GENETIC-VARIABILITY IN THE AREA SEARCHED BY A PARASITIC WASP - ANALYSIS FROM AUTOMATIC VIDEO TRACKING OF THE WALKING PATH

The ability of foraging hymenopterous parasitoid females to discover t heir hosts, and thus to be efficient agents in biological control prog rams, is likely to be related to the surface they are able to prospect per unit of time. However, this behavioural trait has never been accu rately estimated, and its implication in female efficiency has never b een really demonstrated. This paper provides an algorithmic method tha t can be used to estimate this trait from an automatic recording of th e females' walking path. Using stochastic procedures simulating walkin g tracks, this trait is shown to be strongly related to the number of hosts that parasitoid females are able to attack per unit of time. Thi s trait was estimated for individual females of Trichogramma brassicae Bezdenko (Hymenoptera; Trichogrammatidae). On average, females of thi s species are able to prospect about 28 mm(2) s(-1). Finally, the gene tic variation in this trait was studied using the iso-female line meth od. A significant genetic variability was observed, It provides the ba sic information that is necessary to start a genetic selection of mass -reared Trichogramma in order to improve their efficiency in controlli ng target pests in biological control programs. The functional and evo lutionary implications of these results are discussed. (C) 1998 Elsevi er Science Ltd. All rights reserved.