IRRIGATION - THE BASIS FOR INCREASING THE STABILITY OF ENTOMOCENOSES IN ARID CONDITIONS OF SOUTHEAST OF RUSSIA
The article presents materials of perennial (1988-2017) studies on solving problems of stabilizing the phytosanitary situation in irrigated agrocenoses. The paper presents the results of studying the species abundance and insects, the patterns of their change under the influence of irrigation in the Lower Volga region. The effect of irrigation on the change in environmental conditions by the parameters of productivity of agrobiocenoses and microclimate is shown. The difference in air temperature in irrigated by sprinkling and non-irrigated agrocenoses immediately after watering reaches 7-8° C. In general, during the growing season, the average daily air temperatures in the irrigated agrocenosis were 2-4° C lower, compared to the non-irrigated. More mesophytic microclimatic conditions, which are formed under the influence of irrigation, are the leading factor determining the increase in the biodiversity of the entomocomplexes of irrigated agrocenoses due to an increase in species abundance and the number of mesophilic and hygrophilic insects. An increase in species diversity and abundance of meso-and hygrophilic in irrigated agricultural landscapes due to the emergence of new micro-sites (canals, spillways, storage ponds, etc.) is also shown. The formation of irrigated conditions in poly-dominant entomological communities, which increase the balance of the agroecosystem, including by optimizing its trophic structure. The changing ecological situation in irrigated agricultural landscapes determines the cultivation of plants with optimized physiological indicators, and the biological characteristics of the development of harmful and beneficial insects change under irrigation conditions. All this directly affects the relationship between phytophages and plants, as well as their survival, fertility, life expectancy of individual phases and other biological features of populations. It is noted that on irrigated crops there is a more favorable relationship between entomophages and pests, making it possible to self-regulate the entomofauna due to increased activity of entomophages. This creates a real opportunity to save the crop and reduce the pesticide load by 40-50% on irrigated crops.