Over the past century there have been substantial declines in farmland biodiversity as a result of the intensification of agricultural practice. Concerns over these declines have led to the development of agri-environment schemes designed to mitigate the effects of intensive agriculture and to benefit biodiversity. Prior to commencing this thesis it was not clear if flower-rich, pollinator-focused agri-environment schemes had a population level impact on wild bees on farmland. Whilst previous work has shown that the creation of flower-rich habitat can provide suitable foraging resources for bumblebees, little was known about the impact of this management on bumblebee population sizes and even less on whether these resources were used by and benefited solitary bees. This thesis compares bee populations between farms with and without flower-rich, pollinator focused agri-environment schemes in Hampshire and West Sussex, UK. Using genetic techniques to estimate colony density, and hence population size, farms implementing targeted schemes had a significantly higher density of bumblebee nests for the four species studied (212 nests/km2 against 112 nests/km2). However, there was no difference in the species richness of bees between these different farm types. When assessing pollen use by solitary bees, flowering plants sown as part of pollinator-focused agri-environment schemes were not widely used, representing 27% of pollen foraging observations and 23% of pollen collected by volume. Only 35% of solitary bee species were found to use sown plants for pollen to a meaningful extent, with most pollen collected from plants persisting in the wider environment. The creation of flower-rich habitat significantly increased resource availability, but did not increase resource diversity. These results indicate that if diverse bee populations are to be maintained on farmland then agri-environment schemes must be developed that effectively increase the number of flowering plant species present at the farm scale.

Defence against predators is fundamental to increasing an organism's fitness. My thesis explores this central theme in behavioural ecology using stingless bees as study organisms. The thesis contains a general introduction (Chapter 1), three data chapters (2-4) and a final discussion (5). Chapter 2 is a comparative study of aggression in nest defence among stingless bee species, and describes a new form of nest defence, suicidal biting, which is most prevalent in the genus Trigona. Chapter 3 describes a remarkable behaviour in Partamona helleri, which crashes head-first when entering its nest. An experiment suggests that this behaviour helps to avoid predation at the nest entrance. Chapter 4 studies nest defence in the hovering guards of Tetragonisca angustula, and demonstrates that through coordinated vigilance, a group level behaviour rarely observed in animals, the ability of the group to detect predators is enhanced.

When provided with the opportunity to select their diet, most insect herbivores regulate their nutrient intake. However, in a nutritionally heterogeneous environment and with changing demands for growth, development and reproduction, obtaining the required amount and balance of nutrients is a challenge. This is especially true for social insects where the workers bring food into the colony to be shared by nestmates. The ability of insects to self-select their diet is an important trait related to fitness. In this study we investigated whether and how caged worker honeybees meet their nutritional requirements in response to the nutritional composition of the food they find. Using the ‘geometric framework’ we looked at the behavioural and physiological mechanisms used by caged worker honeybees in balancing their diet when provided with different pairs of complementary imbalanced foods. First, we investigated whether caged worker honeybees maintain their intake target by providing them with pairs of complementary imbalanced foods with varying protein to carbohydrate (P:C) ratios. Diets were formulated using different protein sources: casein, royal jelly and Feed-Bee®. Honeybees self-selected or balanced their diet by switching between the complementary foods in accordance with the composition of the food and the type of protein that they encountered. Honeybees selected average P:C ratios of 1:12, 1:14 and 1:11 on casein, royal jelly and Feed-Bee® diets respectively. The level of self-selection was confirmed using two performance measures: survival and ovarian activation. Both survival and ovarian activation differed depending on the type of protein source used. Second, we investigated if honeybees regulated their growth target, which is the amount of nutrients incorporated into growth and storage tissue, by measuring physiological parameters in honeybees confined on imbalanced complementary food combinations having different P:C ratios. Feed-Bee® was used as a protein source. The physiological parameters measured were head fresh mass, hypopharyngeal gland (HPG) development, and protein concentration in the haemolymph. The bees fed on different diet combinations with different P:C ratios maintained each of the performance measures to the same level, which supports the ability of worker honeybees to self-select their diet. The measured physiological parameters were compared with other studies to asses the appropriateness Feed-Bee® diet as a protein source for the bees. In the absence of brood the intake target is directly related to the physiological requirements of the worker bees. The behavior of these individual adult bees gives an insight in to the complex system; similar responses may be seen in nurse bees in the colony condition to obtain protein, carbohydrate and other nutrient requirements from stored pollen and nectar in the hive, either for their own nutritional requirements or for other colony members, especially larvae. / Dissertation (MScAgric)--University of Pretoria, 2010. / Zoology and Entomology / unrestricted

No description available.

