Intraguild parasitism promotes the persistence of facultative hyperparasitoids by extending temporal host availability
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Intraguild predation (IGP) is pervasive in natural food webs, although theoretical models predict restricted parameter space for the coexistence of IG-prey and IG-predators. One potential mechanism is that IGP persistence might be increased when IG-prey extend resource availability for IG-predators. Here we test this hypothesis using manipulative experiments in combination with mathematical modeling. Our experiment system includes Drosophila flies ( Drosophila melanogaster , basal resources), primary larval parasitoids ( Asobara leveri , IG-prey) and facultative pupal hyperparasitoid ( Pachycrepoideus vindemiae , IG-predator). We measured the performance of facultative pupal parasitoids with and without the primary larval parasitoid. Our study revealed that larval parasitoids significantly increased the number of pupal parasitoids emerged from limited host resources, due to the extended resource availability to facultative hyperparasitoid. Specifically, immature primary parasitoids within Drosophila pupae can be explored by facultative hyperparasitoids for up to 14 days, while the healthy fly pupae are available to hyperparasitoids for only 5 days. Despite a significant reduction in offspring fitness of the facultative hyperparasitoids when reared on larval parasitoids versus healthy Drosophila pupae, adult female facultative hyperparasitoids showed no significant preference for healthy fly pupae over immature primary parasitoids. Our theoretical models demonstrated that an extended development period of the primary parasitoid can promote the persistence of the facultative hyperparasitoids and allow their coexistence with the primary parasitoid, although too prolonged development could drive the extinction of the primary parasitoid. As IG-prey often take longer time to develop after consuming the shared resources, extension of temporal resource availability could be a general mechanism contribute to the persistence of intraguild predators.
Open research statement
Data are not yet available, but all of the original experimental data has been displayed in figures 2∼4. The data will be made publicly available upon manuscript acceptance and archived in the Dryad Digital Repository.
