Survey of Invasive Mosquito Surveillance and Control Capacity in Southeastern USA Reveals Training and Resource Needs.

Several invasive mosquito species that are nuisances or of medical and veterinary importance have been introduced into the Southeastern region of the USA, posing a threat to other species and the local ecosystems and/or increasing the risk of pathogen transmission to people, livestock, and domestic pets. Prompt and effective monitoring and control of invasive species is essential to prevent them from spreading and causing harmful effects. However, the capacity for invasive mosquito species surveillance is highly variable among mosquito control programs in the Southeast, depending on a combination of factors such as regional geography and climate, access to resources, and the ability to interact with other programs. To facilitate the development of invasive mosquito surveillance in the region, we, the Mosquito BEACONS (Biodiversity Enhancement and Control of Non-native Species) working group, conducted a survey on the capacities of various public health agencies and pest control agencies engaged in mosquito surveillance and control in seven Southeastern states (Alabama, Florida, Georgia, Louisiana, Mississippi, North Carolina, and South Carolina). Ninety control programs completed the survey, representing an overall response rate of 25.8%. We report key findings from our survey, emphasizing the training and resource needs, and discuss their implications for future invasive mosquito surveillance and control capacity building. By increasing communication and collaboration opportunities (e.g., real-time sharing of collection records, coordinated multistate programs), the establishment of Mosquito BEACONS and the implementation of this survey can accelerate knowledge transfer and improve decision support capacity in response to or in preparation for invasive mosquito surveillance and can establish infrastructure that can be used to inform programs around the world.

Co-occurrence probabilities between mosquito vectors of West Nile and Eastern equine encephalitis viruses using Markov Random Fields (MRFcov).

Mosquito vectors of eastern equine encephalitis virus (EEEV) and West Nile virus (WNV) in the USA reside within broad multi-species assemblages that vary in spatial and temporal composition, relative abundances and vector competence. These variations impact the risk of pathogen transmission and the operational management of these species by local public health vector control districts. However, most models of mosquito vector dynamics focus on single species and do not account for co-occurrence probabilities between mosquito species pairs across environmental gradients. In this investigation, we use for the first time conditional Markov Random Fields (CRF) to evaluate spatial co-occurrence patterns between host-seeking mosquito vectors of EEEV and WNV around sampling sites in Manatee County, Florida. Specifically, we aimed to: (i) quantify correlations between mosquito vector species and other mosquito species; (ii) quantify correlations between mosquito vectors and landscape and climate variables; and (iii) investigate whether the strength of correlations between species pairs are conditional on landscape or climate variables. We hypothesized that either mosquito species pairs co-occur in patterns driven by the landscape and/or climate variables, or these vector species pairs are unconditionally dependent on each other regardless of the environmental variables. Our results indicated that landscape and bioclimatic covariates did not substantially improve the overall model performance and that the log abundances of the majority of WNV and EEEV vector species were positively dependent on other vector and non-vector mosquito species, unconditionally. Only five individual mosquito vectors were weakly dependent on environmental variables with one exception, Culiseta melanura, the primary vector for EEEV, which showed a strong correlation with woody wetland, precipitation seasonality and average temperature of driest quarter. Our analyses showed that majority of the studied mosquito species' abundance and distribution are insignificantly better predicted by the biotic correlations than by environmental variables. Additionally, these mosquito vector species may be habitat generalists, as indicated by the unconditional correlation matrices between species pairs, which could have confounded our analysis, but also indicated that the approach could be operationalized to leverage species co-occurrences as indicators of vector abundances in unsampled areas, or under scenarios where environmental variables are not informative.

West Nile Virus Surveillance in Sentinel Chickens and Mosquitoes in Panama City Beach, Florida, from 2014 To 2020.

