Digital.CSIC. Repositorio Institucional del CSIC

oai:digital.csic.es:10261/347711

Winter mortality and weight loss. File name: ‘raw_data_weights’ CSV file providing pre-wintering weight, percent weight loss and emergence success of O. cornuta females exposed to three simulated wintering treatments. Variables cc_treatment = wintering treatments (C = Current; NF = Near-future; DF = Distant-future) pre_wint_weight_mg = pre-wintering weight in mg weight_loss_per = proportion of body weight loss emergence_succ = 1 (success) or 0 (failure), Phototaxis test. File name: ‘raw_data_phototaxis’ CSV file providing the results of the Phototaxis test for O. cornuta females exposed to three wintering treatments and three doses of the insecticide sulfoxaflor. Variables cc_treatment = wintering treatments (C = Current; NF = Near-future; DF = Distant-future) pest_treatment = pesticide treatments (CONTROL = 0 dose; LD = Low dose; HD = High dose) phototaxis = 1 (i.e. postive, the bee walked to the light source within 60 seconds) or 0 (i.e. negative, the bee walked but did not reach the light source)., Syrup consumption and survival. File name: ‘raw_data_longevity’ CSV files providing the daily syrup consumption and longevity of O. cornuta females exposed to three wintering treatments and three doses of the insecticide sulfoxaflor. Variables cc_treatment = wintering treatments (C = Current; NF = Near-future; DF = Distant-future) pest_treatment = pesticide treatments (CONTROL = 0 dose; LD = Low dose; HD = High dose) longevity = bee longevity (days) event = column required for synergism analysis daily_consumption_ul = daily consumption of the feeding solution (ul), Synergism analysis File name: 'synergism_analysis.R' (R file) Description: Full R script for the analysis of synergism between climate change and insecticide exposure on survival., Bee populations are exposed to multiple stressors, including land-use change, biological invasions, climate change and pesticide exposure, that may interact synergistically. We analyze the combined effects of climate warming and sublethal insecticide exposure in the solitary bee Osmia cornuta. Previous Osmia studies show that warm wintering temperatures cause body weight loss, lipid consumption and fat body depletion. Because the fat body plays a key role in xenobiotic detoxification, we expected that bees exposed to climate warming scenarios would be more sensitive to pesticides. We exposed O. cornuta females to three wintering treatments: current scenario (2007-2012 temperatures), near-future (2021-2050 projected temperatures), and distant-future (2051-2080). Upon emergence in spring, bees were orally exposed to three sublethal doses of an insecticide (Closer, a.i. sulfoxaflor; 0, 4.55 and 11.64 ng a.i./bee). We measured the combined effects of wintering and insecticide exposure on phototactic response, syrup consumption, and longevity. Wintering treatment by itself did not affect winter mortality, but body weight loss increased with increasing wintering temperatures. Similarly, wintering treatment by itself hardly influenced phototactic response or syrup consumption. However, bees wintered at the warmest temperatures had shorter longevity, a strong fecundity predictor in Osmia. Insecticide exposure, especially at the high dose, impaired the ability of bees to respond to light, and resulted in reduced syrup consumption and longevity. The combination of the warmest winter and the high insecticide dose resulted in a 70% longevity decrease. Smaller bees, resulting from smaller pollen-nectar provisions, had shorter longevity suggesting nutritional stress may further compromise fecundity in O. cornuta. Our results show a synergistic interaction between two major drivers of bee declines, and indicate that bees will become more sensitive to pesticides under the current global warming scenario. Our findings have important implications for pesticide regulation and underscore the need to consider multiple stressors to understand bee declines., Funding: Ministerio de Ciencia e Innovación y Ministerio de Universidades., Peer reviewed