Identification of Bacillus Thuringiensis Endotoxins Active Against Adult Asian Citrus Psyllid
Invasive Insect Biocontrol and Behavior Laboratory
Project Number: 1245-22000-272-08
Start Date: Oct 30, 2013
End Date: Apr 30, 2016
The objective of this project is to screen strains of the bacterium Bacillus thuringiensis (Bt) for activity against the Asian citrus psyllid (ACP) and to identify ACP-active crystal (Cry) toxins. ARS will provide a variety of Bt strains with various toxicities. Collaborators will isolate and activate toxins for testing against ACP. Relatively few toxins have been reported to have toxicity against the sap-sucking hemipteran pests. For example, Bt endotoxins have been shown to possess aphidicidal activity against the potato aphid and the pea aphid. The identification of aphid-active Cry toxins suggests that there is sufficient toxin diversity within Bt strains to find toxins active against Asian citrus psyllid. ARS expects to identify psyllid-active Cry toxins which will be useful for management of the psyllid. The use of such toxins would reduce the need for insecticide application against the psyllid, and would reduce the transmission of the bacterial agent responsible for huanglongbing disease.
ARS will screen at least 200 Bt strains for toxicity against ACP. Total crystal proteins from these strains will be purified, activated using bovine trypsin, and tested for ACP toxicity. Individual Cry toxins from ACP-toxic Bt strains will be purified to homogeneity by ion-exchange and gel filtration column chromatography. These individual toxins will then be tested for ACP toxicity and identified by Matrix-assisted laser desorption/ionization Time-of-flight mass spectroscopy/mass spectroscopy. ARS has all of the necessary expertise and resources needed to conduct this research.