Laboratory study of cannibalism in Sphodromantis viridis Forskal (Mantodea: Mantidae):: Effects of prey availability, habitat structure, and predator density

A laboratory study to evaluate the role of available preys, habitat structure and mantid density on the cannibalism among developmental and adult individuals of Sphodromantis viridis Forskal was investigated. Prey availability strongly reduced cannibalism within individuals of the same a-e and others of different ages. Complex habitat structure provides shelter for mantid individuals although it could not prevent cannibalism. High density of mantid nymphs or adults increased cannibalism. Rates of cannibalism increased as the mantid ages increased. First, second and third instar nymphs did not have any cannibal's activity. On the other hand, adult females had the greatest cannibals' activity. Mantid individuals could not cannibals upon higher-age individuals; inversely the later instar nymphs and the adults could not eat (cannibals) the earlier nymphs probably as a result of difficulties of catching behavior. Mantid cannibalism occurred in the presence or absence of preys, through a simple or complex habitat structure and low or high predator's density. This adaptive behavior might improve the chances of survival and provide a defended degree of the mantid against interspecific predation.