Getting more than a fair share: nutrition of worker larvae related to social parasitism in the Cape honey bee Apis mellifera capensis

Besides activation of ovaries and thelytokous reproduction of Cape workers, larval nutrition is an important aspect in parasitism of the African honey bee. When reared by workers of other subspecies, Cape larvae receive more food which is slightly more royal jelly-like. This results in worker-queen intermediates, with reduced pollen combs, enlarged spermathecae and higher numbers of ovarioles. The intermediates weigh more and develop faster than normal workers. The appearance of worker-queen intermediates probably affects parasitism of the African honey bee colonies by Cape workers. Different levels of larval nutrition resulting in less distinct caste differentiation may be important for the reproductive success of Cape workers in their own colonies. Similar processes, albeit less pronounced, may occur in colonies of other subspecies

Maternity of emergency queens in the Cape honey bee, Apis mellifera capensis

During reproductive swarming, some workers of the Cape honey bee, Apis mellifera capensis, lay eggs in queen cells, many of which are reared to maturity. However, it is unknown if workers are able to lay in queen cells immediately after queen loss during an episode of emergency queen rearing. In this study we experimentally de-queened colonies and determined the maternity of larvae and pupae that were reared as queens. This allowed us to determine how soon after queen loss workers contribute to the production of new queens. We were further interested to see if workers would preferentially raise new queens from queen-laid brood if this was introduced later. We performed our manipulations in two different settings: an apiary setting where colonies were situated close together and a more natural situation in which the colonies were well separated. This allowed us to determine how the vicinity of other colonies affects the presence of parasites. We found that workers do indeed contribute to queen cell production immediately after the loss of their queen, thus demonstrating that some workers either have activated ovaries even when their colony has a queen or are able to activate their ovaries extremely rapidly. Queen-laid brood introduced days after queen loss was ignored, showing that workers do not prefer to raise new queens from queen brood when given a choice. We also detected non-natal parasitism of queen cells in both settings. We therefore conclude that some A. m. capensis genotypes specialize in parasitizing queen cells.Centre of Excellence for Invasion Biolog

Differential feeding of worker larvae affects caste characters in the Cape honeybee, Apis mellifera capensis

Sections of brood from colonies of the Cape honeybee ( Apis mellifera capensis), the African honeybee ( A. m. scutellata), and hybrid bees of the two races were exchanged between colonies to study the effect of different brood-origin/nurse-bee combinations on development of caste characters. When Cape larvae were raised by African workers the amount of food provided almost doubled in comparison with Cape larvae reared by their own workers. In contrast, African larvae raised by Cape workers were provided with only half the amount they received from their own workers. After the bees emerged, we found a large degree of plasticity in characters related to caste differentiation, which corresponded closely to the amount of food provided. Super-fed Cape bees had enlarged spermathecae, were heavier than normal workers and developed more rapidly, and had reduced pollen combs, all typical for a more queen-like condition. Ovariole numbers did not appear to be enhanced by additional feeding. Cape bees that behave as social parasites in African bee colonies were most queen-like in the characters studied, albeit within the range that was found for Cape bees from normal colonies, suggesting within-colony selection for characters that enhance reproduction

Factors affecting the dynamics of the honeybee (Apis mellifera) hybrid zone of South Africa

Hybrid zones are found wherever two populations distinguishable on the basis of heritable characters overlap spatially and temporally and hybridization occurs. If hybrids have lower fitness than the parental types a tension zone may emerge, in which there is a barrier to gene flow between the two parental populations. Here we discuss a hybrid zone between two honeybee subspecies, Apis mellifera capensis and A. m. scutellata and argue that this zone is an example of a tension zone. This tension zone is particularly interesting because A. m. capensis can be a lethal social parasite of A. m. scutellata. However, despite its parasitic potential, A. m. capensis appears to be unable to increase its natural range unassisted. We propose three interlinked mechanisms that could maintain the South African honeybee hybrid zone: (1) low fitness of intercrossed and genetically mixed colonies arising from inadequate regulation of worker reproduction; (2) higher reproductive success of A. m. scutellata via both high dispersal rates into the hybrid zone and increased competitiveness of males, countered by (3) the parasitic nature of A. m. capensis.Centre of Excellence for Invasion Biolog

Virgin queen mandibular gland signals of Apis mellifera capensis change with age and affect honeybee worker responses

The mandibular gland secretions of Apis mellifera capensis virgin queens were analyzed by gas chromatography-mass spectroscopy. Changes in the patterns of the mandibular gland volatiles of A. m. capensis virgin queens were followed from emergence until 14-d old. Ontogenetic changes in the mandibular gland secretions were largely quantitative in nature, delineating the age categories (global R = 0.612, P = 0.001), except for 7- and 14-d-old queens, which cannot be separated on their mandibular gland profiles (P = 0.2). (E)-9-Oxodec-2-enoic acid (9ODA) contributes most and most consistently to the dissimilarity between groups as well as the similarity within groups. Worker reactions to introduced virgin queens of various ages were recorded. Workers showed a significant increase in hostile reactions as queens aged (r = 0.615, N = 20, P < 0.05). Consequently, worker reactions and relative 9ODA production exhibit a positive queen age-dependent response. © Springer Science + Business Media, Inc. 2006.Articl

A scientific note on the drone flight time of Apis mellifera capensis and A. m. scutellata

Centre of Excellence for Invasion Biolog

Cheating honeybee workers produce royal offspring

The Cape bee (Apis mellifera capensis) is unique among honeybees in that workers can lay eggs that instead of developing into males develop into females via thelytokous parthenogenesis. We show that this ability allows workers to compete directly with the queen over the production of new queens. Genetic analyses using microsatellites revealed that 23 out of 39 new queens produced by seven colonies were offspring of workers and not the resident queen. Of these, eight were laid by resident workers, but the majority were offspring of parasitic workers from other colonies. The parasites were derived from several clonal lineages that entered the colonies and successfully targeted queen cells for parasitism. Hence, these parasitic workers had the potential to become genetically reincarnated as queens. Of the daughter queens laid by the resident queen, three were produced asexually, suggesting that queens can ‘choose’ to produce daughter queens clonally and thus have the potential for genetic immortality.Centre of Excellence for Invasion Biolog