competitors, have a great influence on what parasitoids do and can
achieve, and we need to incorporate these considerations in our behav-
ioural studies and theoretical models. Simple optimal foraging studies
under a specific set of conditions are becoming less popular, due to
the increasing awareness of the importance of food-web ecology and
complexity in species interactions. This is especially important when we
want to assess the importance of behavioural variation for population and
community processes. The behaviour-based approach, as highlighted in
this chapter, is not only important for gaining insight into why individu-
als act as they do. The individual parasitoids together form the population
and their individual success determines their individual number of off-
spring, which together will be the next generation. Thus behaviour of
individuals determines the spatial distribution of parasitism over patches
and ultimately the population dynamics of both host and parasitoid.
Since insect parasitoids play a significant role in the combat of insect
pests, we need to make a stronger effort to link the behavioural variation
of parasitoids to parasitoid–host population dynamics. The study of the
behaviour of insect parasitoids has a promising future. Its behavioural-
ecological approach of blending theoretical and empirical aspects can
probably serve as a model for behavioural studies with other parasite
species.60 L.E.M. Vetet al.
Fig. 3.2. The behaviour of a parasitoid is the result of a complex integration
process in the central nervous system, with input from and feedback to the sensory
level and the parasitoid’s physiological state.