I. Virus-based strategies for management of insect pests

Baculoviruses are arthropod-specific viruses that have been studied extensively both as protein expression vectors and as insect pest control agents, and more recently for use in human gene therapy. Baculoviruses are being developed as environmentally benign alternatives to chemical pesticides for management of certain insect pests. To enhance their insecticidal efficacy, baculoviruses have been genetically engineered with genes encoding insect-specific toxins that are active within the hemocoel of the insect. On infection of the insect host, the toxin is produced as the virus replicates, and the infected insect dies from the effects of the toxin delivered by the virus. Baculoviruses have been engineered with genes encoding a variety of insecticidal proteins and peptides. The most effective enhancement of insecticidal properties of the virus has been achieved by introduction of genes into the virus genome that encode basement membrane-degrading proteases. Recombinant baculovirus insecticides have been developed that now approach the efficacy of the classical chemical insecticides.

Baculoviruses

1. Identification of molecular determinants of baculovirus host range

We are interested in determining the genetic basis for the greater virulence of Rachiplusia ou multicapsid nucleopolyhedrovirus (RoMNPV) compared to that of Autographa californica MNPV against specific lepidopteran pests. Understanding the genetic determinants of host range may allow for development of designer baculoviruses for management of multiple pest species in a given cropping system.

Harrison, R.L. and Bonning, B.C. 2003. Comparative analysis of the genomes of Rachiplusia ou and Autographa californica multiple nucleopolyhedroviruses. Journal of General Virology 84: 1827-1842. Output files from selection pressure analyses (1.4 MB).

Harrison, R.L. and Bonning, B.C. 2004. Application of maximum likelihood models to selection pressure analysis of group I nucleopolyhedrovirus genes. J. Gen. Virol. 85: 197-210 Output and data summary files (3.04 MB).

Researchers: Wendy Sparks

2. Cost-effective production of baculovirus insecticides

In collaboration with Dr. David Murhammer, we are exploring the possibility of producing a clone of the baculovirus Autographa californica nucleopolyhedrovirus that is stable in continuous cell culture and resistant to insertion of transposons. This would allow for cost-effective, large scale production of baculovirus insecticides.

Researchers: Huarong Li

3. Novel insect toxins for pest management

We are working to determine the mechanism of insecticidal action of the protease ScathL, a Sarcophaga peregrina cathepsin L that specifically degrades basement membrane. This protease has potential for use in insect resistant transgenic plants when combined with an appropriate delivery system. We are also working on development of novel aphicidal toxins.

Harrison, R.L. and Bonning, B.C. 2001. Use of proteases to improve the insecticidal activity of baculoviruses. Biological Control 20: 199-209.

Li, H., Tang, H., Harrison, R.L. and Bonning, B.C. 2007. Impact of a Basement Membrane-Degrading Protease on Dissemination and Secondary Infection of Autographa californica Multiple Nucleopolyhedrovirus in Heliothis virescens L. J. Gen Virol. 88: 1109-1119.

Philip, J., Fitches, E., Harrison, R. L., Bonning, B.C. and Gatehouse, J.A. 2007. Characterisation of functional and insecticidal properties of a recombinant cathepsin L-like proteinase from flesh fly (Sarcophaga peregrina), which plays a role in differentiation of imaginal discs. Insect Biochem. Molec. Biol. 37(6): 589-600.

Researchers: Huarong Li, Hailin Tang, Sijun Liu, Nina Richtman

Schematic diagram of hypothesized mechanism of action of basement membrane degrading protease.

4. Risk assessment of a recombinant baculovirus insecticide that expresses a basement membrane-degrading protease

The Autographa californica nucleopolyhedrovirus was engineered to express the proteolytic enzyme Sarcophaga peregrina cathepsin L that specifically degrades basement membrane. This virus is among the fastest recombinant baculoviruses developed to date. We have shown that this recombinant baculovirus has no deleterious impact on non-target predatory insects, and minimal impact on insects that parasitize lepidopteran larvae.

