Assessing transfluthrin mortality against Aedes aegypti and Culex quinquefasciatus inside and outside US military tents in a northern Florida environment

Authors: MCMILLAN, BENJAMIN - Orise Fellow; Gibson, Seth; Golden, Frances; Aldridge, Robert; MORENO, BIANCA - Orise Fellow; BAYER, BARBARA - Orise Fellow; Linthicum, Kenneth - Ken

Submitted to: Current Research in Parasitology and Vector Borne Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/30/2021
Publication Date: 12/4/2021
Citation: Mcmillan, B.E., Britch, S.C., Golden, F.V., Aldridge, R.L., Moreno, B.J., Bayer, B.E., Linthicum, K. 2021. Assessing transfluthrin mortality against Aedes aegypti and Culex quinquefasciatus inside and outside US military tents in a northern Florida environment. Current Research in Parasitology and Vector Borne Diseases. 2(100067):1-8. https://doi.org/10.1016/j.crpvbd.2021.100067.
DOI: https://doi.org/10.1016/j.crpvbd.2021.100067

Interpretive Summary: We investigated how the mortality of two mosquito species was influenced by passive transfluthrin diffusers under environmental conditions. Environmental variables that were recorded and analyzed were the location of the mosquitoes relative to the treatment diffusers, the length of time for the exposure, the environmental temperature, and the time after initial deployment. All of these measurements took place in/around 2-man military tents in a north Florida habitat from January to March 2021. It was determined that transfluthrin diffusers caused significant mortality in pyrethroid-susceptible Aedes aegypti and Culex quinquefasciatus mosquitoes, and that efficacy changed based on the proximity to the diffusers, the temperature of the environment, and the time after the device was initially deployed. These results suggest that transfluthrin is effective in causing mortality against susceptible Ae. aegypti and Cx. quinquefasciatus mosquitoes under field conditions, but that environmental factors can combine to impact mosquito mortality in a field environment.

Technical Abstract: Mortality caused by passive resin transfluthrin diffusers (~5 mg AI per 24 h release rate) suspended in small 2-person tents was measured for colony reared sentinel pyrethroid susceptible Aedes aegypti and Culex quinquefasciatus female mosquitoes, as well as a pyrethroid resistant strain of Aedes aegypti, in a US military field camp scenario. Mortality effects were investigated for impact by factors such as sentinel cage location (inside tent, tent doorway, outside tent), exposure time (0, 15, 30, 45, and 60 min), and environmental temperature (°C), all of which were examined over an 8-week period. Analyses determined there was a significant interaction between mosquito strain and transfluthrin susceptibility, with the two susceptible strains experiencing significantly greater mean mortality than the resistant Ae. aegypti strain. Significant differences were likewise observed between the mosquito strains over the 8-week study period, where study week and temperature were both positively correlated with an increase in observed mean mosquito mortality. Mosquito proximity to the transfluthrin diffusers was also influenced by week and showed that sentinel cage placement in the environment demonstrates different mortality measurements, depending on the environmental conditions. The required length of exposure to transfluthrin, however, was determined to not be influenced by the study week, and consistently illustrated that increases in exposure duration resulted in increased mean mortality for the two susceptible mosquito strains. These results suggest that transfluthrin is effective in causing mortality against susceptible Ae. aegypti and Cx. quinquefasciatus mosquitoes under field conditions, but that environmental factors can combine to impact mosquito mortality in a field environment.