Submitted to: Journal of Insect Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/3/2007
Publication Date: 5/22/2008
Citation: Mcintosh, A.H., Grasela, J.J., Long, S.H., Shelby, K. 2008. Isolation and characterization of a baculovirus associated with the insect parasite Cotesia marginiventris. Journal of Insect Science. 8:1-19. Interpretive Summary: Baculoviruses are important insect viruses used in the control of insect pests that attack both forest and field crops resulting in the lost of millions of dollars annually. These viruses which are harmless to beneficials and do not infect vertebrates are of great value because they can be used in place of toxic chemical insecticides which pollute the environment and may get into the food chain. In the course of experiments with parasites that attack insect pests, a baculovirus was discovered associated with the parasite and was isolated, identified, characterized and tested for its activity against several agricultural important pests. This virus although related to some existing viruses is nevertheless a new virus and was very effective against the insect pests under study. The impact of such a finding will provide both the scientific community as well as industry with another biological control agent that can be used in the control of insect pests.
Technical Abstract: A multiple nucleopolyhedrovirus was found associated with the parasitoid Cotesia marginiventris and was isolated from stung Trichoplusia ni larvae which were used to rear the parasite. The wild type virus was plaque purified by infecting a Heliothis subflexa (BCIRL-HsAM1) cell line and isolating several clones. A clone designated as CmBMNPVCL9 was used in bioassays against several lepidopteran pests and in comparative studies with the baculoviruses AcMNPV, AgMNPV, AfMNPV, PxMNPV and HzSNPV. Infectivity studies showed that CmBMNPV was highly infectious for Heliothis subflexa and Trichoplusia ni, with an LC50 value 0.07 OB/mm**2 in both species and also infectious for Helicoverpa zea and Heliothis virescens with LC50 values of 0.22 and 0.27 OB/mm**2, respectively. Restriction enzyme analysis revealed profiles that were very similar to AfMNPV but different from the REN profiles of the other baculoviruses. Hybridization studies suggests that the CmBMNPVCL9 was closely related to AfMNPV and AcMNPV-HPP. Further support for this comes from a phylogenetic analysis employing a split-graphs network, comparing the polh and egt genes from CmMNPVCL9 with those from other baculoviruses and suggests that this virus is closely related to the AcMNPV variants, AfMNPV and Rachiplusia ou (RoMNPV). CmBMNPVCL9 although related to other baculoviruses appears to be a new virus.