Thesis (M.S.)--University of North Carolina at Greensboro, 2007. / Title from PDF title page screen. Advisor: Olav Rueppell; submitted to the Dept. of Biology. Includes bibliographical references (p. 42-48).

Thesis (M.Sc.)(Zoology)--University of Pretoria, 2006. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

Thesis (M.S. in entomology)--Washington State University, December 2008. / Title from PDF title page (viewed on Mar. 4, 2009). "Department of Entomology." Includes bibliographical references.

In advanced eusocial hymenopteran societies workers have ovaries and can lay eggs, but are unable to mate. Workers are more related to their own offspring than to every other member of the colony. So worker reproduction contains both worker-worker and worker-queen conflict. The queen- worker conflict is discussed elsewhere, but if the queen mates with more than two males, worker policing should be selected to lower potential conflicts. However in the Cape honeybee it was predicted that worker policing is absent or less expressed than in other honeybee subspecies, because workers produce female offspring thelytokously. So laying workers and their offspring are nearly genetically identical, which results in the fact that other workers are as related to workers derived from eggs laid by the queen as laid by a worker. However, worker reproduction may be costly and therefore worker policing could be an evolutionary adaptation in the Cape honeybee to lower the costs derived from laying worker activity. Indeed, Cape honeybee colonies show efficient egg removal behaviour, suggesting that other factors like colony efficiency could favour egg removal behaviour. Since egg removal behaviour is a colony phenomenon, factors that affect colony performance could also affect egg removal behaviour. Egg removal behaviour was considerably affected by environmental changes, indicating that other tasks have a higher priority than egg removal behaviour. Thousands of queenright colonies of the neighbouring subspecies (A. m. scutellata) were taken over by laying A. m. capensis workers, showing that A. m. capensis workers are facultative social parasites. These observations strongly indicate that laying workers of A. m. capensis are able to evade worker policing and the inhibitory effects of the queen pheromones, but what potential strategies could these laying workers use to increase the survival of their eggs and evade the queen? On the one hand, egg removal behaviour is variable. One behavioural strategy of laying workers to achieve successful reproduction could be that they lay during periods with low egg removal behaviour. On the other hand, the inhibitory effect of the queen’s pheromones diminishes with distance. Maybe the level of egg removal also depends, like the inhibitory effect of the queen pheromones, on the distance from the queen. Indeed, further away from the queen the effect of the queen pheromone and the level of egg removal is reduced, making successful worker reproduction possible. In both subspecies, A. m. capensis and A. m. scutellata, egg removal behaviour is reduced further away from the queen. In the case of A. m. scutellata egg removal is lacking further away from the queen. This explains why colonies of scutellata are so prone to takeovers by laying Cape honeybee workers. One question in the context of parasitic Cape honeybees is how they manage to get into the host colony. One way could be that they get into the colonies during a natural colony merger which is common in African bees. Two unrelated colonies merged and it took them only 24 hours to show effective integration. Because both colonies are unrelated, the potential reproductive conflict among workers should be more strongly expressed than in a normal colony, which is not the result of a merger. Therefore, the effect of nestmate recognition for eggs on the egg removal behaviour was investigated. The results suggest that workers recognise the origin of an egg and that the standard policing experiments overestimate the level of egg removal and only represent relative values. Moreover, the results show that colony specific components on the eggs are more important than a postulated queen egg marking pheromone. Finally, for the first time empirical evidence from a population of the parasitic laying Cape honeybee workers, invading thousands of colonies of A. m. scutellata in northern South Africa, for a short-sighted selection theory is presented.

No description available.

