The Effect ofBacillus thuringiensisBerliner on the Fauna of an Apple Orchard

Abstract

Plots in a bearing apple orchard were sprayed with formulations of Bacillus thuringiensis Berliner on five to seven occasions in each of four consecutive seasons. Larvae of the winter moth, eye-spotted bud moth, orchard tent caterpillar, and fall webworm were less numerous on foliage in plots treated with B. thuringiensis than in the check plot. Numbers of free-living blister mites were reduced by treatment with the bacterium. Other phytophagous mites were not numerous in any of the plots. Injury to fruit by larvae of the codling moth, winter moth, and eye-spotted bud moth and by the mirid Atractotomus mali (Meyer) was lower in plots treated with the bacterium. Only three taxa of predacious arthropods were consistently affected by the application of B. thuringiensis; one was less numerous where the bacterium was applied and two were more numerous.