C. J. Lucarotti


Executive Summary

The gregarine, Leidyana canadensis (Apicomplexa: Eugregarinida) was found infecting the guts of larvae in a declining population of the hemlock looper, Lambdina fiscellaria fiscellaria (Lepidoptera: Geometridae) in Charlotte County, New Brunswick. Total mortality, in rearing, of field-collected larvae and pupae was 75.5% in 1993 and 89.2% in 1994. Leidyana canadensis infections were present in 60.1 % and 80.5% of these dead insects in the two respective years. The incidence of L. canadensis in larvae that died in rearing was greater than 50% for all instars except for those collected in the fifth instar, where the incidence was below 30%. Gregarine infections were present in first-instar larvae on the first days of collection both years and, in 1994, 74% of all first-instar larvae collected were infected with L. canadensis. Of 678 larvae collected in 1994, 73 survived to adults and of these, 44 had harbored L. canadensis as larvae. The incidence of other microbes and parasitoids in dead larvae and pupae were also reported.

Guts of infected larvae were chemically fixed, embedded in epoxy resin, and sectioned for light and electron microscopy to describe the cytology of L. canadensis and its pathology in the larval host.

The polyhedrin gene of the eastern hemlock looper nuclear polyhedrosis virus was cloned, sequenced and compared to the polyhedrin genes of the nuclear polyhedrosis viruses of the western hemlock looper and the western oak looper. Eastern and western hemlock looper nuclear polyhedrosis virus polyhedrin genes shared considerable sequence homology but neither crosshybridized to the polyhedrin gene of the western oak looper nuclear polydrosis virus.