Monitoring Diabrotica v. virgifera (Col.: Chrysomelidae) in southeastern Slovenia: increasing population trend and host spectrum expansion.

Ever since the western corn rootworm (WCR) (Diabrotica virgifera virgifera), an alien invasive species from North America, has been introduced into Europe on at least 3 separate occasions, it spread within 15 years over the entire area of south-eastern and central Europe (except Denmark). Until quite recently, Zea mays L. was the only known host plant whereas in North America WCR also attacks members of the plant family Cucurbitaceae. In August of 2006, we were able to validate these findings also in the Old World by observing WCR visiting blossoms of oil pumpkin (Cucurbita pepo L.). Beside this first report of WCR on this regionally and economically important crop, a population increase in Gaberje near Lendava, Eastern Slovenia, was observed. Some future consequences of multiple hosts for integrated pest management (IPM) of WCR are being discussed.