernema
feltiae (Steinernematidae), could be used to re-address the balance between
T. palmi and its natural enemies in pest ‘hot-spots’, i.e. where BCAs are not
adequately controlling the thrips. At CSL, applications of S. feltiae
suspensions (5000 infective juveniles per ml) containing the adjuvant ‘Agral’
(0.02% v/v) achieved significantly greater mortality of T. palmi second instar
larvae than control treatments; similar mean levels of mortality (30-41%) were
achieved on three hosts – chrysanthemum, cucumber and capsicum. (CSL,
2003). To maximize nematode efficacy, applications should be made to the
foliage at 20C and followed by an 8hr period of high humidity (>90%) (CSL,
2003). There are however, concerns as to whether elevated relative humidity
could be maintained under commercial conditions (see also comments for
entomopahogenic fungi, below). S. feltiae is compatible with 24hr old residues
of the following insecticides recommended in the PHSI Eradication and
Containment handbook for T. palmi: abamectin (‘Dynamec’), deltamethrin
(‘Decis’) and nicotine (‘XL-All Nicotine 95%’) (Justine Head, CSL, pers.
comm.).
4.2
Overseas products
In Japan, five indigenous Orius species, O. sauteri, O. minutus, O. strigicollis,
O. nagaii and O. tantillus, are considered to be major natural enemies of
thrips in the field (Yasunaga, 1997); of these O. sauteri, O. strigicollis and O.
tantillus all prey on T. palmi (Yano, 1999). Orius spp. are capable of preying
on adult thrips and the number of 1st and 2nd instar larvae consumed by 2nd
instar nymphs of Orius spp. does not differ greatly (Kajita, 1986).
O. sauteri is considered to be the most important natural enemy of T. palmi in
sweet pepper and aubergine fields (Hirose, 1990; Kajita, 1985), and
suppressed the incidence of T. palmi on aubergine in greenhouse trials
(Kawai, 1995) and in a screen-house (Nagai et al., 1988b). It will feed on the
11
adults, larvae and eggs of T. palmi (Paik et al., 2003). O. sauteri was
registered as a biopesticide in Japan in 1998. On pepper, O. sauteri (5 adults
per plant) released twice at 1-week intervals, starting 3 days after planting,
reduced the T. palmi population to less than or equal to 1/5 of the original size
for 2 months after planting (Kurogi et al., 1997). However, the induction of
reproductive diapause limits the efficacy of Orius spp. The low reproduction
rates and predation rates of O. sauteri under low temperature conditions
mean that this species is ineffective in winter (Nagai and Yano, 1999, 2000).
O. strigicollis is preferred to O. sauteri for commercial use because of its lower
diapause incidence and the ease for mass production (Shimizu and
Kawasaki, 2001; Yano, 2004); it was registered as a biopesticide in Japan in
2001 and is widely used for controlling T. palmi on aubergines and sweet
peppers in Kochi Prefecture (Yano, 2003). A single O. strigicollis usually eats
more than 200 thrips during its lifetime (including immature and mature
stages, and assuming a stable temperature of 25ºC) (Wang, 1994). Releases
of 100-150, two-three day-old nymphs of O. strigicollis per aubergine per
week in an open field in Taiwan also decreased the number of T. palmi from
50 per leaf to 3 per leaf within 5 weeks (Wang et al., 2001).
O. minutus shows almost the same reproductive diapause as O. sauteri
(Kohno, 1997, 1998; Ito and Nakata, 1998). O. tantillus and O. nagai are not
considered as suitable species to be used for biological control of pests of
greenhouse vegetables (Yasunaga, 1997). Sakimura et al. (1986) refer to a
sixth species, O. similis, which has been detected preying on T. palmi in
China; second instars are said to consume about 10 T. palmi per day (Wei et
al., 1984). In India, Kumar and Ananthakrishnan (1984) studied Orius
maxidentex in the laboratory and in a field near Madras, where it preyed on T.
palmi on the young foliage of sesame. After the crop was harvested, it was
abundant on the weed Croton sparsiflorus, preying on T. palmi until prey
populations died out in September. O. insidiosus is recorded as a predator of
T. palmi in Hawaii (Mau et al., 1989) and is reportedly abundant on aubergine
in Guadeloupe (Etienne et al., 1990). If Orius spp. are to be used in
eradication programmes for T. palmi further work is required to assess their
compatibility with insecticides. Insect growth regulators, such as ‘Nemolt’
(teflubenzuron) tend to disrupt the development of Orius, as does ‘Vydate’
(oxamyl) (Website 4). However, Nagai (1993) reports that O. sauteri is
tolerant to the insecticides pyriproxyfen and buprofezin, both of which are
growth regulators.
5.
Remedial use of entomopathogenic fungi
5.1
UK products
Lecanicillium mucarium (Hyphomycetes) (formerly Verticillium lecanii) has
been used to control T. palmi in greenhouses in Japan; Saito (1992) applied
four sprays per week in May-June against T. palmi and Bemisia tabaci on
melons and maintained populations of both pests at low levels. CSL (2003)
showed that L. mucarium was most effective against T. palmi at 25C and that
efficacy against the adult stage was significantly higher when used with the
12
adjuvant ‘Agral’. However, the relative humidity within a cucumber crop may
be insufficient for the use of L. mucarium (Derek Hargreaves, pers. comm.).
HDC (2000a) tested L. mucarium in combination with the dextrose starch
adjuvant ‘Hugtite’, but the benefits were uncertain and the adjuvant could
encourage the growth of Cladosporium spp. on the leaves.
5.2
Overseas products
UK trials have suggested that the entomopathogenic fungus, Beauveria
bassiana (Hyphomycetes), is effective at a lower relative humidity than V.
lecanii (HDC, 2000a) and can be used to augment releases of A. cucumeris in
the preventative management of F. occidentalis; glasshouse populations of F.
occidentalis were reduced by 65-87% with three consecutive high volume
sprays or low volume mist applications of ‘Naturalis-L’ or ‘BotaniGard WP’,
applied at 6-day intervals (Jacobson et al., 2001a). A. cucumeris on the
leaves were unaffected by high volume sprays of B. bassiana directed at F.
occidentalis and there was no indication that the applications were harmful to
the predators or their prey in opened culture packs that were on the plants
when the sprays were applied (HDC, 2000a). This suggests that B. bassiana
could be incorporated into an IPM programme for thrips pests. However, in
trials specifically with T. palmi, the results have been less encouraging. The
potential of B. bassiana (strains BbH and BbHa) and Paecilomyces
fumosoroseus (strain 97) for the control of T. palmi was studied on green
beans in greenhouse experiments. P. fumosoroseus produced only 0.20%
mortality; 24% mortality of thrips larvae treated with B. bassiana (strain BbHa)
was achieved, but the infection only developed when leaves with larvae were
incubated after being sprayed with the pathogen (Castineiras et al., 1996b).
CSL (2003) also had poor results when using B. bassiana against T. palmi; it
was found to be less effective against the larval stage of T. palmi than S.
feltiae or V. lecanii (CSL, 2003). B. bassiana is also known to naturally infect
the minute pirate bug O. insidiosus (Frantz and Mellinger, 1998), which may
prevent it being used in IPM programmes that utilise this predator.
The best results with B. bassiana are obtained when the spray directly hits the
target. Therefore, good spray cover is essential and the spray techniques
used in commercial UK cucumber crops may need to be improved before B.
bassiana can be used successfully (HDC, 2000a). Alternatively, B. bassiana
may be used to control thrips pupae; a reduction of 50% in adult emergence
of T. palmi was observed when potting soil with pupae was sprayed with B.
bassiana BbHa (Castineiras et al., 1996b).
Neozygites parvispora (Zygomycees) has also been documented infecting T.
palmi on melons in Japan; approximately 10% of T. palmi adults and nymphs
were infected, but the fungus did not control the pest population (Saito et al.,
1989). In addition, an unidentified species of the genus Hirsutella
(Hyphomycetes) was found in Trinidad, British West Indies, infecting
approximately 80% of T. palmi populations in the field (Hall, 1992).
