A novel Bacillus thuringiensis strain and its pathogenicity against three important pest insects

Abstract

A highly pathogenic Bacillus thuringiensis (Bt) strain was isolated from a soil sample in Turkey and characterized in terms of both its 16S-ITS rDNA region and cry gene content. This strain (SY49.1) harboured several cry genes producing crystalline inclusions known to have toxicity on lepidopteran, dipteran and coleopteran pests. The 16S-ITS sequence analysis of Bt SY49.1 showed 98% similarity to Bt serovar andalousiensis BGSC 4AW1. The larvae of Ephestia kuehniella and Plodia interpunctella were treated with a spore-crystal mixture of this strain in the dose range of 50-1000 mu g g(-1). Mortality rates were higher than 90% at the highest concentration for these pests. For Tribolium castaneum much higher concentrations were needed than with lepidopteran pests larvae. At the highest concentration tested of 10 mg g(-1), about 62% mortality was obtained. It was concluded that this native strain of Bt could be used as an effective biocontrol agent against various lepidopteran pests. (C) 2012 Elsevier Ltd. All rights reserved.