Tecnologias integradas para controle biológico, mecânico e genético de Aedes aegypti / Integrated technologies for biological, mechanical and genetic control of Aedes aegypti

Duas tecnologias alternativas para o controle de Aedes aegypti foram avaliadas: a aplicação espacial de larvicida biológico-Bti em potenciais criadouros peridomiciliares, e a liberação de machos estéreis para inviabilização reprodutiva das fêmeas do mosquito. As ações foram realizadas pelos Agentes dos Serviços de Saúde em 15 vilas da Ilha de Fernando de Noronha, e em uma área (900 imóveis) no bairro da Várzea/Recife/Pernambuco. A efetividade dos métodos foi avaliada por indicadores entomológicos,estimados pela presença, quantidade e viabilidade de ovos do mosquito, coletados em armadilhas, e por marcadores genéticos. A aplicação de Bti, com atomizador costal, ocorreu a cada 30 dias em ambas as áreas. Uma redução importante e sustentável da população de A. aegypti,por este método, foi alcançada em 2015/2016 na Várzea e, em 2016, na Ilha, onde a remoção de 18 toneladas de resíduos sólidos em 2015 contribuiu possivelmente para os resultados. Machos esterilizados com radiação gama foram produzidos em massa no laboratório e liberados em uma das vilas da Ilha. A análise espaço-temporal dos indicadores, de dez/2015a ago/2016, revelou redução expressiva da densidade populacional do mosquito e da diversidade genética da população local. Ambas as abordagens parecem ter reduzido o contato homem-vetor e os riscos de transmissão de arboviroses na Ilha, apesar da elevada competência vetorial da população local do mosquito para os vírus Zika e Dengue. Os métodos testados se mostraram eficientes e passíveis de serem integradas às ações do SUS voltadas ao controle de A. aegypti.

Two alternative technologies were evaluated for Aedes aegypti control:the spraying of a biological larvicide (Bti) in potential peridomiciliarybreeding sites and the release of sterile males to promote reproductionblockage in wild females. Actions were carried out by Agents of theHealth Services, in 15 villages of the Fernando de Noronha Island and in 900 properties from the district of Várzea, Recife-PE. The effectiveness of both methods was evaluated by entomological indicators, estimatedby the presence, quantity and viability of eggs from the mosquito collectedin traps and through genetic markers. Bti was delivered by backpacksprayer every 30 days in both areas. A significant and sustainablereduction of the A. aegypti population as a result of this technique wasachieved in 2015/2016 in Várzea and in 2016 in the Island, where it wasstrengthened by the removal of 18 tons of solid waste in 2015. Malessterilized with gamma radiation were mass-produced in the laboratoryand released in one village of the Island. The spatiotemporal analysis ofthe indicators, from Dec/2015 to Aug/2016, revealed a significant reductionin mosquito density, which impacted on the genetic diversity of thelocal population. Both approaches seem to have reduced human-vectorcontact and the risk of arbovirus transmission in the Island, althoughlocal mosquito population presented high vector competence to Zikaand Dengue virus. These methods were efficient and could be integratedinto SUS actions directed to A. aegypti control.

Monitoring temporal fluctuations of Culex quinquefasciatus using oviposition traps containing attractant and larvicide in an urban environment in Recife, Brazil

The use of attractants and larvicides in oviposition traps is of practical interest for the surveillance and control of urban mosquitoes. In addition to increasing the safety of the traps, this combination is essential for an attract-and-kill control strategy based on trapping mosquito eggs. The combination of Bacillus thuringiensis var. israelensis (Bti) and grass infusion (GI) vs. GI alone were tested for their ability to attract in paired BR-OVT traps in the backyards of 10 houses in Recife, Brazil, for a period of 45 days. Results show that females prefer to oviposit in traps containing Bti (363 compared with 251 egg rafts over 45 days). Results from a one-year trial on the efficacy of BR-OVT traps loaded with GI and Bti as a sampling tool to monitor temporal fluctuations in the population densities of Culex quinquefasciatus in an urban environment are also reported. From December 2006-January 2007, one trap per home was installed and maintained for 348 consecutive days in 134-151 houses located in three urban blocks. Throughout the one-year field trial a total of 43,151 Culex egg rafts were collected in the traps. The data show that BR-OVT loaded with GI and Bti is sensitive enough to demonstrate continuous reproductive activity of Cux. quinquefasciatus in the study area throughout the year and to monitor temporal fluctuations in population density.