chemical control

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Acari
Control
1
Monitoring of pests
and natural enemies
Chemical control – aa.ii.
less toxic to natural enemies
Regulatory control
Cultural control –
sanitation, pruning,
rotations, fertilization,
dust management,
and irrigation
Integrated Mite
Management
Host-plant resistance
and host-plant
tolerance
– quarantines, pest
exclusion, and
regulations
Biological control –
classical biological control;
natural enemies conservation;
augmentation
2
BIOLOGICAL CONTROL
CLASSICAL:
• Release of natural enemies in an environment where their native
population is not present (importation and release from the area
of origin of a foreign pest); long period effects, no experiences in
the control of phytophagous mites.
• Efficient applications of classical biological control of weeds by
means of mites (Texas and Australia), of springtails by means of
predatory mites (Bleddose lapidaria and Neomolgus capillatus)
(Australia and South Africa).
3
BIOLOGICAL CONTROL
AUGMENTATIVE strategy distincts in:
INOCULATIVE:
• Release of natural enemies in an environment where the native
population is strongly reduced or absent; short and medium
period effects; requires IMM application.
INUNDATIVE:
• Release of natural enemies in a “isle”; short term effects.
4
BIOLOGICAL CONTROL
Predators (mites or insects) can be «released» in protected
environments (inundative method) or fixing a new ecological
balance (inoculative method) in fields or greenhouses.
More commonly, Phytoseiulus persimilis is released in protected
environments against the two-spotted spider mite.
The application of «biological» pesticides (fungi, microrganisms,
biocides produced by microrganisms) is still limited to a very few
cases of at an experimental step.
Natural enemies and their applications
• Predators
+++
• Parassitoids
--• Parassites and pathogens +
phytoseiids, cheyletids
insect control
fungi
5
MITES AS PREDATORS
• phytoseiids
• cheyletids
• laelapids
bdellid
reared, wide bio-ethological knowledge, applied
some applications in stored environments
promising candidate for the control of Rhizoglyphus
robini, applied
stigmeids
anystid
Other taxa active in the natural control
• ascids, trombidids, tydeids,
tarsonemids
macrochelids
cunaxid
piemotids
6
INSECTS AS PREDATORS
Mainly oligophagous with high prey consumption and high fertility.
They become interesting when phytophagous mites reach high density.
• lady beetles Stethorus punctillum
• lacewings1 reared in bio-firm, some applications are known in
semi-protected environments (e.g. strawberry under
tunnel against two-spotted spider mites)
• antochorids2 promising candidates
Other taxa active in the natural control
• thrips3, mirids, coniopterigids, staphylinids4, cecidomiids, syrphids
1 2
3
4
(from
7 Hoy,
2011)
PREDATORS
Predatory impact
• Stethorus punctillum
an ovigerous female can feed on 50100 spider mites per day.
• Scolothrips sexmaculatus
an ovigerous female can feed on till 85
eggs or not movable instars of spider
mites per day at 35°C
• larvae of Chrysopa spp.
• juveniles of Orius spp.
30-50 mites per day
30-40 eggs of spider mites per day
• Phytoseiulus persimilis
~ 18 eggs of two spotted spider mite
per day
8
Stethorus punctillum
Adult black, 1-1.5 mm long, covered by a
thin hairy. Groups of 4-10 individuals
overwinter under bark crevices and other
sheltered sites.
3 generations/year.
Eggs laid singly or in small groups on the
underside of the leaf.
Larva feeds on till 40 mites/day; ovigerous
female feeds on 50-100 mites/day.
Larvae and adults are sensitive to the
insecticides on the contrary of
pupae and eggs.
9
Stethorus punctillum
Specialized predator of
mites.
It goes away in case the
prey is absent.
It requires a high prey
density to be efficient:
density threshold is 70-80
mites per 100 leaves.
10
FUNGI
Infection by specialised spores which attach to the integument,
germinate and passes through the mite cuticle by developed hyphae.
They require high humidity of the environment and their action is
affected by fungicides.
11
FUNGI
Neozygetes floridana:
Applied against two-spotted spider mite in
the USA.
Hirsutella thompsonii:
Mycar (Abbott, USA – 1975-1985) against
Phyllocoptruta oleivora; in Brasil and
Argentina.
Strains under investigations.
Metarhizium anisopliae:
Applied against ticks.
Beauveria bassiana:
Promising and available on the market.
