Melon aphid resistance management
Aphis gossypii can become
resistant to many insecticides.
(Photo: Clemson University,
(Revised October 2004)
Reason for strategy and update
Melon aphid, Aphis gossypii, also known as cotton aphid, is capable of becoming resistant to a wide range of insecticide groups. Pest management strategies aimed at preventing or minimising resistance will help maintain control and conserve the effectiveness of existing products. This is an update of the resistance management strategy (Martin & Cameron 1997).
Melon aphid is a polyphagous species that can transmit some plant damaging viruses. It has been recorded from more than 50 plant families (Steenis 1995). Melon aphid has a variety of life cycle strategies and it is not known if any populations require special overwintering hosts or if sexual forms occur in New Zealand.
Melon aphid (Aphis gossypii) has an indefinite number of anholocyclic lines (asexually reproducing populations), some of which may have particular host associations (Blackman & Eastop 1984). Each line can have distinct and different host plant preferences.
Melon aphid can transmit over 50 viruses (Blackman & Eastop 1984) including water melon mosaic virus (WMV) and zucchini yellow mosaic virus (ZVMV), which occur in New Zealand. Because feeding damage is less significant than virus infection, it is possible to tolerate larger melon aphid populations when virus sources are removed or reduced.
Products with label claims for melon aphid control in New Zealand
|Pesticide category||IRAC chemical group||Pesticide common and (product) names|
|Parasites||Aphidius colmani (Aphidius, Aphipar)|
|Predators||Aphidoletes aphidimyza (Aphidoletes)|
|Organo-phosphate||1B||acephate (Lancer, Orthene)|
|acephate and triforine (Saprene)|
|chlorpyrifos (Chlorpyriphos, Lorsban, Pychlorex, Spectrum)|
|diazinon (Basudin, Dew, Diazinon, Diazinyl, Gesapon)|
|maldison (Malathion, Yates Maldison)|
|terbufos (No longer registered)|
|thimet (No longer registered)|
|Organophosphates/pyrethroids||1B/3||pirimiphos-methyl + permethrin (Attack) mixture|
|Cyclodiene||2A||endosulfan (No longer registered)|
|Pyrethroid||3||alpha-cypermethrin (Bestseller, Dominex, Fastac)|
|deltamethrin (Decis Forte, Deltaphar)|
|taufluvalinate (Mavrik, Supershield, Guardall)|
|Pyrethrins||3||pyrethrum (Garlic & Pyrethrum, Yates Pyrethrum)|
|Chloronicotinyl||4A||imidacloprid (Confidor 5GR, Gaucho)|
Current status of melon aphid resistance in New Zealand
In New Zealand, a population of melon aphids has been found with resistance to methomyl, demeton-S-methyl and acephate (Martin & Workman 1997).
Overseas, melon aphid is resistant to a wide variety of insecticides, including organochlorines, many organo-phosphates, carbamates and synthetic pyrethroids (e.g. Georghiou 1981; Hollingsworth et al. 1994; Silver et al. 1995).
Resistance management and prevention strategy
The general strategy aims to reduce the need for control of melon aphid by reducing virus sources and aphid reservoirs. Selection pressure on aphids in crops can then be reduced by applying insecticides only when necessary to reduce feeding damage.
Note: Control failure does not always imply resistance.
The following guidelines are recommended:
- Maximise virus control by standard management practices. These include:
- use of virus-free seed (e.g. from pathogen testing schemes) or virus-free transplants
- removal of infected plants within a crop
- elimination of weed sources that may harbour viruses
- removal of volunteer crop plants
- use of virus-resistant cultivars
- use of screens to prevent aphids entering greenhouses
- Remove alternative host plants for melon aphid, e.g. solanums, brassicas and ornamentals to create virus-free zones.
- Maximise biological control (especially in greenhouses) using parasitoids, predators or fungal pathogens of aphids.
- Monitor plants to ensure insecticides are applied only when necessary.
- Choice of effective insecticides should be based on a knowledge of insecticide resistance in local populations. Resistance to pirimicarb, lambda-cyhalothrin and tau-fluvalinate now appears to be widespread.
- Use the correct label rates and application procedures.
- Alternate between insecticide groups.
- If control failures are suspected, crops should be treated with an insecticide from a different chemical group.
The distribution of resistance among the major cropping areas should be assessed regularly.
|Type of label claim for each crop1|
and IRAC chemical group
Pesticide common and (product) names
|Aphidius colmani||A in GH||A in GH|
|Aphidoletes aphidimyza||A in GH||A in GH|
|methomyl||GPA||GPA||GPA||GPA in VB||A||GPA|
|acephate and triforine||A|
|chlorpyrifos||A in SQ||A||A|
|diazinon||A||A||A||A in VB||A||A in CIT||A||A||A|
|dichlorvos||A||A||A in BF||A|
|dimethoate||A in MW||A||CA in VB, A in FB||A|
|terbufos (No longer registered)||A in FB|
|thimet (No longer registered)||A||A||A||A||A|
|organo-phosphates + pyrethroids 1B/3|
|pirimiphos-methyl + permethrin mixture||A in GH||A in GH||A in VB|
|endosulfan||A||A||A in VB||A||A|
|deltamethrin||A in SQ|
|imidacloprid (Confidor 5GR)||A in TSP||A in TSP|
|imidacloprid (Gaucho)||A in SQ||A||A in FB|
1A = aphids, GPA = green peach aphid (Myzus persicae), CA = cabbage aphid, VB = vegetable brassicas, FB = forage brassicas, BF = berry fruit, GH = greenhouses, TSP = transplants, CIT = citrus, SQ = squash, MW = marrow. Beans excludes broad beans.
- Growers should implement virus control strategies.
- Growers should monitor plants to ensure insecticides are only applied when necessary.
- Insecticides registered for use against melon aphid should carry the following label statement:
IMPORTANT - RESISTANCE MANAGEMENT
Resistance to this pesticide may develop from excessive use. To minimise this risk use strictly in accordance with label instructions. Avoid using this insecticide exclusively all season and avoid unnecessary spraying or other methods of application. Maintain good cultural practices.
Blackman RL, Eastop VE 1984. Aphids on world crops: an identification and information guide. John Wiley & Sons, Chichester, UK.
Georghiou GP 1981. The occurrence of resistance to pesticides in arthropods, an index of cases reported through 1980. FAO of UN, Rome. 172 pp.
Hollingsworth RG, Tabashnik BE, Ullman DE, Johnson MW, Messing R 1994. Resistance of Aphis gossypii (Homoptera: Aphididae) to insecticides in Hawaii: spatial patterns and relationship to insecticide use. J. Economic Entomoogy 87: 293-300.
Martin NA, Cameron PJ 1997. Melon aphid resistance management strategy. Proceedings 50th N Z Plant Protection Conference: 551-555.
Martin NA, Workman PJ 1997. Melon aphid (Aphis gossypii): resistance to pesticides. Proceedings 50th N Z Plant Protection Conference: 405-408.
Silver ARJ, van Emden HF, Battersby M 1995. A biochemical mechanism of resistance to pirimicarb in two glasshouse clones of Aphis gossypii. Pesticide Science 43: 21-29.
van Steenis M 1995. Evaluation and application of parasitoids for biological control of Aphis gossypii in glasshouse cucumber crops. Ph. D. Thesis, Wageningen, Netherlands.