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

Abstract

A 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.

THE EUROPEAN SKIPPER,THYMELICUS LINEOLA(LEPIDOPTERA: HESPERIIDAE), IN MANITOBA AND NORTHWESTERN ONTARIO

“…The use of embryo counts from adult green peach aphids, Myzus persicae (Sulzer), for forecasting increases in field populations on potatoes was described by Elliott (1973). The advantage of this method is the ease with which the larger embryos can be counted by their conspicuous red eye spots after clearing the adults with lactophenol.…”