A CASE REPORT ON PRODUCT ROTATION TO MANAGE SEVERE LYSINIBACILLUS SPHAERICUS RESISTANCE IN CULEX PIPIENS FROM SALT LAKE CITY, UTAH

The Salt Lake City Mosquito Abatement District (SLCMAD) detected a 20,000-fold resistance to Lysinibacillus sphaericus (Lsph) in Culex pipiens occurring in catch basins of Salt Lake City during 2016. In response, SLCMAD suspended use of Lsph and rotated use of spinosyn and s-methoprene products for the next three years. At the end of the third year, Lsph was evaluated again and efficacy similar to susceptible colony strains. During the second year of Lsph use, technicians observed lack of control of larvae at some urban sites. Bioassays performed during 2021 showed recurrence of some resistance to Lsph to varying degrees across SLCMAD urban areas. The rapidity with which resistant phenotypes reemerged clarifies that SLCMAD cannot in the near future rely on repeated use of Lsph, even after suspending use for three years and using within-season product rotations. Prior reports in other research groups have found long-term selection to Lsph, as is the case at SLCMAD, to not regress in spite of halting use of the products. However, our findings offer some optimism that regression may be relatively quick. More operational review is needed, and future work should characterize resistance alleles in field populations. Collectively, there is a lack of concrete data supporting the prevailing assumptions from adjacent industries that were adopted into mosquito abatement. We provide this short note as additional guidance for mosquito and vector control districts weighing options to remediate Lsph resistance.

Blinded by the light: does heat or light enhance wild mosquito (Diptera: Culicidae) attraction to CO2-baited traps in the Great Salt Lake area?

The New Jersey Light Trap has been among the earliest trap models used for mosquito surveillance in the United States. This trap was modernized in the 1950s to the miniature CDC light trap, with the addition of CO2 following soon after. The incandescent light has the tendency to attract nontarget insects, as well as losing a substantial portion of their energy as heat. Few studies have delineated whether heat or light in isolation make a difference in field collections using the former traps within the United States. Our study focused on isolating heat and light variables by using incandescent bulbs, light emitting diode (LED) bulbs, and electric heating patches affixed to a base model CO2 trap as designed at the Salt Lake City Mosquito Abatement District. Sites were selected in the urban and suburban foothills and canyons of the Wasatch Mountain front, industrial areas near the Salt Lake City International Airport, and rural wetlands in the marshes outlying the Great Salt Lake. Five traps were replicated within each sector during the summer and fall summer seasons. Collections were composed of Aedes dorsalis (Meigen), Culex pipiens L., Culex tarsalis Coquillett, and Culiseta inornata (Williston). Composition changes were a result of seasonal, rather than spatial, shifts. The results showed that LED light traps depressed collections of key species. Otherwise, there were negligible differences in collections among incandescent, heat film, and base model traps. In the Intermountain West, the miniature CDC trap is reliable enough to make programmatic decisions even if light usage varies by district.

Dancing in the purple rain: color affinity and oviposition choices in Aedes sierrensis (Diptera: Culicidae)

The western tree hole mosquito, Aedes sierrensis (Ludlow) (Diptera: Clucidae), is a pestiferous mosquito with a range extending over the entire pacific seaboard and into portions of the intermountain west. As a peridomestic heartworm vector, it demands at least some level of surveillance to understand its abundance. However, the species is refractory to a majority of conventional vector surveillance approaches for tracking mosquitoes. To find more options for Aedes sierrensis surveillance, a variety of oviposition attractants were evaluated in arena-style choice assays using colony reared adults. A range of infusion treatments (e.g., alfalfa, oak, and beetroot) were examined and then combined with investigations of liquid color as well as ovicup color and entryway position. These studies revealed that Ae. sierrensis have an affinity for purple coloration, plain water, and larger entryway sizes for oviposition cups. A prototype ovicup was 3D-printed using purple filament and multiple types of entryways, and used to re-test infusion waters. No particular attraction differences were detected after normalizing for purple color. Comparisons to black 3D-printed cups yielded surprising observations that male mosquitoes also aggregated on purple cups while females sheltered, but not necessarily oviposited, in black cups. Although this was only a laboratory-based assessment, these studies provide useful information for future field trials of potential oviposition traps for surveillance of Ae. sierrensis.

Diuresis and α-glucosidase inhibition by erythritol in Aedes aegypti (Diptera: Culicidae) and viability for efficacy against mosquitoes

BACKGROUND

Sugar alcohols, such as erythritol, are low-impact candidates for attractive toxic sugar baits (ATSB) to kill mosquitoes. To determine whether erythritol has a viable future in ATSB formulations, a suite of assays was conducted to diagnose toxicity mechanisms and starvation effects on mortality in Aedes aegypti (L.) as a model system.

METHODS

We measured general carbohydrate load, glucosidase levels, and free glucose in intoxicated adult mosquitoes to observe whether sugar digestion was impaired. We assayed the effects of sugar combinations with erythritol on larvae and adults. To measure erythritol effects when mosquitoes were not resource-deprived, additional assays manipulated the prior starvation status.

RESULTS

Up to 50,000 ppm of erythritol in water had no effect on larvae within 72 h, but an ammonia spike indicated diuresis in larvae as early as 4 h (F8,44 = 22.50, P < 0.0001) after sucrose/erythritol combinations were added. Adult consumption of erythritol was diuretic regardless of the sugar pairing, while sucrose and erythritol together generated above 80% mortality (F2,273 = 33.30, P < 0.0001) alongside triple the normal excretion (F5,78 = 26.80, P < 0.0004). Glucose and fructose paired individually with erythritol had less mortality, but still double the fecal excretion. When ingesting erythritol-laced meals, less sugar was detected in mosquitoes as compared to after sucrose meals (χ2 = 12.54, df = 1, P = 0.0004).

CONCLUSIONS

Data showed that erythritol is a linear competitive inhibitor of α-glucosidase, marking it as a novel class of insecticide in the current research climate. However, the efficacy on larvae was null and not persistent in adult mosquitoes when compared across various starvation levels. Despite significant diuresis, the combined effects from erythritol are not acute enough for vector control programs considering ATSB against mosquitoes.

