Aphid biological control in winter wheat and canola in heterogeneous agricultural landscapes

Authors: Elliott, Norman - Norm; GILES, KRISTOPHER - Oklahoma State University; BAUM, KRISTREN - Oklahoma State University; BREWER, MICHAEL - Texas A&M University; ELZAY, SARAH - Fort Hays State University; ROYER, THOMAS - Oklahoma State University

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 5/29/2024
Publication Date: 8/27/2024
Citation: Elliott, N.C., Giles, K.L., Baum, K.A., Brewer, M.J., Elzay, S.D., Royer, T.A. 2024. Aphid biological control in winter wheat and canola in heterogeneous agricultural landscapes. In: Brewer, M.J. Hein, G.L., editors. Arthropod Management and Landscape Considerations in Large-scale Agroecosystems. Boston, MA:CAB International. p. 104-118.

Interpretive Summary: In the U.S. Great Plains winter wheat is a predominant winter crop. In the state of Oklahoma winter wheat is the dominant crop grown in the state with winter canola a rotational crop with winter wheat. There has been substantial research on the influence of landscape structure on parasitoids and aphid parasitism in winter wheat and canola in Oklahoma. Three hymenopteran parasitoid species parasitize aphids in the two crops. Diaeretiella rapae is the dominant parasitoid in winter canola and L. testaceipes dominates in winter wheat. Aphid parasitism in both winter wheat and canola are dependent on landscape structure and both agricultural and semi-natural lands are predictors of aphid parasitism. The effects of semi-natural land on aphid parasitism varies for parasitoid species in each crop. Landcover by wetlands has a positive influence on aphid parasitism by D. rapae in canola but no influence on aphid parasitism by L. testaceipes in winter wheat. Among the landscape metrics investigated only patch density was a predictor of aphid parasitism in both wheat and canola. Even for patch density the strength of the positive effect on parasitism varied markedly among the two crops. Landcover by summer crops was a predictor of aphid parasitism by L. testaceipes in winter wheat indicating bridging of parasitoids from summer crops into winter wheat in late summer through early autumn. Greater aphid parasitism by L. testaceipes and A. nigritus in winter wheat in fields where wheat is double cropped into sorghum stubble compared to fields in continuous wheat production emphasized the importance of summer crops in influencing parasitism of aphids in wheat during autumn. This chapter highlights the effects of landscape composition and configuration on parasitism of aphid pests of wheat and canola, and highlights the importance of these factors to information intensive pest management approaches.

Technical Abstract: There is a large body of information on effects of landscape structure on aphid predators and parasitoids in crops and levels of biological control. In the U.S. Great Plains winter wheat is a predominant winter crop. In the state of Oklahoma winter wheat is the dominant crop grown in the state with winter canola a rotational crop with winter wheat. There has been substantial research on the influence of landscape structure on parasitoids and aphid parasitism in winter wheat and canola in Oklahoma. Three hymenopteran parasitoid species, Diaeretiella rapae (McIntosh), Aphelinus nigritus Howard, and Lysiphlebus testaceipes (Cresson) parasitize aphids in the two crops. Diaeretiella rapae is the dominant parasitoid in winter canola and L. testaceipes dominates in winter wheat. Aphid parasitism in both winter wheat and canola are dependent on landscape structure and both agricultural and semi-natural lands are predictors of aphid parasitism. The effects of semi-natural land on aphid parasitism varies for parasitoid species in each crop. For example, landcover by wetlands has a positive influence on aphid parasitism by D. rapae in canola but no influence on aphid parasitism by L. testaceipes in winter wheat. Among the landscape metrics investigated only patch density was a predictor of aphid parasitism in both wheat and canola. Even for patch density the strength of the positive effect on parasitism varied markedly among the two crops. Landcover by summer crops was a predictor of aphid parasitism by L. testaceipes in winter wheat indicating bridging of parasitoids from summer crops into winter wheat in late summer through early autumn. Greater aphid parasitism by L. testaceipes and A. nigritus in winter wheat in fields where wheat is double cropped into sorghum stubble compared to fields in continuous wheat production emphasized the importance of summer crops in influencing parasitism of aphids in wheat during autumn.