African Journal of
Agricultural Research

  • Abbreviation: Afr. J. Agric. Res.
  • Language: English
  • ISSN: 1991-637X
  • DOI: 10.5897/AJAR
  • Start Year: 2006
  • Published Articles: 6578

Full Length Research Paper

Pollinator diversity, behaviour and limitation on yield of karela (Momordica charantia L. Cucurbitaceae) in Western Kenya

Mary Lucy Oronje1*, Melanie Hagen1,4, Mary Gikungu2, Muo Kasina3 and Manfred Kraemer1 
1Biological Collection, University of Bielefeld, Universitätstrasse 25, 33615 Bielefeld, Germany.  2Centre for Bee and Pollination, National Museums of Kenya, P.O. Box 40658-00100, Nairobi, Kenya.  3Kenya Agricultural Research Institute, National Agricultural Laboratories, 14733-00800, Waiyaki Way, Nairobi, Kenya.  4Ecology and Genetics, Department of Biological Sciences, University of Aarhus, Ny Munkegade Building 1540, DK- 8000 Aarhus C, Denmark.
Email: [email protected]

  •  Accepted: 13 February 2012
  •  Published: 19 March 2012

Abstract

Inadequate pollination is a major constraint to crop yield. Momordica charantia L. is a fruit crop of 
economic interest in Kenya. Pollination ecology, pollinator diversity and their behaviour were studied in 
Western Kenya. Pollination treatments included insect exclusion, open pollination (unrestricted insect
visits), hand cross-pollination and pollen augmentation. Yield components from treatments were 
compared to identify the pollination requirements of this crop. Flowering started 45 days after 
germination with the staminate flowers appearing first followed by rewardless pistillate flowers. The 
ratio of pistillate to staminate flowers was 1: 13. Pollinator species included honey bees (Apis mellifera),
Plebeina hildebrandti, Lasioglossum sp. and carpenter bees (Xylocopa spp). Fruit set and yield were 
pollen limited as all bagged flowers were aborted. Fruit set under natural pollination was very low and 
this revealed the degree of pollen limitation in M. charantia. Low fruit set was consistent with 
observation of high discrimination against pistillate flowers amongst potential pollinators. Smaller bees 
belonging to families Apidae (Plebeina hildebrandti) and Halictidae (Lasioglossum sp.) were the most 
important pollinators. These observations highlight the importance of (1) a diverse fauna of wild bees
and (2) the potential of meliponiculutre in the increasing the yield of M. charantia in Kenya. 
Key words: Plebeina hildebrandti, Lasioglossum, discrimination, deceit pollination, yield.