Food webs and conservation biological control: What do molecular approaches offer?

Both pests and their natural enemies are embedded in food webs where they affect each other directly and indirectly. Consequently, a better understanding of food web interactions in these communities is needed to successfully establish conservation biological control measures. Examining the links in these webs, under field conditions, however, is challenging. The large number of species involved and the difficulty in measuring specific trophic interactions usually impedes the application of conventional methodology. In this talk I will demonstrate that DNA-based approaches of prey and parasitoid detection offer exciting possibilities to examine complex trophic interactions in invertebrate food webs. Using recent work done in my lab, I will show how food web interactions between pests, parasitoids, generalist predators and detritivores change throughout the growing season. Moreover, a study will be presented where the trophic linkages of juvenile generalist predators to both extra- and intraguild prey have been investigated during autumn and winter, a topic where only little information is available so far. The results from these studies highlight that trophic interactions need to be considered at the food web level to further improve pest control strategies. Based on these case studies, the advantages and future challenges of the molecular approach will be discussed as well.