Simple regulatory mechanisms based on the idea of the saturable 'common stomach' can control the regulation of protein foraging and protein allocation in honeybee colonies and colony-level responses to environmental changes. To study the economic benefits of pollen and nectar foraging strategies of honeybees to both plants and honeybees under different environmental conditions, a model was developed and analyzed. Reallocation of the foraging workforce according to the quality and availability of resources (an 'adaptive' strategy used by honeybees) is not only a successful strategy for the bees but also for plants, because intensified pollen foraging after rain periods (when nectar quality is low) compensates a major fraction of the pollination flights lost during the rain. The 'adaptive' strategy performed better than the'fixed' (steady, minimalistic, and non-adaptive foraging without feedback) or the 'proactive' (stockpiling in anticipation of rain) strategies in brood survival and or in nectar/sugar economics. The time pattern of rain periods has profound effect on the supply-and-demand of proteins. A tropical rain pattern leads to a shortage of the influx of pollen and nectar, but it has a less profound impact on brood mortality than a typical continental rainfall pattern. Allocating more bees for pollen foraging has a detrimental effect on the nectar stores, therefore while saving larvae from starvation the 'proactive' strategy could fail to collect enough nectar for surviving winter.

Thesis (MSc)--Stellenbosch University, 2010. / Thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Zoology at Stellenbosch University. / ENGLISH ABSTRACT: Most modern deciduous fruit cultivars are self-incompatible, and require polliniser trees to be planted in the orchard to provide the pollen necessary for cross-pollination, fertilization and fruit set. Polliniser trees are either non-commercial cultivars interspersed in the orchard solely to provide pollen, or crosscompatible cultivars inter-planted in the same orchard. 90% of the commercial crops dependent on bee pollination are courtesy of a single species, Apis mellifera. Both polliniser planting pattern and honey bee colony distance are known to influence crop production and crop quality, resulting in a rapid decrease in fruit weight, fruit set and seed number with increasing distance from the polliniser or honeybee colonies. However, the response of different crops and cultivars to polliniser and pollinator proximity on optimal crop yield is not known for deciduous fruit crops in the Western Cape, South Africa. The effect of polliniser position and honeybee colony distance on fruit set and weight was investigated in plums, apples and pears on the Lourensford Estate. The relationship between fruit set and fruit weight was investigated for deciduous fruit cultivars. In addition, fruit weight and seed number was also investigated in apples and pears. Fruit set tended to increase on sides of trees closer to the polliniser but not significantly so, except for apples. This suggests that there is probably better pollination closer to the pollinisers but this does not equate to increased yield. In fact, smaller fruit was produced on the sides of the trees closer to the polliniser for all orchards and significantly so for plum and for ‘Packham’s Triumph’ in Hillside 1. This negative relationship between fruit set and weight may indicate ‘over-set’ beyond the physiological limits of the trees. Fruits closer to the polliniser had significantly more seeds for both pear and apple cultivars indicating sufficient pollination. A significant relationship was found between the seed number in any particular fruit and the weight of the fruit in all the cultivars except ‘Packham’s Triumph’ where the relationship was negative, suggesting that ‘Packham’s Triumph’ set parthenocarpically. Colony distance had no effect on fruit weight, fruit set and on seed number indicating that colonies were adequately distributed and that there was no “pollination depression” in the centre of the orchards at Lourensford. In conclusion, the fact that we did not get a yield gradient with increased distance from the colonies suggested that the orchards at Lourensford Estate were sufficiently pollinated. / AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar

