How Queen Bees Suppress The Rest

Nine-carbon fatty acids secreted by queen bees repress the fertility of worker bees in a hive.

AsianScientist (Feb. 18, 2015) – Researchers have identified the compounds present in queen manibular pheromone (QMP) that suppress ovary activation in ordinary worker bees. Their results, published in the Journal of Insect Physiology, could be used to help beekeepers control hive fertility.

QMP is a group of (at least) five active compounds produced by queen honey bees. Although the pheromone is known to aid queen control of the colony and colony cohesion, the effects of individual QMP components have never been tested to determine their effects on the reproductive physiology of Apis cerana workers.

Prof. Tan Ken of Xishuangbanna Tropical Botanical Garden (XTBG) of Chinese Academy of Sciences and his colleagues conducted a study to provide groups of queenless A. cerana workers with individual QMP components in their food and determine which of the components are capable of suppressing ovary activation.

The researchers fed one queen equivalent of each of the major components of A. cerana QMP to groups of worker bees twice a day until the workers were ten days old. Half of the cages were also provided with ten percent royal jelly in the food. Workers were sampled each day and dissected to determine the number of ovarioles and the degree of ovary activation (egg development).

The study showed that the major components of the queen mandibular secretions 9-ODA (9-oxo-2-decenoic acid) and 9-HAD (9-hydroxy-(E)-2-decenoic acid) that are common to A. cerana and A. mellifera strongly inhibit worker ovary activation in young A. cerana workers.

The minor components, 10-HAD (10-hydroxy-2-decenoic acid) and 10-HDAA (10-Hydroxydecanoic acid) have minimal effects on ovary activation. Royal jelly was found to enhance ovary activation, but ovary activation was still strongly suppressed by 9-ODA and 9-HDA in bees that have access to royal jelly.

The effect of QMP on ovary activation and ovariole loss in Asian honey bees. Credit: Ken Tan.
The effect of QMP on ovary activation and ovariole loss in Asian honey bees. Credit: Ken Tan.

The ovariole number declines with age, and declines to a greater extent in the absence of queen-associated fatty acids. The queen pheromones inhibit decline in ovariole number over the first ten days of life. This suggests that ovary activation itself causes a decline in ovariole number, or that loss of ovarioles is required for ovary activation in queenless workers.

The results show that 9-ODA alone suppresses ovary activation to a similar or greater degree than it does in a mixture of all compounds. It therefore appears that 9-ODA is the primary signal that mediates worker fertility in A. cerana.

The article can be found at: Tan et al. (2015) Pheromones Affecting Ovary Activation and Ovariole Loss in the Asian Honey Bee Apis cerana.


Source: Chinese Academy of Sciences; Photo: USGS Bee Inventory and Monitoring Lab/Flickr/CC.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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