Diversity and Abundance of Native Bees Foraging on Hedgerow Plants in the Kakamega Farmlands, Western Kenya

Journal of Apicultural Research ISSN: 0021-8839 (Print) 2078-6913 (Online) Journal homepage: http://www.tandfonline.com/loi/tjar20 Diversity and abundance of native bees foraging on hedgerow plants in the Kakamega farmlands, western Kenya David Mwangi, Muo Kasina, John Nderitu, Melanie Hagen, Mary Gikungu & Manfred Kraemer To cite this article: David Mwangi, Muo Kasina, John Nderitu, Melanie Hagen, Mary Gikungu & Manfred Kraemer (2012) Diversity and abundance of native bees foraging on hedgerow plants in the Kakamega farmlands, western Kenya, Journal of Apicultural Research, 51:4, 298-305, DOI: 10.3896/IBRA.1.51.4.02 To link to this article: http://dx.doi.org/10.3896/IBRA.1.51.4.02 Published online: 02 Apr 2015. Submit your article to this journal Article views: 22 View related articles Citing articles: 3 View citing articles Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=tjar20 Download by: [University of Nairobi Library] Date: 17 March 2017, At: 00:49 Journal of Apicultural Research 51(4): 298-305 (2012) © IBRA 2012 DOI 10.3896/IBRA.1.51.4.02 ORIGINAL RESEARCH ARTICLE Diversity and abundance of native bees foraging on hedgerow plants in the Kakamega farmlands, western Kenya David Mwangi1, Muo Kasina2*, John Nderitu1, Melanie Hagen3, Mary Gikungu4, and Manfred Kraemer3 1Department of Plant Science and Crop Protection, University of Nairobi, PO Box 30197- 00100, Nairobi, Kenya. 2Department of Entomology, KARI-NARL, PO Box 14733-00800 Nairobi, Kenya. 3Faculty of Biology: Biological Collection, Bielefeld University, PO Box 100131, 33501 Bielefeld, Germany. 4Department of Zoology, National Museums of Kenya, PO Box 40658-00100, Nairobi, Kenya. Received 14 May 2010, accepted subject to revision 12 June 2012, accepted for publication 22 August 2012. *Corresponding author: Email: [email protected] 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. Diversidad y abundancia de las abejas nativas pecoreando en los setos de las granjas de Kakamega en el oeste de Kenia Resumen Se determinó la diversidad y abundancia de abejas nativas que pecorean en las flores de los setos y se documentó la composición de las plantas que forman dichos setos desde Octubre del 2008 hasta Marzo del 2009 en Kakamega, en el oeste de Kenia. Se hicieron observaciones sobre distintos sectores de setos ubicados en cinco usos de suelo distintos: el bosque de Kakamega; carreteras; plantaciones de caña de azúcar; cultivos de maíz o judías; y tierras de pastoreo. Nuestros resultados muestran la alta diversidad de abejas que es soportada por los setos. Dicha diversidad y abundancia es significativamente distinta (P < 0,05) en los cinco tipos de uso de suelo. Se halló un total de 82 especies de abejas pertenecientes a tres familias (Apidae, Megachilidae y Halictidae), siendo Apidae la que presentaba una mayor abundancia y riqueza de especies. La idoneidad de los setos como fuentes de forrajeo para las abejas difiere en gran medida, excepto para la familia Megachilidae. Las plantas más importantes para las abejas pertenecen a las familias Acanthaceae, Asteraceae y Fabaceae. Concluimos que los setos juegan un importante papel como proveedores de comida para las abejas y pueden ser usados para el manejo de abejas en las áreas de granja de Kakamega. También sugerimos la inclusión de setos según el manejo de la comunidad de abejas en áreas donde los setos están presentes o tienen la posibilidad de tener éxito, ya que pueden mantener la vida de las abejas y por ende la polinización de los cultivos en ecosistemas agrícolas. Keywords: Bee forage plants, conservation, farmlands, hedgerow flowers, pollinators, Kakamega, Kenya Bees of hedgerows plants in Kakamega, Kenya 299 Introduction diversity of flower-visiting bees and their abundance in the hedgerows as well as to document bee forage plants in the hedges. Such The dependence of human diets on insect pollinated plants is information would enhance utilization of the hedgerows at Kakamega considerable (Maheshwari, 2003), and amongst the known pollinators, for the provision of crop pollination services and also act as a guide to bees are the most important, providing about 75% of the pollination policy makers to ensure national management of pollinators in service of insect pollinated crops. Only a small fraction (12%) of the farmlands. world’s known bees