Resistance to insecticides used to control mosquito vectors threatens the ability of mosquito-control organizations to protect public health. Aedes aegypti (Linnaeus) and Aedes albopictus (Skuse) are invasive species widely distributed throughout Florida and have been implicated in recent epidemics of Zika, dengue, and chikungunya viruses. Knowledge of the susceptibility status of these mosquito species to pyrethroid and organophosphate active ingredients (AIs) is needed to inform product selection and treatment decisions. The susceptibility of 37 Ae. aegypti and 42 Ae. albopictus populations from Florida was assessed in response to six pyrethroid and three organophosphate AIs using the CDC bottle bioassay method. Of all bioassays completed with a pyrethroid AI, 95% for Ae. aegypti and 30% for Ae. albopictus resulted in a resistant outcome. For organophosphate AIs, ~31% of assays conducted for both species were classified as resistant. The highest frequency of susceptibility for both species was observed in response to the organophosphate AI, naled. Lambda-cyhalothrin was the only pyrethroid to result in a susceptible status for Ae. aegypti and also had the highest frequency of susceptibility for Ae. albopictus. Resistance was detected to every AI tested for both Ae. aegypti and Ae. albopictus, but there was a pronounced trend of pyrethroid resistance in Florida populations of Ae. aegypti. The results of this work provide evidence for the need to decrease reliance on pyrethroids and to implement different methods of control of Ae. aegypti in Florida.

Aedes aegypti and Aedes albopictus are invasive mosquito species with geographic ranges that have oscillated within Florida since their presence was first documented. Local transmission of dengue, chikungunya, and Zika viruses serves as evidence of the public health importance of these two species. It is important to have detailed knowledge of their distribution to aid in mosquito control efforts and understand the risk of arbovirus transmission to humans. Through a partnership involving the University of Florida Institute of Food and Agricultural Sciences Cooperative Extension Service and the Florida Medical Entomology Laboratory; the Florida Department of Health; and mosquito control agencies throughout Florida, a container mosquito surveillance program involving all life stages was launched in the summer of 2016 to detect the presence of Ae. aegypti and Ae. albopictus. Results from this survey were mapped to provide a picture of the current known distribution of Ae. aegypti and Ae. albopictus in Florida. Aedes aegypti and/or Ae. albopictus were detected in the 56 counties that were part of the survey. Only Aedes albopictus was detected in 26 counties, primarily in the panhandle region of Florida. The results of this work underscore the importance of maintaining container mosquito surveillance in a state where chikungunya, dengue, and Zika viruses are present and where there is continued risk for exotic arbovirus introductions.

The vector competence of mosquitoes for pathogens has been shown to be influenced by the status of insecticide resistance in the mosquito population. However, to date, only two studies has explored the impact of insecticide resistance on arbovirus transmission. The global and widespread use of pyrethroids has led to the development of insecticide resistance in many mosquito species, including Aedes aegypti (Linnaeus) (Diptera: Culicidae), the primary vector of Zika virus. Strains of Ae. aegypti that were genetically similar, but responded differently to pyrethroid exposure, were developed using backcrossing techniques. These populations were orally infected with Zika virus and susceptibility to infection, disseminated infection, and transmission potential were evaluated. Analyses revealed differences in susceptibility to infection and disseminated infection between the pyrethroid susceptible and resistant strains of Ae. aegypti during the infection period. Here, we identify an additional challenge to that of widespread pyrethroid resistance. Specifically, resistance is associated with altered phenotypic traits that influence susceptibility to arbovirus infection and progression of infection in the mosquito, factors which ultimately influence risk of arbovirus transmission. These findings support the need to 1) consider insecticide resistance status during times of arbovirus transmission and 2) to implement insecticide resistance management/ mitigation strategies in vector control programs.

Container mosquitoes (Diptera: Culicidae) oviposit their eggs in both natural and artificial containers. Many container mosquito species also serve as important vectors of disease-causing pathogens including Aedes aegypti, Ae. albopictus, and Ae. triseriatus. Control of these species can be done through the use of adulticide sprays. The efficacy of these treatments is highly dependent on the insecticide susceptibility status of the local mosquito populations. This paper provides protocols on collecting and rearing container mosquitoes for use in the Centers for Disease Control and Prevention (CDC) bottle bioassay. A brief description of the CDC bottle bioassay is provided as well as a standardized protocol for the incorporation of a 24-h mortality to the CDC bottle bioassay. Results from this 24-h holding addition to the CDC bottle bioassay reveal that some forms of resistance may be missed without the incorporation of the additional mortality reading. These protocols provide a foundation for new laboratories to establish rearing protocols and begin conducting resistance monitoring.

Dengue poses a significant public health threat and results in ~96 million clinical cases every year. Central America is a region burdened by neglected tropical diseases, including dengue. The primary vectors of dengue, Aedes aegypti and Aedes albopictus, are widely distributed in Honduras. Additionally, sustained and consistent mosquito control is lacking in the country. Successful control of container mosquitoes relies heavily on participation from community leaders, stakeholders, and the community itself. We conducted a pilot study in San Pedro Sula, Honduras where community leaders and stakeholders were trained on mosquito biology and control and were able to apply that knowledge to an underserved community in San Pedro Sula. Surveys to assess the number and type of containers in the community and the number of containers on the residence identified associations with select socioeconomic factors and other variables based on survey questions. The average number of containers on the premises was 15 (± 2.3) and the most prevalent containers (>50%) were flowerpots, garbage, and toys, which could be targeted in mosquito control programs. This pilot study offers a framework for training community leaders and stakeholders to create a sustainable community-based vector control program for container mosquitoes.

Laboratory and field trials were performed to evaluate the attractiveness and efficacy of commercial baits (cyantraniliprole; methomyl + (Z)-9-tricosene; dinotefuran + (Z)-9-tricosene; imidacloprid granular + (Z)-9-tricosene; and imidacloprid liquid + (Z)-9-tricosene). In choice tests; flies were most attracted to cyantraniliprole bait > dinotefuran + (Z)-9 > methomyl + (Z)-9 bait > imidacloprid granular + (Z)-9 bait > imidacloprid liquid + (Z)-9 bait. Significant degradation in bait efficacy was observed after two weeks of aging excluding imidacloprid granular; which began to degrade in field conditions after one week. Cyantraniliprole; the new fly bait active ingredient in Zyrox^®; had the longest time to knockdown in the laboratory tests; but on susceptible flies; achieved 95%–100% knockdown within an hour of exposure. Zyrox^® was resistant to weathering for a week; and was more attractive to flies in the field when compared to methomyl + (Z)-9 bait.