CSL Pest Risk Analysis for Listroderes difficilis
CSL copyright, 2002
02/9178
PPM Point 7.4
CSL PEST RISK ANALYSIS FOR Listroderes difficilis
(Syn =L. costirostris)
STAGE 1: PRA INITIATION
1. What is the name of the pest?
Listroderes difficilis Germain Coleoptera
Curculionidae
Synonyms (from Morrone, 1993)
Desiantha nociva French
Listroderes costirostris Schoenherr
Listroderes elongatulus Klug
Listroderes hipocrita Aravena
Listroderes hypocritus Hustache
Listroderes lugubris Germain
vegetable
weevil
Listroderes nociva McCarthy
Listroderes obliquatus Bosq
Listroderes obliquus Klug
Listroderes paranensis Hustache
Listroderes vicinus Hustache
Merionus costirostris Dejean
Notes on taxonomy
Listroderes difficilis is a species group with a complex taxonomy. Much North American literature uses
Listroderes costirostris obliquus. Wibmer and O'Brien (1986) considered L. obliquus and L. difficilis as
valid species. Morrone (1993) redescribed the species and listed the full synonymy (abbreviated above) and
used Listroderes costirostris as the senior synonym. L. obliquus and L. difficilis were recognised as junior
synonyms of L. costirostris. However, May (1994) recognised L. difficilis as the senior name with L.
costirostris and L. obliquus junior synonyms. Morrone (1993) suggested that until genetic studies had been
carried out, doubts would remain over the synonyms of the species.
For the purposes of this PRA, the most recent senior synonym, Listroderes difficilis is used.
2. What is the reason for the PRA?
Listroderes difficilis first came to our attention (as L. costirostris) during a commodity risk assessment of
potatoes from New Zealand in November 1995. A PRA conducted at the time suggested that this pest be
considered by EPPO as a candidate for the A1 list of quarantine pests.
This PRA updates the previous PRA (MacLeod, 1995) using more recent references.
3. What is the PRA area?
This PRA considers the whole EPPO region concentrating on the European and Mediterranean area, i.e.
EPPO west of the Ural mountains.
STAGE 2: PEST RISK ASSESSMENT
4. Does the pest occur in the UK, EU or EPPO region or does it arrive regularly as a natural migrant
?
UK - No. Listroderes difficilis does not occur in the UK. It is not a natural migrant.
EU – Uncertain. Balachowsky (1963) reported L. difficilis in the Canary Islands in 1950, the Balearic
Islands (1954) and Portugal (1957). In a paper on taxonomy, Morrone (1993) examined Spanish material
collected in the 1960s from Almeria and Teneriffe. A previous UK PRA on this pest (MacLeod, 1995) was
discussed at the January 2000 EPPO Phytosanitary Measures Panel meeting, after which the EPPO
secretariat wrote to the NPPO of Spain and Portugal seeking clarification of the status of the organism in
each country. Spain replied that it had never been found. There was no information from Portugal.
EPPO – There are no EPPO countries where this pest has been recorded (only uncertain records from Spain
and Portugal).
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5. Is there any other reason to suspect that the pest is already established in the UK, EU or EPPO
region?
There is some uncertainty whether Listroderes difficilis occurs in Spain and Portugal (see 4. above).
6. What is the pest’s EU Plant Health Directive status?
Not listed.
7. What is the pest’s EPPO Status?
January 1997: The UK first suggested L. costirostris (syn. L. difficilis) as a candidate for A1 listing to the
EPPO Panel on Phytosanitary Measures. However, due to the UK PRA using much information from the
1970’s, the panel decided this pest did not justify listing.
December 1999: In advance of the EPPO Phytosanitary Regulations Panel meeting in January 2000, EPPO
requested a datasheet on this pest after considering the UK PRA. Whilst collecting information for the
datasheet, reports of the pest in Europe were discovered (see 4. above). Given this new information, and
with no literature reporting damage in Europe no datasheet was completed.
January 2000: The UK PRA was considered as an agenda item at the Phytosanitary Measures Panel (PMP)
in January 2000. It had previously been rejected for listing. However the 6 th ad-hoc EPPO Panel on
European Phytosanitary Measures for Potatoes had identified L. difficilis as a potential quarantine pest.
After the PMP meeting, the EPPO secretariat wrote to the NPPO of Spain and Portugal seeking clarification
of the status of the organism in each country. Spain replied that it had never been found. There was no
information from Portugal.
September 2001: at the 7th ad-hoc EPPO Panel on European Phytosanitary Measures for Potatoes, Smith
(EPPO) suggested that L. difficilis was not a pest of potatoes but that it should be put to the next EPPO
Phytosanitary Measures Panel (January 2002) to be reconsidered.
8. What are its host plants?
Polyphagous, wide range of vegetables (Table 1) and weeds.
Table 1: Listroderes difficilis host vegetables.
