Suggestions for Managing Insecticide Resistance in the Greenhouse
J.P. Sanderson, Dept. of Entomology, Cornell University, Ithaca, NY
Insecticide resistance is a major concern for chemical control of almost all of the important greenhouse insect and mite pests. A combination of the biology of the pests, the intensity of chemical use in the past and present, and several aspects of the greenhouse environment and commercial production practices, has led to insecticide resistance problems. The following suggestions should be considered as a part of any chemical control program.
1. Minimize Insecticide Use. If pest control relies exclusively on synthetic insecticides, then resistance can only be delayed, not avoided. Therefore, the use of non-chemical control tactics (sanitation, eliminate weeds, soil sterilization, screening vents, natural enemies, etc.) should be maximized. The decision to apply insecticides should primarily be based on pest scouting reports, not a calendar schedule.
2. Avoid persistent applications. Ideally, an effective insecticide should be applied at a concentration high enough (within legal limits) to kill all individuals in a population, then quickly disappear from the environment, so that the insecticide residues do not degrade over time to a concentration that will kill only susceptible individuals. For example, aerosol formulations that apply a short "burst" of a high insecticide concentration and do not leave much residue may select for resistance more slowly than full-coverage or systemic applications of the same insecticide, as long as resistance to the insecticide has not already developed in the population.
3. Avoid "Tank Mixes." A mixture of two insecticides may provide superior short-term control than either insecticide used alone, but there is a danger in the long-term use of insecticide mixtures. The assumption behind the use of tank mixes is that if individuals which are resistant to one or the other pesticide in the tank mix are rare in the population, there is little chance that resistance mechanisms to both pesticides would occur together in any one individual. However, if by chance individuals do exist with resistance mechanisms to both chemicals, then continued use of the tank mix will begin to select for these multiply resistant pests. Chemical control would then become much more difficult, because the pests would be resistant to multiple classes of insecticides.
4. Use Long-term Insecticide Rotations. The pesticides used in a rotation scheme should have different modes of action against the pest (see Table 1), and resistance to the chemicals should be at a low (undetectable) level at the start. Organophosphate and carbamate insecticides have similar modes of action and should not be alternated in an insecticide rotation scheme. Use each effective insecticide for at least the duration of one generation of the pest before rotating to a different insecticide. If two insecticides are used within the same pest generation, the selection effect will be essentially the same as using a tank mix. This is because the same individuals would be contacted with both insecticides, although at slightly different times. To minimize the problems of overlapping generations and persistent insecticide residues, it might be wise to use the same insecticide for two or even three generations prior to rotating.
5. Use Pesticides with Non-specific Modes of Action. Insecticidal soaps and horticultural oils both have broad modes of action, and it is therefore unlikely that resistance will occur to either of these. In addition, tank mixes of these materials with effective synthetic organic insecticides might delay resistance to the synthetic insecticide, because the soap or oil will kill many individuals that are resistant. However, some tank mixes that include oil or soap may be toxic to certain plants.
6. Integrate Chemical and Biological
Control. Many of the newer insecticides are compatible with the use
of many kinds of natural enemies.
The effective use of natural enemies can add an additional mortality
factor that does not select for resistance, and may conserve the effectiveness
of insecticides. Effective natural enemies may include predators, parasitoids,
and/or insect pathogens. Many
extension entomologists and commercial insectaries have information on
pesticides that are compatible with various natural enemies. The searchable Koppert Side Effects
List can be found at http://www.koppert.nl/e0110.html.
Table 1. Mode of Action Classification of
Insecticides and Miticides Used in Greenhouses
Most insecticides and miticides
affect insects and mites in specific ways. These ways may be called the pesticide¹s ³mode of
action². The Insecticide
Resistance Action Committee (IRAC) is an organization of chemical companies and
researchers that has classified insecticides and miticides into one of 28
(currently) different modes of action.
The following chart identifies those insecticides and miticides used in
greenhouses by their modes of action.
This chart may be used to identify the mode of action of a pesticide and
to determine other pesticides with different modes of action that may be used
in a pesticide rotation plan. Rotate among pesticides from different major
groups, but not within the same major group. For example, it is OK to rotate a pesticide from Group 1
with another from Group 3, but do not rotate a Group 1A pesticide with a Group
1B pesticide.
Note: As of 2/2006, some
pesticides listed below have not been registered in New York State. Check registration status of all
pesticides before use.
