Rapid Neurotoxicity of Transfluthrin Volatiles and Spatial Repellency of Alternate Deterrents Against Host Seeking Black Flies, Simulium Vittatum (Diptera: Simuliidae).
- 1University of Georgia
Abstract
Spatial repellants are novel tools that aim to disrupt host seeking behavior in hematophagous insects. Outdoor spatial repellents succeed only when the aerodynamic channel is predictable enough to maintain a behavioral repellent field. Though standardized bioassays are essential for characterizing deterrent mediated behavioral responses, substantial knowledge gaps remain about the practical use of high throughput assays to evaluate repellency in outdoor biting species such as Simulium species. This is particularly relevant within the context of spatial repellent formulations for outdoor use. This study evaluated the comparative spatial repellency, knockdown and lethality thresholds of transfluthrin, permethrin, DEET (N, N diethyl meta toluamide), citronella oil and neem oil against host-seeking adult black flies (Diptera: Simuliidae). Concentration response data obtained (T=15, 30mins,1hr and 24hrs) across different concentration scales (0.001ug-10mg/cm2) were analyzed using a nonlinear regression to four parameter logistic equations to calculate half repellency (EC50), half knockdown (KC50) and half lethality (L50) concentration thresholds respectively. Results revealed that black flies exhibited significant repellency, knock down and lethality rates towards transfluthrin in horizontal orientation compared to DEET, permethrin, citronella and neem oil ({chi}{superscript 2} = 48.99, df = 32, P = 0.028). Driven by rapid vapor phase, transfluthrin demonstrated unparalleled repellency at a concentration of 0.1ug/cm2 in horizontal orientation (EC50 values = 0.0201 g/cm{superscript 2}) and vertical orientation (EC50 values = 0.030 g/cm{superscript 2}) compared to DEET (1h EC50 = 39.72 g/cm{superscript 2}). 1h KC50 values revealed rapid knockdown effects (0.0259 g/cm{superscript 2}) compared to DEET (38.24 g/cm{superscript 2}) evidenced by rapid progression of neurotoxic hyper excitation in black flies in both orientations. Permethrin showed least repellency nor knockdown rates even at the highest concentrations (10mg/cm2). Compound concentration significantly impacted chemical diffusion dynamics ({chi}{superscript 2} = 75.85, df = 36, P = 0.000116), revealing that total compound loss through time depends heavily on chemical type. In conclusion, results from this study validates dose dependent spatial repellency of transfluthrin against the outdoor biting insect vector, Simulium vittatum in varied orientation placements using a high throughput repellency assay. This underscores the potential of spatial repellent compounds as a promising novel tool against both vectors of onchocerciasis, Simulium damnosum s.l. and vesicular stomatitis virus, Simulium vittatum.
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BibTeX
@misc{aito2026rapid,
title = {{Rapid Neurotoxicity of Transfluthrin Volatiles and Spatial Repellency of Alternate Deterrents Against Host Seeking Black Flies, Simulium Vittatum (Diptera: Simuliidae).}},
author = {B. O. Aito and S. M. Kerr and E. W. Gray and C. G. Fair},
howpublished = {medRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.22.26366219},
url = {https://www.medrxiv.org/content/10.64898/2026.10.22.26366219v1},
note = {CC BY-ND},
}
RIS
TY - UNPB
TI - Rapid Neurotoxicity of Transfluthrin Volatiles and Spatial Repellency of Alternate Deterrents Against Host Seeking Black Flies, Simulium Vittatum (Diptera: Simuliidae).
AU - B. O. Aito
AU - S. M. Kerr
AU - E. W. Gray
AU - C. G. Fair
PY - 2026
DA - 2026/10/22
PB - medRxiv
DO - 10.64898/2026.10.22.26366219
UR - https://www.medrxiv.org/content/10.64898/2026.10.22.26366219v1
AB - Spatial repellants are novel tools that aim to disrupt host seeking behavior in hematophagous insects. Outdoor spatial repellents succeed only when the aerodynamic channel is predictable enough to maintain a behavioral repellent field. Though standardized bioassays are essential for characterizing deterrent mediated behavioral responses, substantial knowledge gaps remain about the practical use of high throughput assays to evaluate repellency in outdoor biting species such as Simulium species. This is particularly relevant within the context of spatial repellent formulations for outdoor use. This study evaluated the comparative spatial repellency, knockdown and lethality thresholds of transfluthrin, permethrin, DEET (N, N diethyl meta toluamide), citronella oil and neem oil against host-seeking adult black flies (Diptera: Simuliidae). Concentration response data obtained (T=15, 30mins,1hr and 24hrs) across different concentration scales (0.001ug-10mg/cm2) were analyzed using a nonlinear regression to four parameter logistic equations to calculate half repellency (EC50), half knockdown (KC50) and half lethality (L50) concentration thresholds respectively. Results revealed that black flies exhibited significant repellency, knock down and lethality rates towards transfluthrin in horizontal orientation compared to DEET, permethrin, citronella and neem oil ({chi}{superscript 2} = 48.99, df = 32, P = 0.028). Driven by rapid vapor phase, transfluthrin demonstrated unparalleled repellency at a concentration of 0.1ug/cm2 in horizontal orientation (EC50 values = 0.0201 g/cm{superscript 2}) and vertical orientation (EC50 values = 0.030 g/cm{superscript 2}) compared to DEET (1h EC50 = 39.72 g/cm{superscript 2}). 1h KC50 values revealed rapid knockdown effects (0.0259 g/cm{superscript 2}) compared to DEET (38.24 g/cm{superscript 2}) evidenced by rapid progression of neurotoxic hyper excitation in black flies in both orientations. Permethrin showed least repellency nor knockdown rates even at the highest concentrations (10mg/cm2). Compound concentration significantly impacted chemical diffusion dynamics ({chi}{superscript 2} = 75.85, df = 36, P = 0.000116), revealing that total compound loss through time depends heavily on chemical type. In conclusion, results from this study validates dose dependent spatial repellency of transfluthrin against the outdoor biting insect vector, Simulium vittatum in varied orientation placements using a high throughput repellency assay. This underscores the potential of spatial repellent compounds as a promising novel tool against both vectors of onchocerciasis, Simulium damnosum s.l. and vesicular stomatitis virus, Simulium vittatum.
ER -