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Accueil du site → Doctorat → Allemagne → 2007 → Bee pollinators and economic importance of pollination in crop production : case of Kakamega district, Western Kenya

Rheinischen Friedrich-Wilhelms-Universität Bonn (2007)

Bee pollinators and economic importance of pollination in crop production : case of Kakamega district, Western Kenya

Kasina John Muo

Titre : Bee pollinators and economic importance of pollination in crop production : case of Kakamega district, Western Kenya

Auteur : Kasina John Muo

Université de soutenance : Rheinischen Friedrich-Wilhelms-Universität Bonn

Grade : Doktor der Agrarwissenschaften (Dr. agr.) 2007

Résumé partiel
Bees are the main animal pollinators of crops worldwide. In Kakamega, Western Kenya, farmers do not manage them for pollination but rely on feral pollinators from the nearby habitats. The ability of these habitats to continuously support bees depends on how they are managed by the adjacent communities. Therefore, the overall aim of this study was to elucidate strategies that can be used to improve bee pollination in the Kakamega farmland. The following objectives were defined : i) determine whether the presence of Kakamega forest affects bee pollinator diversity and foraging activity density in crops in the farmland, ii) establish the contribution of bee pollination to crop productivity, iii) assess the knowledge of farmers about bees and pollination, and iv) quantify the economic benefit that farmers derive from pollination of their crops by bees. The data were collected : i) through observation of bees along a transect from fields near the forest to fields 8 km away, ii) in experimental plots with crops with and without bee-pollination, iii) through questionnaire administration to 352 farmers, and iv) through secondary data, mainly sourced from the Ministry of Agriculture. The number of bee species recorded in the fields near and far from the forest was not statistically different, implying that bee diversity in the farmland does not necessarily depend on the forest. However, the activity density of some bee populations (e.g., Xylocopa calens) was significantly higher in fields near the forest, indicating that the forest might be an important element in providing sufficient pollination services in the system, while the presence of a sufficient number of bees for pollination will depend on how the farmland landscape is managed. The increase in crop yield due to bee pollination, tested on nine crops (beans, cowpeas, green grams, bambara nuts, tomatoes, capsicum, passion fruit, sunflower and squash) ranged from 25% (tomatoes) to more than 99% (squash). Thus, although some crops can produce without bee pollination, presence of bees is important to increase yields, and hence, food security and income. Similarly, bee pollination is essential for reproduction in other crops. There was a significant increase in the quality of seeds (e.g., 21% ; sunflower oil) and fruit sizes (e.g., capsicum by 29%, leading to a higher market price). The contribution of bee pollination to the farmers’ income in Kakamega in 2005 was about 50% of the annual value of the selected crops (except squash). This was an almost 40% net benefit, suggesting that bee pollination economically benefits crop producers. More than 98% of the farmers knew different bee species but only about 50% knew of the function of bee pollination in crop production. However, after informing them of the role of pollination, more than 98% were willing to pay an estimated US$ 90 per household annually for pollination of their crops by bees. Both the knowledge of pollination and willingness to pay amount correlated significantly with the education of the farmers. This suggests that education of farmers on issues of bees and pollination can have an impact on bee conservation in the Kakamega farmland.


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