Population monitoring and status evaluation of the new invasive pest, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), in various crop systems of Georgia (Sakartvelo)

Abstract

The spotted wing drosophila, Drosophila suzukii (Matsumura, 1931), population fluctuations and distribution were monitored in four susceptible crops (blueberry, strawberry, cherry, wine grapes) and five major agricultural regions of Georgia (Guria, Samegrelo, Imereti, Kartli and Kakheti) during the years 2021 and 2022 with the aim to study the population size and evaluate the pest status. Population monitoring was conducted in four locations of each studied region on a weekly basis from May to November using PHEROCON® SWD traps with PHEROCON® SWD PEEL-PAK™ Broad Spectrum Lures. The investigation indicated significant growth of population from 2021 to 2022 in most of the studied locations. Population increase was detected in all crop orchards except cherries. Τhe absence of alternative host plants at crop proximity was of critical importance to save the crop from pest invasion. The crop plant species did not have a significant impact on D. suzukii. Pest population was significantly larger in summer and autumn compared to spring, possibly influenced by the ripening of alternative crops such as blackberry and elderberry. The sex ratio between male and female individuals was almost 1:1 and remained consistent through the two-year study period and across regions. We consider that D. suzukii entered the country from the southwestern part and extended its distribution range towards the east. No strategies for D. suzukii control have been elaborated in Georgia so far. Sprays of effective pesticides based on pest monitoring as well as sanitation measures involving removal of alternative host plants and any crop residues from the field are necessary to avoid pest outbreak.