ACTIVITY OF CRY1 ENDOTOXINS OF BACILLUS-THURINGIENSIS FOR 4 TREE FRUIT LEAFROLLER PEST SPECIES (LEPIDOPTERA, TORTRICIDAE)

Nine formulated preparations of Cry1 endotoxins of Bacillus thuringien sis Berliner were bioassayed against four tree fruit pest species (Lep idoptera: Tortricidae): Argyrotaenia citrana (Fernald), Choristoneura. rosaceana (Harris), Pandemis pyrusana Kearfott, and Platynota stultan a (Walsingham). Larvae were fed surfaced-treated artificial diet in th e laboratory and direct mortality was scored after 5 and 12 d. The LC( 50)s within species varied as much as 200-fold across preparations. Es timates of LC(50)s were improved in the 12-d versus the 5-d assay for many of the endotoxins. The LC(50)s to the Cry1A and Cry1E(a) endotoxi ns were significantly lower across all four species compared with Cry1 C, Cry1D, Cry1E(b), and Cry1F endotoxins. Larval developmental time an d pupal weights of surviving P. pyrusana were significantly affected i n bioassays with two rates (0.01 and 0.001% stock solution) of each en dotoxin. Larval development was delayed and pupal weight was significa ntly lower for both sexes at the higher rate compared with the lower r ate of each endotoxin. The sex ratio of survivors for each endotoxin/r ate tested was not correlated with larval survivorship.