Laying workers are caused if or when a hive becomes hopelessly queenless or queen and brood pheromones drop to negligible levels. Worker ovary development is normally suppressed by a combination of queen pheromone and brood pheromones, in the absence of a young and vigorous queen, the lack of (or lower level of) pheromones allows some workers to develop ovaries, these are not as well developed as a queen’s ovaries would be, but can produce eggs. As there is no mating involved, all the eggs that are produced will be unfertilised and male (apart from the rare case of Thelytoky.
The pheromones that prevent development of laying workers are brood recognition pheromones… In some cases, a failing queen is not superseded, and laying workers can develop in the presence of this queen. As the queen failure process is gradual the first few laying workers may develop just one ovariole to the state of being able to produce eggs, as the degeneration in the queen continues and there is less brood as well, then a larger number of workers develop up to around a half a dozen active ovarioles (there are only about ten in a worker anyway). The process of laying worker development usually takes weeks to occur, but as this process is gradual it is rarely noticed in it’s early stages and is rapidly accelerated if the queen fails completely, so it is usually quoted as being a delay of seven days or so after queen failure/disappearance.
Identifying laying workers…
Brood pattern is spotty
Laying worker eggs do not have any egg recognition pheromone that is normally deposited by a queen, as a result other workers will remove the eggs (worker policing). This results in a spotty brood pattern, with empty cells scattered throughout frames of capped brood.
Number of eggs in a cell
Queen honey bees will in most cases lay only a one egg in a cell, but laying workers will lay multiple eggs per cell. Multiple eggs in a cell are not absolute proof of laying workers, because a newly mated queen may lay more than one egg per cell, in the early stages of laying.
Position of egg within a cell
Position in the cell that the egg is laid, is a good indicator of whether it was laid by a queen or a laying worker. A Queen’s abdomen is significantly longer than that of a worker, allowing a queen to lay an egg at the bottom of the cell. A Queen will usually lay an egg reasonably centered in the cell. However workers cannot reach the bottom of normal depth brood cells, and will lay eggs on the sides of the cell or off center.
Drone Brood in Worker Cells
A good indicator of laying workers is drone brood in worker sized cells. Drones are normally raised in larger cells that are in patches that are all drone sized. Drones in worker cells (recognisable by bullet shaped cappings), particularly if scattered, are a sign of a failing queen or laying workers.
Laying workers mostly occur in large numbers rather than singularly, if the conditions are right for them to develop at all.
Norman Carreck points out… “There is a whole chapter on laying workers in Ribbands’ “The behaviour and social life of honeybees”, which although published in 1953 is I think still reasonable. There’s a bit in Seeley’s “Wisdom of the hive”, but probably the best account is in Winston’s “The biology of the honey bee”. There’s also a review of the subject in: Page, R.E., Erikson, E.H. (1988) Reproduction by worker honey bees. Behavioral Ecology and Sociobiology 23, 117-126.”
There is a difficulty in re-queening colonies with laying workers, which can be overcome by removing the laying workers and allowing the colony to be totally devoid of egg layers for a time.
The simple cure for laying workers… Move the entire hive into the middle of the field or a hundred yards or so from it’s original position. Shake or brush all bees from every comb and all hive parts on to the ground. All the workers look alike whether ‘normal’ or ‘laying’, so you must not miss one as it could be a laying one. Replace the hive back on it’s original stand for the flying bees to return to. The laying workers will not return to the hive, at least that is the traditional wisdom. However it has been discovered that many laying workers are able to fly normally. Notwithstanding that… In those few cases that I have observed ‘it worked’, exactly what the mechanism was is open to debate.
The period that you need to leave the bees queenless before they will accept a cell or another queen depends to an extent on how long they have been without a queen, but there are no female eggs in the hive at this stage or any larva that are young enough to become emergency queens. So a few hours to a day should be enough, but be aware that some workers may be already on the point of turning into ‘layers’ and any prolonged period without a queen could result in all your hard work going to waste.
Incidence of Dopamine and its metabolites in brains of reproductive workers in honeybees. Has been studied by K. Sasaki and T. Nagao. They set out to explore the role of dopamine and it’s metabolites in worker honey bees. Levels of dopamine and it’s breakdown products were measured in the brains of both normal workers and queenless workers.
Dopamine and two metabolites of dopamine… N-acetyl dopamine (NADA) and norepinephrine were detected in bee brain extracts. The brain levels of dopamine, NADA and norepinephrine were in proportion with ovary development. Individual bees with high dopamine levels also had high levels of NADA or norepinephrine, suggesting that these metabolites may be involved in the change of reproductive developmental state of workers. Dopamine was distributed mainly in the protocerebrum, whereas NADA was also found in the optic lobes. Dopamine levels, in each distinct brain region, were higher in queenless workers than in normal workers, as was the NADA level in the optic lobes.
These results indicate that dopamine may be stored in, and/or released from the protocerebrum and the deutocerebrum. Diffusion to the optic lobes, where dopamine secretory cells are absent, is also possible, giving rise to high NADA levels in the optic lobes. These levels of dopamine and NADA may well aid reproductive development in laying workers or may be a result of such development that was caused by other unsuspected mechanisms.