Weather and landscape influences on pollinator visitation of flowering winter oilseeds (field pennycress and winter camelina)

Authors: FORCELLA, FRANK - Retired ARS Employee; PATEL, SWETABH - Iowa State University; LENSSEN, ANDREW - Iowa State University; HOERNING, CODY - University Of Minnesota; WELLS, M - University Of Minnesota; Gesch, Russell - Russ; BERTI, MARISOL - North Dakota State University

Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2020
Publication Date: 5/1/2021
Citation: Forcella, F., Patel, S., Lenssen, A.W., Hoerning, C., Wells, M.S., Gesch, R.W., Berti, M.T. 2021. Weather and landscape influences on pollinator visitation of flowering winter oilseeds (field pennycress and winter camelina). Journal of Applied Entomology. 145(4):286-294. https://doi.org/10.1111/jen.12854.
DOI: https://doi.org/10.1111/jen.12854

Interpretive Summary: Pollinators, including native and domestic bees, are on the decline in part due to loss of habitat and poor nutrition resulting from increased urbanization and lack of plant diversity across the agricultural landscape. Winter camelina and pennycress, two emerging cash cover crops that flower very early in spring and summer, provide an abundant source of pollen and nectar for pollinators at a critical time for their health and survival. The visitation of pollinating insects to these winter oilseeds during flowering was monitored at three sites in the Upper Midwest. Average seasonal visitation rates across years and sites varied from 1.6 to 5.3 insects per minute for field pennycress and 1.4 to 4.5 insects per minute for winter camelina. Lowest visitation rates occurred in central Iowa and highest rates in southeastern Minnesota for both crops. Visitation of certain pollinator types tended to correlate with select variables. For example, in pennycress, visitation by bumble bees and honeybees increased with greater air temperature at sampling time and annual site precipitation, whereas fly visitation was related to sampling date and flower cover. Similarly, in winter camelina, visitation of solitary bees was linked to increasing air temperature and precipitation, while fly activity correlated to wind speed and flower cover. Pennycress and winter camelina are attractive to pollinating insects across a wide geographic region. However, visitation rates and proportional representation of different pollinator types depended on a range of site and weather characteristics. This research is of value to apiarists, ecologists, conservationists, Natural Resource Conservation Service personnel, and Upper Midwest growers interested in alternative crops.

Technical Abstract: Flowers of two cash cover crops, field pennycress (Thlaspi arvsense L.) and winter camelina [Camelina sativa (L.) Crantz.], produce abundant pollen and nectar in early spring and thereby may be valuable for pollinators. Such insects were monitored for two years at three sites in the Upper Midwest. Average seasonal visitation rates across years and sites varied from 1.6 to 5.3 insects min-1 for field pennycress and 1.4 to 4.5 insects min-1 for winter camelina. Lowest visitation rates occurred in central Iowa and highest rates in southeastern Minnesota for both crops. Multiple regressions showed that visitation rates for specific insect groups were correlated poorly but significantly (P < 0.10) with select variables. For example, in field pennycress, visitation by bumble bees and honeybees (Apis mellifera) (Apidae) increased with greater air temperature at sampling time and annual site precipitation, whereas fly (Diptera) visitation was related to sampling date and flower cover. Similarly, in winter camelina, solitary bees were linked to increasing air temperature at sampling time and annual site precipitation, whereas flies were correlated with wind speed and flower cover at sampling. Field pennycress and winter camelina are reliably attractive to beneficial pollinating insects across a wide geographic region, but visitation rates and proportional representation of various insect groups depended on a range of site and weather characteristics.