Cannibalism in beetles

Abstract

Abstract Beetles are holometabolous insects with egg, larval, pupal, and adult life stages. Cannibalism often involves mobile stages (adults and larvae) eating quiescent stages (eggs and pupae). Adult beetles are sclerotized and invulnerable to cannibalism, with the consequence that cannibalism among mobile stages usually involves larvae eating larvae (Tables 8.1 and 8.2); however, adults occasionally eat larvae and there are two reported cases of adults eating callow adults. Cannibalism in beetles can be classified into two categories (Hamilton 1964a,b; Fox 1975; Polis 1981, 1984): (1) cannibalism of kin, including sibling cannibalism where early hatching larvae cannibalize eggs or later hatching larvae from the same clutch and filial cannibalism where adults eat larval offspring, and (2) non-kin cannibalism in which cannibalism is not specifically directed toward or away from closely related individuals. Non-kin cannibalism in beetles apparently does not involve individuals specifically seeking out and eating one’s own species (Tables 8.1 and 8.2), in fact, such cannibals do not necessarily discriminate between conspecifics and other prey. Indiscriminate or incidental cannibalism are terms that may be used to describe non-kin cannibalism, however, ecological factors and age specificity of cannibalism may bias indiscriminate cannibalism towards unrelated individuals (e.g. Mertz et al. 1984). I use the term non-kin cannibalism to refer to cannibalism when relatedness between victim and perpetrator is variable and/or unknown.