A scientific note on the lack of nepotism in queen larval feeding during emergency queen rearing in a naturally mated honey bee colony

Abstract

Honey bee (Apis mellifera L.) colonies consist of many patrilines (Estoup et al., 1994) and workers can potentially increase their inclusive fitness during queen replacement if they can favour a full-sister offspring queen (Visscher, 1998). There is evidence of preferential rearing of some patrilines in emergency queen rearing (Tilley and Oldroyd, 1997; Osborne and Oldroyd, 1999; Châline et al., 2003), although the reason for this is unclear. Some patrilines could act nepotistically or a “royalty allele” could make some larvae more attractive to workers (Osborne and Oldroyd, 1999). Early studies on behavioural interactions and larval preferences during queen rearing used colonies with limited numbers of patrilines or cross-fostering of larvae between unrelated colonies with naturally mated queens. They showed weak or no evidence of nepotism (Breed et al., 1984; Noonan, 1986; Page et al., 1989). To avoid the problem of unnaturally low number of patrilines and the use of artificial insemination, we used microsatellites to analyse the kinship of feeding workers and queen larvae during emergency queen rearing, for the first time in a colony with a naturally mated queen. The experiment was carried out in double blind in a queenless observation hive containing individually marked bees. This was done by marking bees emerging from two brood combs of the test colony over 6 consecutive days. Before the experimental colony set-up, the marked bees were returned to their mother colony to ensure a normal ontogeny. Twentyfour hours before the set-up, 50 queen cells were initiated in a queen rearing colony by grafting larvae from the test colony. Thirteen of these were then attached to a brood comb from the test colony and transferred in an observation hive with 2000 of the marked workers. During the experiment, three additional queen cells were built naturally. Each queen cell was observed individually for 1/2 h every day until capping. The total observation time was 2130 min. The bees feeding each queen larvae were recorded, as this seemed the best behaviour for the