Location: Temperate Tree Fruit and Vegetable Research
Project Number: 2092-22430-003-037-T
Project Type: Trust Fund Cooperative Agreement
Start Date: May 1, 2021
End Date: Apr 30, 2023
Objectives: Our proposal is to genetically alter CpGV strains to enhance virulence as well as provide multiple modes of action to circumvent resistance. This will be realized through genetic engineering as well as genetic hybridization. (1) For genetic engineering, the candidate gene targeted for insertion into CpGV is a spider venom toxin gene, derived from the Blue Mountains funnel-web spider, known as Hvt. Hvt is specifically toxic to insects, including moths, and has been reported to have no effects on some mammals. Moreover, when transgenically expressed in plants, the toxic effect of Hvt on insects has been demonstrated, suggesting this gene is a solid candidate for transgenic insecticidal activity. CpGV will be genetically engineered to include Hvt, and subsequently tested with efficacy trials in codling moth larvae. (2) Known strains of CpGV with different host resistance-breaking characteristics will be obtained and co-cultivated with the aim to yield genetic hybrids with improved efficacy over their parental strains. These hybrid strains will be identified through molecular screening in conjunction with efficacy trials in codling moth larvae. (4) Simultaneously, OFM may be targeted with efficacy trials, and this approach may be utilized to target oblique banded leafroller (OBLR, Choristoneura rosaceana) with relevant NPVs.
Standard molecular biology methods will be utilized to genetically engineer the candidate toxin gene into the CpGV viral genome. Alternatively, genetic hybridization studies will be mediated through co-cultivation of known viral strains with different genotypes and correlate host resistance-breaking characteristics. These hybrid cultivars will be screen for novel strains with improved efficacy in codling moth control. Our in-house codling moth colony will be used to facilitate propagation of viral strains as well as initial efficacy trials for the genetically engineered and genetically hybrid viruses. Rigorous and well-controlled efficacy trials will be conducted using our codling moth colony, with the genetically engineered virus relative to non-engineered strains as well as mixed genotype strains.