Equivocal Evidence for Colony Level Stress Effects on Bumble Bee Pollination Services

Area of Science:

• Ecology
• Environmental Science
• Entomology

Background:

• Climate change and extreme heat threaten global food security.
• Insect pollinators are crucial for crop production, and their services may be affected by environmental stressors.
• Agrochemicals can potentially exacerbate the impact of heat stress on insect pollinators.

Purpose of the Study:

• To investigate the interactive effects of heat stress and insecticide exposure on bumble bee pollination services.
• To assess whether environmental stressors induce behavioral changes in buff-tailed bumble bees (Bombus terrestris) affecting faba bean (Vicia faba) pollination.

Main Methods:

• Field cage experiments were conducted using buff-tailed bumble bee colonies.
• Colonies were subjected to two temperature regimes (25 °C and 31 °C) and exposure to the neonicotinoid clothianidin.
• A Bayesian approach was used to analyze the impact on faba bean pod set and yield.

Main Results:

• Heat-stressed bumble bee colonies (31 °C) resulted in lower proportional pod set in faba bean plants.
• There was weak evidence suggesting heat stress reduced total bean weight.
• Exposure to clothianidin alone or in combination with heat stress did not significantly affect plant yields or bee foraging behavior.

Conclusions:

• Extreme heat stress at the colony level can negatively impact pollination services, affecting crop yield parameters like pod set.
• The study's findings on yield parameters were not conclusive, indicating a need for further research.
• Understanding environmental stress impacts on plant-pollinator interactions is crucial for crop yield and food security.