Do it yourself: 3D-printed miniature CDC trap for adult mosquito (Diptera: Culicidae) surveillance

The central component of mosquito and vector surveillance programs globally is the adult mosquito trap, which is intended to collect host-seeking mosquitoes. The miniature CDC trap is a widely distributed trap style in part due to its relative affordability and compact nature. Despite already being a simple trap, in-house production methods, such as 3D printing, could improve the accessibility of the CDC trap by eliminating some of the supply chain variables. We present here several trials with the Salt Lake City (SLC) trap, a three-dimensional (3D) printed trap design. Functional assessments were made on secondary components and found no statistically significant differences when comparing CO2 line height (above vs. below fan), battery types (sealed lead acid vs. USB battery pack), and trap body collection shape (funnel body vs. simple/straight body). The SLC trap was compared directly to a commercial equivalent, the ABC trap, with comparative assessment on species diversity and evenness in collections and found to be statistically equivalent on all metrics. Methods also detail an accompanying optional transport system for a pressurized CO2/regulator set-up, should a practitioner elect not to use dry ice. Our final design is presented here with the publicly published stereolithography (STL) files and a detailed outline of the transport container system. Alternative models are available for in-house manufacture of mosquito traps, and we contribute these designs in an effort to stimulate further growth in vector surveillance.

Do It Yourself: A Modernized Gravid Trap Design for Mosquito Surveillance

Gravid traps have become a common and frequently essential surveillance tool for parous Culex spp. vectors of West Nile virus and other encephalitis-causing pathogens. The recent closing of BioQuip Products Inc., an entomological supply company, has jeopardized the commercial availability of gravid traps. The Salt Lake City Mosquito Abatement District presents herein a template for making your own gravid trap, but with some modernizations for quieter fans and longer lasting, light weight, lithium battery packs. At the time of writing, the materials cost for the fan ($14 USD), toolbox ($13), cables ($9), ABS pipe ($2.50), aluminum brackets ($10), catch container with lid ($9), trap net ($10), USB battery pack ($35) and the negligible amount of 3D-printed filament ($2), is approximately half the cost (not including labor) of the formerly available commercial model. Additionally, performance validation in the laboratory (t4,9 = 0.1191, P < 0.9109) and within two field sites (χ2 = 0.107, P < 0.744) demonstrated no significant differences in collections of gravid Culex pipiens. We do not present an overhaul of the previous gravid trap blueprint, but the quality-of-life updates to the trap design, the feasibility of in-house manufacture, and the mirrored collection efficacy to the commercial model can allow improved maintenance of gravid trap surveillance networks without a commercial supplier.

Evaluation of An Aerial Application of Duet Hd® Against Aedes Dorsalis and Culex Tarsalis in Rural Habitats of the Great Salt Lake, Utah

The Salt Lake City Mosquito Abatement District (SLCMAD) has been conducting aerial applications using an organophosphate insecticide against adult mosquitoes for several decades. In order to evaluate a potential rotation product, aerial applications of Duet HD™, a pyrethroid, were conducted under operational conditions against wild populations of Aedes dorsalis and Culex tarsalis and against colony strains of Cx. pipiens and Cx. quinquefasciatus. The erratic wind patterns of the greater Salt Lake area did not prevent sufficient droplet deposition flux at 9 monitoring locations spread across a 5,120-acre (2,072 ha) spray block within rural habitats. Three separate aerial application trials showed great efficacy against Ae. dorsalis. In contrast, Cx. tarsalis exhibited inconsistent treatment-associated mortalities, suggesting the presence of less susceptible or resistant field populations as a result of spillover from agricultural or residential pyrethroid usage. Bottle bioassays to diagnose pyrethroid resistance using field-collected Cx. tarsalis indicated that some populations of this species, especially those closest to urban edges, failed to show adequate mortality in resistance assays. Despite challenging weather conditions, Duet HD worked reasonably well against susceptible mosquito species, and it may provide a crucial role as an alternative for organophosphate applications within specific and sensitive areas. However, its area-wide adoption into control applications by the SLCMAD could be problematic due to reduced impacts on the most important arboviral vector species, Cx. tarsalis, in this area. This study demonstrates the importance of testing mosquito control products under different operational environments and against potentially resistant mosquito populations by municipal mosquito control districts.

Do it yourself: fabricating and evaluating a mosquito (Diptera: Culicidae) blood-feeding device to replace a commercial option

Tools for rearing hematophagous insects, such as mosquitoes (Diptera: Culicidae), in an insectary are essential for research and operational evaluations in vector biology and control. There is an abundance of low-cost options for practitioners without conventional infrastructure. However, few midrange options exist that provide a balance of efficiency and low material waste. We present here a reproducible design for an electrically powered blood-feeding device that offers long-term reusability, low material waste, and customizability for different species or experiments. The limitation is the requirement for electricity, but the gain is a simple, low-skill device that can be modified as needed. To validate the design, assessments of feeding angle and blood-feeding success were compared between the Salt Lake City Mosquito Abatement District artificial membrane feeder (SLAM) and a commercial system (Hemotek). Engorgement in Aedes aegypti (80-90%), Culex pipiens (50-80%), and Culex tarsalis (30-75%) was similar between the 2 units, resulting in nearly identical fecundity outcomes between devices. Additionally, 45° angles were more successful, generally, than presenting the feeders flat or vertical to the mosquitoes (df3,48, P = 1.014 × 10-15). This angle is simple to present with the SLAM device. Materials for in-house reproduction of the SLAM system are now widely available in regions with access to e-commerce and shipped goods. This results in a device schematic that should fit well into a relatively modular, do-it-yourself paradigm where the practitioner needs only to assemble some materials without complex engineering. This article provides schematics, cost comparison, and validation of the in-house-made SLAM system.

Enhancing toxic sugar meals against Aedes aegypti (Diptera: Culicidae) by adulterating with erythritol in combination with other active ingredients

Attractive toxic sugar baits (ATSBs) are an underexploited method for mosquito control. For ATSBs to be more widely accepted, demonstrably effective ingredients need to be verified. We investigated erythritol as a toxic additive in sugar meals against Aedes aegypti (L.) for potential future use in ATSBs. Erythritol is a sugar alcohol that is commonly used as a sugar substitute, while also being toxic to mosquitoes. Our studies tested formulations of erythritol, sucrose, and blends of both. Secondary investigations included combinations with the active ingredients Bacillus thuringiensis israelensis, spinosyn, and boric acid. Adult Ae. aegypti were separated into test groups and provided various combinations. Formulations containing erythritol, with or without another toxicant, exhibited 90% mortality within 72 h of observation (P = 0.03192). Additionally, erythritol appeared more effective when combined with sucrose in a 1:1 ratio (5% concentration each). This combination showed a 24% and 85% increase in mortality when combined with boric acid and Bti, respectively, at 48 h compared with equivalent groups containing only 10% sucrose. Erythritol appears to kill adult mosquitoes, even in relatively low concentrations, without another toxicant being required. However, erythritol also effectively enhances kill of main ingredient toxicants such as boric acid and Bti, showing a supporting role. The low concentration of erythritol needed to provide significant kill, its ability to fill in as both a sugar base and toxicant, and its ability to be safely handled by humans makes erythritol a strong candidate for use as a supporting ingredient in future bait formulations.

