The effect of past and current hosts on reproductive investment by the adult cowpea aphid <i>Aphis craccivora</i>

Abstract 1. A general index of accumulated investment that alate aphids make into reproduction with respect to environmental changes (specifically changes in host at adult moult) was investigated to determine whether and how reproduction in Aphis craccivora Koch changes once aphids migrate to a different host from the one on which they were born and reared. The aphids were monitored for 4 days to determine the immediate effects of a change in host.2. A general index of accumulated investment defined as reproductive index was used; reproductive index is equal to the reproductive output (weight of nymphs born; actual fecundity) plus potential reproduction (weight of embryos within the ovarioles with red eye spots; future fecundity).3. The results revealed that reproductive index is affected by adult weight. The host on which the aphids have been born and reared (source host) has no effect on reproduction other than its influence on adult weight.