LABORATORY STUDIES OF THE EFFECTIVENESS OF BACILLUS THURINGIENSIS SEROTYPE H-14 AGAINST CULEX PIPIENS LARVAE
LABORATORY STUDIES OF THE EFFECTIVENESS OF BACILLUS THURINGIENSIS SEROTYPE H-14 AGAINST CULEX PIPIENS LARVAE
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Date
1986-10
Authors
SHEHU, HAJARA
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Abstract
The effectiveness of Bacillus thuringiensis H-14 as
a biological control agent was tested in the laboratory
against culex pipiens larvae by bic>assay methods. The
second, third and fourth instar larvae were exposed to
different bacterial concentrations. The percentage mortality
of mosquito larvae increased with increase in concentration,
exposure time and water volume but decreased with the
increase in larval age from second to fourth instars.
The LC50 values after 6 and 24 hours in 150 ml of
bacterial suspension were 0.020 mg/1 and 0.0036 mg/3 for
second instars; 0.04 mg/1 and 0.009 mg/1 for third instars;
0.063 mg/1 and 0.013 mg/1 for fourth instar larvae. In 30 ml
of bacterial suspensions, these values were 0.038 mg/1 and
0.008 mg/1; 0.05 mg/1 and 0.015 ng/1; 0.158 mg/1 and 0.017
rag/I for second, third and fourth instar larvae after 6
and 24 hours exposures respectively.
The LC90 values after 6 - 24 hours in 150 ml of
bacterial suspensions for second, third and fourth larval
stages were 0.'i58 mg/1 - 0.022 mg/1, 0.199 mg/1 •• 0.050
mg/1 and 0.251 mg/1 - 0.071 mg/1 while in 30 ml bacterial
suspensions, these values were 0.211 mg/1 - 0.093 mg/1,
0.251 mg/1 - 0.079 mg/1 and 0.791 mg/1 - 0.081 mg/1
respectively.
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Statistical tests to determine differences in
mortality due to exposure time, beakers and larval instars
were all found to be significant (P>0.05).
Description
A THESIS SUBMITTED TO THE POSTGRADUATE SCHOOL,
AHMADU BELLO UNIVERSITY, IN PARTIAL FULFILMENT
OF THE REQUIREMENTS FOR THE DEGREE OF:
Keywords
LABORATORY, STUDIES, EFFECTIVENESS, BACILLUS, THURINGIENSIS, SEROTYPE, H-14 AGAINST, CULEX, PIPIENS, LARVAE