Variations in certain biological aspects of the cotton aphid, Aphis gossypii Glover (Homoptera: Aphididae) in relation to color of its forms

Abstract

The stock populations of two groups of Aphis gossypii Glover (Homoptera: Aphididae) were collected from cucurbitaceous plant leaves cultivated in Assiut and the New Valley Governorates, Egypt. Both aphid groups were brought into the laboratory and used as base line of pirimicarb resistance. Pirimicarb LC₅₀ base line was determined by the dipping technique in successive concentrations of the trade form of pirimicarb mixed in water. The LC₂₅ was determined monthly throughout two years and used in the selection.. This procedure resulted four aphid forms at each location (i.e., base line, mixed, light color, and dark color).  It was found that the total nymphal duration of dark forms collected from both locations did not vary significantly from the base line forms. Data of the reproductive biology of aphids from both locations showed that the fecundity period, longevity and productivity of the dark morphs were significantly higher than those of the base line ones.