The effect of female mating history on sperm precedence in the two-spot ladybird, Adalia bipunctata (Coleoptera, Coccinellidae)

Effects of two different mating regimes on sperm precedence in the two-spot ladybird, Adalia bipunctata, were studied using the polymorphic gene for m elanism as a marker for paternity. Virgin nonmelanic females (homozygous re cessive) were mated to nonmelanic male(s) and then, after laying fertilized eggs, were mated to a melanic male of known genotype. The results after th e two successive single matings showed a highly variable degree of paternit y of the second male. Initial multiple mating with nonmelanic males did not alter the pattern of paternity after the subsequent single mating with a m elanic male, but it had two other effects: (I) the female showed an increas e in rejection behavior, and (2) a longer copulation was required for high success of the melanic male. Additional observations in which families were reared from beetles collected in copula in the held demonstrated that sper m competition also occurs under natural conditions. The outcome of the comp etition was variable with frequent sperm mixing.