Submitted to: Society for Invertebrate Pathology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2001
Publication Date: 8/1/2001
Citation: FILOTAS, M.J., HAJEK, A.E., HUMBER, R.A. EPIZOOTIOLOGY OF THE ENTOMOPHTHORALEAN FUNGUS, FURIA GASTROPACHAE N. COMB. (= F. CRUSTOSA), IN POPULATIONS OF THE FOREST TENT CATERPILLAR. SOCIETY FOR INVERTEBRATE PATHOLOGY ANNUAL MEETING. 2001. Interpretive Summary:
Technical Abstract: The entomophthoralean fungus FURIA GASTROPACHAE (FG; = F. CRUSTOSA) has long been associated with declines in populations of the forest tent caterpillar (FTC), MALACOSOMA DISSTRIA, although its epizootiology and impact on host populations have never been documented. Epizootics of FG were studied in FTC populations. Prevalence of FG in late 5th instar larvae collected from sites in New York was 25.6 plus/minus .8% compared t 22.2 plus/minus 11.3% infection by M. DISSTRIA nuclear polyhedrosis virus and 23.3 plus/minus 8.4% parsitism by tachinid and sarcophagic flies. In Maryland, larvae were collected at three different stages of development. FG was never found in early instar larvae while fungal infections in 4th and 5th instars were 14.5 plus/minus 7.3% and 21.6 plus/minus 17.6%, respectively. For these later instars parasitoids were also important, with 38.3 plus/minus 3.0% and 17.9 plus/minus 1.4%,respectively. Virus infections were observed in less than 5% of larvae collected in Maryland. FG showed a marked tendency toward resting spore production in infected larvae, with 1000% of larvae from NY and >80% of those from MD forming resting spores alone or together with conidia. The appearances of cadavers of larvae killed by FG and NPV were compared. Insects killed by fungus and virus differed significantly only in the presence of external conidia; differences in cadaver appearances were subtle and hard to distinguish in the field. Host range bioassays were conducted in the laboratory. Of the 13 lepidopteran species tested, only 3.3% of DANAUS PLEXIPPUS, 5.6% of PIERIS RAPAE and 3.7% of MANDUCA SEXTA exposed to conidial showers were successfully infected by this highly host-specific fungus.