FLEXIBLE PATCH TIME ALLOCATION BY THE LEAFMINER PARASITOID, OPIUS-DIMIDIATUS

1. The ability to use flexible decision rules can be an advantage to p arasitoid females searching for patchily-distributed hosts. In a serie s of laboratory experiments the hypothesis that Opius dimidiatus, a so litary parasitoid of the chrysanthemum leafminer (Liriomyza trifolii), adjusts the time she allocates to searching for her larval hosts in r esponse to both patch qualities and experiences with hosts was tested by varying such patch parameters as area, presence of host mines and d ensity of host mines, and by allowing ovipositions and encounters with parasitized hosts. 2. Though leaf area was not a factor, the presence of host mines in a leaf did increase the time a female O.dimidiatus s pent searching, over time spent on unmined leaves. 3. When host mine d ensity was increased, females responded by increasing their search per iod in a density-dependent manner, suggesting a perception of patch qu ality. 4. Ovipositions in hosts caused females to reset their 'giving- up time' (GUT), or increase search intensity, by adding an amount of s earch time that increased with each successive oviposition. Conversely , encounters with parasitized (unsuitable) hosts incremented the GUT, but by an amount that decreased with each successive encounter.