The effect of some food industrial wastes and byproducts on the development and insecticidal activity of Bacillus thuringiensis

Today, the knowledge of agricultural and health pest management using biological control method is expanding, and among these, Bacillus thuringiensis as a bio–pesticide with high efficiency and safety have a major role in pest control. However, due to high production costs, it has not yet been able to replace chemical pesticides. In the present study, to promote pesticide and cost–effective cultivation Bt subspecies kurstaki native strain 6R, food waste and by–products including wheat bran, soybean pulp, corn powder and corn steep , fish meal, date juice, sugar beet molasses and sugarcane bagasse were evaluated as raw fermentation media. In this study, the above substances were studied as food culture medium as an extract and as a liquid for propagation. Factors of spore and crystal production were measured during the fermentation process in different cultures for 72 hours, including bioassay on Helicoverpa armigera larval stage three, dry biomass weight, spore content and the effect of pH. The results showed that Bt from wheat bran, sugarcane molasses and corn steep substrates on H. armigera larval stage three has 100% mortality. The highest dry biomass of Bt after the end of fermentation was related to corn powder, wheat bran and corn steep, as 0.903, 0.7804 and 0.559 g per 100 ml of suspension culture, respectively. The results showed that corn steep culture medium with the highest Bt production in laboratory conditions (2.8 × 1012 CFU / ml) was the most efficient. In combination of two culture media, beet molasses (carbon source) with corn steep  (nitrogen source) with 4.22 × 1012 CFU / ml and wheat bran (carbon source) with corn steep  with 3.44 × 1012 CFU / ml, each two had the best performance with 100% mortality on H. armigera larvae. Overall, our findings provided a new strategy for using food waste and by–products with less environmental impact and reduced production costs.