have so far been recorded in sub-Saharan Africa (O’ Toole and Raw, 1991), but studies on Kenyan bees and their pollination are still in the infancy, with new records occurring Materials and methods frequently (e.g. Gikungu et al., 2011). As in other developing countries, agriculture is the backbone of Study Area the Kenyan economy. The intensification of agriculture and other We conducted this study in farmland situated on northern part of anthropogenic activities is a major threat to the survival and existence Kakamega Forest, western Kenya. The area has rich agricultural soils of bees (Kremen et al., 2002). With the current trend in human and receives plenty of rain (over 1500 mm per annum) which is well population growth and demand for food, it is unlikely that agricultural distributed throughout the year with two rainfall peaks, one in April / growth will slow. It thus becomes essential to develop innovative May (long rains) and September / November (short rains) (Ministry of strategies for managing bees and other pollinators in ever changing Agriculture, Kenya, 2006). The mean monthly temperature ranges agroecosystems without jeopardizing agricultural production. This from 11 to 29°C. The area is classified as one of the high potential requires holistic approach where crop practices and habitat areas for agricultural production in Kenya (Jaetzold et al., 2007). Most management are performed. For example, hedgerows have been used inhabitants grow crops and keep livestock in small land units ranging in the past to manage crop pollinators in Europe (Banaszak, 1992). from 0.2 ha to 0.7 ha (Greiner, 1991). While crops such as sugarcane, The way hedgerows interconnect in a farm landscape as well as their tea and maize are grown in the area for commercial purposes, farmers heterogeneous plant structure enables formation of a functional depend on other crops grown in small farm portions for daily dietary network (Barr and Gillespie, 2000). Some earlier studies of hedgerows needs. These other crops gain more from bee pollination and are have shown high species diversity of invertebrates and vertebrates therefore threatened by a decline of pollinators (Kasina et al., 2009b). (Forman and Baudry, 1984), the insect diversity observed being higher than that observed in bean fields and pasture. In Kakamega, Sampling Kenya, hedgerows have been found to be necessary for enhancing We selected 40 hedgerow plots each measuring 50 m long with a diversity and abundance of bee pollinators (Kasina et al., 2009a). A minimum of 2m width, scattered in the farm landscape. We grouped farm survey carried out there, reported hedgerows to have a wide these hedgerows into five categories based on the adjacent land use range of trees, shrubs and herbs flowering at different times of the system: sugarcane plantation; maize-beans intercropping system; year. Farmers were reported to understand these hedgerows and access roads; grazing; and forest. We observed bees visiting flowers their floral calendar and usually managed hedges through trimming for about 40 min per hedgerow plot between 09.00 h and 14.00 h, and weeding (Kasina et al., 2009a). They used hedgerows to mark which is the time bees are most active at Kakamega (Kasina et al., farm boundaries, as a source of fuel and medicine, and as fodder for 2009c). Each plot was sampled twice monthly for six months from their livestock but not for pollinator and biodiversity conservation. October 2008 to March 2009. Weather parameters (wind speed in ms-1 Such traditional hedgerow uses are not unique in Kenya but have also and temperature, °C, using Kestrel 3000 MB Trading) and attributes been reported to cut across communities and societies in different i.e., colour and morphology (open or tubular) of flowers visited by parts of the world (Baudry et al., 2000). In recent times, these bees were recorded during sampling. We observed, counted and hedgerows have provided a potential avenue for managing pollinators recorded all bees that reached either anthers or stigmas of the in the farmlands; a more than 40% net benefit after sales of crops flowers in each transect. was demonstrated as a result of non-Apis bees in Kakamega (Kasina Samples of unknown plants were collected, preserved and taken et al., 2009b), so farmers should be interested in managing these for identification at the University of Nairobi.

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