Assessing Wine Grape Cultivar Susceptibility to Spotted Wing Drosophila and Melanogaster-Type Drosophila in Hungarian Vineyards: Effects of Berry Integrity and Insights into Larval Interactions

The invasive spotted wing Drosophila (SWD) represents new challenges for European and North American fruit producers. The aim of our study was to examine wine grape cultivar susceptibility to this pest and melanogaster-type Drosophila (MTD) by surveying drosophilid populations using field traps and conducting emergence tests. We assessed fly development from intact and artificially injured berries collected from four cultivars. Berries were incubated individually and in pooled samples to evaluate infestation patterns and potential larval interactions. Although grapes are generally considered less favorable hosts for SWD, the pest was consistently present across all vineyard plots. Infestation levels differed significantly among cultivars, with the Hungarian white cultivar Furmint being the most susceptible, while French-origin red cultivars Cabernet Franc and Cabernet Sauvignon, along with the other Hungarian cultivar Rózsakő, were less susceptible. Berry integrity played a crucial role: intact berries showed minimal infestation, whereas physical injuries led to a substantial and significant increase in infestation rates and fly emergence. In contrast to SWD-dominated trap catches and the nearly equal proportions of SWD and MTD observed in intact berries, injured berries were predominantly colonized by MTD. This dominance became even more pronounced in pooled samples, suggesting that larval competition in shared environments favors MTD over SWD. These findings underscore the importance of grape cultivar traits and berry condition in shaping Drosophila infestation dynamics. Further research into the chemical and ecological drivers of host selection and interspecific interactions is warranted to improve vineyard pest management strategies.