Baseline Insecticide Susceptibility Screening Against Six Active Ingredients for Culex and Aedes (Diptera: Culicidae) Mosquitoes in the United States

Abstract

Mosquitoes may develop resistance to insecticide active ingredients (AI). Thus, mosquitoes should be tested for resistance to confirm efficacy of insecticide-based control, inform management decisions, and protect public and environmental health. Our objectives were to determine a baseline of resistance for six AIs used in mosquito control in the United States to assess how resistance differs between mosquito collection location, AI, and mosquito species (container-ovipositing Aedes and Culex that may oviposit in containers or other sources). Field-collected eggs from 26 mosquito populations of five different species or hybrid species (Aedes albopictus Say, Aedes triseriatus Say, Culex pipiens L., Culex quinquefasciatus Say, Culex pipiens/quinquefasciatus) were obtained from four regions across the United States. Centers for Disease Control and Prevention bottle bioassays were used to determine baseline resistance and susceptibility status for six AIs (bifenthrin, deltamethrin, etofenprox, malathion, permethrin, and phenothrin). World Health Organization guidelines were used to classify mosquitoes as susceptible (98-100% mortality at diagnostic time [DT]), possibly resistant (80-97% mortality at DT), or resistant (< 80% mortality at DT). Aedes spp. mosquitoes were less likely to exhibit resistance, compared with Culex spp. mosquitoes. A high degree of resistance to etofenprox and malathion was observed (4-26-fold greater resistance to these two AIs compared with the other examined AIs). Baseline data on resistance and susceptibility for mosquitoes exposed to commonly used insecticides may help us evaluate resistance trends and highlight the importance of assessing local resistance trends before insecticide-based control measures are implemented.

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

“…aegypti in California. Two recent studies using CDC bottle bioassays do indicate resistance in strains from the southern US, but these studies do not provide any quantification of the strength of the resistance nor did they examine the presence of kdr alleles [ 21 , 22 ]. In contrast, Ae .…”

Phenotypic and genotypic pyrethroid resistance ofAedes albopictus, with focus on the 2017 chikungunya outbreak in Italy

“…The few studies conducted on PR in Ae. albopictus from temperate areas have mostly reported full susceptibility, while first evidence of resistance to one or the other compound was recently observed in Spain, Italy and the USA …”

“…albopictus from temperate areas have mostly reported full susceptibility, 14,24,35,36 while first evidence of resistance to one or the other compound was recently observed in Spain, 37 Italy 38 and the USA. 39,40 Resistance mechanisms have been extensively studied in major tropical vector species, but little information is available on mechanisms underlying pyrethroid resistance in Ae. albopictus.…”

Quantification of permethrin resistance andkdralleles in Florida strains ofAedes aegypti(L.) andAedes albopictus(Skuse)

“…aegypti in California. Two recent studies using CDC bottle bioassays do indicate resistance in strains from the southern US, but these studies do not provide any quantification of the strength of the resistance nor did they examine the presence of kdr alleles [19, 20]. In contrast, Ae.…”