Muo Kasina

Farmers' knowledge of bees and their natural history in Kakamega district, Kenya.

Summary The Kakamega district is endowed with good climatic and soil conditions that have favoured agricultural production, and houses the Kakamega Tropical Rain Forest, the only remaining patch of the easternmost end of the Congo Forest. In efforts to halt its fragmentation and to salvage the remaining fragments, studies are being undertaken to convince farmers of the importance of conservation. This study considers bees and their pollinating importance in the livelihood of farmers, in order to understand the level of knowledge local farmers have about bees, and their role in crop production. A questionnaire was sent in January and February 2006 to representatives of 352 households randomly selected from 19,972 households living around the forest. Respondents were shown pictures and specimens of different insects, and after correct identification, were asked to state the food sources and nesting sites of these bees. They were asked to state how they utilize these bees and about their willingness to conserve them as pollinators. We found that Kakamega farmers could identify bees of different species, and had some knowledge of bee floral and nesting needs. Only about 50% were, however, aware of pollination and could relate it to crop productivity, but after having been introduced to the importance of bee pollination in crop production, they showed willingness to conserve bees for such purposes.

Diversity and activity density of bees visiting crop flowers in Kakamega, Western Kenya

Summary We observed bees visiting bean (Phaseolus vulgaris) flowers, the most widely grown crop in farmland near Kakamega forest, Kenya, which has attracted interest due to the presence of the only remaining tropical rain forest in the country. Two transects were created in the north and south of the forest extending to about eight km into the farmland. Observations were carried out on 14 sites on either side of the forest during the flowering period from April to June in 2005 and 2006. We recorded bees belonging to 20 species visiting beans. The honey bee Apis mellifera L. was the most abundant, followed by two solitary bees, Xylocopa calensand Xylocopa incostans. Bee density was low in the farmland in both sides of the forest, but diversity was significantly (P < 0.05) higher in the southern than in the northern transect. One reason for this is that the southern side is heavily populated so hedges and other land are under higher pressure, giving bees no alternative to crop flowers, whilst in the north, the population is low so there is still much land and hedges for alternative food for bees. Hedge management could be improved to support bees, especially when crops are not in flower, by interconnecting the hedges with the forest, so bees will be able to seek refugia and other needs in the forest and be able to provide pollination in the farmland, hence contributing to food security in the country.

Diversity and abundance of native bees foraging on hedgerow plants in the Kakamega farmlands, western Kenya

Summary We determined the diversity and abundance of native bees foraging on hedgerow flowers, and documented the plant species composition of those hedgerows, from October 2008 to March 2009 at Kakamega, western Kenya. We made observations on hedgerow sectors located in five different land use types: Kakamega forest; roads; sugarcane plantations; maize/bean fields; and grazing land. Our findings show that a high diversity of bees is supported by the hedgerows, and that bee diversity and abundance significantly (P < 0.05) differed across the five land use types. A total of 82 bee species belonging to three families (Apidae, Megachilidae and Halictidae) were recorded, with Apidae having the highest species richness and abundance. The suitability of hedgerow plants as bee forage sources differed greatly, except for Megachilid bees. Most important bee plants belonged to the families Acanthaceae, Asteraceae and Fabaceae. We conclude that hedgerow plants play an important role in providing bee food resources and can be used for managing bees in Kakamega farmed areas. We also suggest the inclusion of hedgerows in community based management of bees in areas where hedgerows are present or have viability to succeed, as they can support bee life and hence the pollination of crops in agricultural ecosystems.

Varroa mites, viruses and bacteria incidences in Kenyan domesticated honeybee colonies

ABSTRACT Varroa mite (Varroa destructor Anderson and Trueman) is a major global threat to the western honey bee (Apis mellifera L.). The ectoparasite has been implicated in the spread of honeybee viruses. Beekeeping plays a major role in transmission of the mite. The study aimed at assessing levels of Varroa infestation, bee viruses and bacteria incidences in domesticated honeybee colonies. Samples of adult honey bees, bee brood and Varroa mites were collected from Baringo, Narok, Kwale, Magarini, Voi, Ijara, Busia and Siaya in Kenya. Ten hives in each site were inspected for the presence of Varroa mites on adult bees using the icing sugar technique and forceps in sealed brood cells. The number of mites observed were recorded per site. Ribonucleic acid was extracted from the mites, brood and adult bees and a polymerase chain reaction was performed to detect the black queen cell virus. Pooled RNA samples of brood and adult bees were used in next generation sequencing on a 454 GS FLX platform to detect bee viruses and bacteria. Varroa mites were reported in all the study sites at varying levels. The black queen cell virus and three iflaviruses, European foul brood and its secondary causative agent Enterococcus faecalis were reported. The Kenyan honeybee population is threatened by bee pests and pathogens. There is a need for constant monitoring of bee pests and diseases in honeybee colonies in the country for early detection and to provide data on the status of bee health. All stakeholders in the beekeeping value chain should be enlightened on their role in pest and disease transmission.

Assessment of Yield Loss Caused by the African White Rice Stem Borer (Maliarpha separatella Rag (Lepidoptera: Pyralidae) at Mwea Irrigation Scheme, Kirinyaga County, Kenya

Information on losses caused by the African white rice stem borer, Maliarpha separatella rag, which is an important rice pest in Kenya is scanty. The development and implementation of effective pest management strategies relies on accurately defined Economic Injury Levels (ElL) for that pest. Investigations were, therefore, conducted to determine yield losses caused by M. separatella and economic injury level of the pest. The experiment was conducted in an insect proof screen house at Kenya Agricultural and Livestock Research Organization, Mwea station. The experiment was arranged as a (2×6) factorial design and each treatment replicated three times. First factor was time of infestation at two levels, early and late which was 3 and 6 weeks after transplant date, respectively. Second factor was infestation rate at six levels (0, 1, 2 4, 6 and 8 egg masses). Results indicated that infestation levels of 1, 2, 4, 6 and 8 M. separatella egg masses at early infestation resulted in grain yield losses of 59.8, 83.2, 84.8 90.2 and 90.9%, while losses of same infestation levels at late infestation was 34.3, 52.1, 63.4, 81.8 and 80.8%. There was a strong positive relationship between yield loss and M. separatella population levels (y = -214.29x+ 1693.4, r2 = 0.8416). On the basis of cost benefit ratio, the economic injury level was 6 and 8 egg masses per square meter in the early and late infestation, respectively. The action threshold for early infestation was 4 egg masses and 6 egg masses for late infestation.