Plant-aphid-natural enemy relations and intraguild interaction

To promote the perennial and ubiquitous stinging nettle as a profitable source for aphid management programs in agro-ecosystems, it is of primary importance that the diversity and seasonal abundance of aphids and their natural enemies are known. For this purpose, agricultural and semi-natural habitats were investigated over two full cropping seasons in Gembloux, Belgium. Our field data support the strategies aimed to exploit stinging nettle habitats as important reservoir for aphidophagous insects that tended to occur early on this marginal plant, before attacking aphids in adjacent field crops. Moreover, our findings suggest that stinging nettle habitat offers many important requisites for the survival of natural enemies, such as alternative prey that are not available persistently in annual cultures. Our data on the spatial distribution of aphid predators have identified varied influences, such as the food preferences and intraguild interactions. For natural enemy population management, promising results were obtained from our behavioural bioassays. As a conclusion, stinging nettles can play important roles in agro-ecosystems.