Larvicidal potentiality, longevity and fecundity inhibitory activities of Bacillus sphaericus (Bs G3-IV) on vector mosquitoes, Aedes aegypti and Culex quinquefasciatus

Abstract

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,<em> Bacillus sphaericus</em> (Bs G3-IV), was used to control the dengue and filarial vectors, <em>Aedes aegypti</em> and <em>Culex quinquefasciatus</em>. <em>Bacillus sphaericus </em>(Bs G3-IV) was very effective against<em> Aedes aegypti</em> and <em>Culex quinquefasciatus</em>, showing significant larval mortality. Evaluated lethal concentrations (LC<sub>50</sub> and LC<sub>90</sub>) were age-dependent, with early instars requiring a lower concentration compared with later stages of mosquitoes. <em>Culex quinquefasciatus</em> was more susceptible to <em>Bacillus sphaericus</em> (Bs G3-IV) than was <em>Aedes aegypti</em>. Fecundity rate was highly reduced after treatment with different concentrations of <em>Bacillus sphaericus</em> (Bs G3-IV). Larval and pupal longevity both decreased after treatment with <em>Bacillus sphaericus</em> (Bs G3-IV), total number of days was lower in the <em>B. sphaericus</em> treatments compared with the control. Our results show the bacterial pesticide <em>Bacillus sphaericus </em>(Bs G3-IV) to be an effective mosquito control agent that can be used for more integrated pest management programs.