The “Auto-Dissemination” Approach: A Novel Concept to Fight Aedes albopictus in Urban Areas

Abstract

Background

The main constraint to the fight against container-breeding mosquito vectors of human arboviruses is the difficulty in targeting the multiplicity of larval sources, mostly represented by small man-made water containers. The aim of this work is to assess the feasibility of the “auto-dissemination” approach, already tested for Aedes aegypti, as a possible alternative to traditional, inefficient control tools, against Ae. albopictus in urban areas. The approach is based on the possibility that wild adult females, exposed to artificial resting sites contaminated with pyriproxyfen, can disseminate this juvenile hormone analogue to larval habitats, thus interfering with adult emergence.

Methodology

We carried out four field experiments in two areas of Rome that are typically highly infested with Ae. albopictus, i.e. the main cemetery and a small green area within a highly urbanised neighbourhood. In each area we used 10 pyriproxyfen “dissemination” stations, 10 “sentinel” sites and 10 covered, control sites. The sentinel and control sites each contained 25 Ae. albopictus larvae. These were monitored for development and adult emergence.

Principal Findings

When a 5% pyriproxyfen powder was used to contaminate the dissemination sites, we observed significantly higher mortality at the pupal stage in the sentinel sites (50–70%) than in the controls (<2%), showing that pyriproxyfen was transferred by mosquitoes into sentinel sites and that it had a lethal effect.

Conclusions

The results support the potential feasibility of the auto-dissemination approach to control Ae. albopictus in urban areas. Further studies will be carried out to optimize the method and provide an effective tool to reduce the biting nuisance caused by this aggressive species and the transmission risk of diseases such as Dengue and Chikungunya. These arboviruses pose an increasing threat in Europe as Ae. albopictus expands its range.

Author Summary

Aedes albopictus (the Asian Tiger mosquito) is one of the most invasive and aggressive disease vectors in the world. It is a serious public nuisance and a public health risk, due to its ability to transmit pathogens to humans. The control of this mosquito is complicated by the difficulty in targeting either juveniles (due to their ability to colonise myriad and often cryptic domestic and natural water containers) or adults (due to their diurnal and outdoor resting and biting patterns). The aim of our work was to assess the feasibility of a novel approach to control Ae. albopictus in urban areas. This was based on the possibility that wild adult females, exposed to artificial resting sites contaminated with an insect growth regulator, could subsequently contaminate their breeding sites and kill both the larvae and pupae developing therein. The results obtained from field experiments carried out in highly infested areas in Rome demonstrate that this approach has potential as a valid alternative to traditional (and ineffective) larval control efforts in urban areas. We therefore introduce a new perspective in the fight against the Asian Tiger Mosquito.