Practical application of olfactory cues for monitoring and control of Aedes aegypti in Brazil: a case study

Abstract

The increasing importance of managing the mosquito vectors of dengue, mainly Aedes aegypti, is recognised world-wide as the disease becomes more prevalent in many countries. The complexity of the urban environment where the vectors breed makes it especially difficult to organise control efforts to reduce their numbers and their impact on disease transmission. Existing control programmes depend on larval surveys for population assessment but these are often unreliable and become available too late for the application of control measures to have a significant impact on disease transmission. The need for better and more timely information about the mosquito vectors of dengue has been recognised in Brazil and several new technologies for more reliable information on vector distribution and population densities have emerged that are making control efforts more effective. Olfactory cues from oviposition sites are now being used to lure gravid Ae. aegypti females into sticky traps for population assessments and indices of dengue risk. The development of the so-called MosquiTRAP which incorporates an oviposition attractant is described and its efficiency relative to more traditional monitoring methods is discussed. Volatile chemicals that attract host-seeking female Ae. aegypti have also been identified. These have been formulated for controlled release ('BG-Lure') and incorporated into novel trap designs ('BG-Sentinel') with much improved capture of Ae. aegypti compared to the standard traps that have been used previously. Both trapping systems are now being used to monitor and survey these important disease vectors. The MosquiTRAP is also an important cornerstone of an online GIS-based surveillance system called MI Dengue (Dengue Intelligent Monitoring System) which is being implemented in Brazil. Results to date have demonstrated that the accuracy of its predictions relating to dengue risk is much greater than that obtained using more traditional methods. Real-time decision-making related to vector management is now possible using the new surveillance systems, and this should greatly impact the management of the disease.