PDF(Pubmed)
Abstract：
Eusocial insects have evolved specific defensive strategies to protect their colonies. In termite colonies, soldiers perform a colony-level defense by displaying mechanical biting, head-banging and mandible opening-closing behaviors. However, few studies have been reported on the factors modulating defensive behaviors in termites. Owing to JH (juvenile hormone) being involved in soldier differentiation, JH was speculated to affect defensive behaviors in termite soldiers. To determine the effect of JH on the defensive behaviors of termite soldiers, we performed a JHA-feeding and RaSsp1-silencing experiment and then tested the changes in defense-related behaviors, alarm pheromones and key JH signaling genes. The observed result was that after feeding workers with JHA, soldiers displayed the following: (1) decreased biting events and increased head-banging events; (2) a reduced expression of RaSsp1 and increased expression of Met (methoprene-tolerant, the nuclear receptor of JH) and Kr-h1 (the JH-inducible transcription factor Krüppel homolog 1); and (3) a decreased concentration of alarm pheromones, including α-pinene, β-pinene and limonene (+, -). Further study showed that soldiers silenced for RaSsp1 also exhibited (1) decreased biting events and increased head-banging events and (2) increased expression of Met and Kr-h1. In addition, soldiers stimulated by the alarm pheromone limonene displayed an increase in the frequency of mandible opening-closing and biting behavior. All of these results show that JHA influenced the defensive behaviors of termite soldiers, possibly via downregulating RaSsp1 expression, up-regulating Met and Kr-h1 and stimulating the secretion of alarm pheromones, suggesting that the JH pathway plays important roles in modulating social behaviors in termite colonies.
摘要：
Eusocial昆虫已经进化出特定的防御策略来保护其殖民地。在白蚁群落中，士兵通过显示机械咬伤来执行殖民地级防御，头部撞击和下颌骨开合行为。然而,关于白蚁防御行为调节因素的研究很少。由于JH（少年激素）参与了士兵分化，推测JH会影响白蚁士兵的防御行为。为了确定JH对白蚁士兵防御行为的影响，我们进行了JHA喂养和RaSsp1沉默实验，然后测试了防御相关行为的变化，警报信息素和关键JH信号基因。观察到的结果是，在用JHA喂养工人后，士兵表现出以下特点：（1）减少了咬人事件，增加了头部撞击事件；（2）RaSsp1的表达减少，Met的表达增加（耐甲氧胺，JH的核受体）和Kr-h1（JH可诱导的转录因子Krüppel同源物1）；（3）警报信息素的浓度降低，包括α-pine烯,β-pine烯和柠檬烯（+，-).进一步的研究表明，对RaSsp1沉默的士兵还表现出（1）咬人事件减少和头部撞击事件增加，以及（2）Met和Kr-h1的表达增加。此外,受警报信息素柠檬烯刺激的士兵显示下颌骨开合和咬行为的频率增加。所有这些结果表明，JHA影响了白蚁士兵的防御行为，可能通过下调RaSsp1表达，上调Met和Kr-h1并刺激警报信息素的分泌，提示JH通路在调节白蚁群中的社会行为中起着重要作用。
