Investigation on the Genus Bacillus in the Control of Mosquitoes
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Date
1993-10
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Addis Ababa University
Abstract
Screening programmer to isolate strains of the genus
Bacillus for their potential use in the control of
mosquitoes was done. Over 90 spore-forming bacillus
strains were examined. Six isolates AA-2, AA-6, AA-10,
AA-l1, AA-71, and AA-82) have sho\m killing ability of
which four (AA-2, AA-11, AA-71, and AA-82) were found to
be effective. Biochemical and morphological
characterizations have revealed similarity
between these isolates and the Well Known mosquito pathogens
(B. thuringiensis ancl B. sphaericus).
The effect of temperature and aeralion supply on
biomass production was studied. Isolateswere found to
dliffen:nlly responcl to temperJIUle. Isol"Ias fnunu
to qro\•: h'l'll at 30')C. A,;-ll 11ds been found to huve a widerange of
temperature (23- 40)AA-71 has Sl10WIl io\'erse
relation \,ith temperature, h'hereas isolate "\A-82
demonstrated critical decrease in growth with increase in
temperature and 30~ was found to be optimal. Dry biomass
was founcl to increase with the increase in aeration levels.
The efficacy of the isolates was tested on different
larval stages of mosquito. LC IO that ranged from 43-170
llg/ml \,as obtained. ~o siqnificant difference has been
observed in sensitivity of different larval stages of
mosquito to different bacteria at a significance level of
1% except isolate AA-11. Efficacy of the isolates under
natural conditions was also tested. Some strains (eg.
AA-82) have shown good results.Further confirmatory
characterization is needed as well
as investigation for optimal conditions to increase toxin yield.
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Biology