Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: October 9, 2003
Publication Date: December 2, 2003
Citation: Martin, P.A., Gelman, D.B., Blackburn, M.B., Horise, E., Aldrich, J.R. 2003. Chromobacterium suttsuga: purple bacteria toxic to pest insects in the orders coleoptera, lepidoptera, hemiptera/homoptera, and heteroptera. American Society for Microbiology. Abstract Q-077 Vol. 104. Technical Abstract: Chromobacterium suttsuga, strain PRAA4-1 was found to kill Colorado potato beetle larvae fed on diet containing this strain. Since its discovery, these purple bacteria have been tested against a variety of pest insects and found to be toxic to pests in the orders Lepidoptera, Hemiptera/Homoptera,Heteroptera as well as in the order Coleoptera. Tests on Colorado potato beetle (Leptinotarsa decemlineata) larvae were performed using pellets of freeze-dried artificial diet. For whole cultures of bacteria, application of 10 mg wet weight per diet pellet resulted in 100% mortality in 120 hours. When a feeding stimulant laced with 30 mg/ml C. suttsuga was tested against corn rootworm adults, 80% mortality was observed after 120 hours. Adult whiteflies (Bemisia tabaci, Strain B) that were membrane-fed on artificial diet containing 5% of a cell-free bacterial preparation exhibited 100% mortality after 4 days. One hundred percent of stink bugs (Nezara viridula) that were provided with water containing the bacteria, at a concentration of 15 mg/ml, died within 6 days. For all insects tested, it was not necessary for the bacteria to be living for the preparation to be toxic. Maximum toxicity was observed when the bacterial culture was at least 48 hours old, and harvested culturesretained their toxicity for at least 2 months when stored in liquid suspension at room temperature. Data support the existence of multiple toxins, the identities of which remain elusive. When cells grown on L medium were precipitated by centrifugation, the supernatant was toxic to both whiteflies and stink bugs. However, for Colorado potato beetles, the toxicity was primarily associated with the cellular component, although additional toxic material could be removed from the cells by extraction with either Triton X or CHAPS. When either the bacterial suspension or the supernatant of a centrifuged sample of C. suttsuga was filtered through molecular weight cut-off filters, most of the toxicity was retained by the 100 KDa filter indicating that the toxins are large macromolecules or part of a large aggregate.