13
6.
Chemical control
6.1
UK products
Chemical insecticides which are potentially efficacious for thrips control, and
are registered in the UK, include: spinosad, abamectin, malathion, nicotine,
cypermethrin, deltamethrin, thiacloprid, pirimiphos-methyl smokes, rotenone
and bifenthrin, which controls only adults. At the UK label rate, it is reported
that teflubenzuron (‘Nemolt’) will suppress but not control thrips (Horticulture
Week, 2003).
Spinosad and abamectin are recommended for the control of T. palmi in
peppers in Hawaii (‘Success’ and ‘Agrimek 0.51 EC’) (Website 1) and Florida
(‘Agri-Mek 0.15EC’ and ‘SpinTor 2 SC’) (Maynard et al., 2003). No more than
two sequential applications of abamectin are advised, or three applications of
spinosad in any 21-day period (Maynard et al., 2003). Spinosad has also
been shown to be effective against T. palmi on aubergine (Mau and
Gusukuma-Minuto, 1999) and causes no significant mortality in the thrips
predator, O. insidiotus (Studebaker and Kring, 1999). It is mainly active
against adult and larval thrips, but has some effect on the eggs of selected
species. Chemical control of T. palmi in south Florida includes the use of
multiple applications of imidacloprid, endosulfan, methomyl and spinosad
(Aerts & Mossler, 2000). Other control methods include the release of the
native predator, O. insidiosus, and the destruction of old host plants. Best
control of T. palmi using spinosad or abamectin is reportedly achieved at first
sign of melon thrips infestation, since immature stages are much easier to
control (McHugh & Mau, 1998). In the UK, the 3-day pre-harvest interval in
cucumbers makes spinosad difficult to use once cropping has begun,
although the use of spinosad – which is reportedly compatible with BCAs –
might be required in the absence of a tested IPM programme in order to deal
promptly with a find of T. palmi. However, the compatibility of spinosad with
the BCAs commonly used in cucumber crops needs to be confirmed and the
efficacy of Conserve SC – the only spinosad product registered in the UK –
against T. palmi on cucumbers, also requires urgent investigation. The
Conserve label has no specified rate for T. palmi, just "Thrips (exposed)" in
outdoor or greenhouse settings. Examples of exposed thrips are given on the
label: i.e. Cuban laurel thrips, Gynaikothrips ficorum and WFT. In other
words, this is not a rate for T. palmi. Indeed, the concentration of active
ingredient (Spinosyn A and Spinosyn D) in Conserve is only 11.6%, which is
almost half, or a quarter, that of products registered in other countries such as
the USA: i.e. Success® and SpinTor (both with 22.8% a.i.), Belgium: i.e.
Tracer® (48% a.i.) and Spain: SpinTor (48% a.i.). Recommended rates for
‘thrips’ on cucurbit crops are given as 6-8 fl oz/acre in the US and 200ml/ha in
Belgium. Consultation with the manufacturer will be required to determine the
recommended rate for Conserve against T. palmi, although verification will be
required even if the information is available.
Field studies have shown that abamectin is highly effective in controlling T.
palmi on watermelon, green pepper and aubergine (Mau and GusukumaMinuto, 1999). However, it no longer effectively controls F. occidentalis in UK
14
cucumber crops (Derek Hargreaves, pers. comm.), although the addition of
1% white sugar to the spray mixture has been shown to enhance the kill of
thrips larvae by c. 75% (HDC, 2001). Additionally, abamectin has deleterious
effects on A. cucumeris and Orius spp., although it could potentially be used
in pest ‘hot-spots’ or as an end-of–season clean-up treatment (HDC, 2000b)
in a T. palmi eradication programme, if proven effective.
Although deltamethrin (‘Decis 2.8% EC’) and cypermethrin (‘5% Cyperkill EC’)
have been found to be effective in controlling T. palmi on aubergines in
Taiwan (Su et al., 1985), they are broad-spectrum, contact insecticides, the
use of which is likely to have a deleterious effect on BCAs and can result in
higher populations of T. palmi (Young and Zhang, 1998). Thus, the use of
pyrethroids should be avoided, as they may cause melon thrips population
explosions (Etienne et al., 1990, Seal & Baranowski, 1992) and whitefly
population explosions in UK (Derek Hargreaves, pers. comm.).
Of the other broad-spectrum insecticides registered for thrips control in the UK
(i.e. malathion, nicotine, pirimiphos-methyl, rotenone and bifenthrin), nicotine
is least persistent and BCAs can be re-introduced shortly after application.
Therefore, nicotine has the potential to be used as a ‘spot treatment’ in an
IPM programme. Thiacloprid has a specific-off label approval for use in
protected cucumbers and is effective against F. occidentalis. However, it is
detrimental to the parasitoid Encarsia formosa, which is used for whitefly
control and is therefore unsuitable for use in IPM in cucumbers (Derek
Hargreaves, pers. comm.).
6.2
Overseas products
Good results have been reported against T. palmi using methiocarb
(Sakimura et al., 1986), insecticidal soaps (e.g. Natrasoap, M-Pede) (Young
and Zhang, 1998) and foliar applications of imidacloprid (which are not
available in the UK) (Murai, 2001; Cannon et al., in prep.), although resistance
to imidacloprid has appeared in some districts in southern Japan (Komi,
unpublished data in Murai). Few chemicals have high rates of efficacy
against T. palmi, although Murai (2001) reported on a number of older
chemicals (mainly organophosphates) which exhibited mortalities of 50% or
more – but never more that 80% – against T. palmi: e.g. BPMC, methomyl,
fenvalerate, malathion, prothiophos, methidathion and endosulfan. However,
these results are based on experience gained in Japan in the late 1970’s and
1980’s, are generally of little applicability to the current UK situation.
In Martinique, profenofos, avermectin [spelling for abamectin often used by
some countries] and carbofuran were the most effective insecticides against
T. palmi on outdoor vegetables (Bon and Rhino, 1989). However, many of the
compounds reported as being effective are either not registered for use in the
UK (including those which have been revoked or withdrawn), or are
unavailable in the formulation required for maximum efficacy. Additionally,
there are a number of products, which are only approved for use on
ornamental crops in the UK, or are only applicable to soil-based growing
15
systems. For instance, soil treatments with granular formulations of oxamyl
and carbosulfan have been shown to depress T. palmi populations (Kawai,
2001), but could not be used in hydroponic cucumbers.
Novel insecticides with efficacy against T. palmi include acetamiprid,
chlorfenapyr, chlorfluazuron, emamectin benzoate, flucyrthrinate, flufenoxuron
and pyriproxyfen. Acetamiprid is a chloronicotinyl insecticide with systemic
and translaminar action, which ensures effective control of sucking insects. It
has excellent activity against aphids, whitefly and thrips, including T. palmi
(Anon, 1998), but is very harmful to Orius spp. (Koppert, Side Effects Guide).
Field studies on watermelon, green pepper and aubergine showed that
chlorfenapyr was highly effective in controlling T. palmi (Mau and GusukumaMinuto, 1999). Chlorfenapyr will also be a useful component of IPM schemes
as it conserves the thrips predator, Orius (Mau and Gusukuma-Minuto, 1999).
