Ilia Rochlin

Climate Change and Range Expansion of the Asian Tiger Mosquito (Aedes albopictus) in Northeastern USA: Implications for Public Health Practitioners

The Asian tiger mosquito, Aedes albopictus (Skuse), is an invasive species with substantial biting activity, high disease vector potential, and a global distribution that continues to expand. New Jersey, southern New York, and Pennsylvania are currently the northernmost boundary of established Ae. albopictus populations in the eastern United States. Using positive geographic locations from these areas, we modeled the potential future range expansion of Ae. albopictus in northeastern USA under two climate change scenarios. The land area with environmental conditions suitable for Ae. albopictus populations is expected to increase from the current 5% to 16% in the next two decades and to 43%–49% by the end of the century. Presently, about one-third of the total human population of 55 million in northeastern USA reside in urban areas where Ae. albopictus is present. This number is predicted to double to about 60% by the end of the century, encompassing all major urban centers and placing over 30 million people under the threat of dense Ae. albopictus infestations. This mosquito species presents unique challenges to public health agencies and has already strained the resources available to mosquito control programs within its current range. As it continues to expand into areas with fewer resources and limited organized mosquito control, these challenges will be further exacerbated. Anticipating areas of potential establishment, while planning ahead and gathering sufficient resources will be the key for successful public health campaigns. A broad effort in community sanitation and education at all levels of government and the private sector will be required until new control techniques are developed that can be applied efficiently and effectively at reasonable cost to very large areas.

Predictive Mapping of Human Risk for West Nile Virus (WNV) Based on Environmental and Socioeconomic Factors

A West Nile virus (WNV) human risk map was developed for Suffolk County, New York utilizing a case-control approach to explore the association between the risk of vector-borne WNV and habitat, landscape, virus activity, and socioeconomic variables derived from publically available datasets. Results of logistic regression modeling for the time period between 2000 and 2004 revealed that higher proportion of population with college education, increased habitat fragmentation, and proximity to WNV positive mosquito pools were strongly associated with WNV human risk. Similar to previous investigations from north-central US, this study identified middle class suburban neighborhoods as the areas with the highest WNV human risk. These results contrast with similar studies from the southern and western US, where the highest WNV risk was associated with low income areas. This discrepancy may be due to regional differences in vector ecology, urban environment, or human behavior. Geographic Information Systems (GIS) analytical tools were used to integrate the risk factors in the 2000–2004 logistic regression model generating WNV human risk map. In 2005–2010, 41 out of 46 (89%) of WNV human cases occurred either inside of (30 cases) or in close proximity (11 cases) to the WNV high risk areas predicted by the 2000–2004 model. The novel approach employed by this study may be implemented by other municipal, local, or state public health agencies to improve geographic risk estimates for vector-borne diseases based on a small number of acute human cases.

The rise of the invasives and decline of the natives: insights revealed from adult populations of container-inhabiting Aedes mosquitoes (Diptera: Culicidae) in temperate North America

Container-inhabiting Aedes mosquitoes are successful invaders and important arthropod-borne disease vectors worldwide. In North America, a subtropical assemblage containing introduced Aedes albopictus and Aedes aegypti and the native Aedes triseriatus have served as a model for investigating ecological interactions during invasions and focused on the outcomes at the larval stages. We report a hypothesis driven study of a more temperate container Aedes assemblage at the adult population level monitored in the state of New Jersey during a 9-year period. The invasive A. albopictus and Aedes japonicus abundances increased by a factor of two, whereas A. triseriatus abundance decreased by a factor of three. Spatiotemporal analysis indicated these trends were coincident especially in the areas invaded by A. albopictus, leading to partial displacement of A. triseriatus. Although the invasive species reached peak abundance in highly urbanized areas, the native species’ rate of decline was similar across the urbanization gradient. Higher winter temperatures and precipitation favored increased A. albopictus abundance suppressing A. triseriatus adult populations in turn, whereas A. japonicus abundance was promoted by summer precipitation. The results validate the conceptual framework developed for subtropical container Aedes and suggest that the current climatic trends will favor further spread of A. albopictus, amplifying public health concerns.

