Relationship between parent size and the production of winged forms in the strawberry aphid, Chaetosiphon fragaefolii

Abstract

Parent strawberry aphids, Chaetosiphon fragaefolii, reared in isolation on disks of Fragaria vesca exhibit size (length) differences presumably induced by variation in the nutritional uptake. A positive correlation was observed between increasing size of the parent aphid and the production of alate offspring. Parent aphids reared on severely deteriorated leaf disks were smaller and produced fewer alatae than when reared on fresh leaf disks. These findings appear contrary to the opinion that alate forms occur under conditions of diminishing nutrition. Temperatures above and below the optimal larviposition temperature (20·0°C) during parturition resulted in a decline in alate production. A temperature of 23·9°C during development resulted in reduced size and reduced production of alate offspring irregardless of temperatures during parturition. A temperature of 15·5°C during development had no significant influence on size or alate production when compared to 20·0°C.