In Japan, emamectin benzoate (‘Proclaim’) is used for the control of T. palmi
in aubergines (Crop Protection Monthly, 1998) and at 5-day intervals,
flufenoxuron and chlorfluazuron were the first and third most effective
insecticides, respectively in tests against T. palmi in Venezula (Cermeli et al.,
1993). Chlorfluazuron (e.g. ‘Aim’, ‘Atabron’) is an insect growth regulator
which acts as an anti-moulting agent, leading to the death of thrips larvae and
pupae. It is used to control thrips on vegetables (The e-Pesticide Manual,
2002). Flufenoxuron (e.g. ‘Cascade’) is a chitin synthesis inhibitor with contact
and stomach action (The e-Pesticide Manual, 2002); it inhibits the ecdysis of
first instar T. palmi larvae and metamorphosis of the second instar larvae into
pupae, but does not affect the survival rate and fecundity of females. It can
be used to supress T. palmi populations (Nagai et al., 1988a). Both
chlorfluazuron and flufenoxuron are harmless to nymphs and adults of A.
cucumeris, but are very toxic to Orius spp. (Nagai, 1990c; Koppert, Side
Effects Guide). Pyriproxyfen could also be a valuable component of an IPM
programmes for T. palmi as it controls the pupal stage whilst being harmless
to O. sauteri (Nagai, 1990b). Flucythrinate (31.6% ‘Pay-off EC’) was found to
be effective in controlling T. palmi on aubergines in Taiwan (Su et al., 1985),
but is incompatible with the use of A. cucumeris (Koppert, Side Effects
Guide). In conclusion, there are many potentially useful chemicals for T. palmi
control, but most are not registered in the UK.
Novel compounds with efficacy against thrips in general include azadirachtin,
diafenthiuron, ethiprole, fipronil, novaluron, pyridaben and thiamethoxam. A
non-systemic liquid formulation of fipronil (‘Vinlin’) is registered in the
Netherlands for use on rockwool and soil-based crops, but to date, the only
formulation approved in the UK is a soil-applied granule for the control of vine
weevil in containerised ornamentals.
Pyridaben has both rapid knockdown activity and long residual activity. Due to
its low toxicity to beneficial arthropods, it can be included in integrated control
programmes (Salagarollo and Politi, 1995). In particular, it has been used in
combination with the predatory mite, A. cucumeris, to control F. occidentalis
on cucumber and tomato crops (Nawrocka and Szwejda, 1999) and may
therefore be able to be used in IPM programmes with similar components
against T. palmi.
16
7.
Physical control
A range of physical control methods, such as mulching with silver PE sheets
and the use of UV reflective greenhouses have been tested against thrips
(Chu, 1987), but are slow to have an effect and only have a minor impact on
populations (Wang et al., 2001). In addition, they are more applicable in
situations where the aim is to prevent T. palmi from entering a glasshouse
from outdoors, rather than to the eradication of an isolated population. For
example, vinyl film, absorbing light < 400nm wavelength reduced T. palmi
populations by 30% compared to conventional covering material (Chu, 1987).
Mass trapping with sticky traps has been shown to be effective against T.
palmi in some crops, and is likely to be used in any T. palmi eradication
programme to exert extra pressure on the population, but the indications are
that in cucumbers it is only effective against low-density populations.
Broad spectrum, contact sprays with a physical mode of action, such as
‘Majestik’ and ‘Eradicoat’, can help to control thrips. They work by blocking
spiracles causing suffocation and by coating the outer cuticle preventing
movement. Since they act purely by physical means and are not taken into
the plant, they can be used on any protected crops, whenever required, with
no harvest interval. Their short persistence also makes them compatible with
the use of BCAs. They may be applied as an overall spray 24 hours before
the introduction of beneficials, or as spot treatments during the growing
season. Use of a high volume spray is recommended to achieve the coverage
required for effective pest control.
17
8.
Recommendations (high priority in bold)
1.
Biological Control Agents (BCAs)
Laboratory assessments of the efficacy of novel and existing biological
products for use in IPM systems against T. palmi, under quarantine
conditions, on cucumber plants. Experiments will simulate commercial
glasshouse growing conditions, as far as possible, and appropriate
methodologies will be developed and tested.
A. Prophylactic use of natural enemies
I. Host-specific, foliage and flower-inhabiting species
a. BCAs already registered in the UK (or in development)
1. Amblyseius cucumeris mites: to determine whether the
system currently used in commercial cucumber crops in
the UK for controlling WFT – i.e. ‘slow-release’ sachets of A.
cucumeris at a rate of 1000 per plant – would successfully
control T. palmi.
2. Test other promising thrips predators currently in development,
including:
 A. swirskii
 A. montdorensis
b.
BCAs developed specifically for use against T. palmi in
countries where it is established (e.g. Japan, Korea, etc.)
1. Compare the efficacy of non-native mites such as Amblyseius
asetus, A. mckenziei, A. okinawanus, etc. to that of UKregistered A. cucumeris.
2. Test the predatory thrips, Frankliniella vespiformis
c.
Generalist ground-dwelling and aerial predators
a.
b.
Anthocoris nemoralis
Chrysoperla carnea
B. Remedial use of natural enemies:
a. BCAs already registered in the UK
1.
Orius spp. (Orius laevigatus, Orius majusculus):
determine whether these predatory bugs are efficient
control agents for T. palmi under realistic conditions.
2.
Carry out manipulation experiments (day-length and
temperature) to improve the efficacy of Orius spp.
18
b. BCAs developed specifically for use against T. palmi in
countries where it is established (e.g. Japan, Korea, etc.)
1.
Compare the efficacy of Orius strigicollis vs. UKregistered Orius spp. (O. laevigatus and O. majusculus).
2.
Compare the most efficacious Orius spp. with other
anthocorids, e.g. Bilia spp., Wollastoniella spp..
c.
2.
Insecticides
a.
3.
Entomopathogenic fungi
Spinosad (Conserve SC)
1. Efficacy vs. T. palmi on cucumbers
2. Test wet/dry residues for compatibility with
existing BCAs
3. Ensure UK approval would permit sufficient
applications and that any pre-harvest interval
would allow continuous cropping.
4. Determine the recommended rate against T.
palmi for the UK product (Conserve SC).
SOLAs and Emergency arrangements
CSL to take a strategic approach to securing more T. palmi-effective
products; involving consultation with appropriate authorities (PSD,
ACRE, etc.)
a. Chemicals (SOLAs, Emergency Use Arrangements)
b. BCAs (Emergency Use Permits)
c. Liaison with biocontrol companies to discuss selection,
and ensure availability, of appropriate BCAs for
‘emergency use’.
4.
Knowledge of the pest and its impact
Improving the existing knowledge-base for T. palmi biology and control
on cucumbers and other salad crops
 Contact Japanese, USA [Hawaii, Florida], Australian [not
yet much of a problem] or South America (Venezuela)
scientists and growers with experience of controlling T.
palmi on cucumbers and other crops.
 Obtain more information on the economic injury effects of
T. palmi in cucumbers from those with experience in
affected areas.
 Revise the CSL PRA for T. palmi
19
5.
Integrated pest management and eradication
Developing an effective IPM programme for T. palmi integrating all
existing knowledge.
1. Contingency plans for dealing with the pest in an outbreak
situation under official control, on:
i. Cucumbers
ii. Peppers
iii. Aubergine
2. Longer term IPM programmes in the event of protracted
campaigns and spread.
20
9.
References
Aerts, M. & Mossler, M. 2000. Crop Profile for Eggplant in Florida.
http://pestdata.ncsu.edu/cropprofiles/docs/FLeggplant_.html.
Alvarez, C.F., Guzman, G.E. and Vergara, R. 2002. Biological features of
Thrips palmi (Thysanoptera: Thripidae) and consumption capacity of a natural
enemy under laboratory conditions. Revista Colombiana de Entomologia
28(1), 27-31.
Anon, 1998. Development of a new insecticide, acetamiprid. Journal of
Pesticide Science 23(2), 199-200.
Anon. 2003. Pest Control: Blocking a global problem. Horticulture Week. 4
December 2003.
Bon, H. de and Rhino, B. 1989. Control of Thrips palmi in Martinique.
Agronomie Tropicale 44, 129-136.
Brodsgaard, H.H., Sardar, M.A. and Enkegaard, A. 1996. Prey preference of
Hyposaspis miles (Berlese) (Acarine: Hypoaspidae): non-interference with
other beneficials in glasshouse crops. Bulletin IOBC/WPRS working group on
integrated control in glasshouses 19(1): 23-26.
CABI, 2004. Crop Protection Compendium. CAB International, Wallingford,
Oxon. http://www.cabicompendium.org/cpc/home.asp
Cannon, R.J.C. et al. in prep. Thrips palmi outbreak report. Unpublished CSL
document.
