My basic research is aimed at understanding the foraging behaviour and population dynamics of natural enemies, particularly parasitoids.
These small insects, often less than 2mm long, have to find their host insects in a very diverse environment in order to be able to feed and reproduce. We study the search and parasitizition behaviour of parasitoids in olfactomers, windtunnels and under natural conditions in the field. We try to find out what kind of information parastitoids use to orient themselves and find their hosts. After having arrived in an area with hosts, we determine in what way and how quickly they localize their hosts. When the parasitoid has contacted the host, we investigate how and when they decide to accept the host for egglaying. If they do not oviposit we try to find out why they reject the host. In addition, population fluctuations of parasitoids and hosts are studied in artificial and natural situations, to see if and how parasitoids are able to regulate numbers of their hosts. Side lines in my research are (1) the anatomy and sensory physiology of parasitoid ovipositors and (2) the discovery of insect parasitism.
My applied research focuses on biological and integrated pest management. One research question is how good natural enemies can quickly be distinguished from useless species. We develop selection criteria which can be applied before field evaluations are done. Part of this study is the design of an individual-based simulation model, in which the effect of changes in the biology of the natural enemy, the pest, the crop and the environment, on the biological control effect can be evaluated. Based on the initial selection with these criteria and the simulation model, natural enemies are then selected and tried out under greenhouse or field conditions. Another research project deals with the risks of importing exotic natural enemies and the design of a protocol for evaluation of exotic species. Finally, we develop criteria for quality control of natural enemies.