Larval cold tolerance as a possible explanation for the range expansion and increasing abundance of Aedes aegypti in temperate South America (Buenos Aires, Argentina)

SYLVIA FISCHER; MARÍA SOL DE MAJO; GABRIELA ZANOTTI; RAÚL ERNESTO CAMPOS

Palma de Mallorca

Congreso; 7th International Society of Vector Ecology Congress; 2017

Society for Vector Ecology

Aedes aegypti is the mainvector of dengue in the Americas. Despite its tropical origin, this species hassuccessfully established in temperate regions during the last decades. In Buenos Aires province (Argentina),at the boundary of this species in South America, more than twenty newcities have been colonized by Ae. aegyptiin recent years, expanding the distribution to colder climates. In Buenos Aires city (thelargest urban area within this region), the abundance of Ae. aegypti increased steadily during the past twenty years. Sincelow temperatures are the main limiting factor for Ae. aegypti populations in temperate regions, we studied the tolerance(development time and survival) of immature stages to low temperatures trough:a) a field experiment during the winter season in Buenos Aires city; b) a studyunder constant temperatures within the range of 12-24ºC. The results showed thatall cohorts initiated during the winter season were able to complete larvaldevelopment. Cohorts initiated in early winter (experiencing averagetemperatures of 13-14ºC), exhibited a lower survival (30%) and longerdevelopment time (50 days) than those initiated in early spring (survival of90% and development time of 18 days at average temperatures of 20-21ºC). Under constanttemperatures 20% of individuals completed development in 48 days at 12ºC, andfrom 14ºC onwards survival exceeded 80% and development time decreased withhigher temperatures. The comparison of our results with previous studies fromother regions suggests an increased cold tolerance of immature stages of the BuenosAires Ae. aegypti population.