Mosquito Surveillance for West Nile Virus

Identifying the mosquitoes responsible for transmitting human disease-causing pathogens is of critical importance for effective control of mosquito-borne outbreaks. West Nile virus is often transferred by adult female mosquitoes in the genus Culex, which deposit eggs in a variety of aquatic habitats throughout the world. Herein we describe several methodological approaches to monitor these species in nature, as well as offering details for data collection and analysis.

Origins of high latitude introductions of Aedes aegypti to Nebraska and Utah during 2019

Aedes aegypti (L.), the yellow fever mosquito, is also an important vector of dengue and Zika viruses, and an invasive species in North America. Aedes aegypti inhabits tropical and sub-tropical areas of the world and in North America is primarily distributed throughout the southern US states and Mexico. The northern range of Ae. aegypti is limited by cold winter months and establishment in these areas has been mostly unsuccessful. However, frequent introductions of Ae. aegypti to temperate, non-endemic areas during the warmer months can lead to seasonal activity and disease outbreaks. Two Ae. aegypti incursions were reported in the late summer of 2019 into York, Nebraska and Moab, Utah. These states had no history of established populations of this mosquito and no evidence of previous seasonal activity. We genotyped a subset of individuals from each location at 12 microsatellite loci and ~ 14,000 single nucleotide polymorphic markers to determine their genetic affinities to other populations worldwide and investigate their potential source of introduction. Our results support a single origin for each of the introductions from different sources. Aedes aegypti from Utah likely derived from Tucson, Arizona, or a nearby location. Nebraska specimen results were not as conclusive, but point to an origin from southcentral or southeastern US. In addition to an effective, efficient, and sustainable control of invasive mosquitoes, such as Ae. aegypti, identifying the potential routes of introduction will be key to prevent future incursions and assess their potential health threat based on the ability of the source population to transmit a particular virus and its insecticide resistance profile, which may complicate vector control.

Laboratory evaluation of sugar alcohols for control of mosquitoes and other medically important flies

Insecticide application for vector control is the most controversial component of a public health program due to concerns about environmental and human health safety. One approach to overcome this challenge is the use of environmentally benign active ingredients. Among the most promising emerging strategies are attractive toxic sugar baits. Sugar alcohols-naturally occurring molecules safe for human consumption but potentially toxic to insects when ingested, have received increased attention for use with this approach. For this study, we screened the toxicity of four different sugar alcohols on several mosquito species, a biting midge, and a filth fly. Sugar alcohol mortalities exceeded those in the sucrose (positive control) only group. However, only erythritol and highly concentrated xylitol induced mortalities exceeding those in the water only (negative control) treatment ranging from approximately 40-75%. Formulations containing erythritol and xylitol should be further investigated under field conditions for efficacy in reducing populations of biting flies and for assessing potential non-target impacts.

Toys or Tools? Utilization of Unmanned Aerial Systems in Mosquito and Vector Control Programs

Organized mosquito control programs (MCP) in the United States have been protecting public health since the early 1900s. These programs utilize integrated mosquito management for surveillance and control measures to enhance quality of life and protect the public from mosquito-borne diseases. Because much of the equipment and insecticides are developed for agriculture, MCP are left to innovate and adapt what is available to accomplish their core missions. Unmanned aerial systems (UAS) are one such innovation that are quickly being adopted by MCP. The advantages of UAS are no longer conjectural. In addition to locating mosquito larval habitats, UAS affords MCP real-time imagery, improved accuracy of aerial insecticide applications, mosquito larval detection and sampling. UAS are also leveraged for applying larvicides to water in habitats that range in size from multi-acre wetlands to small containers in urban settings. Employing UAS can reduce staff exposure to hazards and the impact associated with the use of heavy equipment in sensitive habitats. UAS are utilized by MCP nationally and their use will continue to increase as technology advances and regulations change. Current impediments include a dearth of major UAS manufacturers of equipment that is tailor-made for mosquito control, pesticides that are optimized for application via UAS and regulations that limit the access of UAS to national airspace. This manuscript highlights the strengths and weaknesses of UAS within MCP, provides an update on systems and methods used, and charts the future direction of UAS technology within MCP tasked with public health protection.

No Evidence That Salt Water Ingestion Kills Adult Mosquitoes (Diptera: Culicidae)

Various products and insecticides are available that purport to reduce wild populations of adult mosquitoes. Recently, several manufacturers and general public comments on the internet have promoted devices that claim that ingestion of salt will significantly reduce populations of wild mosquitoes to near zero; there are no known scientific efficacy data that support these claims. We tested the survival of nine mosquito species of pest and public health importance across four adult diets: Water Only, Sugar Water Only (8.00%), Salt Water Only (1.03%), and Sugar + Salt Water. Species included the following: Aedes aegypti (L.), Aedes albopictus (Skuse), Aedes dorsalis (Meigen), Aedes notoscriptus (Skuse), Aedes vigilax (Skuse), Anopheles quadrimaculatus (Say), Culex pipiens (L.), Culex quinquefasciatus (Say), and Culex tarsalis (Coquillett). Male and female mosquitoes were placed in cages and allowed to feed on liquid diets under controlled environmental conditions for 1 wk. For seven of the nine species, adult survival was significantly higher in the presence (Sugar Water, Sugar + Salt Water) versus the absence (Water Only, Salt Only) of sugar, with no indication that salt had any effect on survival. Anopheles quadrimaculatus showed intermediate survival in Sugar + Salt to either Sugar Only or no sugar diets, whereas Aedes dorsalis showed low survival in Salt Only versus other diets. Based on our data and coupled with the fact that mosquitoes have physiological and behavioral adaptations that allow them to avoid or process excess salt (as found in blood meals), we conclude that there is no scientific foundation for salt-based control methods of mosquitoes.

