How to Manage Pests
UC Pest Management Guidelines
Green Peach Aphid
Scientific name: Myzus persicae
(Reviewed 12/09, updated 11/12)
In this Guideline:
DESCRIPTION OF THE PEST
Green peach aphid is among the most common aphid species found on peppers. It may be present at any time throughout the year but is most common from March through May and September through November. Generally its color is pale green, although at times individuals may be present that are pinkish. During cool weather, individuals are usually more deeply pigmented. Both winged and wingless forms of the green peach aphid have prominent cornicles on the abdomen that are markedly swollen and clublike in appearance. The frontal tubercles at the base of the antennae are very prominent and are convergent. Winged forms of the green peach aphid have a distinct dark patch near the tip of the abdomen; wingless forms lack this dark patch.
The green peach aphid transmits a number of destructive viruses in pepper including pepper potyviruses and cucumber mosaic cucumovirus. In addition, it can also damage the plant by sucking plant sap. Damaging levels are characterized by large numbers of aphids found on the underside of leaves. Extensive feeding causes plants to turn yellow and the leaves to curl downward and inward from the edges. Honeydew produced by the aphids can be a problem, especially on fresh market peppers. Aphid damage is most prominent on newer, younger leaves in the center of the plant.
Biological and cultural controls can be useful for limiting damage from this aphid. For instance, removing old crop debris from the field will reduce sources of virus and thereby its transmission by aphids, and using reflective mulches early in the season will repel aphids from young plants. Heavy infestations on seedling and young plants may require treatment with insecticides.
The green peach aphid is attacked by a number of common predators, including lacewings, lady beetles, syrphid flies, and parasites, including the parasitic wasps Lysiphlebus testaceipes, Aphidius matricariae, Aphelinus semiflavus, and Diaeretiella rapae, and is susceptible to the fungus Entomophthora spp., that commonly attacks aphids. Aphid sampling should always include an evaluation of the presence and activity of natural enemies.
An important factor in reducing virus spread is good field sanitation, especially the chopping or discing of crop debris immediately after harvest and destruction of alternate host plants. While field sanitation helps control the incidence and spread of viruses transmitted by green peach aphid, it does little to control the aphid itself. The spread of the virus within a geographical area can be reduced by not planting peppers near other pepper fields.
If peppers are planted near large areas of rangeland, it may not be possible to prevent the influx of green peach aphid. Studies have shown, however, that aluminum foil or silver reflective plastic mulches can be effective in repelling aphids from plants.
Organically Acceptable Methods
Biological and cultural controls and sprays of insecticidal soap or pyrethrin are acceptable for use on organically certified crops.
Monitoring and Treatment Decisions
Set out sticky traps before planting and check traps weekly for green peach aphids, along with thrips, tomato psyllid, and whiteflies. Be sure to replace traps as needed. When aphids are observed on traps, start monitoring pepper plants to determine population levels. Treatment thresholds for green peach aphid are not well established. Heavy populations can do extensive damage, particularly on seedlings or young plants. If seedlings or young plants show signs of stress because of aphid feeding, consider an insecticide application. If green peach aphids have been a problem in the past, apply imidacloprid at planting.
UC IPM Pest Management Guidelines:
Insects and Mites
E. T. Natwick, UC Cooperative Extension, Imperial County