Molet Mathieu, Péronnet Romain, Couette Sébastien, Canovas Christophe, Doums Claudie
Sorbonne Universités, UPMC Univ Paris 06, CNRS, Institute of Ecology and Environmental Sciences of Paris UMR7618, 4 Place Jussieu, 75005 Paris, France.
Biogéosciences, UMR CNRS 6282, Univ Bourgogne Franche-Comté, 6 bv Gabriel, 21000 Dijon, France; EPHE, PSL Research University, 75014 Paris, France.
J Therm Biol. 2017 Jul;67:22-29. doi: 10.1016/j.jtherbio.2017.04.013. Epub 2017 Apr 30.
Warm temperatures decrease insect developmental time and body size. Social life could buffer external environmental variations, especially in large social groups, either through behavioral regulation and compensation or through specific nest architecture. Mean worker size and distribution of worker sizes within colonies are important parameters affecting colony productivity as worker size is linked to division of labor in insect societies. In this paper, we investigate the effect of stressful warm temperatures and the role of social environment (colony size and size of nestmate workers) on the mean size and size variation of laboratory-born workers in the small European ant Temnothorax nylanderi. To do so, we reared field-collected colonies under medium or warm temperature treatments after having marked the field-born workers and removed the brood except for 30 first instar larvae. Warm temperature resulted in the production of fewer workers and a higher adult mortality, confirming that this regime was stressful for the ants. T. nylanderi ants followed the temperature size rule observed in insects, with a decreased developmental time and mean size under warm condition. Social environment appeared to play an important role as we observed that (i) larger colonies buffered the effect of temperature better than smaller ones (ii) colonies with larger workers produced larger workers whatever the rearing temperature and (iii) the coefficient of variation of worker size was similar in the field and under medium laboratory temperature. This suggests that worker size variation is not primarily due to seasonal environmental fluctuations in the field. Finally, we observed a higher coefficient of variation of worker size under warm temperature. We propose that this results from a disruption of social regulation, i.e. the control of nestmate workers over developing larvae and adult worker size, under stressful conditions.
温暖的温度会缩短昆虫的发育时间并减小其体型。社会生活可以缓冲外部环境变化，尤其是在大型社会群体中，这可以通过行为调节和补偿或者通过特定的巢穴结构来实现。蚁群中工蚁的平均体型以及工蚁体型的分布是影响蚁群生产力的重要参数，因为工蚁体型与昆虫社会中的劳动分工相关。在本文中，我们研究了高温胁迫的影响以及社会环境（蚁群大小和同巢工蚁的体型）对小型欧洲蚁种尼氏细胸蚁（Temnothorax nylanderi）实验室培育的工蚁平均体型和体型变异的作用。为此，我们在标记了野外出生的工蚁并移除除30只一龄幼虫之外的所有幼虫后，将野外采集的蚁群置于中等温度或温暖温度处理下饲养。温暖的温度导致产生的工蚁数量减少且成年蚁死亡率更高，这证实了这种环境对蚂蚁来说具有胁迫性。尼氏细胸蚁遵循昆虫中观察到的温度体型规律，在温暖条件下发育时间缩短且平均体型减小。社会环境似乎起到了重要作用，因为我们观察到：（i）较大的蚁群比较小的蚁群能更好地缓冲温度的影响；（ii）无论饲养温度如何，拥有较大工蚁的蚁群会培育出体型更大的工蚁；（iii）工蚁体型的变异系数在野外和中等实验室温度条件下相似。这表明工蚁体型变异并非主要源于野外的季节性环境波动。最后，我们观察到在温暖温度下工蚁体型的变异系数更高。我们认为这是由于在胁迫条件下社会调节受到干扰，即同巢工蚁对发育中的幼虫和成年工蚁体型的控制受到干扰所致。
