SPORE COAT PROTEIN SYNERGIZES BACILLUS-THURINGIENSIS CRYSTAL TOXICITYFOR THE INDIANMEAL MOTH (PLODIA-INTERPUNCTELLA)

Sports from Bacillus thuringiensis serovars kurstaki and entomocidus s ynergized crystal protein toxicity for larvae of the Indianmeal moth ( Plodia interpunctella). Preparations of spore-crystal mixtures of eith er serovar were more toxic for the larvae than either purified sports or crystals alone (based on dry weight). Spores lost 53% of their toxi city for the Indianmeal moth after 2 h of W-irradiation, but remained partially toxic (28%) even after 4 h of irradiation, Spore coat protei n was toxic for the Indianmeal moth and was synergistic with B. thurin giensis serovar kurstaki HD-1 crystal protein. Enhanced toxicity of th e combined sport-crystal preparation was attributed to a combination o f crystal and spore coat protein, and included the effects of spore ge rmination and resulting septicemia in the larval hemolymph. Ultraviole t irradiation of spores reduced the toxicity from septicemia but not t he synergism caused by spore coat protein. The potencies of spore-crys tal preparations must be carefully evaluated on the basis of contribut ions from all three factors.