Pine processionary moth, Thaumetopoea wilkinsoni Tams, is an important defoliating lepidopteran pest of pine trees. The aim of this study was to determine the required spore–crystal concentration of local Bacillus thuringiensis (Bt) isolates, optimal ambient temperature, and larval stage to control this troublesome forest pest. | Turkish Journal of Agriculture and Forestry Turk J Agric For (2013) 37: 163-172 © TÜBİTAK doi: Research Article Toxicity of native Bacillus thuringiensis isolates on the larval stages of pine processionary moth Thaumetopoea wilkinsoni at different temperatures 1, 2 3 Semih YILMAZ *, Salih KARABÖRKLÜ , Uğur AZİZOĞLU , 4 4 3 Abdurrahman AYVAZ , Mikail AKBULUT , Musa YILDIZ 1 Department of Agricultural Biotechnology, Seyrani Agricultural Faculty, Erciyes University, 38039 Kayseri, Turkey 2 Department of Biology, Faculty of Arts and Sciences, Osmaniye Korkut Ata University, 80000 Osmaniye, Turkey 3 Graduate School of Natural and Applied Sciences, Erciyes University, 38039 Kayseri, Turkey 4 Department of Biology, Faculty of Science, Erciyes University, 38039 Kayseri, Turkey Received: Accepted: Published Online: Printed: Abstract: Pine processionary moth, Thaumetopoea wilkinsoni Tams, is an important defoliating lepidopteran pest of pine trees. The aim of this study was to determine the required spore–crystal concentration of local Bacillus thuringiensis (Bt) isolates, optimal ambient temperature, and larval stage to control this troublesome forest pest. The susceptibility of T. wilkinsoni larvae decreased with older stage and lower temperatures. The optimum temperature was found to be 15 °C or higher for the control of early larval stages. At the highest spore–crystal concentration (500 µg g–1), the most effective isolate () caused 83% mortality for the second-stage larvae at 5 °C. However, an approximately 4-fold decrease in mortalities was observed in late-stage larvae for all isolates examined at this temperature. Nevertheless, other Bt isolates, excluding , caused nearly complete mortality at 25 °C for early-stage larvae. Considering the distribution of seasonal temperature, Bt products should be applied at the highest ambient temperature
