# Susceptibility of Lutzomyia longipalpis (Lutz & Neiva, 1912) to Fludora FusionPM, a combination of clothianidin and deltamethrin: field and laboratory bioassays

## TL;DR

Fludora FusionPM, a mix of two insecticides, was more effective than Alfatek 200SC in killing sand flies in the lab and field, especially on unpainted walls.

## Contribution

Demonstrates Fludora FusionPM's superior efficacy against sand flies in field conditions, particularly on unpainted surfaces.

## Key findings

- Fludora FusionPM showed 97.3% mortality in field trials, outperforming Alfatek 200SC.
- On unpainted walls, Fludora FusionPM maintained 97.8% mortality, while Alfatek 200SC dropped to 80.7%.
- Fewer adverse effects were reported with Fludora FusionPM compared to Alfatek 200SC.

## Abstract

Insecticides remain a cornerstone in the control of vector-borne diseases. In Brazil, Alfatek 200SC—a pyrethroid (alphacypermethrin)—is recommended for controlling phlebotomine sand flies, the vectors of leishmaniases. For mosquitoes such as Aedes aegypti, a combination of deltamethrin and clothianidin (Fludora FusionPM) is endorsed. This study evaluated the efficacy of Fludora FusionPM against phlebotomine sand flies.

Laboratory bioassays were conducted using Fludora FusionPM-impregnated filter papers stored either at room temperature (25 ± 2 °C) or under cold conditions (3 ± 1 °C). In field trials, painted (PS) or unpainted (US) masonry-plastered walls in selected households were treated with the insecticide. Alfatek 200SC was used as a reference, following the same procedures. Lutzomyia longipalpis females (n = 25 per replicate, in triplicate) were exposed for 60 min using the cone test. Mortality was assessed 1 h and 24 h postexposure and quarterly over 1 year. Structured questionnaires were administered to the community endemic agent (CEA) responsible for spraying and to household residents to document perceived adverse effects.

In the laboratory, the residual activity expressed by average mortality rates over 1 year of paper impregnation was of 97.6% for Fludora FusionPM) and 91.7% for Alfatek 200SC). In the field, 1-year average mortality rates were 97.3% for Fludora FusionPM and 94.6% for Alfatek 200SC for PS. On US walls, Fludora® FusionPM maintained high mortality rate (97.8%) whereas Alfatek 200SC parameter decreased to 80.7%. Adverse effects were informed by three of five residents for Alfatek 200SC and by one of four residents for Fludora FusionPM. The CEA reported side reactions after Alfatek 200SC spraying.

Fludora FusionPM was highly toxic to Lu. longipalpis and outperformed Alfatek 200SC under field conditions, particularly on unpainted masonry-plastered walls. Combining insecticides with complementary modes of action may enhance rotational strategies, reduce costs and resistance risk, and optimize control of multiple vector-borne diseases simultaneously.

The online version contains supplementary material available at 10.1186/s13071-025-07206-y.