Body mass but not wing size or symmetry correlates with life span of honey bee drones.

In social insects such as the honey bee, the quality of drones at the time of their emergence can affect their maintenance in the colony until maturity. Body mass, wing size and wing asymmetry of emerging honey bee drones were measured and correlated with their life span in the colony and compared between individuals reaching maturity or not. The life span of drones differed among colonies in which they were maintained after emergence but not between colonies in which they were reared. More drones heavier at emergence reached sexual maturity at 15 days and had a longer life span compared with light-weight drones of lower mass. The size and symmetry of drone forewings was not correlated with their life span. Our results suggest that body mass at emergence is a good predictor of drone survival in the colony.

The relationship between asymmetry, size and unusual venation in honey bees (Apis mellifera).

Despite the fact that symmetry is common in nature, it is rarely perfect. Because there is a wide range of phenotypes which differs from the average one, the asymmetry should increase along with deviation. Therefore, the aim of this study was to assess the level of asymmetry in normal individuals as well as in phenodeviants categorized as minor or major based on abnormalities in forewing venation in honey bees. Shape fluctuating asymmetry (FA) was lower in normal individuals and minor phenodeviants compared with major phenodeviants, whereas the former two categories were comparable in drones. In workers and queens, there were not significant differences in FA shape between categories. FA size was significantly lower in normal individuals compared with major phenodeviant drones and higher compared with minor phenodeviant workers. In queens, there were no significant differences between categories. The correlation between FA shape and FA size was significantly positive in drones, and insignificant in workers and queens. Moreover, a considerable level of directional asymmetry was found as the right wing was constantly bigger than the left one. Surprisingly, normal individuals were significantly smaller than minor phenodeviants in queens and drones, and they were comparable with major phenodeviants in all castes. The correlation between wing size and wing asymmetry was negative, indicating that smaller individuals were more asymmetrical. The high proportion of phenodeviants in drones compared with workers and queens confirmed their large variability. Thus, the results of the present study showed that minor phenodeviants were not always intermediate as might have been expected.

A test of worker policing theory in an advanced eusocial wasp, Vespula rufa.

Mutual policing is an important mechanism for maintaining social harmony in group-living organisms. In some ants, bees, and wasps, workers police male eggs laid by other workers in order to maintain the reproductive primacy of the queen. Kin selection theory predicts that multiple mating by the queen is one factor that can selectively favor worker policing. This is because when the queen is mated to multiple males, workers are more closely related to queen's sons than to the sons of other workers. Here we provide an additional test of worker policing theory in Vespinae wasps. We show that the yellowjacket Vespula rufa is characterized by low mating frequency, and that a significant percentage of the males are workers' sons. This supports theoretical predictions for paternities below 2, and contrasts with other Vespula species, in which paternities are higher and few or no adult males are worker produced, probably due to worker policing, which has been shown in one species, Vespula vulgaris. Behavioral observations support the hypothesis that V. rufa has much reduced worker policing compared to other Vespula. In addition, a significant proportion of worker-laid eggs were policed by the queen.

Senescence and learning in honeybee (Apis mellifera) workers.

Foraging by honeybee workers was investigated from the moment of the first foraging flight until death. To minimise the influence of factors other than senescence the foragers were trained to collect food from an artificial flower close to their hive. During each foraging trip the workers repeatedly visited an artificial flower, collecting one microlitre of 50% sugar solution per visit. During the first 50 flights the mean time taken to collect one portion of food decreased significantly and the number of visits to the artificial flower per flight increased significantly. During flights following the 50th flight, the mean time taken to collect one portion of food increased significantly and the number of visits to the artificial flower per flight decreased significantly. The results confirm earlier observations that the foraging behaviour of honeybee workers is not only influenced by learning, but also by the effects of senescence.