Evaluation of the Efficacy of Mundulea Sericia(Fabaceae)Extracts on Larval Survival of Anopheles Gambiae and Culex Quinoefasciatus(Diptera:Culicidae)
Loading...
Date
2013-03-21
Authors
Kiania, Nahashon Mugao
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
In this study, two mosquito species which are important disease vectors in Kenya
were studied. These were Anopheles gambiae and Culex quinqefasciatus which are
the principle vectors of malaria and filariasis respectively. Despite the high
prevalence of these diseases in Kenya, the available vector control measures are
ineffective and expensive. Petroleum oils and pyrethroids are the most commonly
used larvicides though they are quite expensive and pollute the environment. The
purpose of this study was-to evaluate the efficacy of Mundulea sericia leaf and
stem-bark extracts on larval survival of An. gambiae and ex. quinqefasciatus with
the long-term aim of developing cost effective and efficacious larvicides from the
extracts. Leaf and stem-bark samples which had been dried under shade to
preserve volatile compounds were pulverized in a mortar and pestle. The resulting
powder was then mixed with water and stored at a temperature of 4°C overnight
for extraction of bioactive compounds. These were used to constitute the stock
solution. The stock solution was serially diluted using water or ethanol during use
to prepare different extract concentrations. The portions of the stock solution
diluted with water formed water extracts while the one diluted with ethanol formed
ethanolic extracts. Larvae of both mosquito species reared in vitro were subjected
to different treatments of the extracts with varying concentrations. Larval mortality
was recorded after every twenty four (24) hours. Each treatment had three
replicates and the mortality means were determined from the collected data. The
relationship between mortality rates, and extract concentration for two mosquito
species was analyzed using linear regression analysis. The mean mortality rates in
both mosquito larvae due to all the four treatments were compared using Analysis
of variance (ANOV A) and the statistical significance in the mean mortality
differences were calculated using the Student's Newmann-Keul's multiple range
test (SNK test). The mortality rates of An. gambiae in both water and ethanolic
extracts were statistically different. In Cx. quinqefasciatus, the mortality rates were
also statistically different except in M sericia leaf water extracts (MSL W). When
the mortality rates between the two mosquito larvae in all the four M sericia
extracts were compared, statistical differences were noted in M sericia leaf water
(MSL W), M sericia stern-bark water (MSSW) and M sericia leaf ethanolic
(MSLE). However, the mortality rates of the two mosquito species larvae in M
sericia stem-bark ethanolic (MSSE) extract were not statistically significant. The
results obtained imply that M sericia extracts have bioactive compounds that are
toxic to mosquito larvae and that they can be exploited in the development of
larvicides.
Description
Department of Zoological Sciences, 58 P. The RA 640 .K4K5 2012
Keywords
Mosquitoes --Control