Simons Meagan A, Smith Adam R
Department of Biological Sciences, George Washington University, Washington, D.C., United States of America.
PeerJ. 2018 Feb 20;6:e4415. doi: 10.7717/peerj.4415. eCollection 2018.
Social insect foragers may specialize on certain resource types. Specialization on pollen or nectar among honeybee foragers is hypothesized to result from associations between reproductive physiology and sensory tuning that evolved in ancestral solitary bees (the Reproductive Ground-Plan Hypothesis; RGPH). However, the two non-honeybee species studied showed no association between specialization and ovary activation. Here we investigate the bumblebee because it has the most extensively studied pollen/nectar specialization of any bumblebee. We show that ovary size does not differ between pollen specialist, nectar specialist, and generalist foragers, contrary to the predictions of the RGPH. However, we also found mixed support for the second prediction of the RGPH, that sensory sensitivity, measured through proboscis extension response (PER), is greater among pollen foragers. We also found a correlation between foraging activity and ovary size, and foraging activity and relative nectar preference, but no correlation between ovary size and nectar preference. In one colony non-foragers had larger ovaries than foragers, supporting the reproductive conflict and work hypothesis, but in the other colony they did not.
群居昆虫觅食者可能会专门针对某些资源类型。蜜蜂觅食者对花粉或花蜜的专门化被认为是由于在祖先独居蜜蜂中进化出的生殖生理与感官调节之间的关联所致（生殖基础计划假说；RGPH）。然而，所研究的两种非蜜蜂物种在专门化与卵巢激活之间未显示出关联。在此，我们对熊蜂展开研究，因为它具有所有熊蜂中研究最为广泛的花粉/花蜜专门化现象。我们发现，与RGPH的预测相反，花粉专门觅食者、花蜜专门觅食者和普通觅食者之间的卵巢大小并无差异。然而，我们也发现对RGPH的第二个预测仅有部分支持，即通过喙伸展反应（PER）测量的感官敏感性在花粉觅食者中更高。我们还发现觅食活动与卵巢大小之间以及觅食活动与相对花蜜偏好之间存在相关性，但卵巢大小与花蜜偏好之间没有相关性。在一个蜂群中，非觅食者的卵巢比觅食者的更大，这支持了生殖冲突与工作假说，但在另一个蜂群中并非如此。
