Submitted to: National Entomological Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: October 29, 2003
Publication Date: December 10, 2003
Citation: Gelman, D.B., Blackburn, M.B., Hu, J.S. 2003. Tcaiii is not required for photorhabdus luminescens toxin complex a's toxicity against adult silverleaf whiteflies (bemisia tabaci strain b). National Entomological Society of America Annual Meeting. 88th Annual Mtg. Aug. 3rd- Aug. 8 Technical Abstract: Artificial diets that will support adult silverleaf whiteflies (SLWF) for 10-15 days have been developed and used to test the toxicity of potential insecticidal compounds. Mean SLWF longevity was not significantly different on diets containing sucrose and either yeast extract or free amine (a mixture of amino acids) or sucrose and both yeast extract and freamine. Diet preparations must be sterilized by filtration since the temperature and pressure attained in the autoclave reduced the nutritional value of the yeast. Photorhabdus luminescens is an enteric symbiont of Heterorhabditid nematodes. These nematodes, upon invading a host insect, regurgitate the bacterium into the hemocoel. The bacteria multiply rapidly creating a raging septicemia that results in the death of the insect. P. luminescens produces a wide array of factors and toxins which disable the immune system of many insects and kill and digest them. Toxin complex A is composed of three gene products, TcaA, TcaB, and TcaC. TcaA and TcaB, in turn, contain three (TcaAi, TcaAii and TcaAiii) and two (TcaBi and TcaBii) subunits, respectively. Our laboratory has developed improved methods for purifying P. luminescens toxin complexes. Diets containing P. luminescens toxin complex A with or without subunit TcaAiii, a 66 kDa peptide, reduced the percent survival of adult SLWFs in a similar dose-dependent manner. Thus, the presence of TcaAiii does not appear to be required for the observed toxicity of P. luminescens Toxin complex A.