Cannon, R.J.C. 2003. General notes and discussions from the R&D
discussion meting on thrips held on Thursday 1st May 2003 at HRI,
Wellesbourne. Unpublished CSL document.
Capinera, J. L. 2000. Common name: melon thrips; scientific name: Thrips
palmi
Karny
(Thysanoptera:
Thripidae).
University
of
Florida.
http://creatures.ifas.ufl.edu/veg/melon_thrips.htm.
Castineiras, A., Baranowski, R.M. and Glenn, H. 1996a. Temperature
response of two strains of Ceranisus menes (Hymenoptera: Eulophidae)
reared on Thrips palmi (Thysanoptera: Thripidae). Florida Entomologist 79(1),
13-19.
Castineiras, A., Pena, J.E., Duncan, R. and Osborne, L. 1996b. Potential of
Beauveria bassiana and Paecilomyces fumosoroseus (Deuteromycotina:
Hyphomycetes) as biological control agents of Thrips palmi (Thysanoptera:
thripidae). Florida Entomologist 79(3), 458.
21
Cermeli, M. Montagne, A., Godoy, F. 1993. Preliminary results on the
chemical control of Thrips palmi Karny (Thysanoptera: Thripidae) on beans
(Phaseolus vulgaris L.). Boletin de Entomologia Venezolana 8(1), 63-73.
Chambers, R. and Long, S. 1991. A new ally for the grower. Grower June 27
1991.
Chambers, R.J., Long, S. and Helyer, N. 1993. Effectiveness of Orius
laevigatus for the control of Frankliniella occidentalis on cucumber and pepper
in the UK. Biocontrol Science and Technology 3, 295-307.
Chu, Y.I. 1987. Physical control of thrips. Proceedings of a Symposium on the
Biology of Thrips Chinese Journal of Entomology, Special Publication 1:27-36.
ChyiChen, H. and WenHua, C. 2001. Life history and feeding amount of
Amblyseius asetus and A. maai (Acari: Phytoseiidae) on Thrips palmi
(Thysanoptera: Thripidae). Formosan Entomologist 21(4), 321-328.
Cooper, B. 1990. Status of Thrips palmi (Karny) in Trinidad. FAO Plant Prot.
Bull. 39(1), 45-46.
Cox, P.D., Walters, K.F.A., Matthews, L., Cannon, R. and MacLeod, A. 2004
Potential for the use of biological agents for the control of Thrips palmi
outbreaks.
Crop Protection Monthly, 1998. Issue 107 – 31st October 1998. www.cropprotection-monthly.co.uk
CSL, 2003. Development of a practical IPM approach for the
control/eradication of Thrips palmi Karny in the UK. PH0168 – Final Project
Report.
Cuellar, M.E., Bellotti, A.C. and Melo, E. L. 2002. Aspects of the biology and
rate of consumption of Neoseiulus cucumeris and Typhlodromalus aripo
(Acari: Phytoseiidae) on the host Thrips palmi Karny (Thysanoptera:
Thripidae). Revista Colombiana de Entomologia 28(1), 1-7.
Etienne, J., Guyot, J. and Waetermeulen, X. van. 1990. Effect of
insecticide, predation and precipitation on populations of Thrips palmi on
aubergine (eggplant) in Guadeloupe. Florida Entomologist 73 (2), 339-342.
Franz, G. and Mellinger, H.C. 1998. Potential Use of Beauveria bassiana for
Biological Control of Thrips in Peppers. Proc. Fla. State Hort. Soc. Paper No.
131.
Gillespie, D.R. and Quiring, D.J.M. 1992. Competition between Orius
tristicolor (White) (Hemiptera: Anthocoridae) and Amblyseius cucumeris
(Oudemans) (Acari: Phytoseiidae) feeding on Frankliniella occidentalis
(Pergande) (Thysanoptera: Thripidae). Canadian Entomologist 124: 11231128.
22
Hall, R.A., 1992. New pathogen on Thrips palmi in Trinidad. Florida
Entomologist 75: 380-383.
Hirose, Y. 1989a. Exploration of natural enemies of Thrips palmi in Southeast
Asia. Insitute of Biological control, Faculty of Agriculture, Kyushu University,
Fukuoka, 58pp.
Hirose, Y. 1989b. Prospective use of natural enemies to control Thrips palmi
(Thysanoptera: Thripidae). Institute of Biological Control, Kyushu University,
Japan: 135-141.
Hirose, Y. 1990. Prospective use of natural enemies to control T. palmi
(Thysanoptera: Thripidae). In The Use of Natural Enemies to control
Agricultural Pests (J. Bay-Petersen ed.). FFTC, Taipei, pp. 135-141.
Hirose, Y., Kajita, M., Takagi, S. Okajima, S., Napompeth, B. and
Buranapanichpan, S. 1993. Natural enemies of Thrips palmi and their
effectiveness in the native habitat, Thailand. Biological Control 3(1), 1-5.
Hirose, Y., Nakashima, Y., Takagi, M., Nagai, K., Shima, K., Yasuda, K. and
Kohno, K. 1999. Survey of indigenous natural enemies of the adventive pest
Thrips palmi on the Ryukyu Islans, Japan. Applied Entomology and Zoology 34,
489-496.
Horticultural Development Council, 2000a. Cucumbers: the development of
remedial treatments for the control of western flower thrips within IPM
programmes (PC 129). Final report 2000.
Horticultural Development Council, 2000b. Protected crops: optimising the
use of abamectin within IPM programmes (PC 160). Annual report 2000.
Horticultural Development Council, 2001. Protected flower crops: Evaluation
of sugar products to improve the control of western flower thrips (PC 177).
Final report 2002.
Ito, k. and Nakata, T. 1998. Effect of photoperiod on reproductive diapause in
the predatory bug, Orius suateri (Poppius) and O. minutus (Linnaeus)
(Heteroptera: Anthocoridae). Appl. Entomol. Zool. 33: 115-120.
Jacobson, R.J. 1993. Control of Frankliniella occidentalis with Orius
majusculus: Experiences during the first full season of commercial use in the
U.K. Integrated Control in Protected Crops. Temperate Climate IOBC/wprs
Bulletin 16(2) pp. 81-84.
Jacobson, R.J. 1995. Egg laying sites of Orius majusculus, a thrips predator,
on cucumber. In Parker, B.L. et al. Thrips Biology and Management. Plenum
Press, New York. pp. 241-244.
23
Jacobson, R.J. 1997. Integrated pest management (IPM) in glasshouses. In:
Thrips as crop pests (Lewis, T. Ed.) CAB International, Wallingford, UK, pp.
639-666.
Jacobson, R.J., Chandler, D., Fenlon, J. and Russell, K.M. 2001a.
Compatibility of Beauveria bassiana (Balsamo) Vuillemin with Amblyseius
cucumeris Oudemans (Acarina: Phytoseiidae) to Control Frankliniella
occidentalis Pergande (Thysanoptera: Thripidae) on Cucumber Plants.
Biocontrol Science and Technology 11: 391-400.
Jacobson, R.J., Croft, P. and Fenlon, J. 2001b. Suppressing Establishment of
Frankliniella occidentalis Pergande (Thysanoptera: Thripidae) in Cucumber
Crops by Prophylactic Release of Amblyseius cucumeris Oudemans (Acarina:
Phytoseiidae). Biocontrol Science and Technology 11: 27-34.
Jacobson, R. J. 2003. PhD Thesis - Implementing Integrated Pest
Management in Glasshouses: Challenges and Solutions.
Kajita, Y. 1985. Predacious natural enemies of Thrips palmi Karny. Pulex 71,
329-330.
Kajita, H. 1986. Predation by Amblyseius spp. (Acarina: Phytoseiidae) and
Orius sp. (Hemiptera: Anthocoridae) on Thrips palmi Karny (Thysanoptera:
Thripidae). Appl. Ent. Zool. 21 (3): 482-484.
Kawai, A. 1995. Control of Thrips palmi Karny (Thysanoptera: Thripidae) by
Orius spp. (Heteroptera: Anthocoridae) on greenhouse eggplant. Applied
Entomology and Zoology 30: 1-7.
