BIOLOGICAL CONTROL OF CULEX PIPIENS PIPIENS (CULICIDAE, DIPTERA): AN EFFECT OF BACILLUS SPHAERICUS RECULTIVATION AND STORAGE ON MOSQUITOES

Abstract

This study is conducted to make a commercial suspension in Algeria in replacement to the harmful and expensive insecticide several morphological and biochemical features were done to identify Bacillus sphaericus in the commercial suspension of Solvay & Cie (Brussels). It was found negative in most of the following tests Voges Proskauer, mannitol mobility, Amidon hydrolysis, conversion of glucose and galactose to acids, and respiratory type. It was also able to grow at 65°C and it was resistant to Streptomycin, bacitracin, and susceptible tonchomycin. Five recultivation from one culture to a new medium showed a loss of toxicity (23 times) to L1 and L2. Culex pipiens pipiens. In the course of three months of storage, for the stock solutions kept at +4 and at -18 °C, the poisonous potential of B. sphaericus, which was grown only once on MBS-tryptose from the commercial suspension, changes between 80 and 123 times. When compared to an emulsion frozen in glycerin, the toxicity of B. sphaericus held at +4 °C is often found to be more stable, especially over the last two weeks. In comparison to the larvicidal activity of the solution held at +4 °C, between the second and the twelfth week, the resistance of the solution stored at -18 °C has deteriorated over a two-week period by a factor of 2.5 to 6. B. sphaericus was only once grown on MBS-tryptose from the commercial suspension and has a variable toxic potential each toxicity test was repeated 3 times with controlled experiments. These experiments were executed in 2015 at Annaba university applied neuroendocrinology laboratory. These series of experiments were executed in 2015 at Annaba university labs. basically to study the effectiveness of B. sphaericus bacteria after the recultivation and the influence of the conservation of it under two temperatures +4 °C and -18 °C to counter Culex pipiens pipiens.

Keywords

• toxicity
• storage
• recultivation
• medium
• bacillus sphaericus
• culex pipiens pipiens