Heat waves and insect pollination

29 January 2016

Dr Jacob Bishop

Dr Jacob Bishop's, Researcher in the Centre for Food Security, recent paper on how insect pollination reduces yield loss following heat stress in faba beans has been published in the Journal of Agriculture, Ecosystems and Environment. The paper investigates how heat waves and insect pollination interact to affect crop production. It shows that crops may become more dependent on insect pollination as heat waves become hotter and more numerous. When we heat stressed my faba bean plants, their flowers were damaged and the plants produced lower yields. Bees were able to reduce this damage and make faba bean yield more resilient to stress. We discuss that this is probably because bees can move pollen from less damaged flowers, to flowers that have been more damaged by the high temperature - but we didn't test that theory in the published paper.

Figure 1b

In the figure to the right, we compare the yields of plants that were pollinated by bees, with plants that we excluded from bees - so we can calculate the benefit that bees provide, or the plants 'dependency' on bees. The dashed line at 1.0 is where plants with bees and plants without bees are equal, anything above the dashed line means that bees improved faba bean yield. In normal conditions (temperatures between 18-26°C), bees increased yield by around 15%. When we damaged the plants with an intermediate heat stress treatment (30°C for 5 days), plants pollinated by bees lost less yield and produced over 50% higher yields than excluded plants. At the very hot temperature (34°C for 5 days) the benefit that bees provided returned to around 15%, probably because other parts of the plant were damaged. The paper is available to read at: doi:10.1016/j.agee.2015.12.007

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