Control of Aedes aegypti with temephos in a Buenos Aires cemetery, Argentina

Avaliou-se a eficácia de um larvicida, temefós, para controlar Ae. aegypti em um cemitério de Buenos Aires, Argentina. Os criadouros reduziram de 18,4 por cento no primeiro período de estudo (nov de 1998 a maio de 1999, sem temefós) para 2,2 por cento no segundo (nov de 1999 a maio de 2000, duas aplicações), e para 0,05 por cento no terceiro (nov de 2000 a maio de 2001, cinco aplicações). As. ovitrampas com ovos diminuíram de 17 por cento no primeiro período para 5,8 por cento no segundo e para 2,9 por cento no terceiro. Os resultados sugerem que, em Buenos Aires, as populações de Ae. aegypti são altamente susceptíveis ao temefós. É recomendável seu uso para prevenir eventuais epidemias e não para o controle rotineiro.

Seasonal pattern of abundance of Aedes aegypti (Diptera: Culicidae) in Buenos Aires city, Argentina

In Buenos Aires, the most crowded city of Argentina, there is a potential risk of dengue virus transmission by the mosquito Aedes aegypti during late summer. The temporal patterns of oviposition activity and abundance of breeding sites of this vector were studied in two cemeteries of the city. Between September 1998 and August 1999, we examined 142 ovitraps weekly and a total of 18,010 water-filled containers. Both study areas showed remarkable differences in the percentages of positive ovitraps (19 percent vs 8 percent) and breeding sites (18 percent vs 1 percent), but similar temporal abundance patterns. The percentage of breeding sites was higher in summer and autumn than in spring and winter, and the percentage of positive ovitraps was higher in summer than in the other three seasons. Immatures were recorded from the first week of October to the second week of July, and oviposition activity from the third week of October until the end of April. In both cemeteries and with both methodologies the highest infestation levels were registered in March (ovitraps: 41.8 percent and 20.6 percent, breeding sites: 39.2 percent and 3.4 percent). These highest abundances took place after several months with mean temperatures above 20§C and accumulated rainfalls above 150 mm. A sharp decline in oviposition activity was observed when monthly mean temperature decreased to 16.5§C, and no eggs were found below 14.8§C. Seasonal fluctuation of Ae. aegypti abundances in mid-latitudes like Buenos Aires would allow reduction of the egg mosquito population through the elimination of containers during the coldest months, which are free of adults.