Dependence of the density of populations of the gray bud weevil (Sciaphobus squalidus (Gyllenhal, 1834)) on the types of stands of plum agroecocenoses and weather conditions

Abstract

Goal. To study the dynamics of population density of the gray bud weevil (Sciaphobus squalidus (Gyllenhal, 1834)) in plum stands of different types, and to study the influence of weather conditions on the number of this pest. Methods. The study was conducted in 2016–2020 with the use of approaches that are traditionally used in the domestic practice of plant protection during entomological research. Statistical processing of the study results was performed by multivariate analysis of variance using the AgroStat software package. Results. The forecast model of colonization of the gray bud weevil of plantations of plum of the studied variety-breeding combinations against the background of average daily air temperatures was built. This model was based on a linear equation, the variables of which were the average daily air temperatures and the number of days of vegetation after bud swelling. It was established that at an average daily temperature of 9.9 °C, the most intensive settlement of pests occurs on the stock of Krymsk 1 and Krymsk 99, respectively, 19.7 and 12.2 insects/tree. On seed stock, the number of beetles was 4.9 insects/tree. An increase in the average daily air temperature by 1°C caused an increase in the number of imago on the stock Krymsk 1 and Krymsk 99, respectively, by 3.89 and 2.23 insects/tree, and on the seed stock by 1.07 insects/tree. Conclusions. It was found that the absence of precipitation and its excess reduced the number of gray bud weevils to 1.5–7.4 insects/tree, regardless of variety-breeding combinations. The accumulation of the sum of effective air temperatures over 10°C to 86.9°C and the sum of precipitation up to 3.4 mm led to an increase in the number of imago. The occupancy of plantations by this pest by 50.4% depended on the type of rootstock and by 12.3% on the plum variety. Significantly, the interaction of the factor «variety» with the factors «type of rootstock» and «seasonal weather indicators» was, respectively, 15.9 and 14.1%.