Genetically engineered insect viruses are being developed by researchers in the Canadian Forest Service and elsewhere for the management of forest insect pests. Genetic engineering is believed to be capable of improving the effectiveness of viruses without affecting their environmentally desirable qualities. Regulatory authorities in Canada will require hard scientific data on environmental fate and effects in order to adequately assess their potential risk to the environment. To that end, methodologies and protocols have been developed, using unmodified nuclearpolyhedrosis viruses of gypsy moth (LdMNPV) and eastern spruce budworm (CfMNPV), to assess host range in larval Lepidoptera, and to assess infectivity in aquatic insects and fish in aquatic microcosms, and in terrestrial microarthropods in soil and litter microcosms. To date, LdMNPV is confirmed to be very host-specific while CfMNPV infects a cluster of Choristoneura species with very low frequency infection in an acrliid moth. No negative effects have been determined for aquatic insects or fish. Further developments are being made with regard to fate in the ability to extract viral materials from soil/litter matrices and from aquatic sediments. Directions being considered are the incorporation of marker genes into the genome of a modified CfMNPV to facilitate discrimination from wild-type virus as well as the use of immunoassay techniques.