Duan Xinle, Zhao Bi'an, Jin Xin, Cheng Xuefen, Huang Shaokang, Li Jianghong
College of Animal Science (Bee Science), Fujian Agriculture and Forestry University, Fuzhou 350002, China.
Fujian Honey Bee Biology Observation Station, Ministry of Agriculture and Rural Affairs, Fuzhou 350002, China.
Insects. 2021 Mar 30;12(4):301. doi: 10.3390/insects12040301.
Symbiotic bacteria could increase the nutrient provision, regulate the physiological state, and promote immunity in their insect host. Honeybee larvae harbor plenty of bacteria in their gut, but their functions are not well studied. To determine their effect on honeybee larvae, the 1-day-old larvae were grafted on to 24-well plates from the comb and artificially reared in the lab. They were treated with penicillin-streptomycin to remove the gut symbiotic bacteria. Then, the 5-day-old larvae and the newly emerged adults were weighted. The developmental periods to pupae and eclosion were investigated, respectively. The bacterial amount, expression of developmental regulation genes ( and ), nutrient metabolism genes (1, 2, 70, 70, 70, and 110), and immunity genes (, , , and ) were determined by qRT-PCR. The result showed that the antibiotics-treated larvae have significantly lower body weights in the 5-day-old larvae and the emerged bees. The expression of 2 and 70 in 5-day-old larvae was down-regulated. The was down-regulated in 5-day-old larvae, but increased in 7-day-old larvae, which disturbed the normal developmental process and caused the extension of eclosion. Moreover, antibiotics treatment significantly decreased the expression of and in 5-day-old larvae, and and in 7-day-old larvae, respectively. These results showed that antibiotics could weaken the nutrient metabolism, disturb the development process, and decrease the immune competence of honeybee larvae, indicating the vital roles of gut bacteria in bee larvae fitness, so the antibiotics should be avoided to control microbial disease in honeybee larvae.
共生细菌可以增加昆虫宿主的营养供应、调节其生理状态并促进免疫。蜜蜂幼虫肠道中含有大量细菌，但其功能尚未得到充分研究。为了确定它们对蜜蜂幼虫的影响，将1日龄幼虫从蜂巢转移到24孔板上并在实验室中进行人工饲养。用青霉素-链霉素处理它们以去除肠道共生细菌。然后，对5日龄幼虫和新羽化的成虫进行称重。分别调查到蛹期和羽化期的发育时间。通过qRT-PCR测定细菌数量、发育调控基因（和）、营养代谢基因（1、2、70、70、70和110）以及免疫基因（、、、和）的表达。结果表明，经抗生素处理的幼虫在5日龄幼虫和羽化后的蜜蜂中体重显著降低。5日龄幼虫中2和70的表达下调。5日龄幼虫中下调，但在7日龄幼虫中增加，这扰乱了正常发育过程并导致羽化期延长。此外，抗生素处理分别显著降低了5日龄幼虫中以及7日龄幼虫中和的表达。这些结果表明，抗生素会削弱蜜蜂幼虫的营养代谢、扰乱发育过程并降低免疫能力，表明肠道细菌对蜜蜂幼虫健康至关重要，因此应避免使用抗生素来控制蜜蜂幼虫的微生物疾病。
