Bacillus velezensis as a Novel Species for Mosquito Control: Impacts of Exposure on Key Life History Traits of Culex quinquefasciatus

<i>Bacillus velezensis</i> is a promising mosquito vector biocontrol agent due to its potent larvicidal properties. This study investigated the lethal and sublethal effects of exposure to crude toxin of <i>B. velezensis</i> strain WHk23 on <i>Culex quinquefasciatus</i>. Toxicity bioassays showed a median lethal concentration of 28.30 µg/mL for third instar larvae. In addition to direct larval mortality, sublethal exposures resulted in concentration-dependent decreases in survival, fecundity, and fertility. Exposure to different concentrations was found to accelerate larval development, resulting in larger females, yet those females exhibited lower lifespan and diminished reproductive success. These results suggest that exposure to <i>B. velezensis</i> not only reduces mosquito populations but also has lasting effects on important life history parameters, ultimately lowering vectorial capacity and disease transmission risk. This study provides valuable insights into the lethal and sublethal consequences of <i>B. velezensis</i> exposure. Given its potent larvicidal properties, <i>B. velezensis</i> represents a promising biocontrol agent for mosquito vectors.