Development of insecticide resistance in Culex quinquefasciatus mosquito from different locations in India

Cider quinquefasciatus is a domestic mosquito known as a primary vector of lymphatic filariasis. We report the development of insecticide resistance in four populations of C. quinquefasciatus Say, 1823 in Jodhpur (JD), Bikaner (BKN), Jamnagar (JMN) and Bathinda (BTH) in India in comparison to a susceptible laboratory population against larvicides such as temephos, fenthion, Bacillus thuringiensis var. israelensis and Neemarin (azadirachtin), and adulticides such as cypermethrin, alpha cypermethrin and lambda cyhalothrin. The resistance ratio (RR) at LC50 between field and laboratory populations was used for resistance expression. JD strain showed 10.8-, 6.94-, 5.29- and 2.82-fold resistance to temephos, fenthion, Neemarin and cypermethrin, respectively. BTH strain showed resistance to temephos, fenthion, lambda cyhalothrin, alpha cypermethrin and cypermethrin (9.06-, 2.06-, 3.33-, 4.96- and 3.19-fold, respectively). RR of BKN strain to temephos, fenthion, Neemarin and alpha cypermethrin was 5.17-, 4.12-, 4.33- and 3.04-fold, respectively; however RR was least in the JMN strain against most insecticides except alpha cypermethrin and fenthion. This study suggests that B. thuringiensis var israelensis and Neemarin may be efficient for larval control as an alternative to fenthion- and temephos-resistant strains of C. quinquefasciatus while lambda cyhalothrin and cypermethrin may be used effectively as an adulticide of this mosquito. (C) Pesticide Science Society of Japan