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BACILLUS THURINGIENSIS VAR. KURSTAKI AFFECTS A BENEFICIAL INSECT, THE CINNABAR MOTH (LEPIDOPTERA: ARCTIIDAE)
Citation:
James, R., J. Miller, AND B. Lighthart. BACILLUS THURINGIENSIS VAR. KURSTAKI AFFECTS A BENEFICIAL INSECT, THE CINNABAR MOTH (LEPIDOPTERA: ARCTIIDAE). U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-93/206.
Description:
The microbial insecticide bacillus thuringiensis Berliner var. kurstaki is used to control forest pests in regions where tansy ragwort, Senecio jacobaea L. occurs. iological control of this noxious weed may be compromised if the cinnabar moth, Tyria jacobaeae (L), is susceptible to B. thuringiensis. n laboratory feeding tests, we found that foliage dipped in B. thuringiensis solutions had very little effect on survival of first, second, and third instars, but fourth and fifth instars were susceptible. ield tests were done to test the effect of B. thuringiensis on larval defoliation of potted tansy ragwort plants at five different application rates. he application rate significantly affected percentage of leaves defoliated and mean number of cinnabar moth-days per plant. n both control plants and those treated with B. thuringiensis, defoliation by cinnabar moth did not affect plant biomass within the 10-d course of the experiment. esults of the laboratory and field experiments suggest that the pesticide could interfere with the biological control of tansy ragwort if applied to areas where the weed occurs and when late-instar cinnabar moths are active. owever, most applications for western spruce budworm, Choristoneura occidentalis Freeman, and gypsy moth Lymantria dispar (L), occur when only early instars of cinnabar moth are present.