Thesis (PhD (Botany and Zoology))--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Insect societies utilize advanced chemical communication systems to organize many aspects of their social life, which among others, include reproduction, thus maintaining colony homeostasis. The queen pheromone complex (QMP), dominated by (E)-9-keto-2-decenoic acid (9ODA) is of integral importance in regulating worker reproductive development. Unique characteristics, associated with reproductive dominance, enabled the successful establishment of Apis mellifera capensis workers as social parasites (or pseudoqueens) in colonies of the neighbouring A. m. scutellata. This suggested that producing a queenlike pheromonal bouquet is one of the proximate factors in their success. In this study we attempted to address the pheromone communication dilemma by investigating whether the phenotypic expression of mandibular gland signals in honeybee workers are under genetic and/or environmental influence. It was hypothesized that the mandibular gland profiles of queens and workers may be closely correlated to specific genotypes in the colony. However, different ageing and rearing environments (social context) can ultimately influence gene expression with respect to mandibular gland signals, highlighting the fact that environmental influences are not necessarily non-significant. In our experiments, both environmental/social conditions and genotypes of our test individuals were manipulated. The capensis workers used in our experiment from their native range (Western Cape area are refered to as native workers, while capensis parasitic workers, from the clonal parasitic lineage, were obtained from the Gauteng area. A. m. scutellata workers were obtained from their native range, north of the hybrid zone. Both native and parasitic workers showed the potential to become reproductively active, but the rapid pheromonal development of parasitic workers placed them at a reproductive advantage. Parasitic workers started producing low levels of 9HDA, the precursor to the queen substance 9ODA, between 12-24 hrs, while native workers only did so after 24 hrs. Despite this, rapid signal development did not culminate in the parasitic clones always pheromonally out-competing native workers. Withinin groups of native workers and a single clonal parasitic worker, the mandibular gland profiles of most workers were dominated by 9ODA and 9HDA (> 80% of extracts) with only 43% of the single parasitic workers producing higher amounts of 9ODA than native workers. Mandibular gland pheromone profiles converged in groups of workers sharing a greater proportion of genes, providing support for a link to genotypic affects. Workers that were 75 – 99% related diverged significantly from groups with lower levels of relatedness was largely due to the presences of 9ODA (Spearman’s rank correlation r = 0.66, p < 0.0001). Despite the tendency for signal to convergence in groups of closer relatedness a considerable amount of signal variability was also observed under varying social conditions. Workers originating from a single capensis queen but aged under queenright and queenless conditions had very distinct mandibular gland profiles (Wilks’ lambda λ = 0.118, χ2 = 331.002, p < 0.0001). This variability was thus a result of the social environment that the workers were exposed to. The physiological traits, namely mandibular gland pheromone production, linked to reproductive potential in honeybee workers seem to be determined by a combination of environmental and genetic factors. Queen mandibular gland pheromone biosynthesis is genetically predisposed in certain workers however the final oxidation step to 9ODA is strongly influenced by the social environment. The signal plasticity observed in this study is adaptive and assists workers to realize their reproductive potential. / AFRIKAANSE OPSOMMING: Insek gemeenskappe gebruik gevorderde chemiese kommunikasie sisteme om verskeie aspekte van sosiale lewe, onder andere reproduksie, te organiseer en sodoende word korf homeostasis handhaaf. Die feromoon kompleks van die koninginby, wat hoofsaaklik uit (E)-9-keto-2-decenoic acid (9ODA) bestaan speel ʼn belangrike rol in die regulering van reproduksie in heuningby werkers. Die suksesvolle vestiging van Apis mellifera capensis werkers as sosiale parasiete (pseudo koninginne) in die korwe van die naburige A. m. scutellata, is bewerkstellig deur hul unieke kenmerke, wat met reproduktiewe oorheersing verband hou. Dit suggereer dat die produksie van ʼn tipiese koningin feromoon sein een van verskeie beduidende faktore is in capensis werkers se sukses. In hierdie studie het ons die dilemma van feromoon kommunikasie probeer aanspreek deur te ondersoek of die fenotipiese uitdrukking van seine van die mandibulêre kliere deur genetiese en/of omgewings faktore beïnvloed word. Die hipotese was dat die mandibulêre klier profiele van koninginne en werkers korreleer met spesifieke genotipes in die korf. Die verskillende omgewings waarin werkers groot gemaak word en verouder (sosiale konteks), kan uiteindelik die uitdrukking van gene, raakende mandibulêre kliere, beïnvloed. Dit beklemtoon die feit dat omgewings faktore nie noodwendig onbeduidend is nie. Beide omgewings/sosiale toestande and genotipes van toets individue is in ons eksperimente gemanipuleer. Die capensis werkers afkomstig uit hul natuurlike habitat (Weskaap area) wat in ons eksperimente gebruik is word na verwys as inboorling werkers, terwyl parasitiese capensis werkers, van klonies parasitiese afkoms, vanuit die Gauteng area verkry is. A. m. scutellata werkers was vanuit hul natuurlike habitat, noord van die, hybried sone, verkry. Beide inboorling en parasitise werkers het die potensiaal getoon om reproduktief aktief te word, maar versnelde feromoon ontwikkeling van parasite werkers het hulle ʼn reproduktiewe voordeel gegee. Parasiet werkers het reeds lae hoeveelhede 9HDA, die voorganger van 9ODA, begin produseer tussen 12 – 24 uur, terwyl inboorling werkers produksie eers na 24 uur begin het. Ten spyte van die versnelde ontwikkeling in parasiet werkers het dit nie gelei daartoe dat kloniese parasiete altyd feromonies die oorhand oor inboorling werkers gekry het nie. In groepe bestaande uit inboorling werkers en ʼn enkele parasite werker, was die mandibulêre klier profiele altyd deur 9ODA en 9HDA (> 80% van ekstrakte) gedomineer. Slegs 43% van parasite werkers het groter hoeveelhede 9ODA as inboorling werkers geproduseer. In groepe werkers, wat ʼn groter proporsie gene in gemeen gehad het, het mandibulêre klier profiele konvergeer. Dit ondersteun die bestaan van ʼn verband met genotipiese invloed. Werkers van 75 – 99% verwantskap het beduidend verskil van groepe met laer verwantskapsvlakke, hoofsaaklik as gevolg van die teenwoordigheid van 9ODA (Spearman’s rank korrelasie r = 0.66, p < 0.0001). Ten spyte van die konvergerende neiging van profiele, van meer verwante groepe, was aansienlike veranderlikheid onder verskillende sosiale toestande waargeneem. Werkers, afkomstig vanaf ʼn enkele capensis koninginby, maar òf in die teenwoordigheid òf afwesigheid van ʼn koningin verouder is, het baie kenmerkende mandibulêre klier profiele getoon (Wilks’ lambda λ = 0.118, χ2 = 331.002, p < 0.0001). Die veranderlikheid was dus ʼn gevolg van die sosiale omgewing waaraan die werkers blootgestel was. Dit blyk asof die fisiologiese kenmerke wat met reproduksie potensiaal in heuningbye verband hou, naamlik mandibulêre klier feromoon produksie, deur ʼn kombinasie van genetiese – en omgewings faktore beïnvloed word. Sekere werkers is meer geneig tot die biosintese van koningin mandibulêre klier feromoon as gevolg van hul genetika, terwyl die finale oksidasie na 9ODA onder sterk omgewings invloed is. Die plastisiteit in mandibulêre seine waargeneem in hierdie studie, is aanpasbaar en help werkers om hul reproduksie potensiaal te bereik.

