Understanding plant-mediated interactions between two major maize pests of eastern Europe – from phytochemical patterns to management recommendations

Insect herbivores interact with each other via shared host plants. Understanding the consequences of plant-mediated interactions between different consumers is crucial to elucidate distribution patterns in nature and to understand how insect communities influence plant fitness and yield in agroecosystems. Here, we propose to study how root-infestation by the western corn rootworm Diabrotica virgifera influences oviposition and performance of the European corn borer Ostrinia nubilalis. These two insects are the major maize pests in Eastern Europe and have a massive impact on agricultural productivity in Serbia and Hungary. As D. virgifera only recently invaded the region, very little is known about its interaction with the native O. nubilalis. Studying how these two insects influence each other will not only fill a major gap of fundamental knowledge regarding the influence of root feeders on stem-borers, but will be indispensable to develop integrated pest management recommendations that enable farmers to optimize their cultural practices.By combining the expertise of the consortium partners, a series of experiments will be carried out to gain a detailed and agriculturally relevant picture on the interaction between D. virgifera on O. nubilalis. First, a field experiment in Serbia will be conducted to find out how root-attack changes the oviposition behavior of O. nubilalis. The results will be complemented with laboratory studies and volatile analyses with gas chromatography/mass spectrometry (GC/MS) and gas chromatography/ electorantennography (GC/EAD) in Hungary to identify the compounds that are responsible for the observed behavior. Second, a field experiment will be performed to investigate how D. virgifera influences O. nubilalis larval growth, performance and migration patterns. Again, the field data will be supplemented by a series of laboratory experiments in Switzerland involving high performance liquid chromatography (HPLC) metabolite profiling to pinpoint the phytochemical changes behind the field patterns. In a third experiment, the net effect of both herbivores on plant damage and yield will be measured in a realistic field setting in order to create detailed pest management recommendations for Serbian farmers