Quantification of permethrin resistance and kdr alleles in Florida strains of Aedes aegypti (L.) and Aedes albopictus (Skuse)

Authors: ESTEP, ALDEN - Navy Entomology Center Of Excellence, Cmave Detachment; Sanscrainte, Neil; WAITS, CHRISTY - Navy Entomology Center Of Excellence, Cmave Detachment; BERNARD, SARAH - Navy Entomology Center Of Excellence, Cmave Detachment; LLOYD, AARON - Pasco County Mosquito Control; LUCAS, KEIRA - Collier Mosquito Control District; BUCKNER, EVA - Manatee County Florida; VAIDYANATHAN, RAJEEV - Clarke Mosquito Control; MORREALE, RACHEL - Lee County Mosquito District; CONTI, LISA - Florida Department Of Agriculture And Consumer Services; Becnel, James

Submitted to: PLOS Neglected Tropical Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/22/2018
Publication Date: 10/24/2018
Citation: Estep, A.S., Sanscrainte, N.D., Waits, C.M., Bernard, S.J., Lloyd, A.M., Lucas, K.J., Buckner, E.A., Vaidyanathan, R., Morreale, R., Conti, L.A., Becnel, J.J. 2018. Quantification of permethrin resistance and kdr alleles in Florida strains of Aedes aegypti (L.) and Aedes albopictus (Skuse). PLOS Neglected Tropical Diseases. 12(10):e0006544. https://doi.org/10.1371/journal.pntd.0006544.
DOI: https://doi.org/10.1371/journal.pntd.0006544

Interpretive Summary: Scientists at the Center for Medical, Veterinary and Agricultural Entomology and collaborators characterized the permethrin resistance status of 21 strains of Aedes mosquitoes collected from peninsular FL locations. They also performed genetic analysis to identify insecticide resistance markers from 62 populations. Results showed all strains of Aedes aegypti were resistant although the strength of the resistance varied. In contrast, Aedes albopictus strains were not resistant to permethrin. This resistance information will be useful for improved mosquito control operations.

Technical Abstract: Recent outbreaks of locally transmitted dengue and Zika viruses in Florida have placed more emphasis on the importance of integrated vector management plans for Aedes aegypti (L.) and Aedes albopictus Skuse. Adulticiding, primarily with pyrethroids, can be the best option available for the immediate control of potentially arbovirus-infected mosquitoes during outbreak situations. While pyrethroid resistance is common in Ae. aegypti worldwide and testing is recommended by CDC and WHO, resistance to this class of products has not been widely examined or quantified in Florida. To address this information gap, we performed the first study to quantify both pyrethroid resistance and genetic markers of pyrethroid resistance in Ae. aegypti and Ae. albopictus strains in Florida. Using direct topical application, we examined 21 Ae. aegypti strains from 9 counties and found permethrin resistance (resistance ratio (RR)=6-61-fold) in all strains when compared to the susceptible ORL1952 control strain. Permethrin resistance in five strains of Ae. albopictus was very low (RR<1.6) even when collected from the same containers producing resistant Ae. aegypti. Characterization of two sodium channel kdr alleles associated with pyrethroid-resistance showed widespread distribution in 62 strains of Ae. aegypti. The 1534 phenylalanine to cysteine (F1534C) single nucleotide polymorphism SNP was fixed or nearly fixed in all strains regardless of RR. We observed much more variation in the 1016 valine to isoleucine (V1016I) allele and observed that increasing frequency of the homozygous V1016I allele correlates strongly with increased RR (Pearson corr= 0.905). In agreement with previous studies, we observed a very low frequency of three kdr genotypes, IIFF, VIFF, and IIFC. In this study, we provide a statewide examination of pyrethroid resistance, and demonstrate that permethrin resistance and the genetic markers for resistance are widely present in FL Ae. aegypti. Resistance testing should be included in an effective management program.