Over 20 years since its introduction, the West Nile virus (WNV) continues to be the leading cause of arboviral disease in the USA. In Panama City Beach (Bay County, FL), WNV transmission is monitored using sentinel chickens and testing mosquito pools for presence of viral RNA. In the current work, we monitored WNV transmission from 2014 to 2020 through weekly serology sampling of sentinel chickens; mosquito populations through biweekly mosquito collections by suction traps (1 m and 9 m) and weekly gravid trap collections; and mosquito infection rates using a reverse transcriptase-polymerase chain reaction (RT-PCR) assay. Samples were sent to the Bureau of Public Health Laboratories (Tampa, FL) for testing presence/absence of WNV via RT-PCR assay. Our results indicated that canopy surveillance could augment ground collections, providing greater proportions of Culex mosquitoes with less bycatch compared with ground collections. Serology indicated 94 seroconversions to WNV in the study area from 2014 to 2020. The most active year was 2016, which accounted for 32% (n = 30) of all seroconversions reported during the study period. We detected 20 WNV-positive mosquito pools from Culex quinquefasciatus during 2014-17; mosquito infection rates ranged from 2.02 to 23.81 per thousand (95% CI). Climate data indicated anomalously high precipitation in 2014-19 preceding WNV transmission. Data analyzed herein indicate utility in year-round continuous and diversified surveillance methodologies. This information is needed to properly calibrate future models that could assist with predicting transmission events of WNV in Panama City Beach, FL.

Mosquito Communities Vary across Landscape and Vertical Strata in Indian River County, Florida.

Mosquito and arbovirus surveillance is essential to the protection of public health. A majority of surveys are undertaken at ground level. However, mosquitoes shelter, breed, and quest for hosts across vertical strata, thus limiting our ability to fully describe mosquito and arboviral communities. To elucidate patterns of mosquito vertical stratification, canopy traps were constructed to sample mosquitoes at heights of 1.5, 5.0, and 8.7 m across three different landscape types in a Florida coastal conservation area. We assessed trapping efforts using individual-based rarefaction and extrapolation. The effects of height, landscape, site location, and sampling date on mosquito community composition were parsed out using permutational ANOVA on a Hellinger-transformed Bray-Curtis dissimilarity abundance matrix. Lastly, a generalized linear mixed effects model (GLMM) was used to explore species-specific vertical patterns. We observed differences in sampling effort and community composition structure across various heights and landscapes. Our GLMM revealed significant effects of trap height for Aedes taeniorhynchus, Anopheles crucians, Anopheles quadrimaculatus, and Culex coronator, but not for Culex nigripalpus, the ultra-dominant species present in this area. Together these data provide evidence that height and landscape significantly affect mosquito community structures and highlight a need to develop sampling regimes to target specific vector and nuisance species at their preferred height and across different landscape types.

Mosquito Control Priorities in Florida-Survey Results from Florida Mosquito Control Districts.

Florida lies within a subtropical region where the climate allows diverse mosquito species including invasive species to thrive year-round. As of 2021, there are currently 66 state-approved Florida Mosquito Control Districts, which are major stakeholders for Florida public universities engaged in mosquito research. Florida is one of the few states with extensive organized mosquito control programs. The Florida State Government and Florida Mosquito Control Districts have long histories of collaboration with research institutions. During fall 2020, we carried out a survey to collect baseline data on the current control priorities from Florida Mosquito Control Districts relating to (1) priority control species, (2) common adult and larval control methods, and (3) major research questions to address that will improve their control and surveillance programs. The survey data showed that a total of 17 distinct mosquito species were considered to be priority control targets, with many of these species being understudied. The most common control approaches included truck-mounted ultra-low-volume adulticiding and biopesticide-based larviciding. The districts held interest in diverse research questions, with many prioritizing studies on basic science questions to help develop evidence-based control strategies. Our data highlight the fact that mosquito control approaches and priorities differ greatly between districts and provide an important point of comparison for other regions investing in mosquito control, particularly those with similar ecological settings, and great diversity of potential mosquito vectors, such as in Florida. Our findings highlight a need for greater alignment of research priorities between mosquito control and mosquito research. In particular, we note a need to prioritize filling knowledge gaps relating to understudied mosquito species that have been implicated in arbovirus transmission.

Comparison of the Effect of Insecticides on Bumble Bees (Bombus impatiens) and Mosquitoes (Aedes aegypti and Culex quinquefasciatus) by Standard Mosquito Research Methods.

