is it the same mechansim as sub sister worker policing of non sub sister laying worker eggs, or has that recently been disproved?
This is my understanding of worker policing...
Egg-laying workers and worker policing in a queen-right colony
All worker bees have rudimentary ovaries whose fuller development is inhibited by the presence of queen pheromone and brood pheromones within the nest [1]. Nonetheless, a dissection study revealed that about 4% workers in a queen-right colony have potentially functional ovaries [2]. These bees are recognisable to their sisters who tend to attack them by mandibulation [3]. It has been calculated that perhaps 0.01% workers in a queen-right colony actually lay unfertilised eggs but this can represent up to 7% all drone eggs laid [4]. Within 8 hours, the vast majority of worker-laid eggs are removed by other workers in a behaviour known as “worker policing” [5]. Therefore, hardly any worker-laid eggs successfully hatch into larvae and, as only about 20% these reach pupation, it has been calculated that only about 1 in 1,000 drones reaching sexual maturity in a queen-right colony are derived from worker bee eggs [6].
(Please see attachment, derived from reference 5)
It was believed that queen bees marked their eggs with a pheromone that allowed workers to discriminate between queen-laid and worker-laid eggs, thereby allowing workers to cannibalise the latter [7]. Mathematically, this is in the genetic interests of worker bees [8, 9] because, for any worker, about 25% their genome will be found in any queen-laid drone egg but just 12.5% her genome will be found in any egg laid by a half-sister. Whilst about 37.5% her genome will be found in an egg laid by a super-sister, the probability is that any such egg will be vastly outnumbered by half-sister eggs. If workers are able to discriminate the maternity of eggs to this level of accuracy and the queen was well mated, there will be about 15 workers for whom the destruction of any worker-laid egg is in their genetic interests for every one worker who is best served by its conservation. However, there is no convincing evidence that queens mark their eggs or that workers can distinguish them from worker-laid eggs [10]. In fact, it looks highly probable that straightforward “hygienic behaviour” explains the high removal rate of worker-laid eggs compared to queen-laid eggs [10]. Hygienic behaviour is the rapid removal of diseased or dead brood from the nest by workers, either through cannibalisation or physical elimination. This is done to limit pathogen spread and prevent the outbreak of serious infection within the colony [11, 12, 13] Worker-laid eggs are simply not as viable as queen-laid eggs: they are derived from less well-nourished mothers with less developed ovaries. Furthermore, they are often positioned poorly in the cell [14] which might result in damage. It has also been suggested that worker-laid eggs might be more prone to dehydration [15].
The proportion of laying workers in a colony increases during periods of queenlessness. Furthermore, when a colony has developed swarm cells in preparation for swarming, the ovaries in some workers become more developed. It is estimated that 20-70% worker bees in a swarm are anatomical laying workers. Swarms represent a time of particular danger for queen bees. It can be seen how this strategy of worker ovary development during swarming provides the colony with a rather meagre contingency plan... in the event of the new the colony being/becoming hopelessly queenless, the otherwise doomed colony has one last chance to pass on genetic material to a subsequent generation through the production of physically inferior drones.
References
[1] Slessor K, Foster L, Winston M. Royal flavours: Honey bee queen pheromones. In: Vander Meer R, Breed M, Winston M, Espelie K, editors. Pheromone Communication in Social Insects. Westview, Boulder, CO; 1988. p. 331–344.
[2] Jay S. Factors influencing ovary development in worker honeybees under natural conditions. Can J Zool. 1968;46:345–347.
[3] Visscher P, Dukas R. Honey bees recognise development of nestmates’ ovaries. Anim Behav. 1995;49:542–544.
[4] Visscher P. Reproductive conflict in honey bees: A stalemate of worker egg-laying and policing. Behav Ecol Sociobiol. 1996;39:237–244.
[5] Ratnieks F, Visscher P. Worker policing in the honeybee. Nature (London). 1989;342:796–797.
[6] Visscher P. A quantitative study of worker reproduction in honey bee colonies. Behavioral Ecology and Sociobiology. 1989;25:247–254.
[7] Ratnieks F. Evidence for a queen-produced egg-marking pheromone and its use in worker policing in the honey bee. J Apic Res. 1995;34:31–37.
[8] Woyciechowski M, Lomnicki A. Multiple mating of queens and the sterility of workers among eusocial hymenoptera. J Theor Biol 128, 317–327. 1987;128:317–327.
[9] Ratnieks F. Reproductive harmony via mutual policing by workers in eusocial Hymenoptera. American Naturalist. 1988;132:217–236.
[10] Pirk C, Neumann P, Hepburn R, Moritz J RFA amd Tautz. Egg viability and worker policing in honey bees. PNAS. 2004;101(23):8649–8651.
[11] Woodrow A, Holst E. The mechanism of colony resistance to American foulbrood . J Econ Entomol. 1942;35:327–330.
[12] Spivak M, Gilliam M. Hygienic behaviour of honey bees and its application for control of brood diseases and varroa Part I. Hygienic behaviour and resistance to American foulbrood. Bee World. 1988;79(3):124–134.
[13] Spivak M, Gilliam M. Hygienic behaviour of honey bees and its application for control of brood diseases and varroa Part II. Studies on hygienic behaviour since the Rothenbuhler era. Bee World. 1998;79(4):169–186.
[14] Sakagami S. The False-Queen: Fourth Adjustive Response in Dequeened Honeybee Colonies. Behaviour. 1958;13:280–296.
[15] Velthuis AD HHW, Imperatriz-Fonseca V, Duchateau M. Worker bees and the fate of their eggs. Proc Exp Appl Entomol NEV. 2002;13:97–102.
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