Nectar Production in Oilseeds: Food for Pollinators in an Agricultural Landscape

Abstract

Pollinating insects are in decline throughout the world, driven by a combination of factors including the loss of forage resources. The maize (Zea mays L.)– and soybean [Glycine max (L.) Merr.]–dominated agriculture of the Central and Midwestern United States 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 Minnesota and eastern South Dakota 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. × Cuphea lanceolata W. T. Aiton) produced enough sugar in one hectare to supply the annual sugar needs of a least one managed honey bee (Apis mellifera L.) 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 seasonwide perspective of the flux of nectar resources for pollinators. Adding specialty oilseed crops into current crop rotations could aid in reversing pollinator decline by providing forage resources that are lacking in the current agricultural landscape.

Specialty oilseed crops provide an abundant source of pollen for pollinators and beneficial insects

“…To generate values of pollen and protein weights per hectare, we used flower density data previously published on nectar production that was collected on the same plots and days as the pollen collection dates reported here (Eberle et al., ; Thom et al., ). Mean pollen grains per flower (pgF −1 ) were multiplied by the flower density (F ha −1 ) of the crop on the same day to calculate total daily pollen grains produced per hectare per day (pgD −1 ; pg ha −1 day −1 ) for each crop, and was plotted for each day sampled (Figure ).…”

“…In contrast to conventional crops, specialty oilseeds such as camelina ( Camelina sativa L.), pennycress ( Thlaspi arvense L.), canola ( Brassica napus L.), crambe ( Crambe abyssianica Hochst), echium ( Echium plantagineum L.), borage ( Borago officinalis L.), calendula (Ca lendula officinalis L.), sunflower ( Helianthus annus L.) and cuphea ( Cuphea viscosissima Jacq. × Cuphea lanceolata W. T. Aiton) produce large, showy blossoms with plentiful floral resources (Eberle et al., ; Maurizio, ; Mohr & Jay, ; Thom et al., ). Some specialty oilseeds, such as camelina and pennycress are self‐pollinated, but their flowers are highly visible and produce nectar for pollinators in early spring (Eberle et al., ; Thom et al., ), gaining increased seed set as a result of insect pollination (Groeneveld & Klein, ).…”

“…× Cuphea lanceolata W. T. Aiton) produce large, showy blossoms with plentiful floral resources (Eberle et al., ; Maurizio, ; Mohr & Jay, ; Thom et al., ). Some specialty oilseeds, such as camelina and pennycress are self‐pollinated, but their flowers are highly visible and produce nectar for pollinators in early spring (Eberle et al., ; Thom et al., ), gaining increased seed set as a result of insect pollination (Groeneveld & Klein, ).…”

Mesurer la sécrétion nectarifère : exemple d'une lignée hybride F1 et de son parent mâle stérile chez le colza d'hiver (Brassica napusL.)

“…C'est un facteur particulièrement important pour les espèces protogynes ou protandres, comme le tournesol ou la carotte, où la sécrétion peut varier selon la phase sexuelle qui évolue avec l'âge (Langenberger et Davis, 2002 ;Wist et Davis, 2006, 2008Varga et al, 2013). Il faut également tenir compte de l'effet de la pollinisation, qui peut déclencher précocement le processus de sénescence de la fleur et du coup interrompre la sécrétion (Stead, 1992 ;van Doorn, 1997 ;Rogers, 2006 Thom et al (2016). Et à terme identifier une charge de colonies d'abeilles mellifères par unité de surface à ne pas dépasser si l'on souhaite éviter que les colonies ne rentrent trop en compétition les unes avec les autres pour le nectar.…”

Spread of volunteer and feral maize plants in Central Europe: recent data from Austria

“…However, teosinte—the closest relative of maize—has recently been detected also in Spain where it behaves like an invasive weed of agricultural land (http://www.agpme.es/index.php?option=com_content&view=article&id=181:el-teosinte&catid=44:articulos&Itemid=68, accessed 30th of July 2016). Even though maize is a mainly wind-pollinated crop [4], it has also been observed to function as pollen source for honey bees [5]. So, non-target organisms that collect pollen of maize plants are exposed directly to GM pollen.…”