vol. 168, no. 2 the american naturalist august 2006 Natural History Miscellany Complicity or Conflict over Sexual Cannibalism? Male Risk Taking in the Praying Mantis Tenodera aridifolia sinensis Jonathan P. Lelito * and William D. Brown † Department of Biology, State University of New York, Fredonia, New York 14063 Submitted June 24, 2005; Accepted May 5, 2006; Electronically published July 12, 2006 abstract: Male complicity versus conflict over sexual cannibalism in mantids remains extremely controversial, yet few studies have attempted to establish a causal relationship between risk of canni- balism and male reproductive behavior. We studied male risk-taking behavior in the praying mantid Tenodera aridifolia sinensis by altering the risk imposed by females and measuring changes in male behavior. We show that males were less likely to approach hungrier, more rapacious females, and when they did approach, they moved more slowly, courted with greater intensity, and mounted from a greater distance. Similarly, when forced to approach females head-on, within better view and better reach of females, males also approached more slowly and courted with greater intensity. Thus, males behaved in a manner clearly indicative of risk avoidance, and we support the hypothesis of sexual conflict over sexual cannibalism. Keywords: sexual cannibalism, sexual conflict, mate choice, praying mantis, Mantidae. Sexual cannibalism in praying mantids is legendary, and a great majority of species display sexual cannibalism at least occasionally (reviewed in Elgar 1992; Maxwell 1999a). Benefits of sexual cannibalism to the female are contro- versial in some species (Arnqvist and Henriksson 1997; Maxwell 2000), but in the Chinese mantis Tenodera ari- difolia sinensis, the benefits are clear: females gain valuable reproductive resources through cannibalism. When fe- males consume more prey or larger prey, they lay larger oothecae (egg cases) that contain more eggs, and they ultimately produce a greater number of offspring (Eisen- * E-mail: jpl207@psu.edu. † Corresponding author; e-mail: william.brown@fredonia.edu. Am. Nat. 2006. Vol. 168, pp. 263–269.  2006 by The University of Chicago. 0003-0147/2006/16802-41154$15.00. All rights reserved. berg and Hurd 1977; Eisenberg et al. 1981; see also Matsura and Mooroka 1983 for Tenodera angustipennis). A single ootheca may weigh 30%–50% of a female’s biomass and thus represents a tremendous investment (Eisenberg et al. 1981; Hurd 1989). Yet in the field, females are often food limited (Hurd et al. 1978, 1995), making males valuable as a food source, and hungry females are more likely to cannibalize males than are satiated females (Liske and Da- vis 1987). Hurd et al. (1994) estimated that males in one population of T. sinensis made up 63% of the diet of adult females. In contrast to these nutritional benefits to females, the possibility that males may also benefit from sexual can- nibalism remains extremely controversial (see Gould 1984; Johns and Maxwell 1997). Unlike some sexually canni- balistic spiders (e.g., Sasaki and Iwahashi 1995; Knoflach and van Harten 2001; Andrade and Banta 2002; Foellmer and Fairbairn 2003), male mantids can mate repeatedly and potentially fertilize multiple females during their life- time (Bartley 1982; Lawrence 1992; Hurd et al. 1994). Sexual cannibalism obviously eliminates the possibility of future mating for the male and thus imparts a clear cost— the total loss of future reproduction. All else being equal, this cost will generate strong sexual conflict over canni- balism. Yet male mantids can initiate copulation even after cannibalism has begun, and decapitation by cannibalism may even increase copulatory behavior (Roeder 1935; Liske 1991). Thus, precopulatory attacks by females may not diminish a male’s mating success with the current female and may even increase the chance of successfully mating. One of the original theoretical models of sexual cannibalism shows that a male should be willing to sacrifice his life to an inseminated partner if he can expect little subsequent mating and if his value as a food item would allow the female to rear substantially more offspring (Bus- kirk et al. 1984; see also Parker 1979; Polis 1981; Birkhead et al. 1988; Maxwell 2000). More recent work on spiders has shown that males may also achieve a paternity ad- vantage through sexual cannibalism if cannibalism can ex- tend the period of insemination, decrease the chance of