Mosquitocidal Activity and Mode of Action of the Isoxazoline Fluralaner.
Mosquitoes, such asAedes aegyptiandAnopheles gambiae, are important vectors of human diseases. Fluralaner, a recently introduced parasiticide, was evaluated as a mosquitocide in this study. OnAe. aegyptiandAn. gambiaefourth-instar larvae, fluralaner had 24-h LC50(lethal concentration for 50% mortality) values of 1.8 ppb and 0.4 ppb, respectively. Following topical application to adultAe. aegypti, fluralaner toxicity reached a plateau in about 3 days, with 1- and 3-day LD50(lethal dose for 50% mortality) values of 1.3 ng/mg and 0.26 ng/mg, suggesting a slowly developing toxicity. Fipronil outperformed fluralaner by up to 100-fold in adult topical, glass contact, and feeding assays onAe. aegypti. These data show that fluralaner does not have exceptional toxicity to mosquitoes in typical exposure paradigms. In electrophysiological recordings onDrosophila melanogasterlarval central nervous system, the effectiveness of fluralaner for restoring nerve firing after gamma-aminobutyric acid (GABA) treatment, a measure of GABA antagonism, was similar in susceptible Oregon-R and cyclodiene-resistantrdl-1675 strains, with EC50(half maximal effective concentration) values of 0.34 µM and 0.29 µM. Although this finding suggests low cross resistance in the presence ofrdl, the moderate potency, low contact activity, and slow action of fluralaner argue against its use as an adult mosquitocide for vector control.
Emerging Pathogens Institute, Department of Entomology and Nematology, University of Florida, Gainesville, FL 32610, USA. shiyao.jiang@ufl.edu.
Shiyao
S
Jiang
Emerging Pathogens Institute, Department of Entomology and Nematology, University of Florida, Gainesville, FL 32610, USA. maia.tsikolia@ars.usda.gov.
Maia
M
Tsikolia
USDA-ARS, Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, FL 32608, USA. uli.bernier@ars.usda.gov.
Ulrich R
UR
Bernier
Emerging Pathogens Institute, Department of Entomology and Nematology, University of Florida, Gainesville, FL 32610, USA. jbquist@epi.ufl.edu.
Jeffrey R
JR
Bloomquist
D000330:Aedes; D000818:Animals; D000852:Anopheles; D015415:Biomarkers / Q000378:metabolism; D002490:Central Nervous System / Q000187:drug effects / Q000378:metabolism; D004331:Drosophila melanogaster / Q000187:drug effects / Q000378:metabolism; D007306:Insecticides / Q000494:pharmacology; D007555:Isoxazoles / Q000494:pharmacology; D007814:Larva / Q000187:drug effects; D007928:Lethal Dose 50; D011720:Pyrazoles; D018079:Receptors, GABA / Q000378:metabolism
C000591860:A1443 compound; D015415:Biomarkers; D007306:Insecticides; D007555:Isoxazoles; D011720:Pyrazoles; D018079:Receptors, GABA; C082360:fipronil
Aedes aegypti; Anopheles gambiae; Drosophila melanogaster; GABA receptor; fipronil