12
BIOLOGICAL CONTROL: predator requirements
• Comparison on the speed growth between predator/prey: predator
cycle length ≤ prey cycle length; phytoseiids have cycle shorter
than spider mites; insects have life cycle largely longer than that
of mites as preys;
predator
prey (means in days)
Tetranychus urticae
Phytoseiulus persimilis
15°C 20°C 25°C
3.0
1.1 0.6
3.9
1.4
0.8
4.1
1.6
0.8
11.0
4.1
2.2
instair
L
Pn
Dn
total
15°C 20°C 25°C
6.7
2.8
1.3
5.3 2.3 1.2
6.6
3.1
1.4
18.6
8.2
3.9
13
BIOLOGICAL CONTROL: predator requirements
• prey density: ability of predators to remain into the sites also with low
prey density. Stethorus requires high prey density; some phytoseiid
species are efficient also with low prey density;
• alternative preys and food
Ecological classes in phytoseiids
• obligatory predators
Phytoseiulus persimilis,
Metaseiulus occidentalis
• generalist predators
Typhlodromus pyri
• generalist and facultative predators
- oligophagous
- polyphagous
Typhlodromus exhilaratus
14
BIOLOGICAL CONTROL: predator requirements
• reproductive fitness: scarce meaning in a short term control. The
phytoseiids have a low mean fertility and a long egg-laying
period;
• amount of prey: Stethorus punctillum is very voraceous; specific
predators feed on a large amount of mites;
• micro-habitat: similar to those of the prey;
• chemical messengers perception
• good ability in prey searching also at a low prey density.
Phytoseiids are characterized by a notably mobility but they
inspect a small surface; Stethorus and lacewings can inspect a
larger surface;
• ability of adaptation at the environment (tolerance to the adverse
environmental conditions: climate and pesticides).
15
BIOLOGICAL CONTROL: weak points
• Release rates (depending on plant feeders density, host plant,
and environment);
• Timing of release;
• Multiple release;
• Expensive;
• Shipping;
• Handling at release;
• Pesticide resistance;
•
•
•
•
Agricultural production practices;
Pesticide applications;
Nectar and pollen sources;
Overwintering sites.
16
CULTURAL CONTROL
• Dust management: dust on foliage makes it easier for spider
mites to become serious pests;
• Water management: water stressed plants allow spider mite
populations to increase more rapidly.
• Polycropping;
• Crop rotation:
• Fertilizing management.
(from Hoy,172011)
CHEMICAL CONTROL
Kind of application depends on:
crop
• annuals, non horticultural crops unusual applications
• annuals, horticultural crops, ornamentals
frequent applications, mainly on
protected ones
• orchards
possible applications
populations
• Presence/absence of natural enemies
• density and thresholds of the phytophagous species
18
Active ingredients
In Europa
ABAMECTIN
Authorized
ACRINATHRIN
Revoked
BEAUVERIA BASSIANA ATCC 74040
Authorized
BIFENAZATE
Authorized
CLOFENTEZINE
Authorized
CYPERMETHRIN
Authorized
DELTAMETHRIN
Authorized
DIFLUBENZURON
Authorized
DIMETHOATHE
Authorized
ETOXAZOLE
Authorized
FENAZAQUIN
Revoked
FENBUTATIN OXIDE
Revoked
FENPYROXIMATE
Authorized
FLUFENOXURON
Revoked
HEXYTHIAZOX
Revoked
IMIDACLOPRID
Authorized
METHIOCARB
Authorized
MILBEMECTIN
Authorized
PIRETHRIN
Authorized
PIRIMPHOS METHYL
Authorized
PROPARGITE
Revoked
PYRIDABEN
Revoked
SPIRODICLOFEN
Authorized
TAU-FLUVALINATE
Authorized
TEBUFENPYRAD
Authorized
SULFUR
Authorized
(at 20 Oct 2011)
Revoked available
up to 31 Dec 2011)
19
CHEMICAL CONTROL
Kind of application depends on:
Target instar/s
Active ingredient/s
eggs
clofentezine, spirodiclofen, (spiromesifen)
eggs and mobile instars etoxazole, hexythiazox
mobile instars
others
Timing of application
• winter (related to the overwintering populations)
• late winter
• spring and summer
20
CHEMICAL CONTROL
Acaricides
Chemical classification
Active ingredient/s
Inorganic compounds
sulfur
Organic containing nitrogen
clofentezine, etoxazole, fenazaquin (R), fenpyroximate,
pyridaben (R), tebufenpyrad, bifenazate
Organic containing nitrogen and hexythiazox (R)
sulphur
Organotin
fenbutatin oxide (R)
Tetronic acids
spirodiclofen, (spiromesifen)
Antibiotics
abamectin, milbemectin
Sulfur-organic