Kawai, A. and Kitamura, C. 1987. Studies on population ecology of Thrips
palmi Karny. XV. Evaluation of effectiveness of control measures using a
stimulation model. Applied Entomology and Zoology 22(3), 292-302.
Kirk, W.D.J. (1997) Feeding. In: Thrips as crop pests (Lewis, T. Ed.) CAB
International, Wallingford, UK, pp. 119-174.
Kohno, K. 1997. Photoperiodic effects on incidence of reproductive diapause
in Orius sauteri and O. minutus (Heteroptera: Anthocoridae). Appl. Entomol.
Zool. 32: 644-648.
Kohno, K. 1998. Thermal effects on reproductive diapause induction in Orius
sauteri (Heteroptera: Anthocoridae). Appl. Entomol. Zool. 33: 487-490.
Kohno, K. and Hirose, Y. 1997. The Stilt Bug Yemma exilis (Heteroptera:
Berytidae) as a Predator of Aphis gossypii (Homoptera: Aphididae) and Thrips
palmi (Thysanoptera: Thripidae) on Eggplant. Appl. Entomol. Zool. 32 (2):
406-409.
Kumar, N.S. and Ananthakrishnan, T.N. 1984. Predator-thrips interactions
with reference to Orius maxidentex Ghauri and Carayonocoris indicus
24
Muraleedharan (Anthocoridae: Heteroptera). Proceedings of the Indian
National Science of Academy B 50: 139-145.
Kurogi, S., Nakamura, M. and Kawasaki, Y. 1997. Studies on integrated
control of major insect pests of sweet pepper in a greenhouse [in Japan]. 3.
Control of Thrips palmi with 2 species of predators, Orius sauteri and
Amblyseius cucumeris. Proceedings of the Association for Plant Protection of
Kyushu 43: 106-109.
Lenteren, J.C. van. 1995. Integrated pest management in protected crops. In:
Integrated Pest Management (DENT, D. Ed.) Chapman and Hall, London, UK,
pp.311-343.
Loomans, A.J.M. and Heijboer, A. 1999. Frankliniella vespiformis (Crawford):
a polyphagous predator preying on thrips eggs. Proceedings of Experimental
and Applied Entomology, The Netherlands Entomological Society (N.E.V.) 10:
143-150.
Loomans, A.J.M. and Vierbergen, G. 1999. Franklinothrips: perspectives for
glasshouse pest control. IOBC/WPRS working group on integrated control in
glasshouses 22 (1), 157-160.
John J. McHugh, Jr. & Ronald F. L. Mau 1998. Pepper. Table 2. Insect and
Mite Control Recommendations.
http://www.extento.hawaii.edu/kbase/reports/recommendations/peppers.asp
Mau, R.F.L., Johnson, M.W., DeFrank, J.J., Welter, S.C. 1989. Biological
analysis of Thrips palmi in the Pacific Basin. In: Tropical and subtropical
agricultural research under PL 89-106, special research grants. Progress and
achievements, the Pacific Basin group, 1989, p.15.
Mau, R.F.L. and Gusukuma-Minuto, L. 1999. Insecticidal management of key
thrips pests of fruiting vegetables, onions and corn in Hawaii. Proceedings:
Sixth International Symposium on Thysanoptera, Akdeniz University, Antalya,
Turkey 27th April-1st May, 1998. Akdeniz University, Faculty of Agriculture,
Department of Plant Protection, Antalya, Turkey: 1999. 107-112. 8 ref.
Maynard, D.N., Hochmuth, G.J., Vavrina, C.S., Stall, W.M., Kucharek, T.A.,
Webb, S.E., Taylor, T.G., Smith, S.A., Simonne, E.H. and Olson, S.M. 2003
Chapter 34. Pepper Production in Florida. Document HS732, horticultural
Sciences Dept., UF/IFAS, Florida Cooperative Extension Services,
September 2003.
Murai, T. 2001. The pest and vector from the East: Thrips palmi. Thrips and
Tospoviruses: Proceedings of the 7th International Symposium on
Thysanoptera: Thrips, Plants, Tospoviruses: the Millennial Review, Reggio
Calabria, Italy, 2nd - 7th July 2001.
25
Nagai, K., Hiramatsu, T. and Henmi, T. 1988a. Effect of flufenoxuron on
Thrips palmi Karny. Japanese Journal of Applied Entomology and Zoology
32(4), 297-299.
Nagai, K., Hiramatsu, T. and Henmi, T. 1988b. Predatory effect of Orius sp.
(Hemiptera: Anthocoridae) on the density of Thrips palmi Karny
(Thysanoptera: Thripidae) on eggplant. Japanese Journal of Applied
Entomology and Zoology 32: 300-304.
Nagai, K. 1990a. Suppressive effect of Orius sp. (Hemiptera: Anthocoridae)
reared on Thrips palmi Karny (Thysanoptera: Thripidae). Japanese Journal of
Applied Entomology and Zoology 34: 109-114.
Nagai, K. 1990b. Effects of a juvenile hormone mimic material, 4 –
phenoxyphenyl (RS) – 2 – (2 – pyridyloxy) propyl ether, on Thrips palmi Karny
(Thysanoptera: Thripidae) and its predator Orius sp. (Hemiptera:
Anthocoridae). Applied Entomology and Zoology 25: 199-204.
Nagai, K. 1990c. Effect of insecticides on Orius sp., the natural enemy of
Thrips palmi Karny. Japanese Journal of Applied Entomology and Zoology
34(4), 321-324.
Nagai, K. 1993a. Integrated pest management of Thrips palmi Karny in
eggplant fields. Proceedings International Symposium on the “Use of
biological control agents under integrated pest management”. Fuukuoka,
Japan, October 4-10, 1993, 384-404.
Nagai, K. and Yano, E. 1999. Effects of temperature on the development and
reproduction of Orius sauteri (Poppius) (Heteroptera: Anthocoridae), a
predator of Thrips palmi Karny (Thysanoptera: Thripidae). Appl. Entomol.
Zool. 34: 223-229.
Nagai, K. and Yano, E. 2000. Predation by Orius sauteri (Poppius)
(Heteroptera: Anthocoridae) on Thrips palmi Karny (Thysanoptera: Thripidae):
functional response and selective predation. Appl. Entomol. Zool. 35: 565574.
Nakashima, Y., Uefune, M., Tagashira, E. Maeda, S., Shima, K., Nagai, K.,
Hirose, Y. and Takagi, M. 2004. Cage evaluation of augmentative biological
control of Thrips palmi with Wallastoniella rotunda in winter greenhouses.
Entomologia Experimentalis et Applicata 110, 73-77.
Nawrocka, B. and Szwejda, J. 1999. Influence of soilless cultures on
development and control of western flower thrips, Frankliniella occidentalis
(Pergande) occurring on glasshouse vegetable crops. Vegetable Crops
Research Bulletin 50, 47-54.
Paik, C-H., Hwang, C-Y., Lee, G-H., Kim, D-H., Choi, M-Y., Na, S-Y. and Lim,
S-S. 2003. Development, reproduction and longevity of predator Orius sauteri
26
Poppius (Hemiptera: Anthocoridae) when reared on three different prey.
Korean J. Appl. Entomol. 42(1): 35-41.
Parker, B.L., Skinner, M. and Lewis, T. 1995. Predatory capacity of
Campylomma chinensis Schuh (Hemiptera: Miridae) and Orius sauteri
(Poppius) (Hemiptera: Anthocoridae) on Thrips palmi. Thrips biology and
management: Proceedings of the 1993 International Conference on
Thysanoptera. Plenum Publishing Co. Ltd, London, USA: 1995. 259-262.
Rosenheim, J.A., Welter, S.C., Johnson, M.W., Mau, R.F.L. and Gusukuma
Minuto, L.R. 1990. Direct feeding damage on cucumber by mixed-species
infestations of Thrips palmi and Frankliniella occidentalis. Journal of Economic
Entomology 83,1519-1525.
