The combination of the entomopathogenic fungus Metarhizium anisopliae with the insecticide Imidacloprid increases virulence against the dengue vector Aedes aegypti (Diptera: Culicidae)

A sub-lethal concentration of IMI that did not significantly alter the daily survival rates or mean survival percentages of mosquitoes was identified to be 0.1 ppm. This sub-lethal concentration was combined with M. anisopliae conidia (1 × 109 conidia mL-1). Both the combined treatment and the conidia alone were able to reduce the survival of A. aegypti compared with untreated or IMI treated mosquitoes. Importantly, mosquito survival following exposure to the combined treatment for 6 and 12 hrs was significantly reduced when compared with mosquitoes exposed to conidia alone.This is the first time that a combination of an insecticide and an entomopathogenic fungus has been tested against A. aegypti. Firstly, the study showed the potential of IMI as an alternative to the currently employed pyrethroid adulticides. Secondly, as an alternative to applications of high concentrations of chemical insecticides, we suggest that adult A. aegypti could be controlled by surface application of entomopathogenic fungi and that the efficiency of these fungi could be increased by combining the fungi with ultra-low concentrations of insecticides, resulting in higher mortality following relatively short exposure times.During the 2008 Dengue epidemic in Brazil, 743,517 cases were registered, falling to 387,158 cases in 2009, resulting in 98 deaths from dengue haemorrhagic fever and 58 deaths for Dengue related complications [1]. Up until October 2010, 936,260 cases had been notified with 592 Dengue related deaths [2]. With the development of a multi-sorotype vaccine still a distant goal, the only means of reducing infection rates is to control the insect vector.Conventional mosquito control measures in Brazil consist of year-round vigilance, continuous applications of chemical or biological larvicides, elimination of breeding sites and during Dengue outbreaks, spray application of insecticides for reduction of adult mosquito populations [3]. The efficiency of year-round interventions ha