Abstract
A preliminary study was conducted to evaluate the effects of nine methanol fungal extracts on fourth instar larvae of Aedes caspius and Culex pipiens (Diptera: Culicidae). None of the extracts tested showed larvicidal activity except for the Paecilomyces lilacinus extract, which showed 100% mortality against the larvae of Ae caspius after 24 h. The LC50 values of the P. lilacinus extract after 24 h were 190.66 g/mL against Ae. caspius and 254.25 g/mL against Cx. pipiens, respectively. After 48 h, meanwhile, the LC50 values were 65.70 and 164.13 g/mL, respectively. Histological analysis of the midgut of the treated larvae of Ae. caspius and Cx. pipiens revealed changes such as cell destruction, spacing between the cells and disruption of the microvilli, resulting in an appearance of vacuolization in the midgut. This article is the first report of the use of P. lilacinus extract for the control of Ae. caspius and Cx. pipiens larvae and the data obtained may help to provide a better understanding of the mode of action of P. lilacinus as an insecticide against mosquito larvae.