dc.description.abstract |
Pollination is an important ecosystem service in the maintenance of biodiversity and most
importantly in food production as it brings about fruit formation and seed production.
Pollination is, however, on the decline due to several factors including habitat loss, exotic
pest invasions, pollution, overharvesting, and land use changes. The Ocimum
kilimandscharicum plant is known for its medicinal values and has gained more attention
locally and internationally for its commercial use in production of pharmaceutical
products. This study analyzed the flower visitors’ activity of Ocimum kilimandscharicum
in Kakamega forest. Specifically, the study sought to: (i) assess the diversity and
abundance of the flower visitors with increasing distance from the forest edge(ii) assess
the effects of temperature and precipitation on flower visitors’ diversity and (iii) Identify
the most efficient flower visitor using seed set analysis. Data were collected through
direct observations and sweep-netting for specific objective one and two. Data collection
for specific objective three involved the bagging method where flowers were covered
using a pollinator bag pre-anthesis and allowed a single visit from a flower visitor. The
pollinator was then captured and a color tag attached to the flower. Seed sets from the
flowers were collected and counted. Six study sites were identified along two transect
each 2.5 km long and labeled A to F. Distance in meters from the forest edge for each site
was; A=221, B=72, C=83, D=198, E=113 and F=50. Diversity indices of different flower
visitors was calculated using the Shannon-Wiener diversity index. One-way analysis of
variance was used to compare significant differences between sites and a two sample t –
test was used to identify mean significant differences in species diversity between the
closest and the furthest sites. A total of 645 individuals belonging to 35 species were
captured from 4 families; Apidae, Megachilidae, Halictidae and Collectidae. The highest
diversity was at Site F (H’ = 2.38) which was closest to the forest edge and the lowest
diversity was from Site A (H’ = 1.44) which was furthest from the forest edge. Distance
from the forest edge significantly influenced species diversity (F (3, 20) = 14.67, p = 0.024).
Distance from the forest edge also significantly influenced species abundance between
the furthest sites A, D and E and the nearest sites F, B and C to the forest edge (p=0.0315)
and species richness (p=0.0187). There were no significant correlations between;
temperature/species richness, temperature/diversity, precipitation/species richness and
precipitation/diversity. The highest number of seed set, 12,944 was collected under the
Apis mellifera making this species, the most efficient pollinators. Apis mellifera also had
the highest visitation frequency at 30. This study shows that Ocimum kilimandscharicum
flower visitors play essential roles in pollination and the higher the number of visits, the
higher the number of seeds set. Many of these pollinators are associated with the forest
hence the need to conserve the Kakamega forest as a source pool for pollinators. This
pool of pollinators has direct implications on food security to communities surrounding
the forest. Further studies are required to determine the extended roles of these pollinators
on the surrounding farmlands. |
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