Residual efficacy of the neonicotinoid insecticide clothianidin against pyrethroid‐resistant Aedes aegypti

Abstract

BACKGROUND Here we report the residual efficacy of the neonicotinoid insecticide clothianidin against pyrethroid‐resistant Aedes aegypti. We first conducted a range‐finding evaluation of clothianidin on three different substrates (wall, wood, cloth) using three doses (100, 300 and 600 mg a.i. m−2) and conducting World Health Organization (WHO) cone bioassays to assess acute (24 h) and delayed (up to 7 days) mortality. In experimental houses located in Merida (Mexico) and using free‐flying pyrethroid‐resistant Ae. aegypti females, we quantified the acute and delayed mortality after a 24‐h exposure to the targeted indoor residual spraying (TIRS) of two clothianidin doses (100 and 300 mg a.i. m−2). RESULTS Range‐finding studies with WHO cones showed low (<50%) acute mortality for all surfaces, doses and times post spraying. Delayed mortality was higher, with average values above or close to the 60% mark (and 95% confidence interval estimates crossing 80% for the 600 mg a.i. m−2 dose). In experimental houses, a similar low acute mortality was quantified (range of mortality across 12 months was 2–44% for 100 mg a.i. m−2 and 8–61% for 300 mg a.i/m2). However, delayed mortality showed a strong effect of clothianidin on free‐flying Ae. aegypti, with values above 80% up to 7 months post‐TIRS. CONCLUSION Novel residual insecticide molecules have a promising outlook for Ae. aegypti control and can contribute to the expansion and adoption of TIRS in urban areas. clothianidin can contribute to the control of resistant Ae. aegypti and provide residual control for up to 7 months after application. © 2022 Society of Chemical Industry.

Preventive residual insecticide applications successfully controlled Aedes aegypti in Yucatan, Mexico

“…aegypti from the trial site showed that cone bioassays provide poor results in surfaces treated with SumiShield 50 WG compared to the insecticide's impact on free-flying mosquitoes (released in experimental houses). While delayed mortality in cones reached a maximum of 60% at 1 month post-spraying, delayed mortalities higher than 80% were maintained up to 7 months when mosquitoes were exposed in experimental houses 49 . This difference may be the product of the insecticide mode of action.…”