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ABSTRACT
A major challenge for achieving successful mosquito
control is overcoming insecticide resistance. Bacillus thuringiensis which
is one of the most effective biolarvacide for control of species of mosquitoes
and monitoring of larval susceptibility is essential to avoid resistance
development. Mosquito larvacidal activity of Bacillus thuringiensis was
assessed by isolating them from ecologically different soil habitats in and
around Enugu metropolis. The isolate organisms were confirmed as Bacillus
thuringiensis based on biochemical characterization and microscopic
observation. The larvacidal activity of Bacillus thuringiensis isolates
was tested against the larval of mosquito by using the standard cup bioassay.
The isolates of Bacillus thuringiensis showed a significant level of
variation in their larvacidal activity.
CHAPTER ONE
INTRODUCTION
Bacillus thuringrensis (Bt) is a
well known and widely studied bacterium which is known for its use in pest
management. Today it is the most successful commercial xenobiotic with its
worldwide application when compared with the chemical pesticides; Bacillus
thuringiensis has the advantages of being biologically degradable,
selectively active on pests and less likely to cause resistance. Safety of Bacillus
thuringiensis formulations for humans, beneficial animals and plants
explains the replacement of chemical pesticides in many countries with these
environmentally friendly pest control agents.
Bacillus thuringiensis was first
isolated by the Japanese Scientist Ishiwata (1901) from skilkworm larvae,
bombyxmori, exhibiting sotto disease. After 10 years, Berliner (1911) isolated
the square gram (+) positive, spore-forming, rod shaped soil bacterium from
disease flour moth larvae, Anngasta Kachmiccalla, in the Thuringia region of
the Germany and named it as Bacillus thuringiensis.
In the early 1930s Bacillus thuringiensis was
used against Ostrinianubilis, the European corn borer. The first commercial
product was available in 1938 in France, with the trade name sporeine (Weiser,
1986). It was Bacillus thuringiensis subspecies Kurstaki that was used
for the control of the insect
(Lepidopteran) pests in agriculture and forestry
(Luthy & Ebersold, 1981). New commercial products arrived in 1980s after
the discovering of subspecies thuringiensis opened the gate for black
fly and mosquito larvae control.
Like all organisms, insect are susceptible to
infection by pathogenic microorganisms, many of these infections agents have a
narrow host range and therefore, do not cause uncontrolled destruction of
beneficial insects and are not toxic to vertebrates. Bacillus thuringiensis is
a major microorganism, which shows entamopathogenic activity (Glazer &
Nikaido, 1995, Schnepf, et al. 1998) which forms parasporal crystals during the
stationary phase of its growth cycle.
Most Bacillus thuringiensis preparations available
on the market contain spores with parasporal inclusion bodies composed of δ –
endotoxins. In commercial production, the crystals and spores obtained from
fermentation are concentrated and formulated for spray on application according
to conventional Agriculture practices (Baum, Kakefuda, & Gawron-Burke,
1996). There are many strains of Bacillus thuringiensis having
insecticidal activity against insect order (eg Lepidoptera, Diptera, Homoptera,
Mollaphage, Coloptera). Only a few of them have been commercially developed.
Department: Microbiology and Biotechnology
Format: Microsoft Word
Format: Microsoft Word
Chapters: 1 - 5, Preliminary Pages, Abstract, References.
Delivery: Email
Delivery: Email
No. of Pages: 50
Price: 3000 NGN
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