A METHOD OF PREDICTING SHORT TERM POPULATION TRENDS OF THE GREEN PEACH APHID, MYZUS PERSICAE (HOMOPTERA: APHIDIDAE), ON POTATOES

Abstract

AbstractA method which uses the number of large embryos per adult to predict increases or decreases of green peach aphids, Myzus persicae (Sulzer), on potatoes over 3–4 or 7–8 days is presented. The population change between two successive counts 1 and 2, expressed as an increase factor (count 2 divided by count 1), is related to the average number of embryos per adult, at the time of count 1, by a linear regression (significant, P < 0.001). If there are more than about three embryos per adult, the population increases. Parasitism by Aphidius nigripes Ashm. reduces the number of embryos per adult in the field. In the laboratory, with no parasitism, the number of embryos per adult declines with age and is directly related to the daily birth rate which also declines with age.