The ventricular epithelia of adult worker honey bees were investigated biochemically and ultrastructurally. The midgut tissues were shown to produce an endoprotease with trypsin-like activity. Enzyme activity was highest in the midgut tissues and the ectoperitrophic space of free-flying honey bees and of caged bees fed pollen. Lower levels of activity occurred in caged bees restricted to sucrose or fed artificial diets. The trypsin-like activity declined as the protein intake of the bees decreased with age. Ultrastructural studies revealed columnar cells in the posterior midgut engaged in the synthesis and release of membrane-bound vesicles. The apical cytoplasm of the epithelial cells in this region contains numerous electron dense vesicles which are released into the ectoperitrophic space of the midgut lumen. The microvilli in the crypts of this region are short, branching, and microvesiculate. Throughout the remainder of the midgut, the microvilli are profuse and elongate. The presence of the endogenously produced endoprotease and the regional variation in cell ultrastructure suggest that the honey bee may rely on countercurrent flow to distribute enzymes and nutrients efficiently throughout the midgut. Ultrastructural cytochemistry localized acid phosphatase and nonspecific esterase activity in primary and secondary lysosomes dispersed throughout the midgut tissues. Alkaline phosphatase activity was localized within large electron lucent microbodies that are present in all midgut columnar cells. The peroxisomal marker enzymes, catalase and L-α-hydroxy acid oxidase, were also localized in the same microbodies which previously had been described as holocrine secretory granules involved in dietary mineral regulation. Morphological and cytochemical assays suggest that the holocrine secretory granule arises from a microperoxisomal compartment involved in intermediary metabolism in the midgut of adult honey bees.

Honey bees mark artificial flowers with scents that advertise about the previous history of the flower to subsequent foragers. Unrewarding flowers are marked with a scent, after a single visit, that makes the flower less attractive to subsequent foragers. Previously rewarding flowers are initially less attractive than unvisited flowers but become more and more attractive with each rewarding visit. Flowers that have rewarded bees four times are more attractive than unvisited flowers. This attractant is applied by the bees in response to the presence of nectar and is not, as has been suggested by other researchers, inadvertently applied to anything on which the bee lands. Similar scent-markings are applied to a real flower, Lotus corniculatus. One visit was enough to make a flower less attractive to subsequent foragers but flowers that consistently offered high amounts of nectar became more attractive than unvisited flowers. Repellents may be used by bees to avoid revisiting recently emptied flowers while attractants may be applied to flowers within a patch that consistently offer high rewards. The possible selective pressures responsible for the evolution of scent-marking was investigated by doing an energetic analysis. The presence of scent-markings in a patch results in a 33% increase, over an unmarked patch, in the amount of sugar obtained per time. The attractive scent-marking was extracted from a glass flower and maintained its biological activity when applied to a clean glass flower. The extract was chemically analyzed using gas chromatography-mass spectrometry. Four chemicals were identified; none of the chemicals has previously been found in honey bees. Mandibular glands were analyzed as a possible source of the attractant. Although none of the components was found in the gland extracts, two previously unidentified chemicals were found. / Graduation date: 1994