Harrison, R.L. and Bonning, B.C. 2001. Use of proteases to improve the insecticidal activity of baculoviruses. Biological Control 20: 199-209.

Boughton, A.J., Obrycki, J.J, Bonning, B.C. 2003. Effects of a protease-expressing recombinant baculovirus on nontarget insect predators of Heliothis virescens. Biological Control 28(1):101-110.

Nusawardani, T., Ruberson, J.R., Obrycki, J.J. and Bonning, B.C. 2005. Effects of a protease-expressing recombinant baculovirus insecticide on the parasitoid Cotesia marginiventris (Cresson). Biological Control 35(1):46-54.

Dicistroviruses

Use of small RNA viruses for aphid control

In collaboration with Dr. W. Allen Miller, we are examining the potential use of the aphid virus, Rhopalosiphum padi virus for management of aphid pests.

Boyapalle, S., Pal, N., Miller, W.A., Bonning, B.C. 2007. A glassy-winged shartpshooter cell line supports replication of Rhopalosiphum padi virus (Dicistroviridae). J. Invertebr. Pathol. 94(2): 130-139.

Pal, N., Boyapalle, S., Beckett, R., Miller, W.A. and Bonning, B.C. 2007. A baculovirus-expressed dicistrovirus that is infectious to aphids. J Virol. (in press).

Researchers: Pending (see positions available)

Luteoviruses

In collaboration with Dr. Allen Miller, we are investigating the potential for exploitation of aphid-transmitted viruses for management of aphids. See project summary.

Researchers: Sijun Liu, Zhaohui Wang (Miller lab)

II. Analysis of a juvenile hormone esterase binding protein

Juvenile hormone esterase (JHE) helps to regulate the titer of juvenile hormone and, hence, larval development in insects. JHE is cleared from the hemolymph by athrocytes via receptor-mediated endocytosis, and is degraded in lysosomes. We are currently investigating the role of a novel 29 kDa JHE binding protein (P29) in relation to the biology of JHE. We are using both the tobacco hornworm Manduca sexta, and the fruit fly Drosophila melanogaster as model systems for the study of the JHE binding protein. Disruption of the intracellular trafficking of JHE has potential as a target for development of novel insecticides.

Bonning, B.C., Ward, V.K., van Meer, M.M., Booth, T.F. and Hammock, B.D. 1997. Disruption of lysosomal targeting is associated with insecticidal potency of juvenile hormone esterase. Proceedings of the National Academy of Sciences USA 94 (12):6007-6012. [Full Text]

Bonning, B.C., Possee, R.D. and Hammock, B.D. 1999. Insecticidal efficacy of a recombinant baculovirus expressing JHE-KK, a modified juvenile hormone esterase. Journal of Invertebrate Pathology 73: 234-236.

Shanmugavelu, M., Baytan, A., Chesnut, J.D. and Bonning, B.C. 2000. A novel protein that binds juvenile hormone esterase in fat body and pericardial cells of the tobacco hornworm Manduca sexta L. Journal of Biological Chemistry 275(3): 1802-1806. [Full Text]

Shanmugavelu, M., Larysa Porubleva, Parag Chitnis, and Bonning, B.C. 2001. Ligand blot analysis of juvenile hormone esterase binding proteins in Manduca sexta L. Insect Biochem. Molec. Biol. 31(1): 51-56. [Full Text]

Liu, Z., Ho, L., Bonning, B.C. 2007. Localization of a Drosophila melanogaster homolog of the putative juvenile hormone esterase binding protein of Manduca sexta. Insect Biochem. Molec. Biol. 37(2): 155-163.

Liu, Z., Pal, N., Bonning, B.C. 2007. Potential ligands of DmP29, a putative juvenile hormone esterase binding protein of Drosophila melanogaster. Insect Biochem Molec Biol 37: 838-846.

Researchers: Pending