Adult emergence inhibition and adulticidal activity of leaf crude extracts against Japanese encephalitis vector, Culex tritaeniorhynchus

Mosquitoes have developed resistance to various synthetic insecticides, making its control increasingly difficult. Insecticides of botanical origin may serve as suitable alternative biocontrol techniques in the future. The aim of this study was to evaluate the adult emergence inhibition (EI) and adulticidal activity of the leaf hexane, chloroform, ethyl acetate, acetone, and methanol extracts of Aegle marmelos (Linn.) Correa ex Roxb, Andrographis lineata Wallich ex Nees., Andrographis paniculata (Burm.f.) Wall. ex Nees., Cocculus hirsutus L. Diels, Eclipta prostrata L. and Tagetes erecta L. were tested against japanese encephalitis vector, Culex tritaeniorhynchus Giles (Diptera: Culicidae). All plant extracts showed moderate EI and adulticidal activity effects after 24 h of exposure at 1,000 ppm; however, the highest EI activity was found in leaf methanol extracts of A. marmelos, A. paniculata, T. erecta, and chloroform extract of E. prostrata (EI50 = 141.94, 214.17, 166.43, and 184.58 ppm; EI90 = 590.26, 882.34, 532.00 and 571.81 ppm); and the effective adulticidal activity was observed in acetone extract of A.marmelos, hexane of A.lineata, ethlyl acetate of A.paniculata, methanol extracts of C.hirsutus, E.prostrata, and T.erecta (LD50 = 139.05, 251.24, 205.06, 222.10, 166.73, and 232.74 ppm; LD90 = 426.19, 837.09, 813.59, 794.42, 579.43 and 807.41 ppm), respectively against C. tritaeniorhynchus. These results suggest that the leaf methanol extract of C. hirsutus, E. prostrata, and T. erecta have the potential to be used as an ideal eco-friendly approach for the control of the C. tritaeniorhynchus. Therefore, this study provides first report on the mosquito EI and adulticidal activity of plant extracts against a vector.