Comparative Efficacy of Selected Biorational Insecticides against Larvae of Southern House Mosquito Culex quinquefasciatus Say (Diptera: Culicidae)

Abstract

Mosquitoes are unquestionably the important arthropod vectors of diseases such as malaria, dengue, filariasis and systemic allergic reactions in humans. Southern house mosquito Culex quinquefasciatus Say is found in tropical and subtropical regions of the world and transmits many zoonotic diseases in humans and in wild and domestic animals. It is primarily controlled by the extensive use of conventional synthetic insecticides against most of which it has developed resistance. This study was aimed at determining the toxicity of selected microbial and synthetic insecticide formulations and botanical extracts against C. quinquefasciatus larvae. Among the n-hexane extracts of 40 indigenous plant species collected from Soon Valley and surrounding salt range of Pakistan bioassayed against C. quinquefasciatus larvae, eighteen botanicals exhibited more than 50% larval mortality in 48 h exposure. The most effective botanical extracts were Maerua arenaria Forsk, Nerium indicum Mill., Withania coagulans Dunal, Suaeda fruticosa (L.) Delile, Olea ferruginea Wall., Adiantum capillus-veneris L. and Dicliptera bupleuroides Nees exhibiting 87, 84, 83, 81, 79, 78 and 77% larval mortality, respectively with minimum LC50and LC90values. Among the microbial and synthetic insecticides, the highest larval mortality was recorded by Metarhizium anisopliae NCIM 1311 (83%) and Bacillus thuringiensis subsp. israelensis (63%), and by pyriproxyfen (86%) and indoxacarb (85%), respectively. Hence, these botanical, microbial and synthetic insecticides are recommended for the efficient control of C. quinquefasciatus larvae in field to reduce the environmental pollution caused by persistent synthetic insecticides.