Comparative Analysis of Distribution and Abundance of West Nile and Eastern Equine Encephalomyelitis Virus Vectors in Suffolk County, New York, Using Human Population Density and Land Use/Cover Data

Abstract Five years of CDC light trap data from Suffolk County, NY, were analyzed to compare the applicability of human population density (HPD) and land use/cover (LUC) classification systems to describe mosquito abundance and to determine whether certain mosquito species of medical importance tend to be more common in urban (defined by HPD) or residential (defined by LUC) areas. Eleven study sites were categorized as urban or rural using U.S. Census Bureau data and by LUC types using geographic information systems (GISs). Abundance and percent composition of nine mosquito taxa, all known or potential vectors of arboviruses, were analyzed to determine spatial patterns. By HPD definitions, three mosquito species, Aedes canadensis (Theobald), Coquillettidia perturbans (Walker), and Culiseta melanura (Coquillett), differed significantly between habitat types, with higher abundance and percent composition in rural areas. Abundance and percent composition of these three species also increased with freshwater wetland, natural vegetation areas, or a combination when using LUC definitions. Additionally, two species, Ae. canadensis and Cs. melanura, were negatively affected by increased residential area. One species, Aedes vexans (Meigen), had higher percent composition in urban areas. Two medically important taxa, Culex spp. and Aedes triseriatus (Say), were proportionally more prevalent in residential areas by LUC classification, as was Aedes trivittatus (Coquillett). Although HPD classification was readily available and had some predictive value, LUC classification resulted in higher spatial resolution and better ability to develop location specific predictive models.

The Effects of Integrated Marsh Management (IMM) on Salt Marsh Vegetation, Nekton, and Birds

An integrated marsh management (IMM) project in an urbanized watershed on Long Island, New York, USA, aimed to mitigate salt marsh degradation and to reduce mosquito production by an innovative combination of restoration and open marsh water management methods. The grid ditch network at two treatment marshes was replaced with naturalized tidal channels and ponds. Effects of the hydrologic alterations were monitored utilizing a before–after–control–impact approach. The treatment marshes experienced a number of beneficial outcomes including a fourfold reduction in the invasive Phragmites australis and increased native vegetation cover in the most degraded portions of the marsh, increased abundance and diversity of marsh killifish and estuarine nekton species, higher shorebird and waterfowl densities, and increased avian species diversity. The successful implementation of IMM concept led to improved marsh health and diminished mosquito production. Therefore, this study may serve as a template for similar large-scale integrated salt marsh restoration projects.

SALT MARSH AS CULEX SALINARIUS LARVAL HABITAT IN COASTAL NEW YORK

ABSTRACT Culex salinarius is considered one of the most likely bridge vectors involved in the human transmission cycle of West Nile virus (WNV) and eastern equine encephalomyelitis virus (EEEV) in the northeastern USA. The larval habitats of this species in the coastal region of New York State are currently poorly known. Between 2005 and 2007, a larval survey was carried out to identify and characterize possible larval habitats in Suffolk County, encompassing natural and man-made freshwater wetlands, artificial containers, and salt marshes. Only relatively undisturbed salt marsh yielded Cx. salinarius larvae in considerable numbers from several sites over a period of 2 years. The immature stages of this species were found associated with Spartina patens and S. alterniflora of the upper marsh at salinities ranging from 4.3 to 18.8 parts per thousand. Both heavily impacted and relatively undisturbed salt marshes produced several hundreds of adult Cx. salinarius per Centers for Disease Control and Prevention (CDC) light trap per night, an order of magnitude higher than CDC light traps deployed at upland sites. The ability of Cx. salinarius to use both heavily impacted and relatively undisturbed salt marshes for reproduction has significant repercussions for marsh restoration and vector control practices.

Integrated Marsh Management (IMM): a new perspective on mosquito control and best management practices for salt marsh restoration

Salt marsh management often embraces diverse goals, ranging from the restoration of degraded marshes through re-introduction of tidal flow to the control of salt marsh mosquito production by altering marsh surface topography through Open Water Marsh Management (OMWM). However, rarely have these goals been incorporated in one project. Here we present the concept of Integrated Marsh Management (IMM), which combines the best management practices of salt marsh restoration and OMWM. Although IMM offers a comprehensive approach to ecological restoration and mosquito control, research evaluating this concept’s practical implementations has been inadequate. A long-term IMM project at Wertheim National Wildlife Refuge located in a highly urbanized watershed on Long Island, New York, USA was designed to fill this knowledge gap. A combination of restoration and OMWM techniques was employed at two treatment marshes, the results monitored before and after alterations, and compared to two adjacent control marshes. The treatment marshes experienced decreased mosquito production, reduced cover of the invasive common reed (Phragmites australis), expansion of native marsh vegetation, increased killifish and estuarine nekton species abundance, as well as increased avian species diversity and waterbird abundance. This demonstration project validated the IMM conceptual approach and may serve as a case study for similar IMM projects in the future.

