Multi-year observation of the population development of Drosophilidae in the vineyard and its surroundings

On the one hand, several Drosophilidae species are classified as pests in viticulture (D. suzukii, D. melanogaster, D. simulans), as they can damage the berries and/or use them to lay eggs, thus being vectors of undesired microorganisms. On the other hand, the diversity of this group of animals in the vineyard habitat has hardly been studied, so little is known about their significance in this regard. This paper aims to reduce this knowledge gap. Using traps containing 0.5 l of a lure liquid made from wine (3/4) and fermenting grape juice (1/4), the Drosophilidae fauna of a vineyard ('Pinot Noir'), of the surrounding forest edge ( shrubbery deciduous forest) and of food waste dumped in the open (compost) was investigated. All 15 trap locations were along the southwestern slopes of the Leithagebirge near Eisenstadt. A total of 42 Drosophilidae species were detected, and their abundance changes were documented over the course of the year. By far the species with the greatest number of individuals was the neozoon Drosophila suzukii, to which more than half (approx. 46,000) of the total of over 80,000 specimens examined and determined at species level could be assigned. The year 2016 was exceptional, accounting for the vast majority (60 %) of all catches. The most important contribution to this annual difference was made by D. suzukii. The year 2016 was characterized by a late frost at the end of April, a particularly high rainfall in late spring and early summer and a comparatively cool August. In 2016, in contrast to the other years in the vineyard, D. suzukii was dominant over the other Drosophilidae species, the sample from the vineyard near the forest edge containing significantly more individuals of this species than samples further in the vineyard (depending on the year between 40 % and 228 %). A marginal effect is assumed because D. suzukii showed a significantly higher abundance at the tree line than in the vineyard and was the dominant species here besides D. subobscura. With the exception of 2016, D. suzukii only played an insignificant role in compost (7 % and 15 % of all individuals, resp.). The temporal course of the change in abundance of D. suzukii and other species (D. melanogaster, D. simulans, D. subobscura, D. immigrans, D. phalerata and D. kuntzei) is shown for the study years and with different climate parameters (air temperature, precipitation, sunshine duration and global radiation). With regard to Drosophilidae species diversity and species composition, the surroundings of the vineyard are of great importance.