Project Materials

BIOCONTROL POTENTIAL OF BACILLUS THURINGIENSIS ISOLATED FROM SOIL SAMPLES AGAINST LARVA OF MOSQUITO

ABSTRACT

Overcoming pesticide resistance is a significant problem for successful mosquito control efforts. Bacillus thuringiensis is a highly effective biolarvacide for mosquito control, and monitoring larval susceptibility is critical to preventing resistance development. Bacillus thuringiensis’ mosquito larvacidal activity was tested by isolating mosquito larvae from ecologically diverse soil habitats in and around Enugu metropolis. The isolate organisms were identified as Bacillus thuringiensis through biochemical analysis and microscopic examination. The larvacidal activity of Bacillus thuringiensis isolates was assessed against mosquito larvae using the conventional cup bioassay. Bacillus thuringiensis isolates demonstrated substantial heterogeneity in larvacidal activity.

Chapter one

INTRODUCTION

Bacillus thuringiensis (Bt) is a well-known and extensively researched bacterium known for its application in pest management. When compared to chemical pesticides, Bacillus thuringiensis is the most successful commercial xenobiotic, with a global application. It has the advantages of being biologically degradable, selectively active on pests, and less prone to produce resistance.

Bacillus thuringiensis formulations are safe for humans, beneficial animals, and plants, which is why many countries have replaced chemical pesticides with these environmentally benign pest control agents.

Bacillus thuringiensis was first isolated by Japanese scientist Ishiwata (1901) from skilkworm larvae, bombyxmori, which had sotto illness.

Berliner (1911) identified the square gramme (+) positive, spore-forming, rod-shaped soil bacterium from pathogenic flour moth larvae, Anngasta Kachmiccalla, in the Thuringia region of Germany and called it Bacillus thuringiensis.

Bacillus thuringiensis was utilised in the early 1930s to combat the European maize borer, Ostrinianubilis. The first commercial product, known as sporeine, was introduced in France in 1938 (Weiser 1986).

Bacillus thuringiensis subspecies Kurstaki was employed to control insect pests (Lepidoptera) in agriculture and forestry (Luthy & Ebersold, 1981).

New commercial products appeared in the 1980s, with the discovery of Bacillus thuringiensis, which opened the door to black fly and mosquito larvae control.

Insects, like all organisms, are susceptible to infection by pathogenic microbes; however, many of these infection agents have a limited host range and thus do not cause unchecked elimination of beneficial insects or are hazardous to vertebrates.

Bacillus thuringiensis is a significant microbe that has entamopathogenic activity (Glazer & Nikaido, 1995; Schnepf et al., 1998) and produces parasporal crystals during the stationary phase of its life cycle.