The "Gredouno" Cross Target: a new tool adapted to control Glossina palpalis gambiensis in the mangrove forests of Guinea.

Abstract

Background: In the mangroves of Guinea, where the most active foci of human African trypanosomiasis in West Africa are located, vector control against tsetse flies using insecticide-impregnated Tiny Targets was first introduced in 2012. While annual deployments of Tiny Targets have resulted in an overall 90% reduction in tsetse fly densities in control areas, managing tsetse densities in specific biotopes such as mangrove channels, which are susceptible to significant climatic disturbances, presents greater challenges. Thus, a new three-dimensional model called the Cross Target was designed to address this situation.

Methods: In the first phase, we evaluated the attractiveness of the Cross Target along with three other devices (the Tiny Target, the biconical trap, and the pyramidal trap) in a Latin square design. In a second phase, we assessed the efficacy of the Tiny Target and the Cross Target to control tsetse densities in a pilot field study led in two adjacent mangrove channels.

Results: In the Latin square study, the Cross Target was significantly more attractive than the other devices, with a catch index of 2.23 (P = 0.03), 1.63 (P = 0.004), and 2.39 (P = 0.003) as compared with the biconical trap, the Tiny Target, and the pyramidal trap, respectively. In the pilot experimental field evaluation the Cross Target also showed its superiority, with tsetse density reduction reaching 90% 15 months after the initial deployment, whereas densities remained high in the channel where Tiny Targets were deployed.

Conclusions: This study underscores the superiority of the new three-dimensional Cross Target in terms of attractiveness to tsetse flies and its resilience to climatic disturbances as compared with the conventional Tiny Target. The Cross Target presents a promising solution to enhance vector control effectiveness in challenging environments, such as mangroves or other hard-to-access areas, where target maintenance is particularly difficult.