In Argentina, more than 25,000 cases of dengue were reported in the summer of 2009, even The domestic mosquito Aedes aegypti is the primary vector of dengue, the most important vector-borne arbovirosis in the world. Since vaccines against dengue are not yet available, vector monitoring and control are the only present options for the prevention of outbreaks. Currently, chemical treatment is one of the most important components in an integrated campaign (WHO 2000). In 1986, Ae. aegypti re-invaded the northern and central provinces of Argentina, reaching infestation levels even higher than those previously observed in periods prior to the termination of the control campaign in 1964 (Carbajo et al. 2001). In 1997, dengue was reintroduced in Argentina by infected persons with travel histories to Brazil, Ecuador and Venezuela (Avilés et al. 1999) and outbreaks were confirmed in northern provinces close to endemic countries (Salta, Jujuy, Misiones, Formosa and Corrientes), resulting in about 4,700 dengue cases until 2007 (Vezzani & Carbajo 2008 containers are treated with temephos, an internationallyused organophosphorus larvicide (focal treatment), and a new cis-permethrin ultra low volume formulation (Seccacini et al. 2006) is employed as an adulticide in the event of an outbreak (spatial treatment).Susceptibility levels to insecticides used on Ae. aegypti must be constantly screened in different geographical areas to develop successful control strategies because artificial selection of resistant mosquito lines could result in control failures (WHO 1995). Biber et al. (2006) detected differences in resistance levels of Ae. aegypti to temephos [Abate 1G (1%)] in four natural Argentinean subpopulations previously identified by their different haplotypes. Moreover, temporal variation of larval susceptibility to temephos was analysed in Clorinda and Iguazú between 2004 and summer 2006 through summer 2007 and a weak augmentation in the resistance levels to the larvicide was observed in both cities. The resistance ratio (RR) values obtained in that study (3.099 for Clorinda and 3.057 for Iguazú) indicated an incipient resistance and no control failures were detected (Seccacini et al. 2008).To advance understanding of the resistance of Argentinian Ae. aegypti to temephos, we determined the susceptibility levels of individuals from seven populations collected during summer 2007 through summer 2008.Samples were collected in seven cities (Clorinda, 25º17'S 57º43'W, Formosa Province; Iguazú, 25º36'S 54º34'W, Misiones Province; Puerto Rico, 26º47'S 55º02'W, Misiones Province; Orán, 23º08'S 64º19'W, Salta Province; Ledesma, 23º49'S 64º47'W, Jujuy Province; Chepes, 31º20'S 66º35'W, La Rioja Province; Cór-doba, 31º24'S 64º10'W) throughout the summer months from December 2007-January 2008 (Fig. 1). Larvae were taken from artificial water containers and eggs were obtained by ovitraps randomly distributed in the sampled cities, except in Puerto Iguazú, where ovitraps were located only in the proximity of the national park. In Clori...

Aedes albifasciatus is a floodwater mosquito widely distributed in Argentina. It is important from economic and medical points of view. A 4-year survey of seasonal variation in allele frequencies in a population of this species was undertaken to determine possible changes in the genetic structure and their correlation with environmental conditions. Significant temporal variation was detected at most of the loci, but it did not follow a cyclic or seasonal pattern. Multivariate analysis of principal components showed a remarkable homogeneity of samples collected from December 1993 to April 1995 and a clear differentiation of the November 1991, March 1992, and November 1993 samples. This variation could be correlated with the magnitude of rainfall occurring in the area. Passive transport of larvae by water streams and river freshets produced by floods would have mixed larvae from breeding sites with different allele frequencies, causing the genetic differentiation observed.