Factors shaping resource partitioning in predators of clumped patches of bamboo woolly aphids.

Prey-predator interactions favor the aggregation of generalist predators adept at avoiding competition in foraging on temporary food resources. There is scant information on the predator guild on clumpy patches of woolly aphids on bamboo host plants in forested landscapes. Results of a field-cum-laboratory study explain the aggregation of generalist and specialist predators in patchy resources of the bamboo-feeding woolly aphid, Ceratovacuna silvestrii, with particular reference to the specialist giant ladybird predator, Anisolemnia dilatata. This predator's larvae share food resources for 26 weeks including 11 weeks of coexistence with 2 small-sized generalist predators and 11 weeks with the larvae of specialist moth predator. Results show a preference for low prey density patches by small-sized predators in contrast to high prey density by the giant ladybird predator. Between the two woolly aphid prey-specialist predators, the moth caterpillars (Dipha aphidivora) avoided competition with the giant ladybirds by foraging in silken nests in less aggregated aphid patches. Eggs and larvae of the giant ladybird predator are defended from heterospecific and conspecific predators. This trait deters other predators of the guild that avoid prey patches visited by the giant ladybirds. Bigger size, preference for high-density prey patches, and anti-predation trait of eggs and larvae confer selection advantages to giant ladybirds as the top predator of the guild of woolly aphids. This has evolutionary significance for the ecological stability of prey-predator dynamics in a forested landscape.