|
Group |
Primary Site of
Action |
Chemical Class |
Trade Name (Active
Ingredient) |
|
1A |
Acetylcholine esterase inhibitors |
Carbamates |
Sevin (carbaryl) Measurol (methiocarb) |
|
1B |
Organophosphates |
Orthene (acephate) Dursban
(chlorpyrifos) |
|
|
2A, 2B |
GABA-gated chloride
channel antagonists |
None used on
ornamentals |
-- |
|
3 |
Sodium channel
modulators |
Pyrethroids |
Talstar
(bifenthrin) Decathalon
(cyfluthrin) Discus
(cyfluthrin+imidacloprid) Scimitar
(lambda-cyhalothrin) Tame
(fenpropathrin) Astro (permethrin) |
|
Pyrethrins |
Pyreth-It
(pyrethrins) |
||
|
4A |
Nicotine
acetylcholine receptor agonists/antagonists |
Neonicotinoids |
TriStar
(acetamiprid) Celero
(clothianidin) Discus (cyfluthrin+
imidacloprid) Marathon
(imidacloprid) Flagship
(thiomethoxam) Safari
(dinotefuran) |
|
4B |
None used on
ornamentals |
-- |
|
|
4C |
None used on
ornamentals |
-- |
|
|
5 |
Nicotine
acetylcholine receptor agonists/antagonists (not Group 4) |
Spinosyns |
Conserve (spinosad) |
|
6 |
Chloride channel
activators |
Avermectins |
Avid (abamectin) |
|
7A |
Juvenile hormone
mimics |
Juvenile hormone
analogues |
Enstar II
(kinoprene) |
|
7B |
None used on
ornamentals |
-- |
|
|
7C |
pyriproxyfen |
Distance
(pyriproxyfen) |
|
|
8A |
Compounds of
unknown or non-specific mode of action (fumigants) |
Methyl bromide |
Methyl bromide |
|
8B |
None used on
ornamentals |
-- |
|
|
8C |
None used on
ornamentals |
-- |
|
|
9A |
Compounds of
unknown or non-specific mode of action (selective feeding
blockers) |
None used on
ornamentals |
-- |
|
9B |
Pymetrozine |
Endeavor
(pymetrozine) |
|
|
9C |
Flonicamid |
Aria (flonicamid) |
|
|
10A |
Compounds of
unknown or non-specific mode of action (mite growth
inhibitors) |
Clofentazine |
Ovation
(clofentazine) |
|
Hexythiazox |
Hexygon
(hexythiazox) |
||
|
10B |
Etoxazole |
TetraSan
(etoxazole) |
|
|
11A1 |
Microbial
disruptors of insect midgut membranes (including
transgenic plants expressing Bacillus thuringiensis toxins) |
B.t. var israelensis |
Gnatrol (B.t. var israelensis) |
|
11A2 |
None used on ornamentals |
-- |
|
|
11B1 |
None used on
ornamentals |
-- |
|
|
11B2 |
B.t. var kurstaki |
Dipel (B.t. var kurstaki) |
|
|
11C |
None used on
ornamentals |
|
|
|
12A |
Inhibitors of
oxidative phosphorylation, disruptors of ATP formation |
None used on
ornamentals |
-- |
|
12B |
Organotin miticides |
|
|
|
13 |
Uncoupler of
oxidative phosphorylation via disruption of H proton gradient |
Chlorfenapyr |
Pylon
(chlorfenapyr) |
|
14 |
Inhibition of
magnesium-stimulated ATPase |
None used on
ornamentals |
-- |
|
15 |
Inhibitors of
chitin biosynthesis, type 0, Lepidopteran |
Benzoylureas |
Adept
(diflubenzuron) Pedestal
(novaluron) |
|
16 |
Inhibitors of
chitin biosynthesis, type 1, Homopteran |
Buprofezin |
Talus (buprofezin) |
|
17 |
Inhibitors of
chitin biosynthesis, type 2, Dipteran |
Cyromazine |
Citation
(cyromazine) |
|
18A |
Ecdysone
agonist/moulting disruptor |
Diacylhydrazines |
Confirm
(tebufenozide) |
|
18B |
Azadiractin |
Azatin, Ornazin
(azadiractin) |
|
|
19 |
Octopaminergic
agonist |
None used on
ornamentals |
-- |
|
20A |
Site II electron
transport inhibitors |
None used on
ornamentals |
-- |
|
20B |
Acequinocyl |
Shuttle
(acequinocyl) |
|
|
20C |
None used on
ornamentals |
|
|
|
21 |
Site 1 electron
transport inhibitors |
Mitochondrial
electron transport inhibitors, acaricides |
Akari
(fenpyroximate) Sanmite (pyridaben) Shuttle
(napthoquinone derivative) |
|
22 |
Voltage-dependent
sodium channel blocker |
None used on
ornamentals |
-- |
|
23 |
Inhibitors of lipid
synthesis |
Tetronic acid
derivatives |
Judo (spiromesifen) |
|
24 |
Site III electron
transport inhibitors |
None used on
ornamentals |
-- |
|
25 |
Neuroactive
(unknown mode of action) |
Bifenazate |
Floramite
(bifenazate) |
|
26 |
Aconitase
inhibitors |
None used on
ornamentals |
-- |
|
27A |
Synergists |
P450 monooxygenase
inhibitors |
Piperonyl butoxide |
|
27B |
None used on
ornamentals |
-- |
|
|
28 |
Ryanodine receptor
modulator |
None used on
ornamentals |
-- |
|
UNA |
Compounds with
unknown modes of action |
None used on
ornamentals |
-- |
|
UNB |
-- |
||
|
UNC |
Dicofol |
Kelthane (dicofol) |
|
|
UND |
paridalyl |
Overture
(paridalyl) |
|
|
NS |
Miscellaneous
non-specific, multi-site action |
|
Tartar emetic |