Mating, longevity, and fecundity in northern corn rootworm in relation to male and female size

Male insects often compete over access to female ova. In combat larger males usually have a competitive edge over smaller males. However, female insects may discriminate against potential mates based on body size. This discrimination can occur during courtship, copulation, or post-copulation. Here, we report on the mating success, longevity, and fecundity of northern corn rootworm as they relate to male and female size. We used pupal weight as initial size indicators, and paired combinations of large and small males with large and small females in 60 x 15 mm petri dishes. Large and small individuals were greater than and less than 1 SD from the mean. Average sized males and females were also paired for comparisons, which were within 1 SD of the mean for each sex. To insure virginity, all individuals were obtained as pupae and reared to adults. Mating pairs were used only once. We videotaped all male and female pairs for at least two hours and successful mating pairs until copulation was completed. Females were housed individually with ample food, water, and oviposition dishes and placed in growth chambers. Oviposition dishes were changed weekly until the females died. We report the data with respect to mating success and fecundity based on male and female size.