Patch Time Allocation and Search Intensity of Asobara Tabida Nees (Braconidea), a Larval Parasitoid of Drosophila

Abstract

We studied three factors affecting the allocation of patch time and the intensity of searching by the larval parasitoid Asobara tabida Nees. We found that: 1. A. tabida reacts to a water-soluble kairomone, produced by its host Drosophila melanogaster Meigen in that a) time spent on a patch (yeast patch in which D. melanogaster larvae had crawled and fed) increased in a S-shaped fashion with increasing kairomone concentration. b) the searching intensity by the parasitoid increased with increasing kairomone concentration until it levels off at higher concentrations. 2. A. tabida recognized areas previously searched by a conspecific and spent less time and searched less intensely on such patches as compared to unsearched patches. 3. Patches with a reduced quality (reduced amount of living yeast) for the host are less attractive for the parasitoid which spends less time and searches less intensely on such patches than on patches with a better quality for the host. The response of the parasitoid to these three factors contributes to the optimization of time allocation. The increase in search intensity can eventually cause a sigmoid functional response and may enhance population stability.