Survey for natural enemies of the invasive alien chrysomelid, Diabrotica virgifera virgifera, in Central Europe

摘要

The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is the most destructive pest of maize (Zea mays L.) in North America, and began to successfully invade Central Europe in the early 1990's. This paper reports a three-year field survey conducted in Hungary, Yugoslavia, and Croatia, which are currently the focal points of invasion, with the aim to determine the occurrence of indigenous natural enemies of D. v. virgifera in Europe. A total of 9,900 eggs, 550 larvae, 70 pupae and 33,000 adults were examined for the occurrence of parasitoids, nematodes, and fungal pathogens. It can be concluded from the survey results that effective indigenous natural enemies are not attacking any of the life stages of D. v. virgifera in Europe. The exception is the occurrence of the fungi Beauveria bassiana (Bals.) Vuill. (Mitosporic fungi; formerly Deuteromyces) and Metarhizium anisopliae (Metsch.) Sorok (Mitosporic fungi) attacking adults of D. v. virgifera at an extremely low level (< 1). However no other entomopathogenic fungal pathogens, entomopathogenic nematodes, or parasitoids were found on eggs, larvae, pupae or adults. While several natural enemies in North and Central America are known to attack D. v. virgifera, it is apparent that indigenous natural enemies in Europe have not adapted to the high population density of the alien invasive species D. v. virgifera. Classical biological control may provide an opportunity to reconstruct the natural enemy complex of an invading alien pest, and its application to manage D. v. virgifera populations in Europe should be considered.