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Data and code from: Insecticides alter wild and managed pollination dynamics on oil crop yield

Nottebrock, Henning12; Stiles, Shane2; Klein, Alexandra-Maria1; Lundgren, Jonthan3; Fenster, Charles2

Published Jun 25, 2026 on Dryad. https://doi.org/10.5061/dryad.gxd254828

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Abstract

Background: There is increasing global production of Ethiopian rape (Brassica carinata), a crop used for biofuel production and animal feed. Its similarity to other mustard seed oil crops, such as canola and rapeseed, suggests that it may provide floral resources for pollinators within crop rotations. However, evidence on the benefits of mass-flowering crops for pollinators is mixed, and the provision of floral resources does not necessarily imply a dependence on pollination. Consequently, the role of pollination in B. carinata remains poorly understood.

Aim: This study investigates the pollination system of B. carinata experimentally at the farm scale. We aim to obtain a mechanistic understanding of how the availability of floral, regular insecticide applications, and the use of managed honey bee hives, affects crop pollination and crop yield.

Methods: Data were collected from 35 experimental field sites (0.404 ha = 1 acre each) across two consecutive years in the Prairie Coteau region of the Northern Great Plains, South Dakota, USA. Over 800 focal B. carinata individuals were monitored by collecting data on pollinator visitation, pollinator diversity, flower traits, and yield. We generated estimates of floral resource availability to quantify the relationship between pollinator visitation rate and yield at plant, square and site scale. We additionally quantified pollinator movement to assess the effects of insecticide treatment on pollinator behavior to provide a mechanistic explanation of the interaction of floral resource availability and insecticide treatment on pollinator visitation and yield.

Results: Pollinators increased seed set of B. carinata by 26.8%, with 28 species recorded visiting flowers. Wild pollinators were more efficient than honeybees, contributing on average 1.01 seeds per visit compared to 0.79 seeds per visit by honeybees, likely reflecting differences in pollen removal and deposition. In insecticide free fields, interactions between wild pollinators and honeybees led to non-additive effects on pollination, which may reflect underlying trade-offs between competition and facilitation. On fields with insecticides, wild pollinators were disproportionately suppressed, while honeybees partially compensated by maintaining visitation, buffering overall seed set losses. However, across spatial scales, wild pollinators consistently outperformed honeybees, though their advantage diminished under insecticide treatment. These results highlight scale and context-dependent interactions, with trade-offs in untreated fields and compensatory dynamics under chemical stress.

Synthesis and Application: Our findings emphasize that combining honeybee hives with pesticide use do not automatically optimize crop yield. Policy frameworks for pollinator conservation need to recognize scale-dependent pollination processes, as enhancing pollinator diversity and floral resources at the farm scale is key to maintaining resilient and productive agroecosystems Thus, we recommend a holistic strategy that integrates pesticide reduction, habitat enhancement and conservation of wild pollinators to optimize pollination services, promote biodiversity and support sustainable agricultural systems.