Efficacy of Bacillus thuringiensis israelensis and Lysinibacillus sphaericus cultured with raw material in the kitchen against Culex quinquefasciatus larvae in Laboratory and simulated field trial

Abstract

Culex, a large group of mosquitoes, can be the vectors of many diseases in humans. The long term of Chemical insecticide application can cause residual effect in environment and also has insecticide resistance problem. The bio- agents that widely used for controlling mosquito larvae are Bacillus thuringiensis israelensis (Bti), and Lysinibacillus sphaericus (Ls), and they are a safe alternative agent. This study was experimental research, Bti and Ls were cultured with four types of raw materials in the kitchen, i.e. mature coconut water, soy pulp water, rice washing water, and soup from instant cubes. Cultured media were tested for larvicidal activity in the laboratory (LC50) and residual effect in simulated field trial against early 4th instar larvae. The results showed the most effective medium for Bti was soy pulp water followed rice washing water, mature coconut water and soup from instant cubes, with LC50 values of 3.94, 17.39, 18.21 and 25.17 ppm, respectively. The most effective medium for Ls was soup from instant cubes followed by soy pulp water, mature coconut water and rice washing water, with LC50 values of 0.19, 0.42, 0.96 and 8.21 ppm, respectively. However, considering of cost of bio-agent, soy pulp water was selected for culturing both of Bti and Ls. The results of simulated field trial indicated Ls bio-agent was highest efficacy followed by Bti mixed with Ls and Bti bio-agent, measured by the application rate for control of Culex larvae within two weeks, at 0.30, 0.60 and 3.03 L/m2, respectively. Therefore, Ls cultured with soy pulp medium was effective at controlling Culex larvae and it was an example of waste material utilization.