LARVICIDAL AND REPELLENT EFFICACY ORGARLIC (Allium sativum) AND GINGER (Zingiber officinale)AGAINST THE MOSOUITO DISEASE VECTORSAnopheles stephensi AND Aedes aegypti

摘要

Insecticides play a major role in the control of mosquitoes but due to rapid resistance develop- ment, toxic effects on the environment and human health, there is an increasing need to concentrate on the development of medicinal plant-based natural insecticides. Essential oils were extracted from twomedicinal plants, Allium sativum and Zingiber offic- inale, and were evaluated for larvicidal and repel- lent activities against mosquito disease vector spe- cies; Aedes aegypti and Anopheles stephensi, ac- cording to the bioassay guidelines of World Health Organization. The extracted oil of A. sativum showed toxicity against the third instar larvae of A. aegypti with LCso of 0.314 and LCo of 12.323 after 24 hours. Similarly, the LCso was 0.40 and LCo were 2.13 after 24 h against An. stephensi. The extracted oil of Z. officinale showed toxicity against third instar larvae of A. aegvpti with LCso value of 186.33 and LCon value 11602.4 after 24 h against A. aegypti while LCso value 43.14 and LCoo value 6453.54 after 24 h against An. stephensi, respective-ly. The aqueous extracts of A. sativum and Z. offici- nale have a lower repellent effect against A. aegyptii and An. stephensi when compared with Mospel (DEET). A. sativum oil extract resulted into thehighest repellent effect at 20 dose with a meanprotection time of 130 and 140 minutes, while Z. officinale gave 80 and 90 min protection time against both An. stephensi and A. aegypti adults, respectively and Mospel (DEET) had 7.5-8 hours of protection. Our results revealed that A. sativum oil had a strong insecticidal effect while Z. offici- nale had not exhibited significant activity againstboth tested mosquito species. As repellent, aqueous extract was less effective when compared with gold standard DEET and both plants extract needs to be furthered evaluated under field conditions as insec- ticides as well as for improved repellent efficacy.