Pesticidal and Mosquitocidal Activities of Clausena excavata Burm. F. (Rutaceae) against Spodoptera litura (Fab.) (Noctuidae: Lepidoptera) and Aedes aegypti L., Anopheles stephensi Liston, and Culex quinquefasciatus Say. (Diptera: Culicidae)

The aim of this paper is to evaluate the larvicidal and ovicidal activities of hexane, diethyl ether, dichloromethane, ethyl acetate, and methanol extract of Indian medicinal plant, Clausena excavata, at different concentrations against lepidopteran agricultural field pest, Spodoptera litura (Lepidoptera: Noctuidae), and Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus (Diptera: Culicidae). Twenty-five early fourth instar larvae of S. litura and A. aegypti, An. stephensi and C. quinquefasciatus were exposed to various concentrations and were assayed in the laboratory by using specific protocols. The 24？h LC50 and LC90 values of the C. excavata leaf extract was determined by probit analysis. The ovicidal activity were determined against S. litura and A. aegypti, An. stephensi, and C. quinquefasciatus and was assessed 120？hrs after treatment. Results of this study show that the selected Indian medicinal plant C. excavata may be a potential source of natural larvicidal and ovicidal activities against selected pest and vector mosquitoes. 1. Introduction Spodoptera litura (Fab.) is a lepidopteran polyphagous pest, widely distributed throughout India. It has a wide range of hosts, feeding on 180 plant species worldwide, of which more than 60 species are known from India. The larvae of this pest can defoliate many economically important crops possessing a high dispersal capability. This pest has often generated high levels of agricultural losses which accounts for 69 percent reduction in yield. Traditional farmers have been practicing synthetic pesticides to eliminate S. litura and hence it has developed resistance against almost all the commonly used pesticides in several countries [1–6]. Most of the dipteran insects generally and mosquitoes in particular threaten the health and life of humans and animals often due to the transmission of agents of severe diseases like malaria, dengue fever, yellow fever, filariasis, and Japanese encephalitis that cause millions of deaths every year [7]. Mosquito bite also cause allergic responses in humans that include local skin and systemic reactions such as angioedema [8, 9]. Aedes aegypti (Linn.) spreads arbovirus responsible for dengue fever and its prevalence is common to Southeast Asia, the Pacific island area, Africa, and the Americas. The disease remains endemic in more than 100 developing tropical countries and its control is a major goal for improved worldwide health [10]. Anopheles stephensi (Liston) is the common vector of malaria in India and other West Asian countries. Malaria remains one of the