Larvicidal efficacy of stock Bacillus sphaericus on local species of Anopheles mosquito in Sokoto, Nigeria

Abstract

Graded concentrations (15, 30, 60, 90, 100, 120 mg/l) of stock, water dispersed powder of Bacillus sphaericus (SPH88: lot number BSP247) and potency of 17001TU/mg obtained from Pasteur Institute in Paris, France was tested against fourth instar larvae of local breed of Anopheles gambiae for larvicidal efficacy. LC50 value obtained was 60 mg/l or 0.016 ìg/l on the probate graph. Larval mortality increased with increased concentration of larvicide but F-statistics at 5% confidence limit, showed no significant difference (p>0.05) between efficacies of the different concentrations of larvicide at causing mortality of the malaria vector. Time of exposure to larvicide also had insignificant influence (p>0.05) on rate of larval mortality. It was concluded that employed larvicide had limited activity against local breed of mosquito with risk of early resistance against this biological agent.

Keywords: larvicide, Bacillus, mosquito.

Nigerian Journal of Parasitology Vol. 29 (2) 2008: pp. 103-105