Changes in a Moth Community Mediated by Biological Control of the Dominant Species

Abstract

After biological control of the mango shoot caterpillar, Penicillaria jocosatrix Guenée (Lepidoptera: Noctuidae), on Guam, populations of four other species of Lepidoptera using mango increased. These included three species of Geometridae—the widespread Anisodes illepidaria Guenée, Thalassodes sp., and Chloroclystis sp.—and the noctuid Nanaguna breviuscula Walker. Thalassodes sp., Chloroclystis sp., and N. breviuscula were most commonly found on mango inflorescences, and probably became more abundant as a result of an increase in mango flowers. A. illepidaria caterpillars, which eat leaves and flowers, increased l0-fold after suppression of P. jocosatrix . Comparison of its larval biology with the mango shoot caterpillar showed that A. illepidaria preferred slightly older, developing leaves. Survival of A. illepidaria was low on very young leaves, which were highly suitable for P. jocosatrix . Introduced biological control agents acted as keystone predators, preventing the mango shoot caterpillar from preempting mango as a resource for the other Lepidoptera species.