Trap Comparison for Surveillance of the Western Tree Hole Mosquito (Diptera: Culicidae)

The western tree hole mosquito, Aedes sierrensis (Ludlow), is a common nuisance mosquito and vector of Dirofilaria immitis (Leidy), the etiologic agent of dog heartworm, in western North America. Here, we compare weekly mosquito collections made with Mosquito Magnet (MM) traps, Biogents Sentinel (BGS) traps, and Biogents Bowl (BGS Bowl) traps set in Salt Lake City, UT, from the start of June to mid-August 2017. We found the number of mosquitoes decreased with rainfall and temperature independently of trap type. The highest number of mosquitoes were caught by BGS traps baited with carbon dioxide (CO2) and BG lure, which collected 62% (n = 422) of all mosquitoes, followed by the MM at 31% (n = 213), and both the BGS and BG Bowl with BG lure had 3.5% (n = 24) each. Aedes sierrensis females were caught weekly at similar densities (mean ± SD) in BGS with CO2 and lure (1.17 ± 2.93) and the MM (1.17 ± 2.66) traps during the study period. Given that BGS with CO2 and lure traps have several operational advantages over MM traps, including a quicker setup, smaller size, and lower cost, we consider BGS with CO2 and lure traps as the best suited surveillance tool to detect and remove Ae. sierrensis in the western United States and similar settings throughout North America.

West Nile Virus Mosquito Vectors in North America

In North America, the geographic distribution, ecology, and vectorial capacity of a diverse assemblage of mosquito species belonging to the genus Culex determine patterns of West Nile virus transmission and disease risk. East of the Mississippi River, mostly ornithophagic Culex pipiens L. complex mosquitoes drive intense enzootic transmission with relatively small numbers of human cases. Westward, the presence of highly competent Culex tarsalis (Coquillett) under arid climate and hot summers defines the regions with the highest human risk. West Nile virus human risk distribution is not uniform geographically or temporally within all regions. Notable geographic 'hotspots' persist with occasional severe outbreaks. Despite two decades of comprehensive research, several questions remain unresolved, such as the role of non-Culex bridge vectors, which are not involved in the enzootic cycle, but may be involved in virus transmission to humans. The absence of bridge vectors also may help to explain the frequent lack of West Nile virus 'spillover' into human populations despite very intense enzootic amplification in the eastern United States. This article examines vectorial capacity and the eco-epidemiology of West Nile virus mosquito vectors in four geographic regions of North America and presents some of the unresolved questions.

Truck-mounted area-wide applications of larvicides and adulticides for extended suppression of adult Aedes albopictus

BACKGROUND

Given the lack of vaccines for most vector-borne diseases, vector control is often the primary option for disease control. Aedes albopictus are difficult to control because the immatures primarily develop in containers ubiquitous in residential properties. Conventional adulticide campaigns often result in brief, rebounding population declines, so incorporating new techniques into an integrated pest management program is imperative. We performed combined area-wide applications of the larvicides Bacillus thuringiensis var. israelensis and pyriproxyfen with the adulticide sumithrin and prallethrin to achieve extended suppression of Ae. albopictus populations in Trenton, NJ, USA. We deployed bioassay cups to assess the spatial penetration and efficacy of the applications.

RESULTS

Inhibition of adult emergence was significantly higher in the treatment bioassay cups than in laboratory controls (z = 4.65, P < 0.0001) and field control bioassay cups (z = 8.93, P < 0.0001). We observed a lower trend in adult numbers following season-long combined application of pyriproxyfen and adulticide, with numbers of adult Ae. albopictus at the treatment site up to five times lower than at the control site.

CONCLUSION

Pyriproxyfen is a powerful mosquito larvicide and pupacide with low mammalian toxicity that shows promise for area-wide vehicle-mounted (either ground or airborne) applications. © 2018 Society of Chemical Industry.

High Resistance to Bacillus sphaericus and Susceptibility to Other Common Pesticides in Culex pipiens (Diptera: Culicidae) from Salt Lake City, UT

Biorational mosquito larvicides based on microbial organisms and insect growth regulators (IGRs) have played a vital role in integrated mosquito control, particularly since the invasion of West Nile virus to the United States in 1999. Products that are formulated with technical powder of the bacterium, Bacillus sphaericus Neide (recently Lysinibacillus sphaericus Meyer and Neide), are among the ones that have been extensively applied to combat Culex and other mosquito species. Due to the simplicity of the binary toxins, resistance to this pesticide in laboratory and field populations of Culex pipiens L. complex has occurred globally since 1994. A Cx. pipiens population with a high level of resistance to B. sphaericus (VectoLex WDG) was identified in Salt Lake City, UT, in September 2016. The resistance ratios in this population were 20,780.0- and 23,926.9-fold at LC50 and LC90, respectively, when compared with a susceptible population of a laboratory reference colony of the same species. This B. sphaericus-resistant population remained mostly susceptible to other commonly used pesticides to control arthropods of public health and urban significance, including ones based on microbial organisms (Bacillus thuringiensis subsp. israelensis, spinosad, spinetoram, abamectin), IGRs (pyriproxyfen, methoprene, diflubenzuron, novaluron), organophosphate (temephos), neonicotinoid (imidacloprid), phenylpyrazole (fipronil), oxadiazine (indoxacarb), and pyrethroid (permethrin). Results are discussed according to the modes of action of the pesticides tested, and suggestions are made to manage B. sphaericus-resistant mosquito populations.

Using Bloodmeal Analysis to Assess Disease Risk to Wildlife at the New Northern Limit of a Mosquito Species

The historically southeastern mosquito species Culex erraticus has over the last 30 years undergone a marked expansion north. We evaluated this species' potential to participate in local disease cycles in the northeastern USA by identifying the vertebrate sources of blood in Cx. erraticus specimens from New Jersey. We found that the majority of bloodmeals (92.6%) were derived from birds, followed by 6.8% from mammals (of which half were human), and a single amphibian bloodmeal from a spring peeper (0.56%). Medium- and large-sized water birds from the order Pelecaniformes made up 60.4% of the bird species and 55.9% of all identified hosts. This group of birds is known enzootic hosts of arboviruses such as eastern equine encephalitis virus, for which Cx. erraticus is a competent vector. Additionally, we screened blooded mosquitoes for avian malaria parasites and identified three different lineages of Plasmodium, including what may represent a new Plasmodium species (likely a wetland bird specialist) in bloodmeals from Green Herons, a Great Egret, and a Double-Crested Cormorant. Our results support the utility of mosquito bloodmeals as sources of information about circulating wildlife pathogens and reveal the potential of range-expanding species to intensify local zoonoses and bridge enzootic pathogens to humans.

