Diversity, rate, and distribution of wheat midge parasitism in the Peace River region of Alberta, Canada

Citation

Dufton, S.V., Laird, R.A., Floate, K.D., Otani, J.K. (2021). Diversity, rate, and distribution of wheat midge parasitism in the Peace River region of Alberta, Canada, 153(4), 461-469. http://dx.doi.org/10.4039/tce.2021.7

Plain language summary

Wheat midge is a major, economic pest of spring wheat in the Canadian prairies. It was first reported in the Peace River region of northwestern Alberta in 2011. Natural enemies, including predators and parasitoids, are an important component of the integrated pest management of wheat midge. In particular, parasitoids can regulate and help reduce the severity and frequency of wheat midge outbreaks. Parasitoids are organisms that parasitize but ultimately kill their hosts. In North America, three species of wasp parasitoids were introduced to help manage wheat midge including: Macroglenes penetrans, Euxestonotus error, and Platygaster tuberosula. Although parasitism is an important factor of mortality in wheat midge elsewhere, little is known about the prevalence, species, or distribution of wheat midge parasitoids in the Peace River region. This knowledge gap was addressed by conducting a survey of wheat midge parasitoids in commercial wheat fields across the region in 2016 and 2017. Wheat midge larvae were collected from wheat heads and were overwintered. The following spring, the emergence of wheat midge adults and parasitoid adults was recorded. For a given field, parasitism of wheat midge larvae ranged from 36 to 71%. All but one parasitoid (n = 2,167) were identified as Macroglenes penetrans. The exception was a specimen in the genus Inostemma tentatively identified as I. walkeri. These findings identify parasitism as an important factor that is suppressing populations of wheat midge in the Peace River region, provide the first report of Inostemma walkeri for North America, and provide the first report of this species as a parasitoid of S. mosellana. Parasitoids make up an important, environmentally sustainable component of wheat midge management in Canada. In the Peace River region, the rates of parasitism in this study indicate that M. penetrans helps suppress wheat midge populations and efforts should be made to promote and preserve it. Further research in this region should focus on changes to parasitoid diversity and how parasitism works within a broader program of wheat midge management.

Abstract

© 2021 Cambridge University Press. All rights reserved.Wheat midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), is a major pest of wheat (Poaceae) that was first reported in the Peace River region of northwestern Alberta, Canada in 2011. Although parasitism is an important factor of mortality in wheat midge elsewhere, little is known about the prevalence, species, or distribution of wheat midge parasitoids in the Peace River region. To address this knowledge gap, we conducted a survey of wheat midge parasitoids in commercial wheat fields across the region in 2016 and 2017. For a given field, parasitism of wheat midge larvae ranged from 36 to 71%. All but one parasitoid (n = 2167) were identified as Macroglenes penetrans (Kirby) (Hymenoptera: Pteromalidae). The exception was a specimen in the genus Inostemma tentatively identified as I. walkeri Kieffer (Hymenoptera: Platygasteridae). These findings identify parasitism as an important factor that is suppressing populations of wheat midge in the Peace River region, provide the first report of Inostemma walkeri for North America, and provide the first report of this species as a parasitoid of S. mosellana.

Publication date

2021-08-01

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