Toxicity of Bacillus thuringiensis var. kurstaki to three nontarget Lepidoptera in field studies

摘要: Bacillus thuringiensis Berliner val. kurstaki is used extensively in aerial sprays for control of forest defoliators such as gypsy moth, Lymantria dispar (L.), and western spruce budworm, Choristoneura occidentalis Freeman. Although the short half–life B. field believed to minimize its impact on nontarget Lepidoptera, there increasing concern over immediate long-term effects widespread application this microbial insecticide. We examined toxicity persistence toward larvae tree-feeding swallowtail butterflies ( papilio glaucus L. p. canadensis Rothschild & Jordan) promethea Callosamia (Drury), seven their natural host plants. applied trees at a rate 40 BIU/ha with backpack sprayer equipped rotary atomizer nozzle (Micronair) was toxic early later (fourth) instars, regardless were feeding on. Long–term potted tulip placed exposed or below–canopy locations monitored 0, 10, 20, 30, d after spray. Toxicity early–instar persisted up 30 1992 1993 studies. Survival sprayed tended be lower locations, but differences not always significant. The results these studies indicate that are some lepidopterans least