Patriline differences in emergency queen rearing in the honey bee, <Emphasis Type="Italic">Apis mellifera</Emphasis>

Summary In the polyandrous honey bee, Apis mellifera, workers can potentially increase their inclusive fitness by rearing full-sister queens. If the mother queen dies suddenly, workers feed a few larvae in worker cells with royal jelly and rear them into queens (emergency queen rearing). Using DNA microsatellite markers we determined the patriline of emergency queens reared in two colonies headed by naturally-mated queens before being made queenless. We found that some patrilines were reared more than others in one colony, but not in the other. These differences between colonies suggest that selective rearing is not always present and this might explain the mixed results of previous nepotism studies in the honey bee.Received 10 February 2003; revised 7 March 2003; accepted 17 March 2003.     

Life span of queens in the antFormica exsecta

Summary The antFormica exsecta commonly has two types of colonies: either polygynous and polydomous or monogynous and monodomous. The longevity of queens was studied in monogynous colonies in southern Finland by indirect methods using genetic markers; these data were also used to estimate the number of matings and queen replacement. The average genetic relatedness among worker nest mates was 0.72. Taking inbreeding into account (the inbreeding coefficient wasF=0.16), this value agrees with the assumption that 40% of the queens mated with one male and 60% with two males. The distribution of genotypes within colonies remained stable in successive years, indicating that queen replacement did not occur or was extremely rare. This means that the life span of nests reflects directly the life span of the queens. Eleven of the 16 nests found in 1979 were still alive ten years later. This corresponds to an annual mortality of 3.7% and a mean life span of 27 years. A total of 57 colonies were mapped in the population over a period of ten years. Averaging over the years, the annual mortality was estimated to be 4.9%. This represents a mean life span of 20 years if mortality was independent of age.     

Social factors affecting queen fecundity in the ant Myrmica rubra

ABSTRACT. At the end of winter, normal populations of the polygyne ant Myrmica rubra L. consist of queens, workers and larvae; the latter are dormant and all in the third stadium. During experimental culture in artificial nests in the laboratory, the starting number of all three of these categories was varied and in some, food supply was restricted too. In a population of workers and larvae, queens do not interfere with each other sufficiently to reduce their fecundity; they avoid congestion by dispersing under the canopy of workers. Queens suffer if food is withheld; they probably feed themselves and are thus largely independent of the number of workers. Even in favourable conditions with full food, the distribution of egg-batch sizes is not normal but follows a hollow curve that is well described by the negative binomial series. A poor food supply accentuates the hollow shape by increasing the number of non-laying queens and reducing the number that are able to lay large batches. Larvae also suppress fecundity but only if they have sufficient food to grow actively; as their number increases, egg production by queens decreases exponentially.     

The importance of daylength and queens for larval care by young workers of the ant Myrmica rubra L.

ABSTRACT. Workers whilst still less than a month from emergence rear early stage larvae better in a 16h day than in one of 14h. The callows must perceive the diel rhythm directly because there are no foragers to give them a clue, and the larvae are kept in the dark and cannot respond directly. This, and the study of egg-laying by young workers that preceded it, indicates that the extra hours daylight enable the workers to avoid the reproductive diapause that normally prepares them for hibernation. They retain active ovaries, ingest and share food with larvae either as trophic eggs or as a regurgitate from the crop.
In late summer, callows can rear sexual larvae in spring condition. Queens have a small negative effect on this, expressed as a smaller, though still gyne, pupa produced a little earlier. This weak response to queens develops into a strong negative one at a constant temperature of either 10 or 20°C. The workers then behave as they normally do in spring, and feed a watery regurgitate (dietary control) or, if this fails to arrest sexual development, physically harass the larvae by biting them in the ventral thorax (manipulative control). Large workers then result instead of gynes.     

Ecdysteroid production during caste differentiation in larvae of the ant, Plagiolepis pygmaea

ABSTRACT. Variations in ecdysteroids were measured by radio-immunoassay in worker-biased and queen-biased larvae of the ant Plagiolepis pygmaea Latr. (Hymenoptera, Formicidae) during late larval development, i.e. from the end of winter diapause up to the prepupal period. At the end of diapause, larvae are bipotential and, depending on culture conditions, can become either queens or workers. Ecdysteroid profiles revealed that there are striking differences between the two castes: worker larvae showed high titres during their development, queen larvae had low titres over the same period.