Field evaluation of sticky BR-OVT traps to collect culicids eggs and adult mosquitoes inside houses

Abstract INTRODUCTION: Culex quinquefasciatus is a mosquito of importance to public health, as it represents a real and/or potential risk for the transmission of pathogens to humans, such as some arthropod-borne viruses and nematodes that cause filariasis. In Brazil, three municipalities in the Metropolitan Region of Recife (RMR) that are endemic for lymphatic filariasis conducted control actions targeting this vector. With the goal of contributing novel C. quinquefasciatus collection strategies, a sticky trap capable of collecting eggs and imprisoning mosquitoes was investigated. METHODS: To evaluate the performance of the sticky BR-OVT trap, tests were carried out in the neighborhoods of Caixa d'Água and Passarinho (Olinda-PE-Brasil) between August 2011 and June 2012. Sixty traps were installed in the indoor areas of residences in the two districts. RESULTS: During the 11-month study, 0.52 [standard deviation (SD) = 1.52] Culex egg rafts, 2.16 (SD = 4.78) C. quinquefasciatus/trap/month, and 0.55 (SD = 1.28) Aedes/trap/month were caught. Female specimens predominated the traps (59% of C. quinquefasciatus and 96% of Aedes spp.). CONCLUSIONS The results demonstrated that the sticky BR-OVT trap is a useful tool for the collection of adult culicids of medical importance and offers an innovative way to collect C. quinquefasciatus eggs and adults in a single trap.

Impact of small variations in temperature and humidity on the reproductive activity and survival of Aedes aegypti (Diptera, Culicidae) / Impacto de pequenas variações de temperatura e umidade na atividade reprodutiva e sobrevivência de Aedes aegypti (Diptera, Culicidae)

In short space of time increase in temperature and rainfall can affect vector populations and, consequently, the diseases for them transmitted. The present study analyzed the effect of small temperature and humidity variations on the fecundity, fertility and survival of Aedes aegypti. These parameters were analyzed using individual females at temperatures ranging from 23 to 27 °C (mean 25 °C); 28 to 32 °C (mean 30 °C) and 33 to 37 °C (mean 35 ºC) associated to 60±8 percent and 80±6 percent relative humidity. Females responded to an increase in temperature by reducing egg production, oviposition time and changing oviposition patterns. At 25 ºC and 80 percent relative humidity, females survived two-fold more and produced 40 percent more eggs when compared to those kept at 35 ºC and 80 percent relative humidity. However, in 45 percent of females kept at 35 ºC and 60 percent relative humidity oviposition was inhibited and only 15 percent females laid more than 100 eggs, suggesting that the intensity of the temperature effect was influenced by humidity. Gradual reductions in egg fertility at 60 percent relative humidity were observed with the increase in temperature, although such effect was not found in the 80 percent relative humidity at 25 º C and 30 º C. These results suggest that the reduction in population densities recorded in tropical areas during seasons when temperatures reach over 35 ºC is likely to be strongly influenced by temperature and humidity, with a negative effect on several aspects of mosquito biology.

Em curto espaço de tempo, um aumento na temperatura e precipitação pode afetar a população de vetores e conseqüentemente, as doenças por eles transmitidas. Nesse estudo, analisou-se o efeito de pequenas variações na temperatura e umidade, sobre fecundidade, fertilidade e sobrevivência de Aedes aegypti. Esses parâmetros foram investigados usando-se fêmeas individuais nas temperaturas: 23-27 ° C (média 25 ° C), 28-32 ° C (média 30 ° C) e 33-37 ° C (média 35 º C) associada à umidade relativa: 60 ± 8 por cento e 80 ± 6 por cento. As fêmeas responderam ao aumento da temperatura com redução na produção de ovos, tempo de oviposição e mudança nos padrões de postura. A 25 º C e 80 por cento, fêmeas sobreviveram duas vezes mais e produziram 40 por cento mais ovos, que aquelas mantidas a 35 º C e 80 por cento. No entanto, nos grupos a 35 º C e 60 por cento a postura foi inibida em 45 por cento das fêmeas e apenas 15 por cento puseram mais de 100 ovos, sugerindo que a intensidade do efeito da temperatura seja influenciado pela umidade. Reduções graduais na fertilidade a 60 por cento de umidade relativa foram observadas com o aumento da temperatura, embora esse efeito não tenha sido registrado na umidade de 80 por cento, nas temperaturas de 25 º C e 30 º C. Esses resultados sugerem que a redução na densidade populacional nas zonas tropicais durante estações, em que a temperatura se eleva acima de 35 º C pode ser fortemente influenciada pela interação temperatura e umidade, afetando negativamente diversos aspectos da biologia do mosquito.