A network approach reveals parasitoid wasps to be generalized nectar foragers

Authors: ZEMENICK, ASH - University Of California, Davis; Kula, Robert; RUSSO, LAURA - Trinity College; TOOKER, JOHN - Pennsylvania State University

Submitted to: Arthropod-Plant Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2018
Publication Date: 10/8/2018
Citation: Zemenick, A.T., Kula, R.R., Russo, L., Tooker, J. 2018. A network approach reveals parasitoid wasps to be generalized nectar foragers. Arthropod-Plant Interactions. 13(2):239-251.

Interpretive Summary: Parasitic wasps attack crop and forest pests that cause billions of dollars of damage annually. This paper treats flower-visiting wasps parasitic on plant-feeding insects, including foliage-feeding caterpillars and leaf-mining flies. Parasitic wasp flower visitation data were used to generate flower visitor networks to determine the extent those wasps are generalists or specialists in the use of flowers for nectar. The networks were also used to determine the extent particular plant species provide floral resources to parasitic wasp communities. Parasitic wasps were more generalized in flower visitation than expected under null models. A subset of plant species in the community supported both generalist and specialist wasps foraging nectar. Thus, some plant species supported a more diverse assemblage of wasps than others and are more efficient for conservation biocontrol. This paper will be useful to scientists conducting research in insect pest management and ecology, as well as personnel responsible for managing pest insects.

Technical Abstract: Despite many efforts to sustain parasitoid populations in agroecosystems to help control pests, relatively little is known about parasitoid-flower interactions and how dependent each partner is on the other. There are few comprehensive, species-specific, community-level observations of parasitoid-flower interactions. Observing flower visitation by parasitoid species is challenging because most parasitoids are small-bodied and visit flowers infrequently. Further, the extreme diversity of parasitoids poses challenges for identification, and only a few experts can identify parasitoids to species. To explore the potential for a flower visitor network approach to improve our understanding of parasitoid foraging ecology, we utilized published and publicly available flower-visitor datasets from the Interaction Web Database. Parasitoid species were present in almost half of the flower-visitor datasets in the Interaction Web Database but constituted a very small proportion of all flower visiting species. We analyzed the only parasitoid-flower subnetwork that was both speciose and documented heterogeneity in the number of flowering plant species visited by parasitoids. On average, parasitoids were more generalized in flower visitation than predicted under null expectations, given their prevalence in the network. Further, many individual flower and parasitoid species might be more generalized than they appeared as evidenced by a specialization metric less biased by sampling effects. These species might therefore be more useful for conservation biological control efforts than initially expected. Finally, the nested structure of the network indicates the potential for a subset of the flower community to support generalized, and any potential specialized parasitoid nectar foragers in the field.