Synergistic Effect of Allium sativum and Nigella sativa with Bacillus sphaericus on Culex pipiens Larvae (Diptera: Culicidae)

Abstract

Bacillus sphaericus has a larvicidal activity towards Culex pipiens larvae. Development of resistance in certain populations of Culex sp. is the most common disadvantage of B. sphaericus application. During application, beside, B. sphaericus formulations suffering from long period of sun light and UV which turned them impotent. So, the present study was designed to evaluate the larvicidal activity of Bacillus sphaericus toxin, Allium sativum and Nigella sativa oil extracts solitary and in combination against Culex pipiens 3rd larval instar. Data revealed that, Bacillus sphaericus was the most potent insecticide recording LC value as (0.25ppm.) followed by Allium sativum and Nigella sativa recording 50 (0.45 and 2.46 ppm.), respectively. Addition of Allium sativum generally increased the toxic effect of Bacillus sphaericus, where LC decreased from (0.25 ppm to 0.12 ppm). Addition of 50 Nigella sativa to Bacillus sphaericus decreased the toxicity of Bacillus sphaericus by increasing its LC from (0.01 ppm to 0.119 ppm).The biochemical studies using (SDS-PAGE), 50 revealed that there was an increase in number of protein bands due to treatment with (Bacillus sphaericus combined with Allium sativum and Bacillus sphaericus with Nigella sativa). These impressive results from combinations proved that when joint-action is considered, the application possibilities for vector control increase significantly.