Myzus persicae
Authors: David G. Riley and Alton Sparks, Professors, University of Georgia, 2018
Description
Immature stages: Nymphs are similar to wingless adults in shape and color, but smaller. Unlike most aphids, GPA do not tend to form large colonies, but are generally evenly distributed across leaves.
Adult stage: Winged (alate) adults have a black head and thorax and a yellowish-green abdomen with a large dark patch in the middle of the abdomen as viewed from above. They measure about 2 mm in length, and if found on vegetables, are rounded projections at the base of the antennae (tubercles) that point toward the midline of the head. These projections are on all stages. Wingless adults are yellowish, greenish, or reddish. The cornicles are long and colored similar to the body.
Biology
Life cycle: In vegetable crops in Georgia, winged adults invade fields and can do so throughout the production seasons. Both winged and wingless adults give birth to live young without mating (parthenogenetic reproduction) on vegetable crops. Under favorable conditions, the aphids develop through 4 or 5 instars in about 1 week and give birth to offspring shortly thereafter, with generation time as short as 10 to 12 days. Females are reported to produce 1.6 to 3.75 nymphs per day over a 15 to 20 day reproductive cycle.
Seasonal distribution: Green peach aphids can invade fruiting vegetables throughout the spring and fall production season, but typically are more of a problem in cooler parts of the fall season.
Damage
Green peach aphids can build large populations on a variety of crops. On young plants, they can cause wilting and stunting. The red GPA colonizes the flowering stalk of tobacco plants.
At harvest, they can represent a contaminant both through their direct presence and through production of honeydew which gives rise to sooty mold. In many crops, their greatest threat is transmission of viral diseases, such as cucumber mosaic virus. This species transmits over 100 plant viruses, persistent and non- persistent transmission. Adults and nymphs can transmit viruses, but winged adults are of greatest importance due to mobility. Mummified aphids, golden brown aphid shells, can indicate parasitism.
Management
Green peach aphids are generally controlled with application of insecticides; however, insecticide resistance has been widely documented in this species. The red phase of this pest is reported to generally be more difficult to control.