propargite (R)
Insecticides with acaricides effects
Chemical classification
Active ingredient/s
Pyrethroids
acrinathrin (R), cypermethrin, deltamethrin, tau-fluvalinate
Organic containing nitrogen
diflubenzuron
21
CHEMICAL CONTROL
Acaricides
Mode of action
Active ingredient/s
sulfur
Mite Growth Regulators
clofentezine, etoxazole, hexythiazox (R)
Inhibitors of mitochondrial ATP
synthase
fenbutatin oxide (R), propargite (R)
Mitochondrial complex I Electron
Transport Inhibitors (METI)
fenazaquin (R), fenpyroximate, pyridaben (R),
tebufenpyrad
unknown or uncertain
bifenazate
Inhibitors of acetyl CoA
carboxylase
spirodiclofen, (spiromesifen)
Chloride channel activator
abamectin, milbemectin
22
CHEMICAL CONTROL
Mode of acquiring
Active ingredient/s
contact
clofentezine, pyridaben, propargite, fenbutatin oxide
contact-ingestion
abamectin, milbemectin, bifenazate, fenazaquin, fenpyroximate,
tebufenpyrad, etoxazole, hexythiazox, spirodiclofen
gas
Sulfur – in closed environments (rarely relevant in mites)
Translaminar property
abamectin, milbemectin, tebufenpyrad, clofentezine, etoxazole,
hexythiazox, spiromesifen
23
CHEMICAL CONTROL
Pay attention to:
http://www.irac-online.org/
resistance phenomenon
24
CHEMICAL CONTROL: IRAC recommendations
a - do not apply more than one a.i. of the same class on the same
crop and in the same season; where more than one pest should
be controlled, do not apply aa.ii. belonging to the same class.
b - each a.i. must be applied only once per season and per crop.
c - mixture of aa.ii. of the same class is strongly not recommended.
d - the aa.ii. must be applied according to strategies which can
reduce the side effects on beneficial insects and mites.
e - the aa.ii. must be used at the recommended doses and timing.
f - monitoring for the assessement of the resistance must be carried
out.
25
SULFUR (inorganic compound)
• efficient against powdery mildew
• produces toxic (H2S) gases for sublimation; these
gases have a good diffusion; the sulfur substitutes
oxygen allowing the production of H2S instead of
H2O
• dust in different commercial products
• not toxic for human; can be sprayed just before
the harvesting
• phytotoxic at high temperature (>40°C)
26
• efficient against eriophyoids, tenuipalpids, some tetranychids
(Oligonychus, Eotetranychus, Tetranychus)
• doubtful influence on predators and parassites
Micronized as WP (Thiovit)
27
Micronized as WP (Thiovit)
28
MITE GROWTH REGULATORS (MGRs)
• Some of these aa.ii. are very specific against spider mites and not
dangerous for the natural enemies (selectivity).
• The most of these aa.ii. are able to get the best results on low or
moderately dense populations.
• Good persistence.
Clofentezine, Etoxazole, Hexythiazox
Mode of acquiring
Active ingredient/s
contact
clofentezine, pyridaben, propargite, fenbutatin oxide
contact-ingestion
abamectin, milbemectin, bifenazate, fenazaquin, fenpyroximate,
tebufenpyrad, etoxazole, hexythiazox, spirodiclofen
gas
Sulfur – in closed environments (rarely relevant in mites)
Translaminar property
abamectin, milbemectin, tebufenpyrad, clofentezine, etoxazole,
29
hexythiazox, spiromesifen
MITE GROWTH REGULATORS (MGRs)
Clofentezine
• Applied mainly against overwintering eggs around 15-20 days before
their hatching (pome or stone fruit trees: pre-flowering treatment).
• It inhibits the synthesis of chitin.
• It has a slow action at the beginning, with the first death after 48
hours since the spray, and reaches the maximum activity after 4-5
days since the spray.
• Long persistance (2-3 months at least) which allows reducing the
number of sprays.
• Very high selectivity toward the beneficial fauna.
• Known cases of resistance in spider mites.
30
MITE GROWTH REGULATORS (MGRs)
Etoxazole
• long persistance and large
selectivity;
• inhibits the respiratory
processes in the eggs;
• inhibits the moulting.
31
MITE GROWTH REGULATORS (MGRs)
Hexythiazox
• It can influence the respiratory processes in eggs just laid; it can
influence negatively the synthesis of chitin in eggs laid time ago,
such as on larvae and nymphs.
