The shape of the functional response curve of Dolichogenidea tasmanica (Hymenoptera: Braconidae) is affected by recent experience

• Dolichogenidea tasmanica exhibited a sigmoid functional response in wind tunnels and enclosed cages.
• Parasitism rates were lower in the cages, possibly due to the lack of moving air which provides a directional cue.
• Recent experience with high host densities increases the searching rate of D. tasmanica.
• At lower host densities that are characteristic of wild populations, D. tasmanica responded in a density-dependent manner.
• This manner should contribute to suppression of pest populations before they reach economically damage levels.

Dolichogenidea tasmanica (Hymenoptera: Braconidae) is the most commonly collected parasitoid of light brown apple moth, Epiphyas postvittana (Lepidoptera: Tortricidae; LBAM) in Australia. We studied the functional response of D. tasmanica, and the effect of recent experience on this behavior. The functional response was evaluated in wind tunnels and enclosed cages. In both arenas, D. tasmanica exhibited a sigmoid functional response, but there was no clear tendency for a deceleration in the functional response curve at high host densities as would be expected with a typical type III functional response. Another experiment revealed that recent experience with high host densities increases the proportion of hosts parasitized by D. tasmanica, which explains much of the difference between the observed functional response curve and a typical type III curve. In general the searching behavior of D. tasmanica varies in response to host density in a manner that directly affects its searching rate. Our results have contributed to understanding the behavior of this parasitoid and indicate its capacity to control its host under laboratory conditions. At lower host densities that are characteristic of field populations, D. tasmanica responded in a density-dependent manner that should contribute to suppression of pest populations before they reach economically damaging levels.

Figure optionsDownload as PowerPoint slide