In vitro evaluation of Bacillus thuringiensis larvicide effect on Anopheles subpictus larvae

摘要

Microbial larvacide effects of Bacillus thuringiensis isolates on mosquito (Anopheles subpictus) larvaewas investigated in vitro. The isolates obtained were coded as BTA, BTB and BTC. The bacilli load weredetermined as MacFallan Standard 0.5(1.0 × 108cell), 1.0 (3.0 × 108cell) and 2.0 (6 × 108cell) and timeranging from 0 – 360 mins. The results obtained showed a significant (p 0.5 and r =0.1) correlationbetween the percentage mortality rate of the mosquito larvae, the bacilli load, time of incubation and theisolates type. The positive increase in larvae (percentage) mortality rate against different bacilliconcentrations at various times (minutes) were as follows: 0.5 MacFallan (30:12%, 120:44%, 240:68%),1.0 MacFallan (30:18%, 120:52%, 240: 72%) and 2.0 MacFallan (30: 23%, 120: 68%, 240:92%).Secondly, each isolate demonstrateted slightly different and insignificant (p0.1) mortality rate; exampleat 0.5 MacFallan, isolate BTA, BTB and BTC were seen to have (30:4%, 6% and 5%) while at 120:44%,32%, 46% respectively. Results obtained has shown that proper formulation of B. thuringiensis (var)would be used as a biopesticide to control mosquito larvae at breeding sites, hence the control of malariaand other mosquito vector borne diseases in the public health sector.