Effects of Starvation and Prey Availability on Predation and Dispersal of an Omnivorous Predator Arma chinensis Fallou

Predation and dispersal ability of predators can influence their post-release establishment. As physiological factors may influence the predation and dispersal behavior of insects, we tested the effects of starvation on the predation and dispersal behavior of an omnivorous predator Arma chinensis under different prey densities. Logistic regression showed that A. chinensis exhibited a Holling’s Type II functional response regardless of its hunger level. Starvation significantly increased attack rate and reduced prey handling time of A. chinensis. When prey density was low (3 and 6 per plant) A. chinensis that has been starved for 2 and 4 days consumed significantly more second instar Mythimna separata than satiated ones. No significant difference was found in prey consumption among predators of different hunger levels when prey density was high (>12 per plant). When M. separata was absent, starved A. chinensis dispersed faster and spent less time in the target patch; and less than 50% of individuals remained on the plant. When M. separata was available, A. chinensis spent significantly more time in the target patch, and more than 80% of individuals were uniformly distributed on plant seedlings. Hunger level showed more effects on the dispersal of A. chinensis when prey was absent than when prey was available. The implications of these results for the use of A. chinensis in augmentative biological control programs are discussed.