Resistance assessment of natural populations of grain reserves pest to phosphine

In modern conditions, one of the most important tasks of the state is self-sufficiency in grain reserves. In this context, not least essential is the safety of grain while minimizing its losses and damage by insect pests. According to resent investigations results, one of the efficient means against pests of grain reserves is the phosphine gas. Phosphine has been widely used in Russia since the early 90s of the XX century. The article presents the study results on resistance to phosphine of the fusty flour beetle (Tribolium castaneum), larvae of the khapra beetle (Trogoderma granarium Ev.), imago of the wheat weevil (Sitophilus granaries L.) at every development stage. We have estimated a very close dependence of the mortality of Tribolium castaneum at any development stage in natural and laboratory populations on the concentration of phosphine. The Rostov population of the mace-eared crustacean is better resistant to phosphine than the laboratory population at any development stage. At the same time, imago of both laboratory and Rostov populations are not as resistant to the action of the insecticide as the egg stage. The study has identified a strong correlation between the mortality of active larvae in both natural and laboratory populations of Trogoderma granarium Ev. on one hand and the concentration of phosphine on the other. By the probit analysis results, the Petersburg population of active larvae of the khapra beetle is better resistant than the laboratory population, but their resistance will decrease as the exposure time increases. Experimentally studied and mathematically described is the dependence of adult mortality in natural and laboratory populations of Sitophilus granaries L. on the concentration of phosphine. The resistance index to phosphine in imago of the Stavropol, Krasnodar and Tambov populations is 1.5; 1.4 and 1.6, respectively.