Evaluation of soybean varieties for resistance of agrocenoses to cotton budworm (Helicoverpa armigera) in Samara region
Samer-2 is an undoubted leader in terms of attractiveness as a feed plant both in particular years and on average during the study years. A lower pest population, even in a year with a high number of pests, was shown by Cordoba variety. The rest of the studied varieties can be attributed to medium level of feed preference for cotton budworm. The observed pattern can presumably be explained by the difference in chemical composition of different varieties of soybean, which should be confirmed by further research, as well as by density of soybean plants. The best varieties in terms of protein content in our studies were Prudence, Alaska and Protina; the latter variety does not consistently accumulate this protein, which depends on weather conditions and other factors. The lowest grain moisture was shown by Alaska soybean variety, the agrocenosis of which had a low plant density. And conversely, the wettest grain had Samer-2 variety with a high number of plants per 1 m<sup>2</sup>. On average, over three years of observation, the best and consistently high yield was shown by Cordoba variety, due to, for one of the reasons, high resistance to damage by the cotton budworm. An opposite situation was observed for Protina and Samer-2 variants, a significant number of caterpillars of the studied phytophage led to a substantial yield decrease of these varieties, especially in the year favorable for development of this pest. Prudence and Alaska variants can be classified as medium-suppressed varieties with medium yields. To obtain a stable phytosanitary situation and obtain high-quality soybean crop, it is more expedient to cultivate Cordoba (high-yield) and Prudence (high-protein) varieties, with application of Biosleep BV, Zh insecticide (41/ha) for effective protection against cotton budworm.