Age-dependent investment in death-feigning behaviour in the sweetpotato weevil Cylas formicarius

Because life-history theory predicts that risky behaviours such as mating should increase as life expectancy decreases, predatory avoidance is expected to decrease with age. However, this prediction has not been examined. In the present study, the effect of age on death-feigning behaviour, a form of predatory avoidance behaviour in the sweetpotato weevil Cylas formicarius (Summers) (Coleoptera: Brentidae), is investigated by performing a longitudinal study. Because the effects of mating history and age usually cannot be distinguished, mating history is controlled. The results show that only female weevils decrease the investment in death-feigning behaviour with age, whereas male weevils do not show any age-related change. In addition, death-feigning behaviour of mated females is longer than that of virgin females, possibly because additional mating partners would be not needed by mated females.