The effect of Bacillus thuringiensis serotype kurstaki (Btk) as an insecticide on jack pine budworm in the 2019 Northern Ontario spray program in comparison to historical use

Abstract

Bacillus thuringiensis (Bt) has been used historically as an insecticide by the Ontario Ministry of Natural Resources and Forestry (OMNRF) to suppress jack pine budworm populations in dense outbreaks. In some previous spray programs the methods used to determine spray initiation and calculate success of the spray program was not performed by OMNRF resource technicians, but rather had been contracted out to external workers. 2019 was the first year since the 1990’s that OMNRF resource technicians based out of Thunder Bay Ontario performed on site observations to track spray initiation and success. A comparison of the 2019 operation with previous efforts showed the effectiveness of Btk as a jack pine budworm suppression, contrasting to previous efforts on historical outbreaks. The methodology followed was provided and carried out by the OMNRF forest health program. The results showed that the effectiveness of Btk as a biological insecticide has not decreased over the time it has been used in Ontario. The change of internally performing the development and assessment of the spray led to the 2019 spray program as a success alongside previous spray programs in the province.