An invader supported by a parasite: Mistletoe berries as food and reproduction host for Drosophila suzukii in early spring in Germany

Drosophila suzukii MATSUMURA (Diptera: Drosophilidae), native to Asia, is an invasive pest species in Europe and the Americas. It is able to feed and reproduce on various fruit crops and numerous wild host plants. To identify overwintering sites and early spring hosts, monitoring traps were installed in forests at two heights. Traps in the canopy of pine trees parasitized by mistletoe captured significantly more individuals of D. suzukii than in pine trees without mistletoes. The dissection of ovaries showed mature eggs in spring collected female D. suzukii. Simultaneously berries of mistletoe were ripe. Few adults emerged from mistletoe berries incubated in an environmental chamber. Further, under lab conditions, eggs were laid into mistletoe berries and developed to adults, with higher rates in wounded than unwounded berries. Adult females were able to survive on the berries up to eight days without any other food resource. Analysing the volatile organic compounds (VOCs) of mistletoes showed thirty-two peaks. Wounded and unwounded berries differed significantly in the quantity of 11 VOCs and the whole spectrum showed many similarities of typical berry odours.