Abstracts are listed in alphabetical order by the last name of the senior author.

Agricultural Research Center – Hays, Kansas State University, Hays, KS, U.S.A. jpmi@ksu.edu

We examined sibling egg cannibalism behaviour and its consequences in three aphidophagous coccinellid species that all lay clustered eggs: Cycloneda sanguinea L., Harmonia axyridis Pallas, and Olla v-nigrum Mulsant. There was variation among species in the proportion of eggs laid singly versus in clusters (C. sanguinea > H. axyridis = O. v-nigrum), the synchronicity of egg hatch within clusters (H. axyridis > C. sanguinea = O. v-nigrum) and the proportion of eggs cannibalised by early-hatching larvae (O. v-nigrum > C. sanguinea > H. axyridis). The dispersal of neonate larvae from their egg clusters was delayed by the availability of sibling eggs for cannibalism. Egg cannibals survived to adulthood at the same rate as control larvae in H. axyridis and O. v-nigrum, and at a higher rate in C. sanguinea, suggesting that the Ephestia egg diet was sub-optimal for this species. In all three species, larvae that cannibalised eggs as neonates molted to the second instar sooner than did their non-cannibalising counterparts, regardless of gender. This translated into reduced total developmental time for both sexes in H. axyridis, but only for males in C. sanguinea and only for females in O. v-nigrum. Adult females weighed significantly more than adult males in all three species and female cannibals were heavier as adults than were non-cannibalising females in H. axyridis and O. v-nigrum, whereas males had similar weights. Egg cannibalism had no effect on adult weight in C. sanguinea. We hypothesize that the benefits of sibling egg cannibalism accrue in a gender-specific manner such that females potentially gain more than males, but only if the subsequent larval diet is of high quality.