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Title: Nectar production in oilseeds: Food for pollinators in an agriculture dominated landscape

item Thom, Matthew
item Eberle, Carrie
item Forcella, Frank
item Nemec, Kristine
item Lundgren, Jonathan
item Gesch, Russell - Russ

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/19/2014
Publication Date: 9/19/2014
Citation: Thom, M.D., Eberle, C.A., Forcella, F., Nemec, K.T., Lundgren, J.G., Gesch, R.W. 2014. Nectar production in oilseeds: Food for pollinators in an agriculture dominated landscape [abstract]. In: Miller, T., Alexopoulou, E. and Berti, M.T., editors. International Conference in Industrial Crops and 26th Annual Meeting of the Association for the Advancement of Industrial Crops (AAIC). Program and Abstracts. September 13-19, 2014, Athens, Greece.

Interpretive Summary:

Technical Abstract: Simplified agroecosystems have degraded habitats for beneficial insects throughout the Midwest and Northern Great Plains of the USA. Beneficial insects include pollinators and natural enemies of crop pests, and both rely heavily on floral resources and habitat diversity to maintain healthy populations. Recent national emphasis on increasing biofuel production affords producers the opportunity to reintegrate critical resources into landscapes that were homogenized by modern corn-soybean rotations. Several flower-rich and pollinator-friendly oilseed crops comprise this opportunity, allowing for a potential benefit to both producers and the beneficial insect community. The objective of this study was to determine the diurnal nectar (sugar) production of several oilseed crops throughout anthesis, an important resource for beneficial insects such as pollinators and natural enemies of pest insects. Oilseed crops in this study included borage, calendula, camelina, canola, crambe, cuphea, echium, flax, pennycress, and sunflower. The diurnal flux of nectar was determined by marking flowers, flushing with water, and covering with nylon mesh pollinator exclusion bags. Nectar was extracted after two hours had elapsed, and the entire process was repeated twice throughout the day for a total of three sampling intervals. Nectar volumes were measured with micro capillaries for flowers with nectar volumes greater than 1 microliter (echium, borage, cuphea), with sugar concentration (the major energy source in nectar) determined by a hand refractometer. Nectar extraction for flowers that contained nectar volumes less than 1 microliter (pennycress, camelina, canola, calendula, sunflower, crambe, flax) used water washes followed by HPLC analysis to determine sugar content. Daily sugar production per flower was approximated by summing the sugar production across the three sampling intervals. Sugar production per hectare for each crop (by day and over anthesis) was determined by multiplying daily sugar production per plant by the open flower density on the given day, calculated by Batcheler corrected point distance estimation and Transect Point Density software. Daily sugar production as measured in nectar for each oilseed crop was significantly higher in early and midday samplings as compared to late day. Sugar production also declined significantly throughout anthesis, with the peak production within the first week of flowering for each crop. Many of the oilseeds studied produced high amounts of sugar in their nectar, and flowered at a range of times throughout the growing season. Adding these oilseed crops into the current corn-soybean dominated rotation will provide a rich source of nectar for beneficial insects such as pollinators and natural enemies of crop pests.