Cannibalism behaviour was studied under laboratory conditions in three species of ladybeetle: Cycloneda sanguinea, Olla v-nigrum, and Harmonia axyridis. The propensity for larval cannibalism varied among species, C. sanguinea more than H. axyridis, more than or equal to O. v-nigrum. Larvae of all species increased cannibalism rate in response to reduced food availability (14 h starvation daily), but not in response to reduced food quality (dry Ephestia eggs). Larvae of H. axyridis cannibalised siblings at lower rates than non-siblings, but larvae of C. sanguinea and O. v-nigrum did not. Rates of cannibalism increased significantly with increasing size disparity among larvae of all three species. Cannibalism increased with larval density in C. sanguinea and H. axyridis, but not in O. v-nigrum, suggesting that not all attacks on conspecifics are hunger-driven; some may represent pre-emptive strikes when the risk of cannibalism is high.
Species 1: Coleoptera Coccinellidae Cycloneda sanguinea
Species 2: Coleoptera Coccinellidae Harmonia axyridis
Species 3: Coleoptera Coccinellidae Olla v-nigrum
Keywords: cannibalism
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