Impact of Pollinator Habitat on Pollinators and Soybean
Much has been written about the importance of protecting pollinators and their habitats in today’s agricultural settings. A recent report titled “Evaluating the impact of increased pollinator habitat on bee visitation and yield metrics in soybean crops” by Levenson, Sharp, and Tarpy appears in Agriculture, Ecosystems and Environment, 2022; 331: 107901 (https://doi.org/10.1016/j.agee.2022.107901). In this article, researchers at North Carolina State Univ. report on their findings from the evaluation of the effect of proximity to pollinator habitat on soybean (a pollinator-independent crop–i.e., self-pollinated) yield components. The study was designed to determine if there are benefits of pollinator habitat proximity to a pollinator-independent crop such as soybean. Details about the conduct of and results from the research follow.
• Studies were conducted at eight experimental research stations across North Carolina. Bee pollinators were sampled at three sites within each of the eight stations: 1) an established pollinator habitat planted with commercially available seed mixes; 2) a soybean field planted adjacent to the pollinator habitat; and 3) a soybean field planted an average of 0.6 mile away from the pollinator habitat.
• Objectives of the study were to 1) investigate the impact of increased pollinator habitat on the pollinator communities within the habitat compared to soybean fields, 2) determine if bees within the soybean fields were collecting pollen from the crop, and 3) determine the effect, if any, of bee visits on soybean yield components and yield.
• A prophylactic seed treatment was used at two of the stations, an insecticide was applied at three stations, a herbicide was applied at five stations, a fungicide was applied at one station, and one station had no pesticides applied.
• Visual and netting sampling methods were used to survey/sample pollinators at each location.
• The highest number of bees visited soybean fields during the R2 stage, and quickly dropped off during later stages. In fact, 52% of total bee visits were found during the R2 stage compared to the total number of bee visits during the R3, R4, and R5 stages combined.
• All bees collected from the soybean fields had some soybean pollen present. Overall, bees collected in the habitat sites had significantly lower amounts of soybean pollen, and bees collected in the two soybean field sites at each location did not have significantly different amounts of soybean pollen.
• Soybean growing in fields that were adjacent to pollinator habitat had seed that were 6.52% heavier than seed from fields that were away from the habitat site. Total number of seeds per plant were not different between the two soybean fields.
• The authors made the following statements regarding results from the study. 1) Adding pollinator habitat next to a crop–even a pollinator-independent crop such as soybean–positively impacts both the bee community and some of the yield measures of the crop. 2) Pollinator habitat can serve as an important resource for supporting crop-visiting species. 3) There were significantly more bee visits during the R2 soybean growth stage compared to subsequent stages, which suggests that growers should avoid pesticide application during the R2 stage. 4) The finding of soybean pollen on all specimens collected in the soybean fields suggests that bees are actively collecting resources (pollen and/or nectar) from soybean plants, and that soybean, which is not dependent on pollinators, is still attractive to bees. 5) The heavier seed from soybean plants in fields adjacent to pollinator habitat suggests that having habitat near soybean fields results in more pollinator visits and better pollination services. 6) Bees that were in soybean fields adjacent to pollinator habitat were less likely to leave that soybean field compared to bees in soybean fields that were located farther from the habitat. 7) Finally, the results show that plant-pollinator interactions within a pollinator-independent crop such as soybean should not be overlooked.
These results support the following. 1) Crop producers should consider establishing pollinator habitats on unused land near crop fields in order to benefit both the pollinators and the crop. Such habitats can be an important resource for supporting pollinators that can benefit even pollinator-independent crops such as soybean. 2) Soybean producers should avoid applying pesticides during the R2 stage of development since these results indicate this is the period with the most bee visits during reproductive development in a soybean crop.
Composed by Larry G. Heatherly, Mar. 2022, larryh91746@gmail.com