Submitted to: The Canadian Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/2/2003
Publication Date: 3/4/2003
Citation: FILOTAS, M.J., HAJEK, A.E., HUMBER, R.A. PREVALENCE AND BIOLOGY OF FURIA GASTROPACHAE (ZYGOMYCETES: ENTOMOPHTHORALES) IN POPULATIONS OF FOREST TENT CATERPILLAR (LEPIDOPTERA: LASIOCAMPIDAE). THE CANADIAN ENTOMOLOGIST. 2003. v. 135(3). p. 359-378. Interpretive Summary: Comparatively little has been known of the ecology of the major fungal pathogen affecting forest tent caterpillar, MALACOSOMA DISSTRIA. This paper is a detailed account of the operation of this fungal pathogen in natural populations of M. DISSTRIA in Maryland and New York, with strong emphasis on the way in which the fungus operates and its overall effects on nits host populations. The morphology of the fungus is documented in greater detail than has been published previously, and a taxonomic issue is addressed by proposing a new taxonomic combination, FURIA GASTROPACHAE, as the correct name for this fungus, thus replacing FURIA CRUSTOSA, a more recently name under which this fungus is most widely known. Bioassays of F. GASTROPACHAE against a relatively wide range of other lepidopterans indicate that this fungus displays a considerable degree of specificity for forest tent caterpillar. The considerable expansion and clarification of our knowledge about this fungus and its interactions with its hosts will b of benefit primarily for other scientists dealing with the fungal pathogens affecting insect pests in forests.
Technical Abstract: The entomophthoralean fungus FURIA GASTROPACHAE comb. nov. (= F. CRUSTOSA MacLeod & Tyr.) (Zygomycetes Entomophthorales) has long been associated with population declines of forest tent caterpillar (FTC), MALACOSOMA DISSTRIA (Lepidoptera Lasiocampidae), but its epizootiology & impact on host populations have never been documented. Epizootics of F. GASTROPACHAE Ewere studied in M. DISSTRIA populations in New York & Maryland. The prevalence of fungus in late 5th instar larvae in NY was 25.6+/-7.8% versus 22.2+/-11.3% infection by M. DISSTRIA nuclear polyhedrosis virus & 23.3+/-8.4% parasitism. Larvae were collected at three different stages of development in Maryland. F. GASTROPACHAE was never found in early instars, but fungal infections in 4th & 5th instars were 14.5+/-7.3% & 21.6+/-17.6%, respectively. For later instars dipteran parasitoids were also key natural enemies with 38.3+/-3.0% & 17.9+/-1.4% parasitism, respectively, but virus infected less than 5% of larvae. F. GASTROPACHAE showed a marked tendency toward resting spore production in infected larvae, with 100.0% of larvae collected in NY and > 80% of larvae collected in MD forming resting spores, either alone or together with conidia. The appearance of cadavers of larvae dying from fungal and viral infections was similar, differing significantly only in the presence of external conidia. During laboratory host range bioassays, of the 13 species of Lepidoptera exposed to conidia, only 3.3% of DANAUS PLEXIPPUS (L.) (Danaidae), 5.6% of PIERIS RAPAE (L.) (Pyralidae) and 3.7% of MANDUCA SEXTA (L.) (Sphingidae) were successfully infected by this highly host specific fungus. The morphology of F. GASTROPACHAE isolates from MD & NY is described, and we clarify the nomenclature for this species that has previously been called F. CRUSTOSA.