Mosquito control districts in the United States are limited to two main classes of adulticides, pyrethroids and organophosphates, to control mosquitoes. Two adulticides used to control domestic mosquitoes are Fyfanon EW (malathion, organophosphate) and DeltaGard (deltamethrin, pyrethroid). While the effect of these pesticides on European honeybees (Apis mellifera L., Hymenoptera: Apidae) has been investigated, effects on native pollinators need additional research. The purpose of this study was to investigate the acute nontarget effects of these pesticides on Bombus impatiens Cresson (Hymenoptera: Apidae), a native North American bumble bee species, and compare these effects to wild and laboratory strains of mosquitoes (Aedes aegypti (L.) and Culex quinquefasciatus Say, Diptera: Culicidae) through field and laboratory assays. Bombus impatiens was found to be resistant to Fyfanon EW (x̅ = 6.7% mortality at 50-µg malathion per bottle) at levels that caused significant mortality to study mosquitoes (86.2 ≥ x̅ ≥ 100% mortality) in laboratory bottle bioassays. Comparatively, B. impatiens demonstrated greater mortality to DeltaGard (93.3%) at 2.5-µg deltamethrin/bottle than any mosquito colony assayed (14.1 ≥ x̅ ≥ 87.0% mortality). Only DeltaGard was tested in field applications. In the field, we observed acute effects of DeltaGard on mosquitoes and B. impatiens at 25- and 75-m distance from a truck-mounted ultra-low volume fogger, although treatment effects were not significant for B. impatiens. Additional wild-caught nontarget mortality to DeltaGard field trials was also evaluated. This study indicated that common mosquito control adulticides do cause nontarget mortality to B. impatiens but that impacts are variable depending on pesticide and further studies are needed.

Mosquito Community Composition, Seasonal Distributions, and Trap Bias in Northeastern Florida.

Mosquito control agencies monitor mosquito diversity and abundance through a variety of trap types. Although various long-term ecological data sets exist, little work has been done to address the sampling effort required to capture mosquito community diversity by trap type and few spatiotemporal distributions of vector species have been described. Here, we describe the seasonal distributions of vector species of importance, assess trapping effort needed to capture the diversity of the mosquito community, and use a partial redundancy analysis to identify trap bias from four commonly deployed adult mosquito traps in Volusia County, Florida. Collections were made with American Biophysics Corporation (ABC) light traps, Biogents Sentinel (BGS) traps, chicken coop exit traps, and gravid traps. We collected a total of 238,301 adult female mosquitoes belonging to 11 genera and 36 species, 12 of which we deemed to be vector species of epidemiological importance. We found that ABC traps not only yielded the greatest abundance and diversity but also captured several nonvector species. BGS and gravid traps yielded the highest proportions of vector species; exit traps recorded the lowest abundances and species richness. Wintertime abundances of several species demonstrated a need for year-round surveillance in the study area; partial redundancy analysis revealed that trap type explained a significant proportion of the variance in our data set, with certain vector species associated with specific trap types. Increased awareness regarding the amount of trapping effort needed to detect vector species diversity will help to optimize efforts in the field, leading to more effective resource allocation.

Distance Diminishes the Effect of Deltamethrin Exposure on the Monarch Butterfly, Danaus plexippus.

The monarch butterfly, Danaus plexippus (Lepidoptera: Nymphalidae), is threatened by substantial loss of habitat, extreme weather events linked to global climate change, and nontarget impacts of broad-spectrum insecticides. To investigate the impact of chronic ingestion of pyrethroids on monarchs, wild-type Florida D. plexippus were reared on milkweed (Asclepias curassavica) that was exposed to ultra-low volume applications of DeltaGard by a truck-mounted fogger, at distances of 25 and 50 m. We observed significant negative impacts on monarchs reared on milkweed at 25 m from the DeltaGard spray route, including significant decreases in survival, and significantly longer development times, compared with untreated controls. Larvae reared on host plants closest to the truck spray route were 3 times more likely to experience a mortality event than the control cohort in trial 1 and 6 times in trial 2. Survival of monarch caterpillars reared on milkweed sprayed at 50 m was not significantly different from controls. For monarchs that survived to adulthood, we did not observe statistically significant differences among cohorts for variables measured. These data demonstrate that ultra-low volume treatments of pyrethroids can result in significant mortality in monarchs, but that the effects diminish with distance from the spray route.

Geospatial Analysis and Seasonal Distribution of West Nile Virus Vectors (Diptera: Culicidae) in Southern Ontario, Canada.

