Abstract:
Extracts were obtained from Z. officinale rhizomes and A. sativum cloves. Direct contact of both extracts was tested on Culex pipiens guingguefasciatus using 25%, 50%, and 75% concentrations, through spraying. Each treatment was conducted in triplicate. Mortality rates were compared with those obtained from control set-ups containing pure distilled waster and subjected to the chi-square test. Results indicated that both extracts were toxic to the test insects, and that Z. officinale brought about quicker mortality than A. sativum. Mortality rates were also observed to increase with a corresponding increase in extract concentration (Z. officinale – 75% > 50% > 25%; A sativum – 75% > 50% > 25%). The order of degree of toxicity from the greatest to the least is as follows: 75% Z. officinale > 75% A. sativum > 50% Z. officinale > 50% A. sativum > 25% Z. officinale > 25% A. sativum.
Fumigant toxicity was tested using concentrations prover to the most effective in the first part of the study and by placing a screen divider between the test insects and the extracts. Fumigant toxicity was proven positive for both, but to a lesser extent as compared to direct contact toxicity. Again, Z. officinale was proven to be more toxic than A. sativum.
It was therefore determined that Z. officinale was more effective than A. sativum in terms of both direct contact and fumigant toxicity.
