stephensi against 100 ppm as compared to Bsph. However, the same effect (P=0.054) was observed for field collected Culex quinquefasciatus against 100 ppm Bsph.
Microbial larvicides (Bacillus thuringiensis var israelensis (Bti) and Bacillus sphaericus (Bsph) are processed bacterial compounds which are registered for mosquito larvae control agents in outdoor areas.
Biological control with Bti and Bsph larvicides proved highly effective yet selective in action (Charles and Nielsen, 2000) and therefore, environmentally safe to non-target organisms as well as for human exposure (WHO 1997).
The current study was designed with specific objective to evaluate the bio- efficacy and residual activity of Bti and Bsph as biological larvicides against late 3rd instars of laboratory reared Anopheles stephensi and wild caught Culex quinquefasciatus.
According to BSPH, the Johns Hopkins Particulate Matter Research Center will map the health risks of PM across the U.S.
BSPH noted that the grant is one of five totaling $40 million awarded to universities across the nation to establish five centers to study the PM component of air pollution.
quinquefasciatus larvae were highly susceptible to Bsph with LC50 and LC95 values of 0.043 and 0.12 ppm, respectively at 24 h, and at 48 h posttreatment, 0.008 ppm (LC50) and 0.11 ppm (LC95).
To date, studies concerning Bti, Bsph, or other biological control agents against mosquitoes in Pakistan including vectors of malaria are rather limited (Rathor et al., 1985).
A technical powder of Bti (VectoBac(r) containing 5000 International Toxic Units (ITU)/mg of Bti) and a technical powder of Bsph (VectoLex(r) 1,380 ITU/mg of Bsph (Valent Biosciences Corp; Illinois, USA) were used in the experiments.
Larval mortality in each treated cup was scored at 24 and 48 h post-treatment with Bti or Bsph; any mortality in corresponding control cups was also checked at these times.