Amsalem Etya, Padilla Mario, Schreiber Paul M, Altman Naomi S, Hefetz Abraham, Grozinger Christina M
Department of Entomology, Center for Pollinator Research, Center for Chemical Ecology, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA.
Department of Statistics, Huck Institute of Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA.
J Chem Ecol. 2017 Jun;43(6):563-572. doi: 10.1007/s10886-017-0858-4. Epub 2017 Jun 24.
Reproduction in social insect societies reflects a delicate balance between cooperation and conflict over offspring production, and worker reproduction is widespread even in species showing strong reproductive skew in favor of the queen. To navigate these conflicts, workers are predicted to develop the means to estimate the queen's fecundity - potentially through behavioral and/or chemical cues - and to adjust their reproduction to maximize their fitness. Here, we introduced bumble bee, Bombus impatiens, workers to queens of different mating and reproductive status and examined worker reproduction and expression levels of two genes which were previously shown to be sensitive to the presence of the queen, vitellogenin and Krüppel-homolog 1. We further explored whether the queen's chemical secretion alone is sufficient to regulate worker reproduction, aggression and gene expression. We found that worker ovary activation was inhibited only in the presence of egg-laying queens, regardless of their mating status. Workers reared in the presence of newly-mated queens showed intermediate vitellogenin expression levels relative to workers reared with mated egg-laying and virgin queens. However, none of the whole-body chemical extracts of any of the queen treatment groups affected ovary activation, aggressive behavior, or gene expression in workers. Our findings indicate that only the presence of a freely-behaving, egg-laying queen can fully inhibit worker reproduction. It remains to be determined if workers detect differences in queen mating status and fecundity through differences in the queens' behavior alone or through the queen's behavior in concert with fertility signals.
社会性昆虫群体中的繁殖反映了后代生产方面合作与冲突之间的微妙平衡，即使在那些表现出强烈生殖偏斜、有利于蚁后的物种中，工蚁繁殖也很普遍。为了应对这些冲突，预计工蚁会发展出评估蚁后繁殖力的方法——可能是通过行为和/或化学信号——并调整自身繁殖以最大化其适合度。在此，我们将熊蜂（西方蜜蜂）工蚁引入处于不同交配和生殖状态的蚁后群体中，研究工蚁的繁殖情况以及之前已证明对蚁后存在敏感的两个基因（卵黄蛋白原和克氏同源物1）的表达水平。我们进一步探究仅蚁后的化学分泌物是否足以调节工蚁的繁殖、攻击性和基因表达。我们发现，只有在产卵蚁后存在时，工蚁卵巢激活才会受到抑制，无论其交配状态如何。与在已交配产卵蚁后和未交配蚁后群体中饲养的工蚁相比，在新交配蚁后群体中饲养的工蚁卵黄蛋白原表达水平处于中等。然而，任何蚁后处理组的全身化学提取物均未影响工蚁的卵巢激活、攻击性行为或基因表达。我们的研究结果表明，只有自由活动的产卵蚁后的存在才能完全抑制工蚁繁殖。工蚁是仅通过蚁后行为的差异，还是通过蚁后行为与繁殖信号协同作用来检测蚁后交配状态和繁殖力的差异，仍有待确定。