A SURVEY OF THE MOSQUITOES OF KOSRAE STATE, FEDERATED STATES OF MICRONESIA, 2016

In response to an outbreak of Zika virus that started in February 2016 on Kosrae Island, Kosrae State, Federated States of Micronesia, we conducted entomological investigations, including a survey to characterize the mosquito fauna on Kosrae, from November 29 to December 8, 2016. Mosquitoes were collected using several surveillance methods in order to sample all stages of the mosquito life cycle. Eggs were collected using ovicups, larvae and pupae were sampled using standard dippers, and adults were collected using aspirators and Biogents-2 Sentinel traps. All species previously recorded from Kosrae State were found in the current survey, confirming their continued presence on the island. Aedes aegypti was detected on Lelu Island, representing a new municipal record. The collection of Ae. vexans nocturnus represents a new species record for Kosrae, increasing the number of known taxa on this island from 6 to 7. The report herein provides updated knowledge of the mosquitoes that occur on Kosrae State, Federated States of Micronesia.

Zika Virus Infection in Patient with No Known Risk Factors, Utah, USA, 2016

In 2016, Zika virus disease developed in a man (patient A) who had no known risk factors beyond caring for a relative who died of this disease (index patient). We investigated the source of infection for patient A by surveying other family contacts, healthcare personnel, and community members, and testing samples for Zika virus. We identified 19 family contacts who had similar exposures to the index patient; 86 healthcare personnel had contact with the index patient, including 57 (66%) who had contact with body fluids. Of 218 community members interviewed, 28 (13%) reported signs/symptoms and 132 (61%) provided a sample. Except for patient A, no other persons tested had laboratory evidence of recent Zika virus infection. Of 5,875 mosquitoes collected, none were known vectors of Zika virus and all were negative for Zika virus. The mechanism of transmission to patient A remains unknown but was likely person-to-person contact with the index patient.

Seasonal field efficacy of pyriproxyfen autodissemination stations against container-inhabiting mosquito Aedes albopictus under different habitat conditions

BACKGROUND

Control of the container-inhabiting mosquito, Aedes albopictus, is difficult using conventional methods due to its selection of cryptic peri-domestic habitats. We evaluated whether autodissemination stations can deliver sufficient pyriproxyfen to sentinel containers to produce significant pupal mortality in different habitats such as competing oviposition sites, peri-domestic habitats, junkyards and tire piles. We also tested how far the pesticide could be transferred over a 200-m range.

RESULTS

Autodissemination stations performed effectively for 8-12 weeks under field conditions. Pupal mortality was reduced in sentinel cups with high-competing oviposition habitats (5 versus 20) in isolated plots; however, similar results were not seen in residential areas. Increasing the number of stations per plot (from 1 to 4) enhanced the efficacy. Peri-domestic habitat trials showed the highest pupal mortality (50.4%) and site contamination with pyriproxyfen (82.2%) among the trials. Autodissemination stations were able to contaminate habitats in a junkyard (50.0%) and tire piles (40.2%). Pyriproxyfen was detected in sentinel cups up to 200 m from stations. Detection of pyriproxyfen by residue analysis (0.005-0.741 µg L^-1 ) in field samples confirmed the transfer of the insect growth regulator.

CONCLUSION

Autodissemination stations have shown promising potential as a novel pest management tool against container mosquitoes in field trials in different habitats confronted by mosquito control personnel. © 2017 Society of Chemical Industry.

Reduced performance of a PVC-coated Biogents Sentinel prototype in comparison to the original Biogents Sentinel for monitoring the Asian tiger mosquito, Aedes albopictus, in temperate North America

Aedes albopictus is a major nuisance pest and also a public health concern because of the role it plays in the transmission of arboviruses. There is a continuing demand for effective surveillance tools for this species. The first generation of Biogents Sentinel (BGS1) traps have proven to be an effective tool for surveillance of Ae. albopictus throughout its range, however, some defects in construction led to the eventual development of the next generation. We compared the performance of the new generation prototype trap (BGS2P) to the original. Studies were conducted in suburban and urban areas in Florida, Louisiana, New Jersey, and Virginia, USA in the summer of 2014 (July-October). BGS1 traps collected significantly more Ae. albopictus when compared to the BGS2P with or without CO2 in all locations (P<0.05). When a white cloth was wrapped around the BGS2P traps, efficiency did not change in Louisiana, New Jersey, and Virginia; however, numbers of adult Ae. albopictus collected from the BGS2P and the BGS1 were significantly different based on lure type (P< 0.0001). Results from Florida showed that BGS1with the BG lure and CO2 collected significantly higher adult numbers compared to BGS2P with a three component cartridge lure and CO2 (P< 0.0001). Overall, our results indicate that despite improvements in construction and durability of the BGS2P, this newer trap type did not increase the capture rates of Ae. albopictus in North America. Biogents modified BGS2P based on the data collected from the current study and updated as Biogents Sentinel 2 is now commercially available and its efficacy in comparison to the original will require further study.

Effectiveness of autodissemination stations containing pyriproxyfen in reducing immature Aedes albopictus populations

Background

Aedes albopictus, the Asian tiger mosquito, is an aggressive, highly anthropophilic, day-biting mosquito with an expanding geographic range. Suppression of Ae. albopictus is difficult because of the abundance and prevalence of larval habitats within peridomestic environments, particularly cryptic habitats such as corrugated extension spouts, fence post openings, discarded food containers, etc. Because of the challenges of eliminating or treating larval habitats of this species, we tested an autodissemination concept to contaminate these habitats with the insect growth regulator pyriproxyfen.

Methods

Our study was conducted in the City of Trenton (Mercer County), New Jersey, USA (40°12′N, 74°44′W). We selected six hot spots, where five or more Ae. albopictus males or females were collected based on weekly trap surveillance. A trapping unit was a city block, approximately 0.8 ha (hot spot), where we deployed 26 to 28 autodissemination stations per treatment plot. To gauge efficacy, we deployed BGS traps, oviposition cups, and sentinel cups in treatment and control locations.

Results

We found a significant reduction in eggs (P < 0.0001) and larval populations (P < 0.0001) as a result of treatment. Pupal mortality, as determined through bioassays, was also significantly higher in the treatment sites (P < 0.0001).

Conclusion

Our results clearly show the potential and unique use of the autodissemination stations to control immature Ae. albopictus in urban areas. Penetration of larvicides with existing methods are difficult to reach cryptic habitats, but the autodissemination approach, which exploits the oviposition behavior of the target pest, can be integrated into intervention programs. New tools are urgently needed to curb the expansion and public health implications of Ae. albopictus and other container-inhabiting species.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-017-2034-7) contains supplementary material, which is available to authorized users.

