Nectar production in oilseeds: Food for pollinators in an agricultural landscape

Authors: Thom, Matthew; Eberle, Carrie; Forcella, Frank; Gesch, Russell - Russ; Weyers, Sharon; Lundgren, Jonathan

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/7/2015
Publication Date: 2/19/2016
Publication URL: http://handle.nal.usda.gov/10113/61958
Citation: Thom, M.D., Eberle, C.A., Forcella, F., Gesch, R.W., Weyers, S.L., Lundgren, J.G. 2016. Nectar production in oilseeds: Food for pollinators in an agricultural landscape. Crop Science. 56:727-739.

Interpretive Summary: Pollinating insects are in decline throughout the world, driven by a combination of factors including the loss of food resources. The corn- and soybean-dominated agriculture of the Central and Midwestern US produces a landscape that has very little nectar and pollen for pollinators. Introducing specialty oilseeds into current crop rotations could provide abundant floral resources for pollinating insects as well as a high-value crop for growers. We showed that the oilseed crop echium produced the most sugar from nectar, at 421 lbs per acre. All of the oilseed crops were found to attract a wide variety of pollinating insects including bees, flies, butterflies and beetles. Beekeepers will benefit from the fact that several of the oilseeds were found to have produced enough sugar in 2.5 acres to supply the annual sugar needs of a least one managed honey bee colony. Pollinators like the Monarch butterfly will benefit from the planting of oilseeds because they are a great source of nectar for adults. Other pollinators help produce fruits and vegetables, so providing a food resource like fields of oilseeds will help those that use nectar and pollen to feed their young. Farmers/producers will benefit because oilseed crops are high value crops that require less water and fertilizer than corn, and provide food for insects that may help control pest infestations, saving time and money spent on pesticide application. Finally, the general public will benefit from the oils that are produced by these crops, used in fuel, food, and other everyday products.

Technical Abstract: Pollinating insects are in decline throughout the world, driven by a combination of factors including the loss of forage resources. The corn- and soybean-dominated agriculture of the Central and Midwestern US produces a landscape relatively devoid of nectar and pollen resources. Introducing specialty oilseeds into current crop rotations could provide abundant floral resources for pollinating insects as well as a high-value crop for growers. We investigated the nectar sugar resources and insect visitation throughout flower anthesis of nine specialty oilseed crops in west-central MN and eastern SD during the 2013 and 2014 growing seasons. Total sugar produced over anthesis (TS) was highest for echium (Echium plantagineum L.) at 472 kg ha-1. Canola (Brassica napus L.), crambe (Crambe abyssinica Hochst.), echium, borage (Borago officinalis L.), and cuphea (Cuphea viscosissima Jacq. x Cuphea lanceolata W. T. Aiton) produced enough sugar in one hectare to supply the annual sugar needs of a least one managed honey bee colony. Pollinators visited flowers of all crops, with as many as 90 insects min-1 observed. Our study is unique as we measured nectar sugar production, flower density, and insect visitation throughout anthesis for multiple specialty oilseed crops, providing a season-wide perspective of the flux of forage resources for pollinators. Adding specialty oilseed crops into current crop rotations would aid in reversing pollinator decline by providing forage resources that are lacking in the current agricultural landscape.