The purpose of this study was to establish geospatial and seasonal distributions of West Nile virus vectors in southern Ontario, Canada using historical surveillance data from 2002 to 2014. We set out to produce mosquito abundance prediction surfaces for each of Ontario's thirteen West Nile virus vectors. We also set out to determine whether elevation and proximity to conservation areas and provincial parks, wetlands, and population centres could be used to improve our model. Our results indicated that the data sets for Anopheles quadrimaculatus, Anopheles punctipennis, Anopheles walkeri, Culex salinarius, Culex tarsalis, Ochlerotatus stimulans, and Ochlerotatus triseriatus were not suitable for geospatial modelling because they are randomly distributed throughout Ontario. Spatial prediction surfaces were created for Aedes japonicus and proximity to wetlands, Aedes vexans and proximity to population centres, Culex pipiens/restuans and proximity to population centres, Ochlerotatus canadensis and elevation, and Ochlerotatus trivittatus and proximity to population centres using kriging. Seasonal distributions are presented for all thirteen species. We have identified both when and where vector species are most abundant in southern Ontario. These data have the potential to contribute to a more efficient and focused larvicide program and West Nile virus awareness campaigns.

West Nile virus in Ontario, Canada: A twelve-year analysis of human case prevalence, mosquito surveillance, and climate data.

West Nile Virus (WNV) first arrived in Ontario, Canada in 2001 and has since spread throughout most of the province, causing disease in humans. The provincial government established a province-wide surveillance program to monitor WNV transmission throughout the 36 regional health units. Here we have acquired records of WNV human and mosquito surveillance from 2002 to 2013 to describe seasonal and geographic trends in WNV activity in southern Ontario. Additionally, we obtained climate data from seven municipalities to investigate how temperature and precipitation affect WNV transmission dynamics. We identified a strong quadratic relationship between the number of confirmed human cases and positive Culex mosquito pools recorded at the end of each year (R2 = 0.9783, p < 0.001). Using Spearman rank correlation tests, we identified that the minimum infection rate of Culex pipiens/restuans pools are the strongest predictor of human cases at a 1 week lag period. We also identified positive correlations between minimum infection rates, temperature, vector abundance, and cumulative precipitation. Global Moran's I index indicates strong positive autocorrelation and clustering of positive Culex pool counts in southern Ontario. Local indicators of spatial association tests revealed a total of 44 high-high and 1 high-low trap locations (n = 680). In the current work we have identified when and where hot spots of WNV activity have occurred in southern Ontario. The municipalities surrounding the western shore of the Lake Ontario and Windsor-Essex County have the largest records of positive mosquitoes and human cases. We identified that positive mosquitoes are a strong indicator of human cases to follow in the coming weeks. An epidemic action threshold of cumulative positive Culex pools was established, allowing Ontario public health officials to predict an epidemic at epidemiological week 34 (rho = 0.90, p < 0.001). These data have the potential to contribute to more efficient larvicide programs and awareness campaigns for the public.

Zika Virus: Quantification, Propagation, Detection, and Storage.

Zika virus (ZIKV), belonging to the family Flaviviridae, genus Flavivirus, is an arthropod-borne virus that was first discovered from the Zika forest in Uganda in 1947. Recent outbreaks in South America have linked ZIKV to cases of microcephaly and Guillain-Barré syndrome in humans. With the increased interest in ZIKV, protocols must be established to facilitate proper research. Here we describe the laboratory techniques required to quantify, propagate, and store ZIVK. We also review the proper safety protocol for the handling of ZIKV, which is classified as a Biosafety Level 2 pathogen by the United States Centers for Disease Control and Prevention. © 2016 by John Wiley & Sons, Inc.

A checklist of the 67 mosquito species of Ontario, Canada.

We provide an updated checklist of 67 endemic mosquito species known from Ontario, Canada. Nine endemic species are added to the checklist found in Darsie and Ward (2005) : Aedes cantator, Ae. churchillensis, Ae. nigripes, Ae. pullatus, Anopheles perplexens, An. crucians, An. smaragdinus, Culex erraticus, and Cx. salinarius. Only 4 specimens of Ae. albopictus have been recorded in Ontario since 2001 despite concerted efforts to find this species; therefore, it is considered an "accidental" species and is excluded from the checklist.