Investigation of the species composition and harmfulness of dominant phytophages of onions in the Right-Bank Forest-Steppe of Ukraine

Abstract

The research is aimed at studying the species composition, dynamics of the number and harmfulness of dominant pests, which is extremely important for the development and improvement of elements of the onion protection system. After all, the analysis of literature sources showed insufficient information about the distribution and harmfulness of the main phytophages under modern conditions of growing onions in the Right Bank Forest-Steppe of Ukraine. We conducted the monitoring of the phytosanitary condition of onion crops during 2017–2020 and determined the species composition of dominant phytophages. We studied the complex of soil pests: larvae of Melolontha sp., the population density of which over the years of research was 0.8–2.5 specimens/m², larvae of Elateridae sp., or click beetles (wireworms) – 0.9–2.2 specimens/m² and Gryllotalpa gryllotalpa L. – 2.5 specimens/m². Dominant species of phytophages in onion crops included onion fly (Delia Antigua Mg.), onion thrips (Trips tabaci Lind.), and Ceuthorrhynchus jakovlevi Schultze. The four most vulnerable phases of growth and development of onions before colonization and damage by major phytophages were identified: 1) phase of leaf development (a primary shoot) (ВВСН 1–19); 2) phase of the beginning of thickening of leaf base – bulb formation (ВВСН 41–43); 3) phase of bulb formation – beginning of leaf splitting (ВВСН 45–47); 4) phase of the completion of growth and development (state of physiological rest) (ВВСН 48–49)