Ruberson, J.R., Bush, L. and Kring, T.J. 1991. Photoperiod effect on diapause
induction and development in the predator Orius insidiosus. Environmental
Entomology 20(3), 768-780.
Saito, T., Kubota, T. and Shimazu, S. 1989. A first record of the
entomopathogenic fungus, Neozygites parvispora (MacLeod and Carl) Rem.
and Kell., on Thrips palmi Karny (Thysanoptera: Thripidae) in Japan. Applied
Entomology and Zoology 24: 233-235.
Saito, T. 1992. Control of Thrips palmi and Bemisia tabaci by a
mycoinsecticidal preparation of Verticillium lecanii. Proceedings of the Kanto
Tosan Plant Protection Society. 39: 209-210.
Sakimura, k., Nakahara, L.M. and Denmark, H.A. 1986. A thrips, Thrips palmi
Karny. Fla. Dept. Agric. and Consumer Serv. Division of Plant Industry.
Entomology Circular No. 280 4pp.
Salagarollo, V. and Politi, A. 1995. Pyridaben (Nexter ®): a new acaricide.
Informatore Fitopatologico 45(5), 28-32.
Seal, D.R. and R.M. Baranowski. 1992 Effectiveness of different insecticides
for the control of melon thrips, Thrips palmi Karny (Thysanoptera: Thripidae)
affecting vegetables in south Florida. Proc. Fla. State Hort. Soc. 105: 315319.
Searca, S. 1991. Management of thrips and mites attacking potato in the
lowland. SEAMEO Research and Development Programme. SEAMEO
Quarterly 14 (4), 41-43.
Shimizu, T. and Kawasaki, K. 2001. Geographic variability in diapause
response of Japanese Orius species. Entomol. Exp. Appl. 98: 303-316.
Shipp, J.L. and Ramakers, P.M.J. 2000. Biological control of thrips in
protected greenhouse vegetables. In Heinz, K.M., Driesche, R.G. van and
Parrella, M.P. Biological Control in Protected Culture. Ball Publishing,
Chicago.
27
Song, J-H., Kim, S-N., Lee, K-S and Han, W-T. 2002. Analysis of Spatial
Coincidence of Thrips and Orius sauteri on Greenhouse Eggplants. Korean J.
Appl. Entomol. 41(1): 27-32.
Studebaker, g.E. and Kring, T.J. 1999. Lethal and sub-lethal effects of
selected insecticides on Orius insidiosus. 1999 Proceedings Beltwide Cotton
Conferences, Orlando, Florida, USA, 3-7 January 1999: Volume 2. National
Cotton Council, Memphis, USA: 1999. 1203-1204.
Su, C.Y., Chiu, T.S. and Lin, Y.J. 1985. Study of population fluctuation of
Thrips palmi and its insecticidal control in the field on eggplant. Chinese
Journal of Entomology 5(2), 101-118.
Try, Y. and Hung, H. Q. 2003. Composition of natural enemies (parasitoids,
predators) of Thrips palmi Karny attacking on Soybean. Tap chi KHKT Nong
nghiep, Tap 1.
Wada, T. 1999. Development of Cucumeris ® and its future prospect.
Agrochemicals Japan. No. 73, 17-19.
Walker, A.K. 1994. A review of the pest status and natural enemies of Thrips
palmi. Biocontrol News and Information 15(1): 7N-10N.
Wang, C.L. 1994. The predacious capacity of two natural enemies of Thrips
palmi Karny, Camplylomma chinensis Schuh (Hemiptera: Miridae) and Orius
sauteri (Poppius) (Hemiptera: Anthocoridae). Plant Protection Bulletin
(Taiwan) 36: 141-154.
Wang, C-L., Lee, P-C., and Wu, Y-J. 2001. Field augmentation of Orius
strigicollis (Heteroptera: Anthocoridae) for the control of thrips in Taiwan.
http://www.agnet.org/library/article/eb500.html
Wei, C.S., Peng, Z.J., Yang, G.Q., Cao, Y., Huang, B.Z. and Chen, X. 1984.
Natural Enemies of Insects 6: 32-40.
Welter, S.C., Rosenheim, J.A., Johnson, M.W., Mau, R.F.L. and Gusukuma
Minuto, L.R. 1990. Effects of Thrips palmi and western flower thrips
(Thysanoptera: Thripidae) on the yield, growth, and carbon allocation pattern
in cucumbers. Journal of Economic Entomology 83:2092-2101.
Yano, E. Recent progress in integrated pest management of vegetables.
Yano, E. 1999. Recent advances in the study of biocontrol with indigenous
natural enemies in Japan. IOBC/WPRS Bulletin 22(1): 291-294.
Yano, E. 2003. Biological control of vegetable pests with natural enemies.
APO Bulletin, Asian Productivity Organization, Tokyo.
28
Yano, E. 2004. Recent development of biological control and IPM in
greenhouses in Japan. Journal of Asia-Pacific Entomology 7(1): 5-11.
Yasunaga, T. 1995. A new species of the genus Wooastoniella, predator of
Thrips palmi in aubergine gardens of Thailand. Applied Entomology and
Zoology 30, 203-205.
Yasunaga, T. 1997. The flower bug genus Orius Wolff (Heteroptera:
Anthocoridae) from Japan and Taiwan, Parts I, II, III. Appl. Entomol. Zool. 32:
355-364, 379-386, 387-394.
Young, G. and Zhang, L. 1998. Control of melon thrips, Thrips palmi. Agnote
753. No. I45. Agdex 230/612. Department of Primary Industries and Fisheries,
Northern Territory. www.nt.gov.au/dbird/dpif/pubcat
Websites
1 http://www.extento.hawaii.edu/kbase/reports/recommendations/pepper
2 http://pest.cabweb.org/Archive/Pestofmonth/n-thripl.htm
3 http://www.agrofrontier.com/staff/development.html
4 http://www.novartis-agri.com/
5 http://www.koppert.nl/e005.shtml
6 http://www.agrofrontier.com/staff/development.html
29
Appendix 1
Cucumber Grower Association Proposed Strategy for the
Management of Thrips palmi in Cucumber Crops
30
A Proposed Strategy for the Management of
Thrips Palmi in Cucumber Crops
The Purpose of the Cucumber Growers’ Association:
The CGA exists to look after the collective interests of the UK industry and, where possible,
anticipate and prepare for new problems.
CGA’s approach to pest control:
UK cucumber growers currently combat up to 14 pest species with a sophisticated integrated
pest management (IPM) programme.
If we consider the ultimate goal in pest control to be the cost-effective production of adequate
supplies of high quality produce in the absence of synthetic chemical toxins, then UK
cucumber growers are among the most advanced practitioners in the world. It is a tribute to
the whole industry that, despite many new challenges over the last 15 years, they have
remained dedicated to the principles of IPM and have become even more focused on their
quest to eliminate chemical pesticides from their production systems.
Importance of IPM to marketing British cucumbers:
Throughout the 1990s, the major UK retailers responded to consumer fears about pesticide
residues in food by introducing Codes of Practice for their suppliers, which set demanding
standards for food production including restrictions on pesticide usage.
UK cucumber growers rose to this challenge and have developed good relationships with
retailers despite increasing competition from overseas. The latter, and in particular
Mediterranean growers, still tend to use routine chemical pest control strategies based on
relatively inexpensive products that are often not available in this country. Although this
provides them with a financial advantage, it is not what the customer ultimately wants, and it
is therefore vital that UK growers continue to build on their IPM advantage. One means of
doing this is to perfect methods of growing all year round crops that will reduce the retailers’
dependence on Mediterranean produce between October and February.
There is no doubt that the continued use of IPM is vital to the future of the UK cucumber
industry.
Threat posed by Thrips palmi
The CGA are aware of the threat posed by Thrips palmi to the UK industry. We are also
aware of the approaches taken by Plant Health when outbreaks of this pest have
31
occurred on individual cucumber and cut flower nurseries in the past. Our current pest control
programme is heavily dependent on biological control agents and we are very concerned that
the use of broad spectrum chemical pesticides against Thrips palmi will prevent us from
continuing to use this strategy.
