The effect of sex peptide and calorie intake on fecundity in female Drosophila melanogaster.

The accessory gland proteins (Acps) of the male Drosophila cause changes in the behavior and physiology of female flies. Sex peptide (SP) is one of the Acps that initiates many changes, including an increase in egg production. The data presented here show that SP overexpression in transgenic (G-10) female flies increases egg production when females are kept on a standard and high-calorie diet, relative to controls that do not express SP. Particularly, a high increase in egg production observed in G-10 females on a high-calorie diet suggests that SP overexpression magnifies the female response to caloric uptake. However, on a calorie-restricted diet, the fecundity of G-10 females overexpressing SP is lower than control females. On a high-calorie diet, mating increases early egg production in G-10 and control females, but lifelong total egg production is only increased in control females, most likely due to the physiological changes set off by substantial initial egg production in G-10 females.