An interval of 2-3 minutes between each dip was used to
allow larvae and pupae to return to the surface. In every pond,
larval and pupal densities in five dips were counted and recorded.
The pH and temperature of water in the ponds were also recorded
everyday evening. Larvae were provided with Tetramin® fish food.
Each test was replicated five times from separately reared batches
of larvae. Percentage reduction of larval and pupal density was
calculated using the Mulla’s formula (Mulla et al., 1971). Follow
up tests to check for any residual efficacy of the test materials was
carried out from the 14th day using 100 fresh early third instar An.
gambiae s.s. larvae. The test solutions were not changed in the
experimental ponds.