The circadian and endocrine systems influence many physiological processes in animals, but little is known on the ways they interact in insects. We tested the hypothesis that juvenile hormone (JH) influences circadian rhythms in the social bumble bee Bombus terrestris. JH is the major gonadotropin in this species coordinating processes such as vitellogenesis, oogenesis, wax production, and behaviors associated with reproduction. It is unknown however, whether it also influences circadian processes. We topically treated newly-emerged bees with the allatoxin Precocene-I (P-I) to reduce circulating JH titers and applied the natural JH (JH-III) for replacement therapy. We repeated this experiment in three trials, each with bees from different source colonies. Measurements of ovarian activity confirmed that our JH manipulations were effective; bees treated with P-I had inactive ovaries, and this effect was fully reverted by subsequent JH treatment. We found that JH augments the strength of circadian rhythms and the pace of rhythm development in individually isolated newly emerged worker bees. JH manipulation did not affect the free-running circadian period, overall level of locomotor activity, or the amount of sleep. Given that acute manipulation at an early age produced relatively long-lasting effects, we propose that JH effect on circadian rhythms is mostly organizational, accelerating the development or integration of the circadian system.

中文翻译：

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少年激素影响年轻大黄蜂（Bombus terrestris）工人的昼夜节律的发育和强度

昼夜节律和内分泌系统影响动物的许多生理过程，但关于它们在昆虫中相互作用的方式知之甚少。我们测试了这样的假说，即少年激素（JH）影响社交性大黄蜂Bombus terrestris的昼夜节律。JH是该物种中主要的促性腺激素，可协调诸如卵黄发生，卵子发生，蜡的产生以及与繁殖相关的行为等过程。然而，还不清楚它是否也会影响昼夜节律。我们用尿囊毒素Precocene-I（PI）局部处理了新出现的蜜蜂，以减少循环JH滴度，并应用天然JH（JH-III）进行替代治疗。我们在三个试验中重复了该实验，每个试验中都有来自不同来源菌落的蜜蜂。卵巢活动的测量结果证实我们的JH操作有效。用PI处理的蜜蜂卵巢无活性，随后的JH治疗完全恢复了这种效果。我们发现JH增强了个体隔离的新近出现的工蜂的昼夜节律强度和节奏发展速度。JH的操作不会影响自律性昼夜节律，运动活动的总体水平或睡眠量。考虑到早期的急性操作会产生相对较长的影响，因此我们建议JH对昼夜节律的影响主要是组织性的，从而加速了昼夜节律系统的发展或整合。JH的操作不会影响自律性昼夜节律，运动活动的总体水平或睡眠量。考虑到早期的急性操作会产生相对较长的影响，因此我们建议JH对昼夜节律的影响主要是组织性的，从而加速了昼夜节律系统的发展或整合。JH的操作不会影响自律性昼夜节律，运动活动的总体水平或睡眠量。考虑到早期的急性操作会产生相对较长的影响，我们建议JH对昼夜节律的影响主要是组织性的，从而加速了昼夜节律系统的发展或整合。