ARS | Publication request: CHROMOBACTERIUM SUBTSUGAE—INSECTICIDAL EFFECTS ON CROP PESTS

Submitted to: National Entomological Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: June 30, 2005
Publication Date: November 11, 2005
Citation: Gelman, D.B., Martin, P.A., Blackburn, M.B., Hu, J.S. 2005. Chromobacterium subtsugae—insecticidal effects on crop pests. National Entomological Society of America Annual Meeting. Ft. Lauderdale, FK 12/15/05-12/18/05

Technical Abstract: Chromobacterium subtsugae, a recently discovered species of Chromobacterium, produces toxins that are insecticidal to the whitefly (Bemisia tabaci), the Colorado potato beetle (Leptinotarsa decemlineata), the Southern and Western corn rootworms (Diabrotica undecimpunctata and Diabrotica virgifera, respectively) and the diamondback moth (Plutella xylostella). Nymphal and adult whiteflies fed on artificial diets containing an aqueous extract of C. subtsugae exhibited reduced percent survival. Adult B. tabaci fed on diet containing 5% of a cell-free bacterial preparation exhibited 100% mortality after 4 days. L. decemlineata 2nd instars exhibited 100% mortality after 72-96 hours when fed on a diet that had been rehydrated with a whole culture (WCu) of C. subtsugae. For the two species of corn rootworm adults (fed on dental wicks rehydrated with a WCu of C. subtsugae) and for P. xylostella 2nd instars (fed on leaf discs having an an aliquot of a WCu of C. subtsugae) respectively, 80 – 100% mortality was achieved in six days, and 90% in seven days, after feeding was initiated. Both less than 30 kilodalton and greater than 100 kilodalton fractions (prepared using molecular weight cut-off filters) were active in B. tabaci and L. decemlineata. However, the lower molecular weight fraction was much more active in the whitefly than in the beetle causing only 20% mortality in 2nd instars of L. decemlineata. After boiling, the higher molecular weight fraction was relatively stable (B. tabaci) or slightly more toxic (L. decemlineata), while the lower molecular weight fraction was inactive (B. tabaci). Data support the existence of at least two toxins, the identities of which have yet to be determined.