Field Comparisons of the Gravid Aedes Trap (GAT) and BG-Sentinel Trap for Monitoring Aedes albopictus (Diptera: Culicidae) Populations and Notes on Indoor GAT Collections in Vietnam

We report on the use of the Gravid Aedes Trap (GAT) as a surveillance device for Aedes albopictus (Skuse) relative to the BG-Sentinel (BGS) trap in field studies conducted in Trenton, NJ, and on Hammond Island, Queensland, Australia. A parallel study conducted in Nha Trang, Vietnam, assessed the use of the GAT as an indoor surveillance device as well as the use of canola oil as a noninsecticide killing agent. In Trenton and Hammond Island, the GAT collected fewer male (0.40 ± 0.12 and 0.43 ± 0.30, respectively) and female (3.05 ± 0.67 and 2.7 ± 2.3, respectively) Ae. albopictus than the BGS trap (males: 3.54 ± 1.26 and 3.75 ± 0.83; females: 4.66 ± 1.18 and 3.9 ± 0.23) over their respective sampling periods (i.e., 24 h for the BGS and 1 wk for the GAT). Despite differences in capture rates, the percentage of traps positive for female Ae. albopictus was similar between the BGS and GAT (Trenton: 60.1 ± 6.3% and 64.4 ± 4.1%; Hammond: 87.5 ± 6.9% and 80.0 ± 8.2%). In Nha Trang, the GAT was equally effective indoors and outdoors with (10 g hay or 3 g fish food) and without (water or empty) infusion. Additionally, no significant decrease in collections was observed between GATs set with canola oil or long-lasting insecticidal net. In summary, both traps were successful in monitoring female Ae. albopictus over their respective trapping intervals, but would be best used to complement each other to monitor both sexes and all physiological stages of female Ae. albopictus. However, the versatility and low-cost of the GAT makes it an attractive alternative to the more expensive BGS trap.

Anthropogenic impacts on mosquito populations in North America over the past century

The recent emergence and spread of vector-borne viruses including Zika, chikungunya and dengue has raised concerns that climate change may cause mosquito vectors of these diseases to expand into more temperate regions. However, the long-term impact of other anthropogenic factors on mosquito abundance and distributions is less studied. Here, we show that anthropogenic chemical use (DDT; dichlorodiphenyltrichloroethane) and increasing urbanization were the strongest drivers of changes in mosquito populations over the last eight decades in areas on both coasts of North America. Mosquito populations have increased as much as tenfold, and mosquito communities have become two- to fourfold richer over the last five decades. These increases are correlated with the decay in residual environmental DDT concentrations and growing human populations, but not with temperature. These results illustrate the far-reaching impacts of multiple anthropogenic disturbances on animal communities and suggest that interactions between land use and chemical use may have unforeseen consequences on ecosystems.

Insect populations have fluctuated enormously over the past century, with many changes being attributed to anthropogenic climate change. Rochlin et al. show that the pesticide DDT and increasing urbanization are more strongly associated with changes in the number and diversity of mosquitoes on both coasts of North America.

The Eye of the Tiger, the Thrill of the Fight: Effective Larval and Adult Control Measures Against the Asian Tiger Mosquito, Aedes albopictus (Diptera: Culicidae), in North America

The Asian tiger mosquito, Aedes albopictus (Skuse), is a highly invasive container-inhabiting species with a global distribution. This mosquito, similar to other Stegomyia species such as Aedes aegypti (L.), is highly adapted to urban and suburban areas, and commonly oviposits in artificial containers, which are ubiquitous in these peridomestic environments. The increase in speed and amount of international travel and commerce, coupled with global climate change, have aided in the resurgence and expansion of Stegomyia species into new areas of North America. In many parts of their range, both species are implicated as significant vectors of emerging and re-emerging arboviruses such as dengue, chikungunya, and now Zika. Although rapid and major advances have been made in the field of biology, ecology, genetics, taxonomy, and virology, relatively little has changed in the field of mosquito control in recent decades. This is particularly discouraging in regards to container-inhabiting mosquitoes, because traditional integrated mosquito management (IMM) approaches have not been effective against these species. Many mosquito control programs simply do not possess the man-power or necessary financial resources needed to suppress Ae. albopictus effectively. Therefore, control of mosquito larvae, which is the foundation of IMM approaches, is exceptionally difficult over large areas. This review paper addresses larval habitats, use of geographic information systems for habitat preference detection, door-to-door control efforts, source reduction, direct application of larvicides, biological control agents, area-wide low-volume application of larvicides, hot spot treatments, autodissemination stations, public education, adult traps, attractive-toxic sugar bait methods, lethal ovitraps, barrier-residual adulticides, hand-held ultra-low-volume adulticides, area-wide adulticides applied by ground or air, and genetic control methods. The review concludes with future recommendations for practitioners, researchers, private industry, and policy makers.

TrapTech R-Octenol Lure Does Not Improve the Capture Rates of Aedes albopictus (Diptera: Culicidae) and Other Container-Inhabiting Species in Biogents Sentinel Traps

Aedes albopictus (Skuse) and other container-inhabiting species have become important public health concerns due to the transmission of dengue, chikungunya, and Zika viruses. Effective surveillance is dependent on the ability to collect a sufficient number of mosquitoes for population monitoring and pathogen isolation. The Biogents Sentinel (BGS) trap supplied with a proprietary human skin lure has become the standard tool for container-inhabiting Aedes species collections worldwide. Recently, R-octenol, a single isomer of the well characterized mosquito attractant octenol, was shown to greatly improve the capture rate of some Aedes species when utilized with the Center for Disease Control and Prevention (CDC) light traps and Mosquito Magnet traps. This study evaluated the effectiveness of the TrapTech lure (TT lure), containing R-octenol, alone or in combination with the human skin lure in a BGS trap to capture Ae. albopictus and other species. BGS traps with human skin lures or a combination of the two lures collected approximately twice as many Ae. albopictus females compared to those with TT lures. Unlike previous studies, baiting BGS traps with TT lures did not result in increased diversity of mosquito species, or in higher numbers of other container-inhabiting Aedes species. Although human skin lures were clearly superior to TT R-octenol lures in BGS traps, R-octenol lures are more widely available and might still be used as an alternative lure, especially when Ae. albopictus populations are high.

Suppression of Aedes albopictus, the Asian tiger mosquito, using a 'hot spot' approach

BACKGROUND

Recent changes in climate and human behavior have led to dramatic increases in the abundance and geographic expansion of invasive mosquito vectors such as Aedes albopictus. Although source reduction has been shown to be effective in reducing mosquito populations, thousands of backyards need to be inspected during door-to-door campaigns, which is labor intensive and expensive. We identified 'hot spots' as high (five or more female or male Ae. albopictus) adult mosquito populations at very focal locations. We tested whether hot spot source reduction efforts were effective in reducing mosquito populations in the early summer season (June to July).

