Zhao Huiyue, Liu Yanjie, Zhang Hong, Breeze Tom D, An Jiandong
Key Laboratory for Insect-Pollinator Biology, Ministry of Agriculture and Rural Affairs, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing 100093, China.
Centre for Agri-Environmental Research, School of Agriculture, Policy and Development, Reading University, Reading RG6 6AH, UK.
Insects. 2021 Nov 9;12(11):1008. doi: 10.3390/insects12111008.
Queen-worker conflict over the reproduction of males exists in the majority of haplodiplioidy hymenpteran species such as bees, wasps, and ants, whose workers lose mating ability but can produce haploid males in colony. Bumblebee is one of the representatives of primitively eusocial insects with plastic division labor and belongs to monandrous and facultative low polyandry species that have reproductive totipotent workers, which are capable of competing with mother queen to produce haploid males in the queenright colony compared to higher eusocial species, e.g., honeybees. So, bumblebees should be a better material to study worker reproduction, but the reproductive characteristics of worker-born males (WMs) remain unclear. Here, we choose the best-studied bumblebee to evaluate the morphological characteristics and reproductive ability of WMs from the queenless micro-colonies. The sexually matured WMs showed smaller in forewing length and weight, relatively less sperm counts but equally high sperm viability in comparison with the queen-born males (QMs) of the queenright colony. Despite with smaller size, the WMs are able to successfully mate with the virgin queens in competition with the QMs under laboratory conditions, which is quite different from the honeybees reported. In addition, there was no difference in the colony development, including the traits such as egg-laying rate, colony establishment rate, and populations of offspring, between the WM- and the QM-mated queens. Our study highlights the equivalent reproductive ability of worker-born males compared to that of queens, which might exhibit a positive application or special use of bumblebee rearing, especially for species whose males are not enough for copulation. Further, our finding contributes new evidence to the kin selection theory and suggests worker reproduction might relate to the evolution of sociality in bees.
在大多数单倍二倍体膜翅目昆虫（如蜜蜂、黄蜂和蚂蚁）中，存在蜂后与工蜂在雄蜂繁殖问题上的冲突，这些昆虫的工蜂失去了交配能力，但能在蜂群中产生单倍体雄蜂。熊蜂是具有可塑性分工的原始群居昆虫的代表之一，属于单配偶兼性低多配偶物种，其工蜂具有生殖全能性，与更高等的群居物种（如蜜蜂）相比，在有蜂后的蜂群中，工蜂能够与蜂后竞争产生单倍体雄蜂。因此，熊蜂应该是研究工蜂繁殖的更好材料，但由工蜂产生的雄蜂（WM）的繁殖特性仍不清楚。在这里，我们选择研究得最透彻的熊蜂来评估无蜂后微型蜂群中由工蜂产生的雄蜂的形态特征和繁殖能力。与有蜂后蜂群中由蜂后产生的雄蜂（QM）相比，性成熟的由工蜂产生的雄蜂前翅长度和体重较小，精子数量相对较少，但精子活力同样高。尽管体型较小，但在实验室条件下，由工蜂产生的雄蜂能够在与由蜂后产生的雄蜂竞争中成功与未交配的蜂后交配，这与报道的蜜蜂情况有很大不同。此外，由工蜂产生的雄蜂交配的蜂后和由蜂后产生的雄蜂交配的蜂后在蜂群发育方面没有差异，包括产卵率、建群率和后代数量等特征。我们的研究强调了由工蜂产生的雄蜂与蜂后具有同等的繁殖能力，这可能对熊蜂饲养具有积极的应用或特殊用途，特别是对于雄蜂数量不足以进行交配的物种。此外，我们的发现为亲缘选择理论提供了新的证据，并表明工蜂繁殖可能与蜜蜂社会性的进化有关。
