Spermatophore size and mate fecundity in the bruchid beetle Callosobruchus maculatus

Abstract

Savalli & Fox (1999) have recently shown that in the bruchid beetle Callosobruchus maculatus, females inseminated by large males lay more eggs than those inseminated by small males. Here we report the results of a very similar experiment, on the same species, which yielded the opposite result; females inseminated by small males laid more eggs than those inseminated by large males. On analysing the methods and results, two differences in experimental design become apparent; male age at first copulation and population origin. We suggest these two differences may have produced the contrasting results and believe they offer important evolutionary and developmental insights into ejaculate composition.