# Efficacy of the Insecticide Formulation SumiShield® 50WG for Malaria Vector Control in Experimental Huts in Madagascar

## TL;DR

This study tested SumiShield® 50WG, an insecticide, for malaria control in Madagascar and found it effective for up to 8 months against mosquitoes.

## Contribution

The study evaluates the long-term efficacy of SumiShield® 50WG against malaria vectors in Madagascar, including its performance on different wall substrates.

## Key findings

- SumiShield® 50WG achieved over 80% mosquito mortality for 8 months post-spray.
- The insecticide did not cause mosquitoes to avoid treated huts or reduce blood-feeding.
- Efficacy lasted through the malaria transmission season in Madagascar.

## Abstract

Indoor residual insecticide spraying and the distribution of insecticide-treated nets have undoubtedly led to a significant reduction in the global malaria burden. However, insecticide resistance poses a threat to the effectiveness of these recommended control methods. In the present study, the aim was to determine the efficacy of SumiShield® 50WG (Sumitomo Chemical Co. Ltd., Tokyo, Japan), an insecticide containing clothianidin, a neonicotinoid, in controlling malaria vectors in Madagascar. The study was conducted over 9 months after the initial spraying in experimental huts made with walls coated using different substrates, and both wild anopheline mosquitoes and an Anopheles arabiensis (An. arabiensis) insecticide-susceptible laboratory strain were used. Mortality in wild mosquitoes remained above the WHO threshold of 80.0% for up to 8 months post-spray, when assessed up to 96 hours after capture, depending on the type of wall surface. SumiShield 50WG did not induce exophily or inhibit blood-feeding in wild mosquitoes because no significant differences were observed between treated and control huts regarding the rates of exophily and blood-fed mosquitoes. In An. arabiensis, the WHO mortality threshold was also met for up to 8 months post-spray when assessed up to 96 hours after exposure. However, during the ninth month, this threshold was not achieved, even when mortality was assessed up to 120 hours after exposure. The residual efficacy of the formulation, which lasts up to 8 months, is sufficient to cover the malaria transmission season in most endemic areas of Madagascar.