Flies associated with floral canopies of the new oilseed crop, pennycress, in the Midwestern U.S.A.

Authors: FORCELLA, FRANK - Retired ARS Employee; PETERSEN, MATTHEW - University Of Minnesota; PERRY, WILLIAM - Illinois State University; WELLS, SAMANTHA - University Of Minnesota; HARD, ALEX - University Of Minnesota; Gesch, Russell - Russ; Mohammed, Yesuf; HOERNING, CODY - University Of Minnesota; WESLEY, TAD - Western Illinois University; AMBROSI, E - University Of Minnesota; PHIPPEN, WINTHROP - Western Illinois University

Submitted to: Great Lakes Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2024
Publication Date: 3/1/2024
Citation: Forcella, F., Petersen, M., Perry, W., Wells, S.S., Hard, A., Gesch, R.W., Mohammed, Y.A., Hoerning, C., Wesley, T.L., Ambrosi, E., Phippen, W. 2024. Flies associated with floral canopies of the new oilseed crop, pennycress, in the Midwestern U.S.A. Great Lakes Entomologist. 56(3-4):154-165. https://doi.org/10.22543/0090-0222.2463.
DOI: https://doi.org/10.22543/0090-0222.2463

Interpretive Summary: Pennycress is a new winter oilseed crop being developed for biofuels, that fits into Midwestern crop rotations serving as a cash cover crop. Flies are significant pollinators of mustard plants like pennycress. However, the extent of fly visitation to pennycress flowers and the identity of them is largely unknown. Fly visitation to flowering pennycress was examined over five site-years in Illinois and Minnesota. The number of fly species that visited averged16 per site-year. Syrphid flies (aka hover flies) were common visitors, and their larvae tend to prey on aphids, which is a beneficial trait. However, the most common fly visitors belonged to the family Anthomyiidae, which made up 51% of all collected flies. Although adult flies from this family are known pollinators, the larvae of some species can damage seedlings of common summer crops. Therefore, close observation of this insect group may be needed in the future if pennycress is grown widely as a cash cover crop. Results will benefit scientists, industry, and producers working to develop pennycress as a commercial crop.

Technical Abstract: Flies are frequent visitors to and can be significant pollinators of many species of plants within the mustard family (Brassicaceae). Field pennycress (Thlaspi arvense L.) is a mustard specie that is being developed as a new “cash cover crop,” i.e., an autumn-sown cover crop whose oil-rich seeds can be harvested profitably in spring. Although pennycress is largely self-pollinated, its flowers also attract insect visitors. However, the extent of visitation to pennycress flowers by flies remains largely unknown, especially the identities of those flies. Thus, we examined fly visitation to pennycress flowering canopies at five site-years in Illinois and Minnesota. The number of fly species averaged 16 per site-year. Hover flies (Syrphidae) were common visitors to pennycress flowers, representing 24% of all Diptera collected. Toxomerus marginatus Say (margined calligrapher), whose larvae are aphid predators, was especially abundant within this family. However, the most common flies detected were Anthomyiidae, in particular Delia spp. Meigen, which averaged 51% of all flies collected. Adults of these flies are known pollinators, but their larvae also are pests that can damage seedlings of common summer crops. Although seedling damage to plants relay- (i.e., interseeded) or double-cropped with pennycress has not been observed yet, close observation of this insect group may be needed if pennycress is widely sown in the future as a cash cover crop.