Binomial name
English common name
Allium cepa
onion
Allium sativum
garlic
Arachis hypogaea
peanut/groundnut
Beta vulgaris
beetroot
Brassica napus var. napus
rape
Brassica oleracea
cabbages, cauliflowers
Capsicum annuum
bell pepper
Cichorium endivia
endives
Daucus carota
carrot
Lactuca sativa
lettuce
Lycopersicon esculentum
tomato
Nicotiana tabacum
tobacco
Pastinaca sativa
parsnip
Petroselinum crispum
parsley
Raphanus raphanistrum
wild radish
Solanum melongena
aubergine
Solanum tuberosum
potato
Spinacia oleracea
spinach
In Taiwan (Hsu & Chiang, 1983) L. difficilis was found attacking chrysanthemum and winter vegetables,
including Gynura bicolor and various brassica crops.
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9. What hosts are of economic and/or environmental importance in the PRA area?
Beans, beet, lettuce, cabbage, carrot, cauliflower, parsley, potato, rape, spinach, tomato, turnip.
10. If the pest needs a vector, is it present in the PRA area ?
No vector needed.
11. What is the pest’s present geographical distribution ?
L. difficilis is a native of South America but has been reported in all other continents except Antarctica. Its
status in Europe is unclear (see 4.)
North America:
South America:
Europe:
Africa:
Asia:
Oceania:
USA (distribution within the USA is shown in Annex 1).
Argentina, Bolivia, Brazil, Chile, Paraguay, Uruguay, Venezuela
uncertain (old records from mainland Spain, Canary Is. & Portugal)
Morocco, South Africa
China (Taiwan) , Japan, N. Korea.
Australia (Northern Territory, New South Wales, Queensland, South
Australia, Tasmania, Victoria, Western Australia),
New Zealand
12. Could the pest enter the PRA area?
Yes. L. difficilis is a native of South America which has been accidentally introduced into other many other
continents. Thus further spread into the EPPO region is possible.
13. Could the pest establish outdoors in the PRA area?
Considering the wide availability of hosts in the EPPO region and the similarity of climates in some regions
where this pest already occurs, e.g. in the southern tip of South America, in Tasmania, in the South Island of
New Zealand and in northern Japan, L. difficilis could establish outdoors in much of the EPPO region.
Listroderes difficilis has a poor low-temperature tolerance but is found in northern Japan where winters can
be very cold. Adult and larvae L. difficilis avoid freezing temperatures during winter by searching out places
in crops where temperatures remain above freezing. Such behaviour enables L. difficilis to survive the winter
in northern Japan (Tsumuki et al.,1993).
In North America L. difficilis has spread northwards, is clearly adaptable and has potential as a pest of
potatoes, vegetables and ornamentals in the UK and wider EPPO region.
14. Could the pest establish in protected environments in the PRA area?
There are no records of L. difficilis as a pest in protected cultivation although this does not exclude it from
becoming a pest within protection in the EPPO region.
15. How quickly could the pest spread within the PRA area?
Fairly fast. Although adults rarely fly, they are sturdy and inconspicuous and shelter in debris, boxes and
other transportable objects distributed during movement of hosts. When inactive, adults need no food thus
survival in transit can be high. Females are parthenogenetic, and lay 300 to 1500 eggs, consequently a single
female can start a colony. L. difficilis has a wide host and climatic range giving it a good chance of finding
suitable environments where it could establish.
Note: Morrone (1993) provides a description of a male, indicating that this weevil is not always
parthenogenetic.
16. What is the pest’s potential to cause economic and/or environmental damage?
Both larvae and adults damage plants. Feeding occurs at night on buds, foliage, stems and roots. Larvae may
skeletonize leafy hosts but can also tunnel into roots. In Australia, Listroderes difficilis adults can strip the
foliage of potato and tomato plants (Hely et al., 1982). Stems of some plants e.g. young potato plants, may
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be cut at the soil level so damage resembles that of cutworms (Horton & Ellis, 1999). Principle damage to
potatoes and tomatoes is caused by adults in late spring and early summer (Metcalf & Metcalf, 1993).
Larvae and adults can cause serious damage to carrots, parsnips and celery. Larvae eat the growing tips of
carrots, preventing further growth. During spring feeding, adults cause large craters at the top of carrot roots.
L. difficilis larvae also attack beetroot and silverbeet. Larvae eat the centres of young beet and later the
underside of leaves to give a shot-hole appearance (Hely et al., 1982). Autumn sown crops are more
susceptible than summer sown crops since plants are larger by the beginning of winter when damage occurs.
L. difficilis can also attack and damage onions (Hely et al., 1982)
17. What is the pest’s potential as a vector of plant pathogens?
L. difficilis is not a vector. However feeding damage would allow secondary infection by pathogens.
STAGE 3: PEST RISK MANAGEMENT
18. What are the prospects for continued exclusion?
Low - All of the vegetable hosts of L. difficilis have been found infested with larvae and adults. Spread of
the pest can occur in green or root vegetables, either on the plant or secluded in the shipping container
(High, 1939). Eggs are laid in the soil around host plants. Larvae occur in the roots and stem of host plants.