Thesis (MScConsEcol (Conservation Ecology and Entomology)--University of Stellenbosch, 2009. / Apiculture in the Western Cape is a well-developed industry based on honey production and pollination services to agriculture. Apart from Eucalyptus trees, fynbos vegetation serves well as bee forage to managed honeybee colonies outside the agricultural pollination season. Eucalyptus trees are cleared as invasive plant species while fynbos are rigorously protected as one of the 34 Biodiversity Hotspots identified worldwide. Thus, bee forage is in short supply and is most probably the only limitation to the number of honeybee colonies that beekeepers can feasibly maintain. The impact of a collection of commercially managed honeybee colonies on other floral resource-dependent species in the Cape Floristic Region is unknown. This is one of the first studies on the topic in South Africa and specifically in the Western Cape. Managed hives were introduced to near pristine fynbos habitat in De Hoop Nature Reserve and Marine Protected Area during July. The aim was to induce stronger competition for floral resources through greater resource exploitation by managed honeybee colonies and record the change in foraging behaviour for several insect guilds on specific plant species. The results suggest that eight hives per site proved insufficient to increase honeybee density above the natural density of honeybees. Honeybee abundance did not increase during the presence of the managed hives, while honeybee visitation frequency was significantly greater during the presence of the managed hives. Neither the abundance nor the visitation frequency of non-Apis bees and wasps differed significantly between treatments. Honeybees were the most abundant foragers on the three focal plant species during all three treatments and also made the most visits to flowers. Honeybee abundance and visitation frequency increased with distance from the managed hives. The significant increase in honeybee visitation frequency during hive presence, coupled with a significant decrease in the time honeybees spent per flower extracting nectar, were an indication of a lower standing crop of nectar during that treatment. Nevertheless, no competition for floral resources was obvious, as the number of honeybees did not increase the abundance and visitation frequency of all other insect guilds (except for a significant decrease in Muscidae, which could be ascribed to changes in weather conditions).