• It has also sterilizing effects on ovigerous females which can lay
eggs unable to hatch.
• Known cases of resistance.
• Known its selectivity toward phytoseiids.
• Period between treatment and harvesting: 7-14 days.
32
ORGANOTINS
• They are considered unable to develop resistance.
• Selective
• Persistent
(usage authorized up to 31.xii.2011) Fenbutatin oxide
Mode of acquiring
Active ingredient/s
contact
clofentezine, pyridaben, propargite, fenbutatin oxide
contact-ingestion
abamectin, milbemectin, bifenazate, fenazaquin, fenpyroximate,
tebufenpyrad, etoxazole, hexythiazox, spirodiclofen
gas
Sulfur – in closed environments (rarely relevant in mites)
Translaminar property
abamectin, milbemectin, tebufenpyrad, clofentezine, etoxazole,
33
hexythiazox, spiromesifen
METI = Mitochondrial electron transport inhibitors
•
•
•
•
•
•
They can cause a sudden mortality of the target.
Risk of cross resistance.
Selectivity is not always relevant.
Some are phytotoxic for some host plants.
Some have long persistance (tebufenpyrad)
Efficacy is influenced by the temperature (fenazaquin – 10-30°C)
Fenazaquin (Magister), Fenpyroximate (Miro), Pyridaben
Tebufenpyrad (Oscar)
Mode of acquiring
Active ingredient/s
contact
clofentezine, pyridaben, propargite, fenbutatin oxide
contact-ingestion
abamectin, milbemectin, bifenazate, fenazaquin, fenpyroximate,
tebufenpyrad, etoxazole, hexythiazox, spirodiclofen
gas
Sulfur – in closed environments (rarely relevant in mites)
Translaminar property
abamectin, milbemectin, tebufenpyrad, clofentezine, etoxazole,
34
hexythiazox, spiromesifen
Inhibitors of the oxydative phosphorilation
Propargite
• Long persistance.
• Killing effects visible after 24 hours after the spray, with a peak at
5 days since the treatment.
• Some problems with resistance, phytotoxicity and mixture
incompatibility.
Inhibitors of the lipid synthesis
Spirodiclofen
• Resistance apparently scarcely probable.
• Efficient against all the developmental instars of
tetranychids and eriophyoids:
- causes a reduction on the hatching rate of eggs;
- inhibits the moulting in juveniles;
- interferes with the egg development and laying.
35
Neurotoxic
Bifenazate
• It inhibits the passage of stimulus from the nervous system to the
muscolar system; it inhibits the ATP synthesis at the level of
mythocondria.
• The treated mites are hyperactive within 3 hours and the mortality
occurs within 3-4 days.
• Contact and ingesting pesticide.
36
Abamectin
• Acaricide, nematocide and insecticide isolated from a
toxin produced by Streptomyces avermitilis.
• Avermectin B1a (80%) and avermectin B1b (20%)
O
O
HO
HO
O
O
O
O
O
O
H
O
O
25
O
O
H
O
O
O
O
O
O
OH
O
25
O
O
OH
O
H
OH
Avermectin B1a
H
OH
Avermectin B1b
37
Abamectin
It inhibits the transmission of neuromuscular signals (it blocks the
gamma-aminobutyric acid) and provokes the individual paralysis.
VERTIMEC binds to GABA & Glutamate-H receptor sites
-GABA
- receptor
VERTIMEC
(chloride channel)
- -- -
---- - - muscle
-- - --ve
- -
GABA
release
--
Glutamate H-receptor
(chloride channel)
-
-
Irreversible flow of - chloride
ions into muscle
PERMANENT RELAXATION
• Traslaminar property, able to penetrate rapidly into the plant cells
where can persist for a long time (28 days).
• The residues on the vegetal surface is rapidly deteriorated
ensuring a good selectivity toward the beneficial fauna.
38
CHEMICAL CONTROL
Abamectin
• Larvicide (mortality) - adulticide (effect on the fertility).
VERTIMEC protects plants from
feeding damage within few hours of
application
INGESTION
CHLORIDE
FLOW
MUSCLE
PARALYSIS
FEEDING
STOPS
DEATH
39
CHEMICAL CONTROL: weak points
• Harmfulness to natural enemies (selectivity), soil, water
supply, agricultural workers;
• Risk of residues on foods
• Timing of application;
• Multiple applications;
• Expensive;
• Development of resistance;
• Few new products;
• High costs to develop and register new products;
• Long time to develop and register new products.
40
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