Cannibalism Reverses Male-Biased Sex Ratio in Adult Mantids: Female Strategy against Food Limitation?

• Published in: Oikos Vol. 69; no. 2; pp. 193 - 198
• Main Authors: Hurd, L. E., Eisenberg, R. M., Fagan, W. F., Tilmon, K. J., Snyder, W. E., Vandersall, K. S., Datz, S. G., Welch, J. D.
• Format: Journal Article
• Language: English
• Published: Oxford Munksgaard International Publishers, Ltd 01-03-1994; Blackwell
• Subjects: Adult insects; Animal and plant ecology; Animal cannibalism; Animal, plant and microbial ecology; Animals; Autoecology; Biological and medical sciences; Censuses; Female animals; Food; Fundamental and applied biological sciences. Psychology; Invertebrates; Life cycle; Male animals; Mantidae; Mantodea; Mating behavior; Mortality; Protozoa. Invertebrata; Sex ratio; Tenodera sinensis; United States; North America; Maryland; America; Insecta; Mantidae; Mortality; Male; Cannibalism; Enumeration(counting); Mating; Sex ratio; Nutrient requirement; Oogenesis; Reproduction; Diet; Arthropoda; Adult animal; Invertebrata; Food supply; Dictyoptera
• ISSN: 0030-1299; 1600-0706
• DOI: 10.2307/3546137

Adult populations of the mantid, Tenodera sinensis (Saussure) initially were male-biased, but females outnumbered males by the end of the life cycle because mortality was higher among males than among females. Male mantids were the most frequent items in the diet of females during oogenesis, when food limitation generally is greatest. Males had an 83% chance of escaping cannibalism during any given encounter with a female; however, females continued to attract males after first mating, raising the cumulative probability of male death with increasing number of intersexual encounters. We suggest female mantids continue to attract and cannibalize males beyond their need for sperm as a strategy to alleviate food limitation during oogenesis. This is more parsimonious than the adaptive suicide hypothesis, in which male fitness is enhanced by investment of his biomass in his offspring, since our hypothesis does not require that the victim share parenthood with his cannibal.