LABORATORY ASSESSMENT OF THE EFFECTS OF BACILLUS-THURINGIENSIS ON NATIVE LEPIDOPTERA

The effect of 2 formulations of Bacillus thuringlensis subsp, kurstaki (Foray 48B and Dipel 8AF) was evaluated on 42, species of native Lepi doptera in laboratory bioassays using instars that are present in the field at the time of gypsy moth suppression applications. Mortality wa s significant for 27 of the 42 species evaluated against Foray 48B, an d 8 of 14 species evaluated against Dipel 8AF. Susceptible species wer e noted in 5 of 6 families assayed-Papilionidae, Nymphalidae, Geometri dae, Lasiocampidae, Saturniidae, and Noctuidae. The 1 species treated in the Lymantriidae family was not susceptible to B. thuringensis. Tre ated individuals that survived for a week were likely to reach adultho od. Intrageneric differences in susceptibility to B. thuringiensis wer e recorded among 8 species of Catocala and 3 species of Lithophane ass ayed. Of the 18 species assayed as Ist or 2nd instars, mortality was s ignificant, usually exceeding 95%. By contrast, 9 of 11 species not su sceptible to B. thuringiensis were assayed as penultimate or ultimate instars. However, species susceptible to B. thuringiensis were found i n both early and late instars.