A phenological and bioclimatic analysis of honey yield in South Africa
- Authors: Illgner, Peter Mark
- Date: 2004
- Subjects: Bee culture -- South Africa -- Statistics Honeybee -- South Africa Bee culture -- South Africa -- Management Honey plants -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5813 , http://hdl.handle.net/10962/d1007153
- Description: This study has investigated the interaction between honeybees and their forage plants and the impact of selected climatic variables on honey production in South Africa. Twenty-seven scale-hive records from 25 localities have been used as a measure of colony honey reserves. At least 944 plant species are visited by honeybees in South Africa for their nectar and/or pollen, with more than half providing both rewards. The entire honeybee flora encompasses 532 genera and 137 families. The flowering phenologies of the different reward categories of the indigenous forage plants are all significantly and positively correlated at the 0.05 level. Similarly, species offering both rewards are significantly and positively correlated with the flowering phenology of the null flora. The same results were obtained for correlations between the different reward categories of the exotic forage plants in South Africa. Of the 30 species pairs which fulfilled the criteria for selection, 23 occurred in sympatry, 5 in allopatry and 2 in possible parapatry. There is evidence for both competition and facilitation within different indigenous species pairs. The lack of geographical correlation in the intra-annual variation in honey stores and the near absence of any statistically significant (p < 0.05) honey related intra-annual intracolonial correlations may indicate that the former is more important than the latter for the determination of the level of honey reserves within a colony. Only one statistically significant correlation was found between either scale-hive record from the University of Pretoria Experimental Farm and any of the selected climatic variables. A one month lag period and/or possible seasonal effects were detected for each variable, with the exception of the duration of sunshine, in the autocorrelation analyses. A possible 12 month seasonal period was also identified in the single series fourier analyses for a number of variables. Similarly, 12 months was also the most frequently recurring period in the crossspectral results for the one scale-hive record (H42). Any activities which have an impact on the landscape have the potential to affect honeybees and/or their forage plants. Honeybee crop or plant pollination may also enhance yields for commercial farmers and facilitate rural food security.
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The ecology and control of small hive beetles (Aethina tumida Murray)
- Authors: Ellis, James Douglas
- Date: 2004
- Subjects: Bee culture , Bee culture -- United States , Nitidulidae , Beetles -- Ecology , Beetles -- Control
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5917 , http://hdl.handle.net/10962/d1016253
- Description: The small hive beetle (Aethina tumida Murray) is an endemic scavenger in colonies of honey bee (Apis mellifera L.) subspecies inhabiting sub-Saharan Africa. The beetle only occasionally damages host colonies in its native range and such damage is usually restricted to weakened/diseased colonies or is associated with after absconding events due to behavioral resistance mechanisms of its host. The beetle has recently been introduced into North America and Australia where populations of managed subspecies of European honey bees have proven highly susceptible to beetle depredation. Beetles are able to reproduce in large numbers in European colonies and their larvae weaken colonies by eating honey, pollen, and bee brood. Further, adult and larval defecation is thought to promote the fermentation of honey and large populations of beetles can cause European colonies to abscond, both resulting in additional colony damage. The economic losses attributed to the beetle since its introduction into the United States have been estimated in millions of US dollars. Although beetles feed on foodstuffs found within colonies, experiments in vitro show that they can also complete entire life cycles on fruit. Regardless, they reproduce best on diets of honey, pollen, and bee brood. After feeding, beetle larvae exit the colony and burrow into the ground where they pupate. Neither soil type nor density affects a beetle’s ability to successfully pupate. Instead, successful pupation appears to be closely tied to soil moisture. African subspecies of honey bees employ a complicated scheme of confinement (aggressive behavior toward and guarding of beetles) to limit beetle reproduction in a colony. Despite being confined away from food, adult beetles are able to solicit food and feed from the mouths of their honey bee guards. Remarkably, beetle-naïve European honey bees also confine beetles and this behavior is quantitatively similar to that in African bees. If confinement efforts fail, beetles access the combs where they feed and reproduce. Two modes of beetle oviposition in sealed bee brood have been identified. In the first mode, beetles bite holes in the cappings of cells and oviposit on the pupa contained within. In the second mode, beetles enter empty cells, bite a hole in the wall of the cell, and oviposit on the brood in the adjacent cell. Despite this, African bees detect and remove all of the infected brood (hygienic behavior). Similarly, European bees can detect and remove brood that has been oviposited on by beetles. Enhancing the removal rate of infected brood in European colonies through selective breeding may achieve genetic control of beetles. Additional avenues of control were tested for efficacy against beetles. Reducing colony entrances slowed beetle ingress but the efficacy of this method probably depends on other factors. Further, the mortality of beetle pupae was higher when contacting species of the fungus Aspergillus than when not, making biological control an option. Regardless, no control tested to date proved efficacious at the level needed by beekeepers so an integrated approach to controlling beetles remains preferred. The amalgamation of the data presented in this dissertation contributed to a discussion on the beetle’s ecological niche, ability to impact honey bee colonies in ways never considered, and the ability to predict the beetle’s spread and impact globally.
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The occurrence of Nosema apis (Zander), Acarapis woodi (Rennie), and the Cape problem bee in the summer rainfall region of South Africa
- Authors: Swart, Dawid Johannes
- Date: 2004
- Subjects: Nosema apis , Bee culture , Honeybee -- South Africa , Honeybee -- Diseases , Honeybee -- Parasites , Mites
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5914 , http://hdl.handle.net/10962/d1015980
- Description: The occurrence of Nosema disease, tracheal mites and the “pseudo-parasitic” behaviour of Cape honeybee workers when placed amongst African honeybees – known as the Cape Bee Problem – were studied over a 18 month period. Three surveys, approximately 6 months apart were done. The aims of this study were to establish the distribution and severity of the diseases and compare the disease with the presence of the Cape Bee Problem. Before this survey commenced European Foul Brood disease, Sacbrood (virus), Nosema, Brood nosema, and Tracheal mite have sporadically been reported in the summer rainfall region of South Africa. In the first survey 1005 colonies in 61 apiaries were surveyed, 803 colonies in 57 apiaries in the second, and 458 colonies in 41 apiaries in the third. Samples for disease and parasite analysis were taken at 4 colonies per apiary. Ten colonies per apiary were inspected for Cape Problem Bees, and samples of workers were collected and dissected at each of these colonies. Even with the addition of apiaries to 'fill-up' lost colonies during the second survey, 63% of all colonies were lost by the third survey. There was only a small difference in colony loss between sedentary and migratory beekeepers of 22% compared to 27%. Nosema was more prevalent amongst commercial beekeepers and increased in migratory operations during the survey period. The percentage of colonies infected increased during the survey period from 23% to 32% to 34%. The placement of colonies in Eucalyptus plantations may boost infection. Trachea mites seem to have spread quite rapidly in South Africa since its discovery. This parasitic mite was present in all regions, although in low numbers in three most northern regions. Sedentary colonies had higher levels of infestation than migratory colonies. The number of colonies infested diminished over the survey period, which may be a result of general colony loss. The Cape Problem Bee was less of a problem than anticipated. Colonies succumbed to Cape Problem Bees in all regions. When beekeepers reported high levels of infestation in their bee stocks the colonies would be dead within six months. In apiaries with low infestation the die-out was slower.
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