Residual knockdown effects of pyrethroid and neonicotinoid-treated nets on Rhodnius prolixus

Chagas disease remains an important public health concern across the Americas, affecting both human and animal populations. The triatomine bug Rhodnius prolixus, an obligate hematophagous vector of Trypanosoma cruzi, is commonly associated with environments where domestic and working animals are housed. Military working dogs (MWDs) deployed or stationed in endemic or expansion zones are particularly vulnerable to infection, which can lead to severe clinical disease and reduced operational readiness. This study evaluated the residual knockdown efficacy of esfenvalerate- and dinotefuran-treated netting against R. prolixus six months after treatment. Replicated modified WHO cone bioassays were conducted using exposure durations of 3, 6, 9, 12, and 15 min, and a total of 375 adult insects were tested across control, dinotefuran, and esfenvalerate treatment groups. Mean knockdown proportions were highest for esfenvalerate-treated netting (0.20-0.32), followed by dinotefuran-treated netting (0.08-0.16). Treatment group had a significant effect on knockdown proportion (ANOVA: F = 33.24, p < 0.001). Analysis of deviance from the binomial generalized linear model indicated a significant effect of treatment group (χ² = 50.89, df = 2, p < 0.001), while exposure time (χ² = 1.48, df = 4, p = 0.830) and the treatment-exposure interaction (χ² = 1.54, df = 8, p = 0.992) were not significant. These findings indicate that insecticide-treated netting retained measurable knockdown activity against R. prolixus six months after treatment. Evaluating residual insecticidal performance is therefore important when considering treated netting as a protective intervention in Chagas disease risk environments.