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.

Detection of Anaplasma phagocytophilum, Babesia microti, Borrelia burgdorferi, Borrelia miyamotoi, and Powassan Virus in Ticks by a Multiplex Real-Time Reverse Transcription-PCR Assay

The understanding of pathogen prevalence is an important factor in the determination of human risks for tick-borne diseases and can help guide diagnosis and treatment. The implementation of our assay addresses a critical need in surveillance of tick-borne diseases, through generation of a comprehensive assessment of pathogen prevalence in I. scapularis. Our finding of a high frequency of ticks infected with Babesia microti in Suffolk County, NY, implicates this agent as a probable frequent cause of non-Lyme tick-borne disease in this area. ABSTRACT Ixodes scapularis ticks are implicated in transmission of Anaplasma phagocytophilum, Borrelia burgdorferi, Borrelia miyamotoi, Babesia microti, and Powassan virus. We describe the establishment and implementation of the first multiplex real-time PCR assay with the capability to simultaneously detect and differentiate all five pathogens in a single reaction. The application of this assay for analysis of ticks at sites in New York and Connecticut revealed a high prevalence of B. microti in ticks from Suffolk County, NY. These findings are consistent with reports of a higher incidence of babesiosis from clinicians managing the care of patients with tick-borne diseases in this region. IMPORTANCE The understanding of pathogen prevalence is an important factor in the determination of human risks for tick-borne diseases and can help guide diagnosis and treatment. The implementation of our assay addresses a critical need in surveillance of tick-borne diseases, through generation of a comprehensive assessment of pathogen prevalence in I. scapularis. Our finding of a high frequency of ticks infected with Babesia microti in Suffolk County, NY, implicates this agent as a probable frequent cause of non-Lyme tick-borne disease in this area.

Aquatic Insects of New York Salt Marsh Associated with Mosquito Larval Habitat and their Potential Utility as Bioindicators

Abstract The aquatic insect fauna of salt marshes is poorly characterized, with the possible exception of biting Diptera. Aquatic insects play a vital role in salt marsh ecology, and have great potential importance as biological indicators for assessing marsh health. In addition, they may be impacted by measures to control mosquitoes such as changes to the marsh habitat, altered hydrology, or the application of pesticides. Given these concerns, the goals of this study were to conduct the first taxonomic survey of salt marsh aquatic insects on Long Island, New York, USA and to evaluate their utility for non-target pesticide impacts and environmental biomonitoring. A total of 18 species from 11 families and five orders were collected repeatedly during the five month study period. Diptera was the most diverse order with nine species from four families, followed by Coleoptera with four species from two families, Heteroptera with three species from three families, then Odonata and the hexapod Collembola with one species each. Water boatmen, Trichocorixa verticalis Fieber (Heteroptera: Corixidae) and a shore fly, Ephydra subopaca Loew (Diptera: Ephydridae), were the two most commonly encountered species. An additional six species; Anurida maritima Guérin-Méneville (Collembola: Neanuridae), Mesovelia mulsanti White (Heteroptera: Mesovelidae), Enochrus hamiltoni Horn (Coleoptera: Hydrophilidae), Tropisternus quadristriatus Horn (Coleoptera: Hydrophilidae), Dasyhelea pseudocincta Waugh and Wirth (Diptera: Ceratopogonidae), and Brachydeutera argentata Walker (Diptera: Ephydridae), were found regularly. Together with the less common Erythrodiplax berenice Drury (Odonata: Libellulidae), these nine species were identified as the most suitable candidates for pesticide and environmental impact monitoring due to abundance, position in the food chain, and extended seasonal occurrence. This study represents a first step towards developing an insectbased index of biological integrity for salt marsh health assessment.