Knockdown effects of pyrethroid- and neonicotinoid-treated netting against the sand fly Phlebotomus papatasi (Diptera: Psychodidae)

BACKGROUND: Phlebotomine sand flies are important vectors of leishmaniasis and pose persistent risks to human and animal health in endemic and operational environments, including military settings. Barrier-based vector control strategies, such as insecticide-treated netting, provide a practical means of reducing sand fly contact. However, comparative data on the performance of different insecticide classes applied to barrier materials remain limited. This study evaluated the knockdown efficacy of two commercially available insecticides, the pyrethroid esfenvalerate and the neonicotinoid dinotefuran, applied to high-blockage (80%) barrier netting against laboratory-reared Phlebotomus papatasi. METHODS: Adult sand flies were exposed to treated and untreated netting for contact durations of 3, 6, 9, 12, and 15 min. Knockdown responses were quantified using standardized laboratory bioassays. The effects of insecticide treatment and exposure time and their interaction were assessed using two-way analysis of variance, with model assumptions verified through residual diagnostics and pairwise comparisons. Probit analyses were conducted to estimate exposure-response relationships and median knockdown times. RESULTS: Knockdown increased significantly with exposure time for both insecticide treatments, whereas no knockdown was observed in untreated controls. Significant effects of treatment (P < 0.001) and exposure time (P < 0.001) and their interaction (P < 0.001) were detected, indicating treatment-dependent temporal differences in knockdown response. Both insecticides produced significantly greater knockdown than controls, with no significant difference in overall mean knockdown between esfenvalerate and dinotefuran (P = 0.89). Although temporal differences in knockdown patterns were observed, probit modeling did not detect a statistically significant difference in fitted slopes between treatments. CONCLUSIONS: Both insecticide-treated barrier nets induced rapid, exposure-dependent knockdown in P. papatasi. These findings support the use of pyrethroid- and neonicotinoid-treated barrier netting as effective chemical barriers within integrated sand fly control strategies to reduce leishmaniasis risk in military and endemic environments.