Estimation of acute toxicity of bioinsecticide Turinbash-G for honey bee Apis mellifera mellifera L.

Introduction. Pesticide poisoning is one of the main causes of mass death of bee colonies observed in different countries of the world. However, at present, abandoning the use of plant protection products is not possible, since insects and crop weeds are responsible for the loss of at least half of the world's food supply. An increase in insect pest activity due to global warming will lead to even greater losses. All this dictates the need for a wider introduction of biological methods of plant protection. Bioinsecticides based on entomopathogens can become an alternative to chemicals that have a pronounced toxic effect on nontarget organisms.

Methods. The object of the study was honey bee Apis mellifera mellifera L. of the Carpathian breed, subjected to oral and contact exposure to Turinbash-G, the active ingredient of which is the bacterium Bacillus thuringiensis subsp. aizawai strain 12K and Bacillus thuringiensis subsp. thuringiensis, strain VNIIVEA-177. As a guide, the work used «Methodological recommendations for assessing the effect and potential hazard of pesticides for honeybees», approved by the Russian Academy of Agricultural Sciences and the Department of Veterinary Medicine of the Ministry of Agriculture of the Russian Federation, as well as GOST 33038-2014 and GOST 33039-2014 «Mеthods for testing chemical products posing a danger to the environment.» In the course of the studies, the acute oral toxicity and acute contact toxicity of the active substance of Turinbash-G.

Results. Studies have not revealed signs of acute toxicity of the Turinbash-Zh bioinsecticide for honey bees both with oral and with contact exposure to the drug. The maximum mortality rate of bees in the experimental groups 96 hours after the end of exposure to the studied drug is 16.7%. LD₅₀ in determining the acute oral toxicity of the active substance of the drug Turinbash-Zh — above the value of 1·10⁶ CFU/bee, LK₅₀ — above 100 ml/l; in determining the acute contact toxicity LD₅₀ above the value of 1·10⁵ CFU/bee, LK₅₀ — above 100 ml/l.

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