Pervasiveness of Parasites in Pollinators

Many pollinator populations are declining, with large economic and ecological implications. Parasites are known to be an important factor in the some of the population declines of honey bees and bumblebees, but little is known about the parasites afflicting most other pollinators, or the extent of interspecific transmission or vectoring of parasites. Here we carry out a preliminary screening of pollinators (honey bees, five species of bumblebee, three species of wasp, four species of hoverfly and three genera of other bees) in the UK for parasites. We used molecular methods to screen for six honey bee viruses, Ascosphaera fungi, Microsporidia, and Wolbachia intracellular bacteria. We aimed simply to detect the presence of the parasites, encompassing vectoring as well as actual infections. Many pollinators of all types were positive for Ascosphaera fungi, while Microsporidia were rarer, being most frequently found in bumblebees. We also detected that most pollinators were positive for Wolbachia, most probably indicating infection with this intracellular symbiont, and raising the possibility that it may be an important factor in influencing host sex ratios or fitness in a diversity of pollinators. Importantly, we found that about a third of bumblebees (Bombus pascuorum and Bombus terrestris) and a third of wasps (Vespula vulgaris), as well as all honey bees, were positive for deformed wing virus, but that this virus was not present in other pollinators. Deformed wing virus therefore does not appear to be a general parasite of pollinators, but does interact significantly with at least three species of bumblebee and wasp. Further work is needed to establish the identity of some of the parasites, their spatiotemporal variation, and whether they are infecting the various pollinator species or being vectored. However, these results provide a first insight into the diversity, and potential exchange, of parasites in pollinator communities

Classifying chimpanzee (Pan troglodytes) landscapes across large scale environmental gradients in Africa

Primates are sometimes categorized in terms of their habitat. Although such categorization can be over-simplistic, there are scientific benefits from the clarity and consistency that habitat categorization can bring. Chimpanzees (Pan troglodytes) inhabit various environments, but researchers often refer to ‘forest’ or ‘savanna’ chimpanzees. Despite the wide use of this forest-savanna distinction, clear definitions of these landscapes for chimpanzees, based on environmental variables at study sites or determined in relation to existing bioclimatic classifications, are lacking. The robustness of the forest-savanna distinction thus remains to be assessed. We review 43 chimpanzee study sites to assess how the landscape classifications of researchers fit with the environmental characteristics of study sites and with three bioclimatic classifications. We use scatterplots and Principal Components 15 Analysis to assess the distribution of chimpanzee field sites along gradients of environmental 16 variables (temperature, rainfall, precipitation seasonality, forest cover and satellite-derived 17 Hansen tree cover). This revealed an environmental continuum of chimpanzee study sites 18 from savanna to dense forest, with a rarely acknowledged forest mosaic category in between, 19 but with no natural separation into these three classes and inconsistencies with the bioclimatic 20 classifications assessed. The current forest–savanna dichotomy therefore masks a progression 21 of environmental adaptation for chimpanzees, and we propose that recognizing an additional, 22 intermediate ‘forest mosaic’ category is more meaningful than focusing on the ends of this 23 environmental gradient only. Future studies should acknowledge this habitat continuum, place their study sites on the forest–savanna gradient, and include detailed environmental data to support further attempts at quantification

Foraging behaviour of equatorial Afrotropical stingless bees: habitat selection and competition for resources

This thesis is a result of fieldwork on foraging ecology of Afrotropical stingless bees in Uganda. This is because most studies on stingless bee ecology are largely based in South America and South-east Asia and have ignored the aspects of Afrotropical stingless bees. The central question is how the Afrotropical bees co-exist by partitioning their resources. Aspects of nesting behaviour of the stingless bees are presented in chapter 3. In BINP there are at least five stingless bee species belonging to two genera: Meliponula (four species) and Hypotrigona (one). The bee species nest in tree cavities, mud house wall crevices and underground. The relative importance of predation, food supply, nesting site and elevation affecting abundance of stingless bees were studied for meliponines in chapter 4. Predators were treated more comprehensively compared to previous field studies. Our figures for nest density for both the honey bee and the combined stingless bee species may agree with estimates from drier parts of Africa and some habitats in the American and Asian tropics. At an average of 12 percent/year, meliponine colony mortality from predators in this study was generally higher than those reported for American and Asian tropics. The use of tools by humans and chimpanzees caused high rates of stingless bee nest mortality. Temporal resource partitioning and climatological factors influencing colony flight and foraging of stingless bees is discussed in chapter 5. Foragers of M. ferruginea and M. nebulata exited their nests in characteristically distinct foraging bouts suggesting the recruitment methods used may be direct leading or ‘piloting’. The number of individuals in a returning bout was less than that in an exiting bout suggesting recruits do not follow experienced foragers the whole distance to food source. Differences in pollen foraging by A. mellifera and stingless bees (M. bocandei and M. nebulata) were studied in chapter 6. Palynological results showed an overlap among the three bee species. A. mellifera the larger bee had the highest diversity while M. nebulata had the lowest. The recruitment technique to food sources is implicated to have been one of the factors accounting for the differences in pollen foraging behaviour. Foragers of M. nebulata flew out in distinct bouts which probably led to the low pollen diversity. Chapter 7 discusses factors influencing sugar concentration of collected nectar. Two stingless bee species (H. gribodoi and M. ferruginea) were used to show co-existence among the two genera. The smaller bee (H. gribodoi) collected nectar of higher sugar concentration. Factors that influenced sugar concentration of collected nectar included botanic origin of the nectar, bee species, bee colonies, month of year, time of day and the local environment. In Chapter 8, a study on seasonal floral resource utilisation and pollen collection by A. m. scutellata was undertaken. Results showed that the flowering time of bee plants varied with the different seasons of the year. Most plants bloomed during the rainy season while agricultural crops flowering depended on sowing date. There was more brood-rearing during the rainy season, when flowers were in bloom

The status of honeybee pests in Uganda

Beekeeping provides enormous potential for income generation, pollination and sustainable use of forest resources. In Uganda, honey production potential is enormous and in 2005; Uganda was licensed to export honey to the EU, creating an immense opportunity. However, the potential for beekeeping is not fully exploited. Many pests attack honeybees causing enormous losses. This descriptive study thattook a participatory action research approach, evaluated how beekeepers managed honeybee pests. Data collection was carried out from 2009 to 2012 from four of the ten agro-ecological zones of Uganda. These zones are classified on the basis of distinct vegetation type, elevation and climatic conditions. Eleven honeybee pests and predators that affect beekeeping production were documented. The important pests causing economic losses were black ants, small hive beetles, wax moths and bee hornets. Effective methods for pest control and management applied by beekeepers included mechanical methods and bio-control. The mechanical methods included keeping the apiary tidy; avoiding throwing combs around apiaries andfrequent smoking to drive out small hive beetles. At least 28% of the beekeepers developed local organic (bee-safe) methods for pest control. To manage the ants, many beekeepers applied ash at the apiaries. They hanged their hives using wires and kept their apiaries tidy. The use of hive stands placed in used engine oil also helped reduce many pests. Some beekeepers swatted bee hornets to reduce colony abscondment. The pests led to absconding of many colonies. Honey production with the traditional hives was most affected by the pests; followed by the top bar hive. Frame hives were the least affected by the pests. Many beekeepers lacked adequate information for managing the pests limiting the methods used to control the pests. There should be detailed study of the important honeybee pests in order to design best management practices.Key words: Honeybees, Honeybee pests, ants, wax moths, small hive beetles, Ugand