Use of flowering plants to enhance parasitism and predation rates on two squash bug species Anasa tristis and Anasa armigera (Hemiptera: coreidae)

Authors: Cornelius, Mary; Vinyard, Bryan; Gates, Michael

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/18/2019
Publication Date: 9/25/2019
Citation: Cornelius, M.L., Vinyard, B.T., Gates, M.W. 2019. Use of flowering plants to enhance parasitism and predation rates on two squash bug species Anasa tristis and Anasa armigera (Hemiptera: coreidae). Insects. 10:318.

Interpretive Summary: The use of floral resources in urban farms can increase ecosystem services, such as pollination and biological control. This study examined the effects of a flowering border on the natural enemies of squash bugs. This study evaluated the effect of a flowering border of buckwheat on rates of egg parasitism, egg predation and adult parasitism on two squash bug species, Anasa tristis (DeGeer) and Anasa armigera Say, by comparing rates in squash fields with and without a flowering border. Further, we evaluated whether there was an edge effect by comparing parasitism and predation rates in plots located in the corner of a squash field with plots located in the center of a squash field for fields with and without a flowering border. Egg parasitism rates were not affected by either treatment (flowering border or control) or plot location (edge or center). Egg parasitism rates increased gradually throughout the season, peaking in the last week of August at 37.7%. The most common egg parasitoid recovered was Gryon pennsylvanicum (Ashmead) followed by Ooencyrtus anasae (Ashmead). Adult parasitism was not affected by treatment, but adult parasitism rates were higher in plots located on the edge of squash fields compared with plots located in the center of squash fields. Because adult parasitoid, Trichopoda pennipes (Fabricius), flies were observed visiting buckwheat flowers, future studies could explore the possibility that the flowering buckwheat may have more impact on adult parasitism if there was a greater distance between fields with and without a flowering border. Although floral resources play an important role in increasing populations of pollinators and other beneficial insects, their role in enhancing parasitoid populations in squash fields requires further investigation.

Technical Abstract: This study evaluated the effect of a flowering border of buckwheat Fagopyrum esculentum Moench on rates of egg parasitism, egg predation and adult parasitism on two squash bug species, Anasa tristis (DeGeer) and Anasa armigera Say, by comparing rates in squash fields with and without a flowering border. Further, we evaluated whether there was an edge effect by comparing parasitism and predation rates in plots located in the corner of a squash field with plots located in the center of a squash field for fields with and without a flowering border. Egg parasitism rates were not affected by either treatment (flowering border or control) or plot location (edge or center). Egg parasitism rates increased gradually throughout the season, peaking in the last week of August at 37.7%. The most common egg parasitoid recovered was Gryon pennsylvanicum (Ashmead) followed by Ooencyrtus anasae (Ashmead). Adult parasitism was not affected by treatment, but adult parasitism rates were higher in plots located on the edge of squash fields compared with plots located in the center of squash fields. Because adult parasitoid, Trichopoda pennipes (Fabricius), flies were observed visiting buckwheat flowers, future studies could explore the possibility that the flowering buckwheat may have more impact on adult parasitism if there was a greater distance between fields with and without a flowering border.