An equal
proportion of Tween 80 was added to the control set of emulsions.
For the experiment involving powdered plant materials, distilled
water was used as blank. The test was triplicated from separately
reared batches of larvae. Numbers of alive larvae and pupae were
recorded every 24 h and any reduction in larval and pupal density
calculated using Mulla’s formula (Mulla et al., 1971):