Green peach aphid resistance management

Myzus persicae can become
resistant to many insecticides.
(Photo: Scott Bauer, USDA
www.insectimages.org)

J.D. Fletcher²
²Crop & Food Research Ltd

(Revised March 2022)

T.J.B. Herman
(Updated August 2024)

Reason for strategy and update

Green peach aphid, Myzus persicae, 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 an earlier resistance management strategy (Cameron and Fletcher 2004).

Background

Green peach aphid is a polyphagous species that is most important because of its ability to transmit viruses and may be regarded as the most important vector of aphid-borne viruses. It can overwinter as eggs on Prunus spp. or reproduce asexually year-round on a large range of secondary hosts, including potatoes, tomatoes, brassicas, beets, cereals, pasture clovers, peas, roses or weeds, such as docks, sow thistle and capeweed.

Viruses transmitted by green peach aphid include alfalfa mosaic, potato leaf roll, tomato yellow top, beet western yellows, cucumber mosaic, lettuce mosaic, potato virus Y, watermelon mosaic virus 2 and zucchini yellow mosaic. Green peach aphid may transmit infection from weed reservoirs harbouring viruses. In addition to the listed hosts, winged green peach aphids have also been found associated with redroot, oxtongue, camomile, chickweed, cleavers, hairy buttercup and scrambling speedwell.

Direct feeding damage by low numbers of green peach aphid causes little damage to plants, although low numbers of aphids can spread unacceptable amounts of plant viruses. In the absence of virus reservoirs, greater green peach aphid populations can be tolerated.

Green peach aphid is distributed worldwide, and several resistant strains have been identified using molecular techniques. A form with a chromosomal translocation is widespread in glasshouses and has been shown to have very high levels of resistance (Blackman & Devonshire 1978).

Current status of green peach aphid resistance in New Zealand

In New Zealand no field assays or bioassays studying green peach aphid insecticide resistance have been initiated since 1988.

Previously insecticide resistance was considered responsible for failures to control green peach aphid in field trials in potatoes (Fellowes & Ferguson 1974). Insecticide resistance was confirmed with bioassays (Cameron & Walker 1988). Resistance in greenhouse populations has also been demonstrated (Baker 1978). These studies record resistance to acephate, deltamethrin, demeton-s-methyl, dichlorvos, dimethoate, lindane, maldison, methomyl, mevinphos, naled, parathion methyl and pirimicarb. In the Pukekohe area, growers have reported the failure of demeton-s-methyl to control green peach aphid. Note that some of these insecticides are no longer registered for use in New Zealand.

Insecticide resistance by green peach aphid is widespread in Europe, Japan, North America, and Australia. There are records of resistance to organophosphates, organochlorines, carbamates and synthetic pyrethroids, but methamidophos, pirimicarb and methomyl have retained their effectiveness in several regions.

**Table 1:** Products with label claims for green peach aphid control in New Zealand (August 2024)
	Crops with label claims (X – green peach aphid, A - aphids)
IRAC chemical group Pesticide common and (product) names
Parasites
Aphidius colmani							A in GH				A in GH
Predators
Aphidoletes aphidimyza							A in GH				A in GH
Mineral oil
mineral oil							X	X
Carbamates 1A
methomyl	X	X			X	X in VB			A
pirimicarb	A	A	A	A	A	A		A
1B Organo-phosphate
acephate		A		A		GPA in VB				A	A
acephate	It is an offence to use this product off label
3A Pyrethroid
alpha-cypermethrin					A			X
tau-fluvalinate				A	X			A		X	A
Sulfoximines 4C
Sulfoxaflor				A	A	A	A
9B Feeding blocker
pymetrozine		A		A	A	A in VB		X		A
Diamide 28
cyantraniliprole				X	X

Resistance management and prevention strategy

The general strategy is to reduce the need for control of green peach 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.

Maximise virus control by standard management practices:

use virus-free seed (e.g. from pathogen testing schemes) or virus-free transplants
remove infected plants within a crop
eliminate weed sources that may harbour viruses
remove volunteer crop plants
use virus-resistant cultivars
use screens to prevent entry of aphids to greenhouses

Remove alternative host plants for green peach aphid, e.g. solanums, brassicas and ornamentals to create virus-free zones.
Maximise biological control (especially in greenhouses) by using parasitoids, predators or fungal pathogens of aphids.
Monitor plants to ensure insecticides are applied only when necessary.
Choose insecticides based on a knowledge of insecticide resistance patterns, where this is available. Resistance to demeton-s-methyl has been identified in Pukekohe.
Use the correct label rates and application procedures.
Alternate between insecticide groups.
If control failures are suspected, treat crops with an insecticide from a different chemical group.

Research strategy

The distribution of resistance among the major cropping areas should be assessed regularly.

Implementation

Growers should implement virus control strategies.
Insecticides registered for use against green peach 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. Maintain good cultural practices.

References

Baker RT 1978. Insecticide resistance in green peach-potato aphid Myzus persicae (Sulz.) (Hemiptera: Aphididae). New Zealand Journal of Experimental Agriculture 6: 77-82.

Blackman RI, Devonshire AL 1978. Further studies of the genetics of the carboxylesterase regulatory system involved in resistance to organophosphorous insecticides in Myzus persicae (Sulzer). Pesticide Science 9: 517-521.

Cameron PJ 1996. Green peach aphid resistance management strategy. In: Bourdot GW, Suckling DM ed. Pesticide Resistance: Prevention and Management. New Zealand Plant Protection Society, Lincoln, New Zealand. Pp. 207-209.

Cameron PJ, Walker GP 1988. Insecticide resistance in green peach aphid from potatoes in South Auckland. Proceedings of the 41st New Zealand Weed & Pest Control Conference: 85-89.

Fellowes RW, Fergusson AM 1974. Field evidence for resistance to certain insecticides to green peach-potato aphid in South Auckland. New Zealand Journal of Experimental Agriculture 2: 83-88.