Parasitism, Predation, and Disease in the Bagworm, Thyridopteryx ephemeraeformis (Haworth) (Lepidoptera:Psychidae)1

Abstract

Approximately 43% of the larval bagworm population in the Athens, Ga., area were killed by naturally occurring biotic factors during the period July through Sept., 1970. About 71% were killed in 1971 and 66% in 1972. Nineteen insect species including parasitoids, hyperparasites, and scavengers were reared from dead bagworm larvae and pupae. The bagworm is a new host record for 9 of these insects. Bagworm pathogens included bacilliform bacteria, a polyhedrosis virus, and fungi belonging to the genera Aspergillus, Penicillium, Geotrichum, Paecilomyces, Hirsutella, Beauveria, Cordyceps, Scopulariopsis , and Pestalotia . An inverse relationship existed between the levels of fungal disease and parasitism in larval populations. During 1971 a high level of fungal disease (51%) and a low level of parasitism (10%) were recorded. In 1970 and 1972, high levels of parasitism (29% and 46%, respectively) and low levels of fungal disease (13% and 17%, respectively) were recorded. It appears that fungi contributed most heavily to bagworm mortality during wet periods and that insect parasitoids were the predominant mortality factor during dry periods.