Morphometric and behavioural characteristics of honeybees, Apis mellifera were analysed using multivariate and bivariate statistical methods to characterise honeybees of southern Ethiopian region. A total of 33800 morphometric character measurements were taken from 2600 individual worker honeybees of 130 honeybee colonies collected at 26 sampling localities with an average inter-locality distance of 89km to determine the occurrence of morphoclusters. 117 experienced farmer beekeepers and beekeeping experts were interviewed on pre-tested questionnaire to investigate the behavioural characteristics of these honeybees in their respective areas. Morphometric characters associated with pigmentation and body size exhibited a higher discriminant power while forewing venation angles (B4, N23 and 026) lack discriminatory power to segregate honeybees in the southern Ethiopian region. Principal components and discriminant analyses using the most discriminatory morphological characters delineated four statistically distinct morphoclusters in the southern Ethiopian region: the smallest and yellow honeybees, A. m. woyi-gambella which are different from all African honeybees, occur in the western and southern lowlands; the small and yellowiest honeybees, Apis mellifera jemenitica in the eastern escarpment; the largest and darkest honeybees, Apis mellifera bandasii in the central and eastern highlands; and dark honeybees, Apis mellifera scutellata in the wet tropical forests. High intracolonial and intercolonial variances within and between the boundaries of the honeybee groups were detected. The former suggests areas of ecological instability, while the latter areas of transitional or natural hybridisation zones. These areas are characterised by transitional ecological zones having intermediate climate and physiography. Even though honeybees of the southern Ethiopian region are generally dark and small, they show a high tendency to reproductive swarming, migration and aggressiveness, great variation in pigmentation, size and behaviour were observed both within and between the groups. A. m. jemenitica honeybees have a high propensity to migration and less a tendency for reproductive swarming. A. m. bandasii and A. m. scutellata have a high inclination to reproductive swarming and the former has a lesser and the later intermediate propensity to migration. A. m. woyi-gambella honeybees have intermediate swarming and migration tendencies. These results revealed that reproductive swarming and migration are higher in resource-rich and resource-poor areas respectively. Honey plants of the central highlands of Ethiopia are predominantly herbaceous in nature and mainly grow on open and cultivated lands. The bulk of pollen collected came comparatively from few genera. Strong correlation was observed between the intensities of flowering and rainfall. Reproductive swarming and migration occur during high and low intensity of flowering respectively.

The Eastern Cape is an area in which Apis mellifera capensis, A. m. scutellata and their hybrid are known to naturally occur. I investigated the mandibular gland profiles and ovarial development of queenright workers from 4 localities. Their queens were then removed to determine how these aspects changed upon queen loss. In addition, drifted bees were analysed in the same way to determine how these factors changed once they had gained entry to a foreign hive. The queenright bees, form all 4 localities were found to have 9HDA as the most abundant of the 5 fatty acids measured and all localities had small percentages of 9ODA in their mandibular gland secretions. This resulted in relatively high queenright 9ODA:10HDA and 9HDA:10HDAA ratios. Despite this the percentage of bees with undeveloped ovaries was consistent with their queenright status. The mean values of these 2 ratios were significantly higher in the bees from East London and Cradock than those from Port Elizabeth. Steynsburg's bees were intermediate in this regard. Upon queen loss, the bees from all 4 localities had an increase in the percentage of 9ODA but the other compound changes in varying ways. East London's bees were the only ones not to become significantly more queen-like after queen loss. After 14 days without a queen, the mean values of these 2 ratios were much higher in the bees from Port Elizabeth than those from the other localities. Certain individuals from Port Elizabeth had values of these ratios that exceeded those found in A. m. capensis queens. Port Elizabeth was the only locality to display any surrogate queens and exhibited the highest increase in the number of bees with partially or fully developed ovaries. While certain individuals from the other localities had values of these ratios that exceeded these values reported in A. m. scutellata queens, Steynsburg's bees were the only ones that did increase in in terms of the number of bees with developed ovaries subsequent. The bees from Steynsburg were shown to suppress the mandibular gland and ovarial development of drifters from Port Elizabeth while bees from East London did not.

The number of drones and genetic diversity among drones are essential components to a well mated queen. Varroa destructor preferentially parasitizes drone brood, and is thought to be responsible for the loss of feral populations that once provided additional drones for honey bee mating areas. It is necessary to use miticides (e.g. coumaphos) in managed colonies to control V. destructor. Little is known about the sublethal effects of these compounds, which are directly introduced into the hive. In response to growing concerns about the successful mating of honey bee queens, drone honey bees were exposed to coumaphos, during drone development. Sperm and seminal vesicles were sampled among drones that were exposed to coumaphos and drones that were not exposed to coumaphos, but were parasitized by Varroa destructor. There were no significant differences found between the two treatments in terms of seminal vesicle size and sperm numbers. These results indicate that drones parasitized by V. destructor have similar sperm quantities as drones exposed to coumaphos. / Graduation date: 2004