Intervention measures to control the transmission of vector-borne diseases include control of the vector population. In mosquito control, synthetic insecticides used against both the larvae (larvicides) and adults (adulticides) create numerous problems, such as environmental pollution, insecticide resistance and toxic hazards to humans. In the present study, a bacterial pesticide, Bacillus sphaericus (Bs G3-IV), was used to control the dengue and filarial vectors, Aedes aegypti and Culex quinquefasciatus. Bacillus sphaericus (Bs G3-IV) was very effective against Aedes aegypti and Culex quinquefasciatus, showing significant larval mortality. Evaluated lethal concentrations (LC50 and LC90) were age-dependent, with early instars requiring a lower concentration compared with later stages of mosquitoes. Culex quinquefasciatus was more susceptible to Bacillus sphaericus (Bs G3-IV) than was Aedes aegypti. Fecundity rate was highly reduced after treatment with different concentrations of Bacillus sphaericus (Bs G3-IV). Larval and pupal longevity both decreased after treatment with Bacillus sphaericus (Bs G3-IV), total number of days was lower in the B. sphaericus treatments compared with the control. Our results show the bacterial pesticide Bacillus sphaericus (Bs G3-IV) to be an effective mosquito control agent that can be used for more integrated pest management programs.
IntroductionMosquitoes are insect vectors responsible for the transmission of many diseases. Mosquito-borne diseases include yellow fever, dengue fever and Chikungunya, transmitted mostly by Aedes aegypti; malaria, carried by the genus Anopheles, and Culex serves as a vector of important diseases such as West Nile virus, filariasis, Japanese encephalitis, St. Louis encephalitis, and avian malaria. Insect-transmitted disease remains a major source of illness and death worldwide. Mosquitoes alone transmit disease to more than 700 million people annually and are responsible for several million deaths every year (WHO, 2012;Taubes, 2000;Kessler & Guerin, 2008).Management of these vectors is a serious concern in a developing country like India, due to development of pesticide resistance and for socio-economic reasons. Every year, a large part of the population is affected by one or more vector-borne diseases. Vector control, which includes both anti-larval and anti-adult measures, constitutes an important aspect of any mosquito control program. Mosquito control using synthetic insecticides is an effective vector control strategy used extensively in daily life. Synthetic insecticides are still at the forefront of mosquito-controlling efforts. However, the environmental threat that these chemicals pose affects on non-target organisms, and resistance of mosquitoes to insecticides have all increased during the last five decades (Wattanachai & Tintanon, 1999;Amer & Mehlhorn, 2006a, 2006b.In recognition of these facts, it is necessary to develop new insecticides for controlling mosquitoes that are environmentally safer, biodegradable, and more target-spe...