Activity of Bacillus thuringiensis cyt1Ba crystal protein against hymenopteran forest pests

A crystal-spore suspension of PS201T6 was toxic to larvae of Diprion similis (Hymenoptera: Diprionidae). Toxicity was at least in part attributable to the Cyt1Ba crystal protein, as demonstrated by bioassays of solubilized protein produced by Escherichia coli expressing PS201T6's cyt1Ba gene. PS201T6 reduced survival and growth of D. similis in a 2-week field experiment. In laboratory bioassays, both toxin and parental strain affected Acantholyda elythrocephala (Pamphiliidae), Pikonema alaskensis (Tenthredinidae), and Neodiprion sertifer (Diprionidae), as well as spruce budworm, Choristoneura fumiferana (Lepidoptera: Tortricidae). Affecting insects across at least four orders (Diptera, Coleoptera, Hymenoptera, Lepidoptera), Cyt1Ba has the broadest insecticidal activity spectrum among Bacillus thuringiensis crystal proteins documented to date. Crown Copyright (C) 2013 Published by Elsevier Inc. All rights reserved.