An effective IPM strategy for the control Thrips palmi is therefore considered to be high
priority.
A sustainable strategy for the control of Thrips palmi
In nature, populations of herbivorous pests are usually constrained by a range of natural
enemies that attack different life cycle stages and/or operate at different prey population
densities.
Similarly, biologically-based control programmes in permanent and semipermanent agricultural ecosystems are most successful in maintaining pest populations below
economic damage thresholds when the natural enemy biodiversity is high and when a large
proportion of the pest’s life cycle is exposed to those natural enemies.
It is proposed that more sustainable biologically-based control programmes against Thrips
palmi will similarly depend on a suite of natural enemies with complementary life styles. This
presents a challenge because the life cycle stages of Thrips palmi are found in so many
different locations within the crop habitat.
Multiple natural enemy approaches to Thrips palmi control could operate at four levels, which
would ideally be based on a foundation of host plant resistance:
1.
prophylactic use of foliage and flower inhabiting natural enemies
2.
prophylactic use of generalist natural enemies on the ground
3.
remedial use of invertebrate natural enemies
4.
remedial use of entomopathogenic fungi
There are many natural enemies available that could be complementary within these four
levels. The CGA’s strategy proposes that these individual control measures be developed as
independent modules that can then be put together in different combinations to suit different
demands (eg pest eradication or management).
Benefits to other horticultural crops:
The modules developed for the control of Thrips palmi on cucumbers could subsequently be
assembled in combinations that are appropriate to other crops that are vulnerable to the pest.
In other words, the cucumber crop could be used as a model experimental system for the
ultimate benefit of all horticultural crops.
Derek Hargreaves, CGA Technical Officer
Rob Jacobson, CGA Secretary
On behalf of CGA Main Committee
32
Appendix 2
A modular approach to integrated control of Thrips palmi
Karny: Concept note
33
A MODULAR APPROACH TO INTEGRATED CONTROL OF THRIPS PALMI KARNY
Concept note
Contact: Keith Walters, Central Science Laboratory, Sand Hutton, York, YO41 1LZ
Tel: 01904 462203; email: k.walters@csl.gov.uk
Consortium:
Central Science Laboratory (CSL; Research participant), Stockbridge
Technology Centre (STC; Research participant); Cucumber Growers Association (CGA;
Commercial advisors)
Background
Thrips are serious crop pests throughout the world causing damage by both direct feeding and
their ability to transmit viruses. Following crop colonisation their thigmotactic caustral
behaviour can make them difficult to detect, short generation times result in rapid population
increases and development of insecticide resistance can result in control failures. In recent
years several species of thrips have been dispersed globally as a result of their association
with the international trade in growing plants or plant produce. Thrips palmi Karny was
known to be widely distributed in Sudan and Taiwan before suddenly becoming a pest in
Japan in 1978, since when it has spread throughout the world. It is a very polyphagous pest,
which can cause significant economic losses in countries where it establishes. Pest Risk
Assessments indicate the species represents a serious threat to the UK protected horticulture
industry, which must therefore be provided with methods to contain and eradicate it.
The limited range of chemical insecticides that are available for the control of T. palmi in
Europe, the development of insecticide resistance and increased public concern about the
potential effects of such pesticides on the environment, underline the need for non-chemical
approaches to thrips control to be developed. In addition, the consequential trend in several
sectors of the horticultural industry towards reduced or no-chemical production systems
reinforces this requirement. Following the successful development and use of biological
control agents (BCAs) as components of integrated pest management (IPM) approaches
designed to eradicate quarantine leafminers (Liriomyza huidobrensis), the initial promise of
similar investigations for the whitefly Bemisia tabaci, and against the background of research
into IPM strategies for F. occidentalis, research has been undertaken into the potential for
using IPM against T. palmi (project PH0168). Laboratory experiments were used to
investigate an approach that utilises both chemical and non-chemical (entomopathogenic
fungi and nematodes). The results established the potential of these non-chemical agents for
the control and eradication of T. palmi but indicate that to be used successfully they must be
incorporated into a planned programme that combines them with other classes of control
agents or with conventional pesticides. Ideally, the system should include two levels of
action.
a. Prophylactic use of BCAs to reduce the potential of establishment in commercial
crops of accidentally introduced T. palmi (or where an outbreak has been detected to
reduce/prevent spread to adjacent glasshouses/holdings).
b. Use of BCA s and/or chemical control agents to eradicate T. palmi outbreaks.
The polyphagous nature of T. palmi make it difficult to predict with accuracy which UK crops
are most at risk of infestation by the species. Accordingly any control strategy devised must
be adaptable for use on a range of commodities. This presents further difficulties in using
BCAs as part of a control strategy, as most such agents are known to be effective on a limited
range of host plants or growing conditions. The solution is to use a commercially important
at-risk crop as a model for the development of the strategy but to ensure that the control
34
agents selected for use on the model crop have equivalents that are appropriate for use on
other commodities.
Cucumber is a major UK horticultural crop at-risk of damage by T. palmi. UK cucumber
growers have already adopted IPM against all the pests that commonly attack their crops but
the programme is currently dependent on occasional use of dichlorvos to regulate existing
thrips’ pests (largely Frankliniella occidentalis). This OP insecticide is currently under
review by the Advisory Committee on Pesticides and could be lost to the industry in the near
future. Furthermore, to survive in the global market, the Cucumber Growers’ Association
(CGA) recognise that they must adapt their production practices and have therefore set
research priorities that include pesticide free production, continuous year-round production
using supplementary lights and increased production of soil-grown organic crops to satisfy
the home market. The need to utilise chemicals for the eradication of quarantine organisms
such as T. palmi is not compatible with the CGA’s objectives and strategies must be
developed that minimise the number of occasions on which this will be necessary in the event
of an outbreak. Cucumber is thus a strong contender as a model crop for research into IPM for
T. palmi that will be used in the proposed research.
Approach
From the published literature and results of project PH0168 it has become clear that reliable
non-chemical control of T. palmi will not be achieved by simply releasing greater numbers of
the BCAs that are currently in commercial use. More sustainable control will inevitably
depend on a suite of natural enemies with complementary life histories and behaviour and this
must be built on a solid foundation of knowledge of the tritrophic interactions between plants,
pests and natural enemies. Recent work in experimental cucumber crops has shown that a
combination of prophylactic and remedial control measures provides a basis for robust control
programmes that would also be appropriate for a wide range of other crops.
In nature, herbivorous invertebrates are usually constrained by a range of natural enemies that
attack different life cycle stages and/or operate at different prey population densities. A more
sustainable IPM package against the important thrips pests of protected crops will similarly
depend on a suite of natural enemies with complementary life styles. The different life cycle
stages of T. palmi may be found in different locations within the crop habitat and biological
control of T. palmi is likely to be enhanced by maximising the proportion of the pest’s life
cycle that is exposed to natural enemies. It is anticipated that this will operate at four levels:
a.
b.
c.
d.
prophylactic use of foliage and flower inhabiting natural enemies
prophylactic use of generalist natural enemies in the surface layer of soil
use of invertebrate natural enemies to eradicate
use of entomopathogens to eradicate
A suite of control modules involving different control agents will be developed for each level.
Those modules best suited to particular crops can then be selected and integrated into an
optimum control strategy for that crop which maximises the control exerted at all levels. The
principles underpinning the approach will be researched and established using cucumbers, but
the potential for extrapolation to named ornamentals will be assessed. Thus the system will be
generic for all protected crops.
