Evaluation of larvicidal efficacy of indigenous plant extracts against Culex quinquefasciatus (Say) under laboratory conditions

Abstract

The present study focused on the insecticidal potential of easily available local botanicals using a simple but effective method.Seven indigenous plants (Cinnamomum tamala (taiz pat), Aloe vera (aloe vera), Datura alba (datura), Allium sativum (garlic), Alliumcepa (onion), Zingiber officinale (ginger), and Ocimum basilicum (niazbo/basil) were tested for their larvicidal efficacy against Culexquinquefasciatus (Say) under laboratory conditions. The evaluation of a series of five concentrations (1%, 2%, 3%, 4%, and 5%) of aqueousplant extracts against the 4th instar larvae revealed convincing larval mortality effects at 24 and 48 h after exposure. Larval mortalityshowed a significant concentration-dependent correlation. No mortality was observed in the control. The $LC_{50}$ values demonstratedgarlic as the most effective (1.37%), followed by taiz pat (1.48%) and aloe vera (1.96%), at 24 h. Moreover, the $LC_{50}$ at 48 h showed highefficiency by aloe vera (0.37%), followed by garlic (0.55%) and taiz pat (0.98%). The sequence of $LC_{50}$ values for the other plants wereonion (2.20%) < datura (2.49%) < niazbo (5.32%) < ginger (7.48%) after 24 h and datura (1.13%) < niazbo (1.17%) < onion (1.24%)< ginger (2.43%) after 48 h. Taken together, the aqueous extracts of all plants exhibited potential efficacy against C. quinquefasciatuslarvae and could be considered as potent natural larvicidal agents. These plants may be recommended for use in mosquito managementprograms as potential alternatives to synthetic insecticides. The simple aqueous extraction method is easy and inexpensive and can beused at the home level for mosquito management.