Reduced water negatively impacts social bee survival and productivity via shifts in floral nutrition

All plant data are for Tomcat clover (Trifolium willdenovii) grown in D-40 Deepots with UC Mix3 soil in a greenhouse with fertilized water and on one of two watering treatments: optimal and reduced (30% less). Optimal water conditions were assessed by determining how much water was required for the soil to be at field capacity. We raised one-day old honey bee larvae, 76 microcolonies of Bombus impatiens, and four cull colonies of B. impatiens on artificial diets that represented the decreased nutritive quality of clover flowers when water was reduced by 30%. Please see main text for details. In short, for honey bees, The optimum water diet consisted of 53% (w/w) royal jelly, 6.5% sucrose, 3.1% glucose, 3.4% fructose and 34% water, while the reduced water diet was comprised of 47.6% royal jelly, 5.4% sucrose, 2.6% glucose, 2.9% fructose and 41.5% water. For bumble bees, the optimum water diet consisted of 0.250 g pollen and a sugar solution of 29.4% sucrose, 13.5% glucose, 15.9% fructose and 41.2% water, while the reduced water diet included 0.225g pollen and a sugar solution of 24.8% sucrose, 11.4% glucose, 13.4% fructose and 50.6% water. All bees were maintained in the lab and monitored daily.

所有植物数据均来源于种植于D-40型深盆（D-40 Deepots）、采用UC Mix3基质的汤姆卡特三叶草（Trifolium willdenovii），栽培环境为温室，灌溉水为施肥水，并设置两种灌溉处理：最优灌溉与减量灌溉（供水量较最优组减少30%）。最优灌溉条件通过测定土壤达到田间持水量所需的灌水量确定。本研究以人工饲料饲养1日龄蜜蜂幼虫、76个印第安熊蜂（Bombus impatiens）微蜂群及4个印第安熊蜂淘汰蜂群，该人工饲料模拟了供水量减少30%时三叶草花的营养品质下降情况。详细实验细节请参见正文内容。简言之，针对蜜蜂的最优含水量饲料组成为：53%（w/w）蜂王浆、6.5%蔗糖、3.1%葡萄糖、3.4%果糖及34%水；减量含水量饲料则包含47.6%蜂王浆、5.4%蔗糖、2.6%葡萄糖、2.9%果糖及41.5%水。针对熊蜂的最优含水量饲料组成为：0.250克花粉及含糖溶液（含29.4%蔗糖、13.5%葡萄糖、15.9%果糖及41.2%水）；减量含水量饲料则包含0.225克花粉及含糖溶液（含24.8%蔗糖、11.4%葡萄糖、13.4%果糖及50.6%水）。所有供试蜂类均在实验室饲养并每日监测。