PHYLLOPLANE STERILIZATION WITH BLEACH DOES NOT REDUCE BTK TOXICITY FOR PAPILIO-GLAUCUS LARVAE (LEPIDOPTERA, PAPILIONIDAE)

Neonate tiger swallowtail larvae (Papilio glaucus) were used to bioass ay the effects of Btk (Bacillus thuringiensis var. kurstaki) at 4 dose s (0.268, 0.034, 0.008, and 0.004 BIU per cm(2) leaf surface) with an untreated control. Larvae, obtained from females captured in Geogria a nd North Carolina, were fed leaves of either tulip tree (Liriodendron tulipfera) or black cherry (Prunus serotina) in experiments that eithe r included a pre-treatment dip and rinse in 5% chlorox bleach or not, before the application of Btk(dipping leaves in serially diluted solut ions of Foray 48B). The results show no difference between North Carol ina and Georgia P. glaucus larval dosage sensitivities, but do illustr ate a clear dosage effect for all 4 treatments (cherry with and withou t bleach pre-treatment; tulip tree with and without bleach pre-treatme nt). The larvae on the bleached leaves do not do better (for cherry or tulip tree host plant) as would be expected if microbial symbionts on the phylloplane synergize the Btk toxicity These results show that Bt k (at doses several thousand-fold less than aerial sprays across fores ts for gypsy moth control) will kill P. glaucus, with or without micro bial synergism on leaf phylloplanes.