Potential BCAs for the control of T. palmi
A range of potential BCAs for use against T. palmi can be identified in the literature
including:
Insect and mite predators:- Aeolothripidae: Franklinothrips vespiformis; Anthocoridae: Bilia
sp.; Carayonocoris indicus; Orius armatus; Orius insidiosus; Orius maxidentex; Orius
minutus; Orius nagaii; Orius sauteri; Orius similis; Orius strigicollis; Orius tantillus;
35
Wollastoniella parvicuneis; Wollastoniella rotund; Berytidae: Yemma exilis; Cecidomyiidae:
Arthrocnodax occidentalis; Chrysopidae: Mallada basalis; Coccinellidae: Coleomegilla
maculata; Propylea japonica; Lygaeidae: Geocoris lubra; Geocoris ochropterus; Piocoris
varius; Stigmatonotu minutum; Miridae: Campylomma austrina; Campylomma chinensis;
Campylomma livida; Deraeocoris; Orthotylus; Phlaeothripidae: Haplothrips victoriensis;
Phytoseiidae: Amblyseius cucumeris; Amblyseius longispinosus; Amblyseius mackenzie;
Amblyseius multidentatus; Amblyseius okinawanus; Amblyseius tsugawai; Phytoseius spp.;
Thripidae: Neohydatothrips portoricensis.
Parasitoids: Trichogrammatidae:
Geotheana shakespearei.
Megaphragma
spp.;
Eulophidae:
Ceranisus
menes;
Fungal pathogens:- Hyphomycetes: Beauvaria bassiana; Cladosporium cladosporioides;
Hirsutella sp.; Verticillium lecanii; Zygomycetes Neozygites parvispora.
Nematodes:- Steinernematidae: Steinernema feltiae
These species will be assessed for their potential as components of the above control levels on
different crop types and a sub set selected for detailed study.
Integration of chemical insecticides
There are two methods of integrating chemicals into IPM programmes; either as highly
selective products that are specific to the target pest or less specific products that may be
applied in a manner, or at a time, which has minimal effect on natural enemies on the crop.
There are currently no truly selective insecticides available for thrips, so control measures are
limited to careful use of more broad spectrum products. Chemicals approved for thrips
species such as T. palmi that may have an important role in chemical control programmes and
could also be a useful addition to the IPM armoury for both ornamental and edible crops will
be tested for compatibility with the selected BCAs. Further studies will also be required to
determine how this insecticide can be utilised in IPM programmes.
Mutual compatibility of control agents
In IPM programmes that utilise multiple control measures, optimisation of each agent relies
upon a sound knowledge of its compatibility with the others. For example, the potential for
utilising two agents in parallel or the interval required between application/release of two
antagonistic agents must be established. Initial screening techniques developed by one of the
partner laboratories to compare mutual compatibility of biological control agents will be
employed to establish optimal selection ands use of agents in each of the modules of the IPM
system.
Objectives
To take advantage of previous research findings to further develop IPM-based
control/eradication programmes against T. palmi in key glasshouse crops within the
constraints of a finite budget by:
1. Evaluating the potential for control of T. palmi of existing and novel biological
control agents, within the following categories:
a. prophylactic use of foliage and flower inhabiting natural enemies of suppress
population development and reduce establishment potential
b. prophylactic use of generalist natural enemies in the surface layer of soil to
suppress population development and reduce establishment potential
c. use of invertebrate natural enemies to eradicate T. palmi populations
d. use of entomopathogens to eradicate T. palmi populations
2. Establishing compatibility of selected BCAs with chemical insecticides used in the
host crop, and mutual compatibility of the selected BCAs
36
3. Evaluating the potential advantages of using the selected control agents in
combination rather than individually in the above categories.
4. Designing, evaluating and refining preliminary modular-based control strategies for
the control of T. palmi under quarantine cage conditions
5. Assess the potential for using the modular-based approach as an IPM strategy in other
crops.
Work plan
1. Organise a project steering Group incorporating representatives of PHD, PHSI,
Growers and CSL PH consultants.
Objective 1:
2. Undertake a literature search to determine the full range of potential BCAs for T.
palmi control and select candidate species for further research.
Prophylactic use of foliage and flower inhabiting natural enemies:
3. Collate existing knowledge of selected control agents, identify relevant gaps and
instigate small-scale experimentation to complete performance data packages.
4. Where available, test the use of existing application technology for each control agent
under quarantine conditions (e.g. culture pack systems).
5. Prepare prototypes of new systems as necessary, determine how long the cultures
remain active and quantify their output compared to any standard system that is
currently used in cucumber crops, and make any modifications necessary to improve
performance.
6. Refine the selection of control agents if appropriate.
Prophylactic use of generalist natural enemies in the surface layer of soil
7. Collate existing knowledge of selected control agents, identify relevant gaps and
instigate small-scale experimentation to complete performance data packages.
8. Quantify the performance of selected agents in various growing media (e.g. soil,
organic compost, peat based growing media).
9. Establish application protocols.
10. Refine the selection of control agents if appropriate.
Use of invertebrate natural enemies to eradicate T. palmi populations
11. Collate existing knowledge of selected control agents, identify relevant gaps and
instigate small-scale experimentation to complete performance data packages.
12. Refine the selection of control agents if appropriate.
13. Establish application protocols.
Use of entomopathogens to eradicate T. palmi populations
14. Collate existing knowledge of selected control agents, identify relevant gaps and
instigate small-scale experimentation to complete performance data packages.
15. Refine the selection of control agents if appropriate.
16. Establish application protocols
Objective 2:
17. Conduct small scale experiments to establish the compatibility of the selected BCAs
within each usage category.
18. Conduct small scale experiments to establish the compatibility of selected BCAs with
appropriate chemical insecticides.
19. Refine the selection of control agents if appropriate.
Objective 3:
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20. Within each usage category and where appropriate, conduct small scale experiments
to establish the impact of simultaneous use of BCAs and compare with the impact of
using them individually.
Objective 4:
21. Where appropriate integrate the findings of objectives 1 - 3 into protocols for the
effective use of the selected control agents against T. palmi.
22. Using these protocols as a basis, design, evaluate and refine preliminary modularbased control strategies for the control of T. palmi in cucumber crops. Ensure that
protocols that both include and do not include the use of chemical insecticides are
drafted.
23. If possible, test protocols using cage experiments under quarantine containment.
Objective 5:
24. Assess the potential for extrapolating the protocols into other at-risk crops
25. Present protocols for all modules and theoretical programmes to the steering group
and predict performance in key crops (i.e. cucumber, chrysanthemum).
26. Estimate the parameters within which the agents will be successful in each situation.
27. Select combinations of complementary modules with potential to form part of a
biological control programmes for each crop. Produce theoretical biological control
programmes for selected key crops.
28. Prepare cost-benefit analyses of biological control programmes. (STC)
Benefits
Difficulties relating to the withdrawal of active ingredients and products from the market,
reluctance of manufacturers to seek registration approval for the use of new products on
commodities representing a small proportion of the worldwide cropping area (e.g. many
horticultural crops) and public concern over environmental issues, result in the need for
improved biocontrol/IPM measures for quarantine pests. The research described in this
proposal represents the first investigation of a flexible modular approach to the use of
biological and chemical agents for the control of a major quarantine glasshouse pest. The
treatments developed would be suitable for nurseries that have existing biocontrol
programmes used in conjunction with chemical pesticides, as well as for those in organic
production. This project would also enable protocols for management strategies to be drawn
up that could be tailored to the constraints of both the ornamental and vegetable industries,
which have markedly different requirements.
The inclusion of Plant Health consultants in the delivery team will ensure that the work is
directed at quarantine issues of immediate concern and takes account of unique considerations
and constraints relating to requirements for containment and eradication of quarantine pests
such as T. palmi. Additionally PHD, PHSI, CSL, consultants and growers will obtain further
benefits because of the technology transfer framework that will be utilised by the project for
optimal delivery of results to those who need them. It is anticipated that output from
components of the research programme could be delivered to the PHSI for immediate field
application before the end of the project. The findings will also provide background
information to assist decisions on the need for and appropriate targeting of future research.
More widely, the results of this project will reduce the UK protected crop industry’s
dependence on chemical insecticides, thus contributing to Defra’s aims and objectives by
providing sustainable pest management programmes based on a combination of compatible
and complementary biologically based control measures and improving the competitiveness
of the UK industry by satisfying retailer and consumer requirements for a reduction in the
amount of chemical toxins used within the produce supply chain.
Cost: £73K per annum for four years
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