Comparative study of essential oil of tagetes erecta (Asteraceae) against third instar larvae of Aedes aegypti (Linnaeus, 1762) and anopheles stephensi (Liston, 1902)
Beena Joshi Bhatt
The objective of the present study was the comparision of essential oil of Tagetes erecta (Asteraceae) against third instar larvae of Aedes aegypti(Linnaeus, 1762) and Anopheles stephensi (Liston, 1902). Essential oil was hydro distilled in the laboratory from the plants obtained from the CAP. Bioefficacy of the essential oil was evaluated under laboratory conditions using III instar mosquito larvae.The number of dead larvae in each beaker was counted after 12, 24 and 48h. Percent-corrected mortality was determined using Abbott’s formula LC50 values (the concentration at which 50% of the larvae were immobilized) was calculated by probit analysis using the PROBIT software by log-probit regression using SPSS 16.0 for Windows/Microsoft Excel Programme. The LC50 values of essential oil of Tagetes erecta for Aedes aegypti were 81.765, 48.951 and 17.729ppm and for Anopheles stephensi, the values were 85.671, 53.451 and 26.484ppm after 12, 24 and 48 hours of exposure respectively. Chi-square values were significant at p˂0.05 level. Even though, the essential oil showed low LC50 17.729 ppm in Aedes aegypti and 26.484 ppm in Anopheles stephensi after 48 hours of exposure period. The larval mortality rate of essential oil was entirely time and dose dependent. The essential oil of Tagetes erecta showed comparatively higher mortality to the larvae of Anopheles stephensi.