Semi Field Evaluation of Freestanding Transfluthrin Passive Emanators and the BG Sentinel Trap as a “Push-Pull control Strategy” Against Aedes aegypti Mosquitoes
Abstract Background The use of volatile pyrethroids and odor-baited traps in a push-pull system has been shown to reduce house entry and outdoor bites for malaria vectors. This technology has the potential to control other outdoor biting mosquitoes such as Aedes aegypti that transmit arboviral diseases. In this study, semi-field experiments were conducted to evaluate whether a push-pull system could be used to reduce bites from Aedes.Methods The push and pull under investigation consisted of two freestanding transfluthrin passive emanators (FTPE), and a BG sentinel trap (BGS) respectively. The FTPE contained hessian strips treated with 5.25 g of transfluthrin active ingredient. The efficacies of FTPE and BGS alone and in combination were evaluated by human landing catch in a large semi-field system in Tanzania. We also investigated the protection of FTPE over six months. The data was analyzed using generalized linear mixed models with binomial distribution.Results Two FTPE have a protective efficacy (PE) of 61% (95% Confidence interval (CI): 52.18–69.91) against human landing rate of Aedes aegypti. The BGS did not significantly reduce mosquito landings; the PE was 2.14% (95% CI: -2.87-7.16). The combination of FTPE and BGS (push-pull) provided the PE of 64.46% (95% CI: 59.06–69.85). However, there was no significant difference in the protective efficacy between the push-pull and the two FTPE against Ae. aegypti (p = 0.286). The FTPE offered significant protection against Ae. aegypti at month three, with a PE of 46.44% (95% CI: 41.12–51.76), but not at six months with a PE of 2.20% (95% CI: -9.00-14.02).Conclusions The protective efficacy of the FTPE and the full push-pull system are similar, indicative that bite prevention is primarily due to the activity of the FTPE. While these results are encouraging for the FTPE, further work is needed for a push-pull system to be recommended for Ae. aegypti control. The three-month protection provided by the FTPE against Ae. aegypti bites suggests it would be a useful additional personal protection tool during dengue outbreaks, that does not require regular user compliance.