Pollination efficiency of apis mellifera and hypotrigona gribodoi on capsicum annuum fruit set and yield in Morogoro region, Tanzania
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Date
2024-05
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Sokoine University of Agriculture
Abstract
Pollination by insects accounts for over 70% of global food crops
production. Among insect species, bees are one of the most efficient
pollinators though their pollination efficiency varies between species.
Amidst rising worries about declining pollinator populations due to
human activities and changes in climate, comprehending diverse
pollinator capabilities is crucial for conservation. While stingless
bees show promise as commercial pollinators, their capacities
compared to Apis mellifera remain insufficiently understood,
resulting in limited domestication and thus threatening their
population.. This study evaluated the pollination efficiency of Apis
mellifera and Hypotrigona gribodoi on yield and fruit set in Capsicum
annuum. A randomized complete block design experiment was
conducted with three replications and three caged treatmentswhich
are Apis mellifera, Hypotrigona gribodoi, and self-pollinated plants.
Each treatment was replicated three times to assess the effects of
pollination on yield and fruit set rates. We made comparison on
bees' foraging activities and computed their impact on fruit set.
Furthermore, we explored the influence of abiotic factors on bees
foraging activities, to a comprehensive analysis of the intricate
relationship between pollination, bee behavior, and environmental
factors. Analysis of variance (ANOVA) was used to compare the
differences in fruit quality, seed quality, and fruit set rate between
the two species. Kruskal wallis was used to test for difference
among data which are not normally distributed. Tukey's Honestly
Significant Difference (HSD) and Dunn tests were used for normally
distributed and non-normally distributed data respectively. To
compare the difference in bee foraging activity, we use the Wilcoxon
rank-sum test. We employed a Generalized Linear Model (GLM) to
investigate the relationship between fruit set rate and foraging
activity, and a Poisson Regression Model to explore the relationship
between foraging activity, abiotic factors, and bee species. The
results show that the number of fruits per plant, fruit transverse
circumference, fruit vertical circumference, fruit weight, and percentage fruit set rate per plant were higher in the plot pollinated
with Hypotrigona gribodoi, followed by Apis mellifera, and lastly the
control plot and the difference was statistically significant (P < 0.05).
However, there was no significant difference in the number of seeds
per fruit and the weight of 100 dry seeds per fruit among the two
species (P>0.05). Hypotrigona gribodoi showed higher flower visits,
pollen-carrying workers, and visitors per flower than Apis mellifera,
with significant differences (P < 0.001). Conversely, Apis mellifera
had more exiting workers (P < 0.001). Moreover no difference in
time spent on the flower (P>0.05). Also the number of workers
entering with pollen (P<0.001), workers exiting the hive (P<0.001),
and time spent on the flower (P<0.05) have a significant effect on
the fruit set rate of Capsicum annuum. The number of visitors per
flower and the number of flowers visited do not have a significant
effect (P>0.05). Temperature and humidity significantly affect the
number of visitors per flower, the time spent on flower and the
number of workers exiting the hives. However, the number of flowers
visited and the number of workers entering the hive with pollen were
not influenced by temperature and humidity. These findings suggest
that Hypotrigona gribodoi is a more efficient pollinator of Capsicum
annuum L. Furthermore, the foraging behavior of Apis mellifera and
Hypotrigona gribodoi is affected by temperature and humidity
affecting the fruit set rate of Capsicum annuum. More research on
the differential pollination efficiency among different bee species in
crop production is imperative.
Description
MSc Dissertation
Keywords
Pollination, Apis mellifera, Hypotrigona gribodoi, Capsicum annuum L., yield, fruit set rate, Foraging behaviour, Abiotic factors temperature - humidity