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science, Johannesburg, South Africa 2017 / Concerns exist over the continual decline of marula trees (Sclerocarya birrea subsp. caffra) as a result of African elephant (Loxodonta africana) impact and a lack of recruitment and regeneration. One strategy of protecting adult marula trees is the usage of elephant mitigation methods. This study took place in Jejane Private Nature Reserve (JPNR), a protected area which recently opened up to the Greater Kruger National Park and had not had elephants in over 100 years. The aim of the study was to investigate the changes to the marula population structure in JPNR three years after the migration of elephants to the area due to fence removal, and to test whether African honeybees (Apis mellifera subsp. scutellata) could be used as a mitigation method for elephant impact on marula trees. A previous size-class survey had been done on a sample of JPNR’s marula population in 2009, prior to the fence removal in 2013. A resurvey of these trees was used to assess the elephant-induced impact and mortality levels on the marula trees and to compare these levels to previously recorded impact and mortality levels on marula trees in the Kruger National Park (KNP). Marula seed predation levels and seedling recruitment were also assessed to address recruitment concerns. The resurveyed marula population had declined by 23.8% post-elephant migration, with the highest annual mortality rates (AMR) and impact scores recorded for trees in the 5 - 11 m height classes. Impact scores on marula trees in JPNR were higher than impact scores recorded on KNP marula trees. Only two marula seedlings were found across all transects, with evidence of high seed predation on marula endocarps. JPNR displayed an adult-dominated marula population with a lack of regeneration, possibly due to a lack of fire which has increased available shelter for seed predators such as small mammals. African honeybees were then used to investigate their effectiveness as an elephant mitigation method and to compare this method against wire-netting (a method experimentally used to prevent ring-barking by elephants). Fifty active beehives were hung from 50 marula trees, with another 50 dummy (inactive) beehives hung from branches on the opposite ends of each beehive tree’s main stem. Fifty additional marula trees were wire-netted and a further 50 were used as control trees. Elephant impact on all 150 trees was measured prior to the addition of treatments and post-treatment addition for nine months. 54% of the control trees received some form of elephant impact, in comparison to 28% of the wire-netted trees and only 2% of the beehive trees. Wire-netting protected marula trees against bark-stripping, but did not prevent elephants from breaking branches. Beehives proved highly efficient at mitigating all forms of elephant impact. The financial cost and maintenance required for the beehive mitigation method is greater than that of wire- netting, but the beehives can provide honey and pollination services as an additional benefit. The results of this study illustrate that African honeybees can be used as an effective non-lethal mitigation method for elephant impact on marula trees and are a viable strategy to reduce human-elephant conflict in South Africa’s protected areas. / MT 2017

Social learning plays a valuable role in the lives of many animal taxa, sometimes allowing individuals to bypass the costs of personal exploration. The ubiquity of this behaviour may arise from the fact that learning from others is often underpinned by simple learning processes that also enable individuals to learn asocially. Insects have proven to be particularly valuable models for investigating parsimonious hypotheses with regards to social learning processes, due to their small brain sizes and the prevalence of social information use in their life histories. In this thesis, I use social insects to further investigate the mechanisms underlying more complex social learning behaviours and explore the circumstances under which social information use manifests. In the first chapter, I investigate the proximate mechanisms underlying social learning and demonstrate that even seemingly complex social learning behaviours can arise through simple associative learning processes. In Chapter two, I investigate whether bees are more predisposed to learning from conspecific cues and discover that social information is learnt to a greater extent than information originating from non-social sources. In Chapter four, I demonstrate that classical conditioning also underpins learning from evolved social signals in honeybees. Finally, I investigate whether social information is used adaptively by bumblebees: Chapter three demonstrates that joining behaviour in free-flying bees is contingent upon whether flowers are familiar or not, and in Chapter six, I show that when social information is costly to acquire, bees are more likely to rely on social information to make foraging decisions. Taken as a whole, my findings suggest that bees may be specially adapted for receiving social information, but the ability to learn from others arises through general associative learning mechanisms.