Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan.
Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8566, Japan.
Sci Rep. 2021 Jan 13;11(1):1183. doi: 10.1038/s41598-021-81006-z.
Temporal division of labor, or age polyethism, in which altruistic caste individuals change their tasks with aging, is widely found in bees and ants (Hymenoptera) and also in other social insects. Here we report the discovery of elaborate age polyethism in a social aphid (Hemiptera). Tuberaphis styraci is a gall-forming aphid in which monomorphic first instar nymphs differentiate into normal nymphs and soldiers upon second instar molt. Soldiers neither grow nor reproduce but perform gall cleaning and colony defense. Using an artificial diet rearing system, we collected age-defined groups of soldiers and monitored their social behaviors. We observed that young soldiers tend to clean whereas old soldiers preferentially attack, thereby verifying age-dependent task switching from housekeeping to defense. Strategic sampling, age estimation and behavioral observation of soldiers from natural galls revealed that (1) young cleaning soldiers tend to inhabit upper gall regions with adult insects, (2) old attacking soldiers tend to be distributed in lower gall regions, particularly around the gall openings, and (3) the gall structure is linked to intra-nest movement, aging and task switching of soldiers in an adaptive manner. These results highlight an evolutionary parallelism comparable to the sophisticated temporal division of labor observed in honeybee colonies.
时间分工，或年龄多态性，即利他性群体个体随着年龄的增长而改变任务，在蜜蜂和蚂蚁（膜翅目）中广泛存在，也存在于其他社会性昆虫中。在这里，我们报告了在一种社会性蚜虫（半翅目）中发现的精细的年龄多态性。葡萄瘿绵蚜是一种形成虫瘿的蚜虫，单态的第一龄若虫在第二龄蜕皮时分化为正常若虫和兵蚜。兵蚜既不生长也不繁殖，而是执行虫瘿清洁和群体防御任务。使用人工饲养系统，我们收集了具有明确年龄的兵蚜群体，并监测了它们的社会行为。我们观察到，年轻的兵蚜倾向于清洁，而年老的兵蚜则优先攻击，从而验证了从家务到防御的依赖年龄的任务转换。对天然虫瘿中的兵蚜进行的战略性取样、年龄估计和行为观察表明：（1）年轻的清洁兵蚜倾向于栖息在有成年昆虫的上虫瘿区；（2）年老的攻击兵蚜倾向于分布在较低的虫瘿区，特别是在虫瘿开口周围；（3）虫瘿结构与兵蚜在巢内的运动、老化和任务转换相关，是一种适应性的方式。这些结果突出了一种与在蜜蜂群体中观察到的复杂时间分工相媲美的进化并行性。