RESULTS

Analysis of historical data from the study sites indicated the proportion of hot spots in the control site relative to the intervention site was much greater in 2011, when hot spot treatments were applied to the intervention site, than in 2012, 2013 and 2014 combined, when no sites were treated [OR (95% CI) = 3.9 (1.8, 8.5), Z = 3.39, P < 0.001).

CONCLUSION

Hot spot treatments can be incorporated into existing integrated mosquito management programs to increase effectiveness while reducing the time, cost and effort spent on methods such as door-to-door source reduction. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Droplet Characterization and Penetration of an Ultra-Low Volume Mosquito Adulticide Spray Targeting the Asian Tiger Mosquito, Aedes albopictus, within Urban and Suburban Environments of Northeastern USA

Adult control of Aedes albopictus via ultra-low volume is difficult because this species occurs primarily in peridomestic habitats where obstacles such as buildings and vegetation can disrupt spray plumes and droplet dispersion. We determined droplet penetration and characterization of a pyrethroid adulticide applied from the ground at mid (46.77 ml/ha) and maximum (93.53 ml/ha) label rates within cryptic habitats of urban and suburban environments. Droplets were collected from all habitats, with no significant differences detected between locations within the same application rate or collection method. No differences were detected in droplet densities (drops per mm²) between rates within urban environments, but more droplets were collected in urban (149.93 ± 11.07 SE) than suburban sites (114.37 ± 11.32) at the maximum label rate (P = 0.003). The excellent penetration of aerosols into cryptic habitats of an urban site was likely due to the shorter spray paths afforded by our network of roads and alleys. Mid label rates displayed similar droplet density values as maximum label rates in urban areas, indicating that lower rates may be used effectively to reduce costs, lessen non-target effects, and increase environmental stewardship. Advances in formulations and technology are driving changes in adulticide applications, leading to use of the minimum effective dose for maximum efficacy, precision, and accountability.

Effects of a Red Marker Dye on Aedes and Culex Larvae: Are There Implications for Operational Mosquito Control?

Marker dyes are often mixed with liquid insecticide formulations prior to field applications to accurately determine the characteristics and penetration of droplets into targeted habitats. We have been using FD&C Red 40 Granular DM food dye at the rate of 20 g/liter in liquid solutions of Bacillus thuringiensis israelensis (Bti) for area-wide larvicide applications against the Asian tiger mosquito, Aedes albopictus. The Bti and dye mix ratio has been recommended by pesticide manufacturers for testing under operational conditions, but no data exist on the effects of the dye itself on mosquito larvae. We tested the effects of the FD&C Red 40 food dye in laboratory bioassays against different strains of Ae. albopictus (New Jersey and Maryland) and Culex pipiens pipiens (Utah) at rates of 0.039 to 80.0 g/liter. We also conducted field application trials to measure dye concentrations up to 100 m downwind when mixed and applied according to manufacturer instructions. In laboratory bioassays, we found that mean survival in cups with dye were significantly different from the controls beginning at 10.0 g/liter for New Jersey Ae. albopictus and at 20.0 g/liter for Maryland Ae. albopictus and Utah Cx. p. pipiens. In field application trials, we recorded a maximum volume density of 1,152.8 nl/cm(2) and calculated the maximum concentration of dye at 9.09 × 10(-3) g/liter. Our results showed that although we detected greater effects of dye on Ae. albopictus in New Jersey experiments than Ae. albopictus in Maryland and Cx. p. pipiens from Utah, concentrations of the dye during operational applications were at least 1,100 times below concentrations that exhibited toxic effects for either species in the laboratory, suggesting that the dye will not interfere with accuracy of field bioassays. Our results conclusively demonstrate that the addition of the FD&C Red 40 marker dye does not alter the efficacy of the pesticide formulation by skewing results, but rather provides a valuable addition to accurately determine pesticide penetration and spectrum by discriminating between intended pesticide and other potential pollutants.

Experimental host preference of diapause and non-diapause induced Culex pipiens pipiens (Diptera: Culicidae)

BACKGROUND

Culex pipiens pipiens plays an important role in the transmission of several vector-borne pathogens such as West Nile virus (WNV) in North America. Laboratory and field studies suggest that this species is ornithophilic but because of genetic hybridization with sibling species during the active mosquito season, it may occasionally feed on mammals. Adult female Cx. p. pipiens undergo a facultative diapause and may serve as an overwintering mechanism for WNV. To determine the effect of diapause on the innate host preference of Cx. p. pipiens emerging from winter hibernation, we conducted host-choice experiments using bird and mammal hosts.

METHODS

Mosquitoes were reared under non-diapause induced (NDI), diapause induced (DI), and field collected from overwintering (OW) hibernaculae. They were released into a large mesh enclosure housing two lard can traps, and given a choice between feeding on a dove or a rat.

RESULTS

Host seeking Cx. p. pipiens were four times more likely to feed on the dove than the rat, regardless of experimental conditions. Under NDI conditions, Cx. p. pipiens were (p < 0.001) more attracted to the bird (79.9% [75.6-84.1]) than the rat (20.1 [15.9-24.4]). Overwintering mosquitoes and those exposed to DI conditions were also significantly (p < 0.001) more attracted to birds (81.6% [75.9-87.3]) than to rats (18.5 [12.7-24.2]).

CONCLUSIONS

We provide new information about the innate host preference of Cx. p. pipiens emerging from diapause in temperate habitats where winter survival is crucial for disease transmission cycles. Although we showed that Cx. p. pipiens prefers an avian to a mammalian host, nearly 20% of emerging mosquitoes in the spring could feed on mammals. Changes in host preferences may also contain valuable clues about transmission dynamics and subsequent timely interventions by vector control and public health practitioners.

