LIFETIME MATING OPPORTUNITIES AND MALE MATING-BEHAVIOR IN SEXUALLY CANNIBALISTIC PRAYING MANTIDS

I examined the number of lifetime mating opportunities and mating beha viour of males in two sexually cannibalistic species, the Mediterranea n, Iris oratoria, and bordered, Stagmomantis limbata, praying mantids (Mantodea: Mantidae). Two approaches estimated the number of lifetime mating opportunities: direct observations of intersexual encounters in the field, and an encounter model. I collected behavioural observatio ns, together with ecological data for use in the model, over three fie ld seasons. The ecological data included an assessment of the feeding condition of S. limbata females in nature; the females fed at a level comparable to females maintained on an abundant diet in the laboratory . As for the number of mating opportunities, individual males of both species encountered two or more females, as predicted by the model. I observed no male, however, in more than one copulation. This result co uld reflect individual variation in the times and places of sexual act ivity or an actual low number of mating opportunities in the field. Fu rthermore, a higher percentage of I. oratoria males encountered two or more females than S, limbata males, as the model indicates. Fewer mat ing opportunities could lead to greater selection upon S. limbata male s to ensure paternity at each mating, which can explain the longer cop ulation times observed for S. limbata males. I considered two hypothes es about male behaviour in light of the number of lifetime encounters with females: male suicide and male reduction of the risk of cannibali sm. Behavioural observations do not strongly support male suicide in e ither species. Certain male behaviours, such as the nature of copulato ry position and, in captivity, mounting females from the rear, are con sistent with the idea that males behave so as to reduce the probabilit y that they are cannibalized during intersexual encounters. Moreover, male I. oratoria preferentially mount well-fed, fecund females in capt ivity. Taken together, these results suggest that the prospect of mult iple mating opportunities has :influenced male mating behaviour over e volutionary time. (C) 1998 The Association for th-Study of Animal Beha viour.