Dengue virus infects 50-100 million people and causes ~200,000 cases of dengue hemorrhagic fever annually. In tropical urban areas worldwide, dengue virus is transmitted exclusively by mosquito species utilizing artificial containers as oviposition habitats. Although the most important vector, Aedes aegypti, was almost eradicated from the Americas in the 1960s, the species has become widely disseminated and increasingly associated with intense dengue transmission. We have made significant progress towards developing a novel lethal trap targeting oviposition behavior in container-inhabiting mosquito species, with a focus on Ae. aegypti. The trap builds on the concept that oviposition is mediated by specific physical and chemical cues in the environment, and once the cues are identified, they can be used not only to improve population monitoring, but more importantly, to create a lure-and-kill control strategy for gravid mosquitoes. Every gravid female eliminated from a population is one less potential vector, and one or more human infections averted. Our work to date has focused on developing three major components needed for this lethal trap: a mosquito-attractive trap design, oviposition attractants and stimulants, and a non-repellent killing medium. We have shown proof of concept for a prototype attractant-baited lethal ovitrap (ALOT) first in large cage trials and then in a pilot-scale field trial conducted in 2006 in New Orleans, Louisiana. Specifically, in large cage trials with alternative oviposition sites available, we achieved 97% mortality of gravid Ae. aegypti over 24 hours. We showed that fermentation-derived attractants enhanced the ALOT, as determined by an increase in female mortality and number of eggs retained by gravid females. We identified essential trap color and shape components, and determined the duration of efficacy of trap components in field conditions. We also identified and continue to refine oviposition attractants, stimulants, and their delivery systems. In the field trial, we deployed 800 ALOTs in a 16 block residential area of New Orleans and compared this to control areas over 14 weeks by monitoring with non-lethal ovitraps, diurnal CO2-baited traps and vacuum aspirators. We are confident that the outcome of this work will be an inexpensive, easy-to-use product which will substantially reduce mosquito populations when deployed alone, or in concert with other control methods targeting this species. It will be especially effective against the most dangerous population member, the previously bloodfed and potentially infective (older) female. Area-wide management of Ae. aegypti with the ALOT promises to be a sustainable strategy because it is based on mosquito biology and behavior. The ALOT will empower communities to make the living and working environments of their residents healthy and safe.
The goal of the proposed project is to demonstrate a reduction in new human infections (from Aedes Stegomyia-borne dengue virus transmission) by area-wide deployment of the ALOT, as a component of community-based dengue management programs. There are 5 objectives to achieve this goal: 1) Finalize structural and toxicant components of the ALOT and validate under field conditions; 2) Complete characterization of oviposition attractants and stimulants, develop delivery systems, and validate under field conditions; 3) Optimize the ALOT containing oviposition attractants and stimulants and validate activity under field conditions; 4) Demonstrate the ALOT efficacy (reduction in mosquito density and dengue incidence) in an experimental field trial; 5) Work with public health officials and vector control experts to establish standards and benchmarks for use of lethal ovitraps. We propose a large scale evaluation of this device in dengue endemic areas in Iqyuitos, Peru, where we will measure changes in mosquito populations and trends in new human dengue infections. We expect that area-wide deployment of the ALOT will result in a measurable decrease in abundance of physiologically old mosquitoes and in new human infections.
This is a collaborative project between Tulane University and North Carolina State University.