The entomological impact of passive metofluthrin emanators against indoor Aedes aegypti: A randomized field trial

Abstract

Background In the absence of vaccines or drugs, insecticides are the mainstay of Aedes-borne disease control. Their utility is challenged by the slow deployment of resources, poor community compliance and inadequate household coverage. Novel application methods are required. Methodology and principal findings A 10% w/w metofluthrin “emanator” that passively disseminates insecticide from an impregnated net was evaluated in a randomized trial of 200 houses in Mexico. The devices were introduced at a rate of 1 per room and replaced at 3-week intervals. During each of 7 consecutive deployment cycles, indoor resting mosquitoes were sampled using aspirator collections. Assessments of mosquito landing behaviours were made in a subset of houses. Pre-treatment, there were no differences in Aedes aegypti indices between houses recruited to the control and treatment arms. Immediately after metofluthrin deployment, the entomological indices between the trial arms diverged. Averaged across the trial, there were significant reductions in Abundance Rate Ratios for total Ae. aegypti, female abundance and females that contained blood meals (2.5, 2.4 and 2.3-times fewer mosquitoes respectively; P<0.001). Average efficacy was 60.2% for total adults, 58.3% for females, and 57.2% for blood-fed females. The emanators also reduced mosquito landings by 90% from 12.5 to 1.2 per 10-minute sampling period (P<0.05). Homozygous forms of the pyrethroid resistant kdr alleles V410L, V1016L and F1534C were common in the target mosquito population; found in 39%, 24% and 95% of mosquitoes collected during the trial. Conclusions/Significance This is the first randomized control trial to evaluate the entomological impact of any volatile pyrethroid on urban Ae. aegypti. It demonstrates that volatile pyrethroids can have a sustained impact on Ae. aegypti population densities and human-vector contact indoors. These effects occur despite the presence of pyrethroid-resistant alleles in the target population. Formulations like these may have considerable utility for public health vector control responses.

Experimental evaluation of a metofluthrin passive emanator against Aedes albopictus

“…Extending findings observed for Ae . aegypti [ 33 ] we show that a 10% metofluthrin passive emanator has high potential to reduce human- Ae . albopictus contacts both indoors and outdoors.…”

“…Furthermore, compared to metofluthrin coils, passive emanators have significantly longer duration and the added benefit of not requiring burning or other source of heat. In Merida, Mexico, household surveys showed that people view very positively the use of metofluthrin emanators as alternative to coils and reported measurable reductions in mosquito bites after their use [ 33 ].…”

“…An entomological randomized field trial conducted in Ticul, Mexico, found that placing emanators at a rate of one per room per house led to a reduction in indoor female Ae . aegypti density of 70% and of >90% reduction in landings compared to houses without emanators [ 33 ].…”

Wolbachia wAlbB inhibit dengue and Zika infection in the mosquito Aedes aegypti with an Australian background

“…Mosquitoes from Cairns WT, WB2, w AlbB2-F4 strains were tested for the presence of mutations in the voltage-gated sodium channel protein (VGSC) gene associated with knock down resistance to pyrethroids using Allele-specific quantitative PCR and melting curve analysis (AS-PCR) [54, 55]. These mutations included single nucleotide mutations causing changes from valine (V) to leucine (L) amino acid substitution at locus 410 (V410L), V to isoleucine (I) at locus 1016 (V1016I) and from phenylalanine (F) to cysteine (C) at position 1534 (F1534C) (numbered according to the homologous locus in the VCSC gene in Musca domestica ).…”

Evaluation of the protective efficacy of a spatial repellent to reduce malaria incidence in children in western Kenya compared to placebo: study protocol for a cluster-randomized double-blinded control trial (the AEGIS program)

“…Current malaria vector control guidelines do not recommend the use of SRs for personal protection [16]. However, various SR products have been shown to reduce mosquito biting [17][18][19][20][21][22][23] and, in epidemiological studies conducted in Indonesia [24], China [25], and Peru [26] have been shown to reduce pathogen transmission in human populations.…”