Nahrungsökologie des invasiven Maisschädlings Diabrotica virgifera virgifera LeConte in Europa

Abstract

The nutritional ecology of the invasive maize pest Diabrotica virgifera virgifera LeConte (Chrysomelidae, Galerucinae) was studied with regard to larval and adult food use and performance on various host plants. The adult beetles are feeding mainly on aboveground maize tissues, while the larvae are root feeders on maize and other Poaceae species. This leaf beetle was first detected 1992 near Belgrade and has spread into 15 European countries already. Models predict infestation to occur in all but northern European countries in the following years.The results of the study aim towards a more detailed understanding of processes which determine the invasion potential and success of this pest species. The use of different food resources by adult beetles in Southern Hungary were studied over a 10 week period. In order to evaluate the use of different maize tissues a gut content analyses was performed. Furthermore a detailed pollen analyses was carried out to estimate the use of alternative pollen sources.The adult beetles showed a high adaptability with regard to their nutritional ecology in their new range. The majority of all flowering weeds were used as alternative pollen sources. The use of maize tissue and pollen from alternative host plants by adult beetle was depending on maize phenology, diversity of flowering weeds in a given habitat and the sex of the beetles. The performance of larvae on maize cultivars from different European countries and several alternative host plants was tested. A new method was developed that allowed to measure how efficient D. v. virgifera larvae performed in transferring plant biomass into own body biomass.Larval performance showed significant differences on different European maize varieties. The larvae performed well on several other grass species which are common weeds in maize fields and also on some monocot crops as winter wheat. They were unable to use roots of dicot weeds as for example Amaranthus sp. Larval performance on different maize varieties and alternative host plants was related to the total nitrogen content, the C/N ratio and the phytosterol composition encountered in the host plant tissues. The results are discussed with regard to counteract the invasion and damage potential by developing measures of integrated pest management.