Abstract:
Mosquitoes are responsible for the transmission of many kinds of vector bone
diseases such as Dengue, Malaria, Lymphatic filariasis and Japanese encephalitis,
yellow fever, and other forms of encephalitis. Among these kinds of diseases,
Malaria is the most devasting disease for many centuries and causes many deaths
annually. In Sri Lanka, Malaria is transmitted by Anopheles species primarily and
secondary. Other than disease transmission mosquitoes can cause painful bites.
So, we must improve personal protection to prevent their being bitten. The present
study has investigated the repellents and insecticidal activities of five herbal
extracts in Sri Lanka namely Calotropis gigantea L., Tagetes erecta L., Lantana
camara L., Vitex negundo L., and Cinnamomum zeylanicum L. against secondary
Malaria vector species of Anopheles tessellatus using WHO standard
susceptibility test kit for adult mosquitoes. Methanolic five-leaf extracts were
evaluated by using ten unfed 2-5 days adult female mosquitoes of A. tessellatus.
The contact irritancy assay was done for the investigation of percentage
repellency and the toxicity assay was done for the investigation of percentage
mortality using three concentrations (1000ppm, 2500ppm, 5000ppm) and each
concentration carried out three replicates. The diluted MeOH was used as control
test. The C. zeylanicum was recorded with the highest percentage mortality
(5000ppm; 100.00±0.00) after 24 hours exposure period; and the highest
percentage repellency (5000ppm; 100.00±0.00) after 1 hour exposure period.
Tagetes erecta was recorded potential percentage mortality (5000ppm;
83.33±3.33) and potential percentage repellency (5000ppm; 55.67±12.67).
Calotropis gigantea were recorded lowest percentage mortality and lowest
percentage repellency for all concentrations. In conclusion C. zeylanicum acted
as best repellent and insecticidal extract among selected extracts against An.
tessellatus. According to findings of this experiment, suggest doing some
investigation of chemical compounds which may affect for repellent and
insecticidal activity of selected extracts in future.
