Experimental heat waves alter floral resources for pollinators

Anthropogenic climate change is causing a surge in frequency and intensity of climactic extremes, including heat waves. Heat stress can alter plant-pollinator interactions by impacting flowering plants, including reducing traits that attract pollinators and the nutritional rewards for pollinators. To investigate this, three eastern temperate native plant species representing diverse life history traits were exposed to a heat wave treatment (day/night, 35°C/22°>C) and compared to plants kept at control conditions (day/night, 25°C/20°C). Between treatments, we compared flower height, number of flowers produced, flower size, and pollen protein lipid ratios. To evaluate how pollinator visitation is impacted by heat modified floral visual and nutritional cues, we performed observation-based field assays. Initial floral trait results indicate that flower height and size can be negatively impacted by extreme heat leading to a smaller floral display—an important cue in pollinator attraction. We plan to analyze pollen macronutrient ratios to determine if pollen nutrition is affected by heat. Further investigation of plant-insect responses to our hotter climate is needed to understand how to better conserve this mutualism through habitat management.