Honey bees (Apis mellifera) and other pollinator populations are declining worldwide, and the reasons remain controversial. Based on laboratory testing, fungicides have traditionally been considered bee-safe. However, there have been no experimental tests of the effects of fungicides on colony health under field conditions, and limited correlational data suggests there may be negative impacts on bees at levels experienced in the field. We tested the effects of one of the most commonly used fungicides on colony health by feeding honey bee colonies pollen containing Pristine® (active ingredients: 25.2% boscalid, 12.8% pyraclostrobin) at four levels that bracketed concentrations we measured for pollen collected by bees in almond orchards. We also developed a method for calculating per-bee and per-larva dose. Pristine® consumption significantly and dose-dependently reduced worker lifespan and colony population size, with negative health effects observed even at the lowest doses. The lowest concentration we tested caused a 15% reduction in the worker population at an estimated dosage that was three orders of magnitude below the estimated LD₁₅ values for previous acute laboratory studies. The enhanced toxicity under field conditions is at least partially due to activation of colonial nutritional responses missed by lab tests. Pristine® causes colonies to respond to perceived protein malnutrition by increasing colony pollen collection. Additionally, Pristine induces much earlier transitioning to foraging in individual workers, which could be the cause of shortened lifespans. These findings demonstrate that Pristine® can negatively impact honey bee individual and colony health at concentrations relevant to what they experience from pollination behavior under current agricultural conditions.

蜜蜂（蜜蜂））和其他传粉媒介的数量在世界范围内正在减少，其原因仍然存在争议。根据实验室测试，传统上认为杀菌剂是蜜蜂安全的。但是，尚没有在田间条件下对杀菌剂对菌落健康的影响进行实验测试，并且有限的相关数据表明，在田间经历的水平下，可能会对蜜蜂产生负面影响。我们通过饲喂含有Pristine®（活性成分：25.2％的鳞片鳞茎，12.8％的吡菌胺酯）的蜂群花粉达到四个水平，该水平与我们在蜜蜂中收集到的花粉所测量的浓度成正比，从而测试了一种最常用的杀菌剂对菌落健康的影响。杏仁园。我们还开发了一种计算每个蜜蜂和每个幼虫剂量的方法。Pristine®的食用量显着且剂量依赖性地减少了工人的寿命和菌落群体的大小，即使在最低剂量下也观察到负面的健康影响。我们测试的最低浓度导致工人人数减少了15％，估计剂量比估计的LD低三个数量级。先前的急性实验室研究的_15个值。在田间条件下增加的毒性至少部分是由于实验室测试遗漏了结肠营养反应。Pristine®通过增加菌落花粉的收集来使菌落对感知的蛋白质营养不良做出反应。此外，Pristine导致单个工人更早地过渡到觅食，这可能是寿命缩短的原因。这些发现表明，Pristine®可以在与蜜蜂在当前农业条件下的授粉行为有关的浓度下对蜜蜂的个体和群体健康产生负面影响。