Dispersal between host populations in field conditions: navigation rules in the parasitoid Venturia canescens


Emmanuel Desouhant, Université C. Bernard, Lyon 1, UMR CNRS 5558 ‘Biométrie et Biologie Evolutive’, Bât- 741 G. Mendel, 43 Bd du 11 Novembre 1918, 69622 Villeurbanne, France. E-mail: desouhan@biomserv.univ-lyon1.fr


Abstract. 1. Dispersal is a life-history trait that can have great ecological and evolutionary consequences, however understanding of how insects disperse is limited.

2. Navigation rules of the solitary koinobiont parasitoid of the pyralid moth larvae Venturia canescens (Gravenhorst) were studied in conditions that it is likely to meet when dispersing between host populations and in the absence of cues related directly to the presence of hosts.

3. Mark–release–recapture experiments were conducted in a natural host-free habitat, and letting the animals disperse for different periods.

4. In the presence of vegetation, wasps seemed to disperse rapidly (1 h for an area of ≥ 1 ha) and capture rates were independent of both dispersal time and distance from the release point.

5. The navigation rules of V. canescens during dispersal between tree stands can be summarised as: move up- or down-wind, avoid or pass through open, sunny areas, and go for shady and dense vegetation.

6. The consequences of the navigation rules for host–parasitoid dynamics are discussed in relation to different spatial scales.