Repeated observations show that the pest may be accidentally transported by people and vehicles (High,
1939).
19. What are the prospects of eradication?
Low – unless outbreaks are found soon after entry in the PRA area. Eggs are small and laid in soil so
destruction would be difficult. Pupation takes only a few days and individuals can live for up to 2 years
(Davidson & Lyon, 1979).
20. What management options are available for containment and control?
Use of insecticides (Scott, 1984).
CONCLUSION OF THE PEST RISK ANALYSIS
On the evidence of its distribution, wide host range, reproductive capacity, and adaptability to climate, L.
difficilis should be regarded as pest of considerable potential to the UK, EU and wider EPPO region.
Further work
Records of this pest from Spain and Portugal need to be checked. With no recent reports from within Spain
and Portugal, L. difficilis may be absent from the EPPO Region.
Documentation in Support of the PRA
Is there a complementary datasheet with supporting information? YES/NO
CABI Crop Protection Compendium: Listroderes costirostris (Full data sheet [A] ).
Has an on-line search of CABI Abstracts been carried out? YES/NO
If “Yes”, on what date ? 07/11/01
References
Balachowsky, A.S. (1963) Entomologie appliquee a l'agriculture, Tome 1, Coleopteres, Volume 2. Masson
et Cie Editeurs, Paris.
Beckham, C.M. (1953) Biology and the control of the vegetable weevil in Georgia. Georgia Agr. Exp. Sta.
Tech. Bull., 2, Paper 317.
Davidson, R.H. & Lyon, W.F. (1979) Insect pests of farm, garden and orchard Eighth Edition, John Wiley
& Sons Ltd., New York.
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Hely, P.C., Pasfield, G. & Gellatley, J.G. (1982) Insect Pests of fruit and vegetables in NSW. Dept. of
Agriculture New South Wales, Sydney.
High, M.M. (1939) The vegetable weevil. US Department of Agriculture Circular 530.
Horton, D.L. & Ellis, H.C. (1999) Vegetable weevil, Listroderes difficilis. In Roberts, P. M. & G. K. Douce,
Coordinators 1999. Weevils and Borers. A County Agent's Guide to Insects Important to
Agriculture in Georgia. Univ. of GA, Col. Ag. Env. Sci., Coop. Ext. Serv., Winter School Top Fifty
Agricultural Insect Pests and Their Damage. http://www.bugwood.org/factsheets/99-009.html
Kuschel, G. (1971) The foreign Curculionoidae established in New Zealand. New Zealand Journal of
Science, 15, 273-289.
Lewis, H.C. (1927) The vegetable weevil in California. California Department of Agriculture, Monthly
Bulletin, 16, 378-392.
MacLeod, A. (1995) Summary pest risk assessment, Listroderes costirostris. In: Commodity risk assessment
of Potatoes from New Zealand, Unpublished CSL Document, November 1995.
Matsumoto, Y. (1961) A food plant list of the vegetable weevil. Japanese Journal of Applied Entomology &
Zoology, 5, 4), 243-253
May BM, 1994. An introduction to the immature stages of Australian Curculionoidea. In: Zimmerman EC,
ed. Australian Weevils. Volume 2. Melbourne, Australia: CSIRO, 365-728.
Metcalf, R.L. & Metcalf, R.A. (1993) Destructive & Useful Insects, 5th Edn., McGraw-Hill, New York pp
Tsumuki, H., Kanehisa, K., Tanaka, F., Nagai, K. & Matsumoto, Y. (1993) Low-temperature tolerance of
the vegetable weevil, Listroderes costirostris Schonherr (Coleoptera: Curculionidae). Japanese
Journal of Applied Entomology and Zoology, 37, 25-27.
Morrone, J. (1993) Systematic revision of the Costirostris species group of the weevil Genus Listroderes
Schoenherr Coleoptera: Curculionidae). Transactions of the American Entomological Society, 119,
4), 271-301.
Wibmer GJ, O'Brien CW, 1986. Annotated checklist of the weevils (Curculionidae sensu lato) of South
America (Coleoptera: Curculionoidea). Memoirs of the American Entomological Institute, 39:1-563.
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Annex 1
_____________________________________________________________________
Figure 1: Distribution of Listroderes difficilis in the USA
Reported from right to left): New Jersey, Maryland, Virginia, North Carolina, South Carolina,
Georgia, Florida, Kentucky, Tennessee, Alabama, Mississippi, Missouri, Arkansas, Louisiana,
Oklahoma, Texas, Arizona, Oregon, California & Hawaii.
_____________________________________________________________________
Name of Pest Risk Analyst: Alan MacLeod
Address: Central Science Laboratory, Sand Hutton, York, YO41 1LZ UK.
Date: November 2001
PC file: T:\ph\ph1\pra\1-summary\Listroderes\Listroderes-pra.doc
Registered file: PPH 2552
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