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United States Department of Agriculture

Agricultural Research Service

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Research Project: Inhibition of Aquaporin for Novel Control of Bemisia Tabaci

Location: Pest Management and Biocontrol Research

2011 Annual Report


1a.Objectives (from AD-416)
The whitefly Bemisia tabaci is one of the most important pests of agricultural and ornamental crops worldwide, causing direct feeding damage, negatively affecting post-harvest of numerous crops, and transmitting devastating plant viral diseases. B. tabaci feeds exclusively on plant sap, and therefore has evolved a unique digestive system that handles excess dietary fluid and maintains osmotic pressure. Previously, we characterized an aquaporin protein from B. tabaci (BtAQP1) that functions as a water channel protein to transport water through the specialized digestive tract. The objective of the proposed cooperative research is to test novel antagonists specifically developed to target aquaporins and ascertain if these agents interfere with water permeability of the BtAQP1 and thus negatively impact B. tabaci. Compounds optimized for efficacy and specificity against insect aquaporin targets represent a novel insecticidal approach for insect pest control.


1b.Approach (from AD-416)
We propose to first evaluate agents that are fast unidirectional blockers of water flux as well as slower bidirectional blockers against BtAQP1 produced using a frog oocyte expression system. Any compounds found to be effective on the BtAQP1 in the oocyte expression system, would then be tested on the developing and adult whiteflies. Compounds will be tested against B. tabaci by direct application and through oral feeding, using both plants and artificial feeding systems. For promising compounds, we will develop a chemical library of analogs around the active structure, and improve potency for selective channel block and whitefly efficacy.


3.Progress Report

The whitefly Bemisia tabaci is one of the most important pests of agricultural and ornamental crops worldwide, causing direct feeding damage, negatively affecting post-harvest yields of numerous crops, and transmitting devastating plant viral diseases. B. tabaci feeds exclusively on plant sap, and therefore has evolved a unique digestive system that handles excess dietary fluid and maintains osmotic pressure. We intend to evaluate specific inhibitors that target channel proteins that regulate water permeation in the digestive tract of B. tabaci and exhibit insecticidal activity against this pest. This nonfunded cooperative agreement contributes directly to the goals of CRIS project 5347-22620-021-00D “Sustainable Pest Management Strategies for Arid-Land Crops,” specifically to Objective 1 – Develop knowledge and control tactics based on the physiology, biochemistry, genetics and vector-pathogen interactions of insect pests. We previously characterized an aquaporin protein from B. tabaci that functions as a water channel protein to transport water through the specialized digestive tract. Host cells (unfertilized frog oocytes) were used to produce the B. tabaci aquaporin channel proteins and demonstrate functionality, and two general aquaporin inhibitors were tested to confirm the type of channel formed. This oocyte expression system is established within the collaborator’s laboratory at the University of Adelaide and will be used to screen additional aquaporin antagonists possessing higher specificity for targeting water channel function. Any compounds found to be effective in the oocyte expression system will then be tested on the developing and adult whiteflies. Compounds will be tested against B. tabaci by direct application and through oral feeding, using both plants and artificial feeding systems. Although optimization of artificial feeding systems for immature and adult B. tabaci is ongoing, prototype bioassays are currently available. Promising compounds demonstrating inhibitory and insecticidal properties against B. tabaci will be modified to generate chemical libraries to increase specificity and inhibitory activity. Progress of project is maintained via email and phone contact between the collaborators, as well as a visit to ALARC by collaborator.


Last Modified: 4/17/2014
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