Moshe Coll, Sulochana Shakya - Department of Entomology, The Hebrew University of Jerusalem, Rehovot, Israel

Omnivory, the feeding on both plant and prey material, and intraguild predation (IGP) are common in ecological systems. For the most part, these complex trophic interactions have been studied separately. Yet some predators are often involved in both omnivory and IGP. We therefore tested these interactions together, in a system that consisted of strawberry plants, western flower thrips (WFT) and two of its predators, the mite Neoseiulus cucumeris and the bug Orius laevigatus. All three are omnivorous consumers that feed on strawberry pollen; WFT damages strawberry fruit, the mite preys on first instar WFT, and the bug feeds on WFT and the mites. We asked: (i) what is the effect of pollen feeding on intensity of IGP? (ii) what is the combined effect of omnivory and IGP on WFT suppression? and (iii) what is the importance of the within-plant distribution of the predators in relation to prey feeding site, for pest-inflicted damage to strawberry fruit? Results show that (i) predation on N. cucumeris by O. laevigatus was significantly lower in the presence of pollen than in its absence; (ii) significantly fewer WFT were killed by the predators in the presence of pollen than in its absence; (iii) in the presence of pollen, WFT and both predators primarily reside in flowers rather than fruit and leaves; (iv) in the absence of pollen, WFT were recorded primarily on fruits; (v) in the presence of pollen, N. cucumeris is found in the flowers only when O. laevigatus is absent; else, the mites are found on the fruits or leaves; and (vi) when both predators are present, significantly lower fruit damage was observed in the absence of pollen than in its presence. Taken together, results show that omnivorous feeding and differential response to heterogeneously distributed resources buffer herbivory and IG predatory interactions. This may allow for complex trophic interactions, such as omnivory and IGP, to persist and be common in nature.