The Reticulitermes flavipes (Kollar) peritrophic matrix: Composition, silencing and viability as a target in termite pest management
The purpose of this research was to develop novel tools for safe and effective termite pest management. The main objective of this dissertation was to generate novel termite control strategies by disturbing the R. flavipes peritrophic matrix (PM). Three specific aims were completed in order to fulfill the project main objective: 1) identify and characterize genes that encode for either structural proteins or enzymes that synthesize the main components of the R. flavipes PM, 2) silence the expression of PM components by RNA interference (RNAi) and 3) evaluate the susceptibility of R. flavipes to xenobiotics and pathogens after altering the structural integrity of the PM. After sequence identification, analysis and expression profiles of potential candidates, a chitin synthase gene (RfCHSB) and two peritrophins ( RfPMP2-III and RfPMP3-IV) were selected as targets for RNAi. The silencing efficacy of force feeding and injection was compared, using three doses of long dsRNAs. The silencing effect of siRNAs was also tested. Force feeding termites with 55 ng and 100 ng of long dsRNAs, targeting RfCHSB and RfPMP3-IV respectively, resulted in the highest gene silencing efficiency. RfCHSB expression was reduced by 70%, whereas the transcript level of RfPMP3-IV was decreased by 90%. Force feeding of 100 ng/termite of a long dsRNA reduced the expression of RfPMP2-III by 30%. Challenging termites with imidacloprid, chlorantraniliprole or noviflumuron, after silencing RfCHSB, significantly increased termite mortality. Force feeding termites a dsRNA cocktail, targeting RfCHSB, RfPMP2-III and RfPMP3-IV at the same time, cause the highest significant increase in termite mortality after challenging the insects with imidacloprid. These results demonstrate the viability of the R. flavipes PM as a target in termite pest management and represent the first step for developing novel tools for safe and effective termite control.
Scharf, Purdue University.
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