Abstract

The second instar larvae of Musca domestica were treated with Bacillus thuringiensis israelensis, (B.t.i.) at concentrations of 0.5, 1.0, 1.5 and 2.0% under laboratory conditions. Cumulative mortality percentage increased gradually with the increase in B.t.i concentrations and this is represented by straight regression lines indicating homogenity. The LC₃₀ and LC₅₀were 0.87 and 1.305%, respectively. The tested concentrations indicate significant prolongation in larval duration compared to control. There was an inverse relation between the concentration and pupation percentage and an increase in pupal duration. An insignificant decrease in percentage of adult emergence was observed. Sex ratio was not affected. 2.0% Concentration of B.t.i. caused the greatest reduction in female fecundity (964.5 eggs/female), and the hatchability of eggs also decreased. The pupae and adults appeared malformed when treated with B.t.i. as a 2^nd larval instar.

Key words: Housefly, larvicide, bioassay, mortality, LC₃₀, fecundity, fertility, malformation.