Project Number: 6402-22000-045-12
Project Type: Specific Cooperative Agreement

Start Date: Jul 14, 2006
End Date: Jul 31, 2009

Objective:
1) To assay sensitivity of susceptible and resistant insects to specific Bt toxins to investigate the spectrum of Bt resistance in D. saccharalis (year 1); 2) To assess the genetic basis of Bt resistance in D. saccharalis in mating studies with susceptible (SS) and resistant (RR) individuals (year 1); 3) To analyze gene regulation using microarray techniques and identify potential candidate genes associated with Bt resistance in D. saccharalis (Year 1); 4) To compare midgut proteinase activity and gene profiles of susceptible and resistant insects to determine if Bt resistance in D. saccharalis is associated with changes in midgut proteinases (Years 1 and 2); and 5) To compare target-site binding affinity and gene structure between susceptible and resistant insects to determine if Bt resistance in D. saccharalis is related to changes in Bt binding receptors (Years 1 and 2).

Approach:
Physiological mechanisms of resistance will focus on insect proteinase activity and target-site binding affinity. Functional genomics analysis of candidate resistance genes (aminopeptidase, cadherin, proteinase, and other potential genes) will elucidate the molecular mechanisms. These techniques will include molecular cloning, gene sequencing, microarray analysis, gene expression, and gene knockout by using double strand RNA interference (dsRNAi).