The hallmark of insect societies is a caste of workers that generally forego reproduction and instead allocate their time and physiological resources to rearing the brood of their mother, the queen. If a honey bee (Apis spp) colony becomes queenless, about 1/3 of young workers activate their ovaries and produce haploid male-producing eggs. In doing so queenless workers maximize their inclusive fitness because the normal option of vicarious production of relatives via their queen’s eggs is no longer available. Queenless honey bees lay eggs but can they produce brood food at the same time?

    Prof. TAN Ken of Xishuangbanna Tropical Botanical Garden (XTBG) and his colleagues of Yunnan Agricultural University conducted a study to determine whether workers of Asian hive bee Apis cerana with activated ovaries behaved differently to those without activated ovaries. They then studied how the reproductive physiology of queenless workers differed from that of queenright workers and whether workers with larger numbers of ovarioles had different foraging preferences to workers with smaller numbers of ovarioles.

  The researchers used generalized linear models based on restricted maximum likelihood to assess the relationship between task group (in-nest, pollen forager, nectar forager), and queen state (queenless or queenright colony) on ovariole number, ovary activation score and hypopharyngeal size. They nested the effect of colony within task group and queenstate, and included all main effects, and the two-way interaction between task group and queen state.

The study found that queenless workers have enlarged hypopharangeal glands and active ovaries. In the queenless colonies only, workers in the brood nest had higher ovary activation scores than workers that were engaged in foraging. The observation supported the hypothesis that reproductive workers should avoid risky foraging. They found no tendency for pollen foragers to have a greater number of ovarioles than nectar foragers. There was a positive association between ovary activation and hypopharyngeal (HPG) size in queenless workers and HPG were larger in queenless workers than in queenright workers regardless of whether the worker was undertaking foraging or brood-rearing tasks. This suggests that there is no tradeoff between egg production and brood food production.

   The study entitled “Associations between reproduction and work in workers of the Asian hive bee Apis cerana” has been published online in Journal of Insect Physiology.

Associations between reproduction and work in workers of Asian hive bees (Image by TAN Ken)

Key words

Honey bee, Asian he bee, ovary activation, hypopharyngeal gland, foraging behavior

Contact

TAN Ken, Ph.D Principal Investigator

Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China

Tel: 86-871-65227717

Fax: 86-871-65227358

E-mail: kentan@xtbg.ac.cn