Area-wide ground applications of Bacillus thuringiensis var. israelensis for the control of Aedes albopictus in residential neighborhoods: from optimization to operation

The increasing range of Aedes albopictus, the Asian tiger mosquito, in the USA and the threat of chikungunya and dengue outbreaks vectored by this species have necessitated novel approaches to control this peridomestic mosquito. Conventional methods such as adulticiding provide temporary relief, but fail to manage this pest on a sustained basis. We explored the use of cold aerosol foggers and misting machines for area-wide applications of Bacillus thuringiensis var. israelensis (VectoBac WDG) as a larvicide targeting Aedes albopictus. During 2010–2013 we performed initially open field trials and then 19 operational area-wide applications in urban and suburban residential areas in northeastern USA to test three truck-mounted sprayers at two application rates. Area-wide applications of WDG in open field conditions at 400 and 800 g/ha killed on average 87% of tested larvae. Once techniques were optimized in residential areas, applications with a Buffalo Turbine Mist Sprayer at a rate of 800 g/ha, the best combination, consistently provided over 90% mortality. Importantly, there was no significant decrease in efficacy with distance from the spray line even in blocks of row homes with trees and bushes in the backyards. Under laboratory conditions Bti deposition in bioassay cups during the operational trials resulted in over 6 weeks of residual control. Our results demonstrate that area-wide truck mounted applications of WDG can effectively suppress Ae. albopictus larvae and should be used in integrated mosquito management approaches to control this nuisance pest and disease vector.

The hidden world of Asian tiger mosquitoes: immature Aedes albopictus (Skuse) dominate in rainwater corrugated extension spouts

BACKGROUND

The primary sources of Aedes albopictus (Skuse) in its exotic range in North America are artificial containers in backyards, which vary widely in accessibility. In this study we examined their prevalence in two container types that are difficult to inspect: catch basins and corrugated extension spouts (CES), the latter used to divert rainwater in downspouts away from house foundations.

METHODS

We conducted larval and pupal surveys in catch basins, CES and open containers such as buckets and plant saucers in three urban locations in Mercer County, New Jersey, USA.

RESULTS

We found that Ae. albopictus were rare in catch basins but prevalent in CES, and were often the only species collected in CES. Specific characteristics of the CES were not significantly associated with the presence or number of Ae. albopictus in them, but those longer and closer to the ground were significantly more likely to contain water, and therefore mosquitoes. During peak season (July-August), the abundance of immature Ae. albopictus was significantly higher in CES than open containers.

CONCLUSIONS

We found that CES are an important source of Ae. albopictus in our region and propose that effective control strategies should be implemented to minimize mosquito populations from these cryptic habitats.

Vertical Oviposition Preferences of the Asian Tiger Mosquito, Aedes albopictus, In Temperate North America

As a hyperaggressive mosquito that is also a public health threat, Aedes albopictus (Skuse), the Asian tiger mosquito, is a major priority for control efforts. We examine one aspect of Ae. albopictus biology: oviposition height. Field-based research in an urban habitat was conducted to determine if a height preference exists for this species. Larval and egg counts showed a significant preference for oviposition at ground level (0 m) compared to heights of 1, 2, 3, or 4 m (P < 0.01). An experiment conducted under semi-field conditions supported our conclusion of oviposition preference at ground level (P < 0.001), and further defines the search image needed by mosquito control personnel when dealing with this invasive species.

Comparative host feeding patterns of the Asian tiger mosquito, Aedes albopictus, in urban and suburban Northeastern USA and implications for disease transmission

Background

Aedes albopictus is an invasive species which continues expanding its geographic range and involvement in mosquito-borne diseases such as chikungunya and dengue. Host selection patterns by invasive mosquitoes are critically important because they increase endemic disease transmission and drive outbreaks of exotic pathogens. Traditionally, Ae. albopictus has been characterized as an opportunistic feeder, primarily feeding on mammalian hosts but occasionally acquiring blood from avian sources as well. However, limited information is available on their feeding patterns in temperate regions of their expanded range. Because of the increasing expansion and abundance of Ae. albopictus and the escalating diagnoses of exotic pathogens in travelers returning from endemic areas, we investigated the host feeding patterns of this species in newly invaded areas to further shed light on its role in disease ecology and assess the public health threat of an exotic arbovirus outbreak.

Methodology/Principal Findings

We identified the vertebrate source of 165 blood meals in Ae. albopictus collected between 2008 and 2011 from urban and suburban areas in northeastern USA. We used a network of Biogents Sentinel traps, which enhance Ae. albopictus capture counts, to conduct our collections of blooded mosquitoes. We also analyzed blooded Culex mosquitoes collected alongside Ae. albopictus in order to examine the composition of the community of blood sources. We found no evidence of bias since as expected Culex blood meals were predominantly from birds (n = 149, 93.7%) with only a small proportion feeding on mammals (n = 10, 6.3%). In contrast, Aedes albopictus fed exclusively on mammalian hosts with over 90% of their blood meals derived from humans (n = 96, 58.2%) and domesticated pets (n = 38, 23.0% cats; and n = 24, 14.6% dogs). Aedes albopictus fed from humans significantly more often in suburban than in urban areas (χ², p = 0.004) and cat-derived blood meals were greater in urban habitats (χ², p = 0.022). Avian-derived blood meals were not detected in any of the Ae. albopictus tested.

Conclusions/Significance

The high mammalian affinity of Ae. albopictus suggests that this species will be an efficient vector of mammal- and human-driven zoonoses such as La Crosse, dengue, and chikungunya viruses. The lack of blood meals obtained from birds by Ae. albopictus suggest that this species may have limited exposure to endemic avian zoonoses such as St. Louis encephalitis and West Nile virus, which already circulate in the USA. However, growing populations of Ae. albopictus in major metropolitan urban and suburban centers, make a large autochthonous outbreak of an arbovirus such as chikungunya or dengue viruses a clear and present danger. Given the difficulties of Ae. albopictus suppression, we recommend that public health practitioners and policy makers install proactive measures for the imminent mitigation of an exotic pathogen outbreak.

Aedes albopictus is one of the most invasive and aggressive disease vectors in the world. The range of this species is currently still expanding, particularly into highly dense human population centers in temperate areas in the USA and Europe, raising the public health threat of emerging and re-emerging diseases such as chikungunya and dengue. The prominence of Ae. albopictus as a major vector was exposed during the global pandemic of chikungunya virus, primarily because of a virus adaptation which enhanced the transmission efficiency by this mosquito species and also because of the first locally-transmitted cases of chikungunya virus in temperate Europe. Blood feeding patterns by mosquitoes are a critical component of virus proliferation and determine the degree and intensity of disease epidemics, particularly in newly invaded areas. We examined the blood meal sources of invasive Ae. albopictus in the northernmost boundary of their range in temperate North America and found that the species fed exclusively on mammalian hosts, with over 90% of their blood meals derived from humans and their associated pets (cats and dogs). The high mammalian affinity of Ae. albopictus suggests that this species may be an efficient vector of mammal-driven zoonoses and human-driven anthroponoses such as dengue and chikungunya viruses in this region.