Research Accomplishment Reports 2011

Genomic Approaches to Analyses of Immune-suppressive Genes of the Campoletis sonorensis Polydnavirus

B.A. Webb
Department of Entomology

 

Non-Technical Summary

Control of insect pests requires novel approaches on an ongoing basis because insects have demonstrated the ability to evolve resistance to many insect control practices. This project seeks to develop novel approaches to insect control that take advantage of new means to suppress the insect immune system.

2011 Project Description

Over the last year, this project has focused on establishing the molecular and biological interactions between a newly discovered insect virus, the Heliothis virescens cypovirus. This virus has two variants, one of which is preferentially associated with the Heliothis larvae and one of which is associated with the Campoletis sonorensis wasp, a parasitoid of H. virescens. At the molecular level, the two variants can be distinguished by a duplication in the viral RNA segment that encodes the cypovirus polyhedrin gene. The presence of this partial duplication is associated with the H. virescens host with the transcript and polyhedrin protein levels elevated relative to the other variant. The variant that is wasp-associated has pathological effects on wasp larvae that reduces the survival of this beneficial insect.

We have developed methods for isolating and propagating the two cypovirus variants and begun to study the biology of transmission and distribution of each variant. It is clear that the cypovirus interacts with wasp parasitism in complex ways. Given that cypoviruses, and other RNA viruses, are common but understudied because of their minimal pathology in lepidopteran we expect that the interactions between cypoviruses, polydnaviruses, parasitic wasps and their lepidopteran hosts are complex and biologically significant. having established some molecular tools and methods, the focus of our studies in the coming year will be elucidation of these relationships.

2011 Impact

We have developed methods for isolating cypovirus variants, raised an antibody to the polyhedrin protein that can be used to track virus infections in tissue extracts, determined the molecular distinctions between the two viral variants and begun to describe the biology of these viral interactions and their impact on the two hosts. I know that these studies are novel in our field and believe that our work will open a new area for future investigations that heretofore has not been appreciated. This is a newly discovered phenomena and our work on this topic is not yet published but we are now working on 3 publications on the topic for submission in the coming year.

2011 Publications

Volkoff A-N, Drezen J-M, Cusson M and Webb B.A. (2011) The organization of genes encoding ichnovirus structural proteins. IN Parasitoid Viruses eds. Beckage N.E. and Drezen J-M Academic Press ISBN 9780123848581, pp 33-46.