Spatiotemporal distribution, abundance, and host interactions of two invasive vectors of arboviruses, Aedes albopictus and Aedes japonicus, in Pennsylvania, USA.

BACKGROUND: Aedes albopictus and Aedes japonicus, two invasive mosquito species in the United States, are implicated in the transmission of arboviruses. Studies have shown interactions of these two mosquito species with a variety of vertebrate hosts; however, regional differences exist and may influence their contribution to arbovirus transmission. METHODS: We investigated the distribution, abundance, host interactions, and West Nile virus infection prevalence of Ae. albopictus and Ae. japonicus by examining Pennsylvania mosquito and arbovirus surveillance data for the period between 2010 and 2018. Mosquitoes were primarily collected using gravid traps and BG-Sentinel traps, and sources of blood meals were determined by analyzing mitochondrial cytochrome b gene sequences amplified in PCR assays. RESULTS: A total of 10,878,727 female mosquitoes representing 51 species were collected in Pennsylvania over the 9-year study period, with Ae. albopictus and Ae. japonicus representing 4.06% and 3.02% of all collected mosquitoes, respectively. Aedes albopictus was distributed in 39 counties and Ae. japonicus in all 67 counties, and the abundance of these species increased between 2010 and 2018. Models suggested an increase in the spatial extent of Ae. albopictus during the study period, while that of Ae. japonicus remained unchanged. We found a differential association between the abundance of the two mosquito species and environmental conditions, percent development, and median household income. Of 110 Ae. albopictus and 97 Ae. japonicus blood meals successfully identified to species level, 98% and 100% were derived from mammalian hosts, respectively. Among 12 mammalian species, domestic cats, humans, and white-tailed deer served as the most frequent hosts for the two mosquito species. A limited number of Ae. albopictus acquired blood meals from avian hosts solely or in mixed blood meals. West Nile virus was detected in 31 pools (n = 3582 total number of pools) of Ae. albopictus and 12 pools (n = 977 total pools) of Ae. japonicus. CONCLUSIONS: Extensive distribution, high abundance, and frequent interactions with mammalian hosts suggest potential involvement of Ae. albopictus and Ae. japonicus in the transmission of human arboviruses including Cache Valley, Jamestown Canyon, La Crosse, dengue, chikungunya, and Zika should any of these viruses become prevalent in Pennsylvania. Limited interaction with avian hosts suggests that Ae. albopictus might occasionally be involved in transmission of arboviruses such as West Nile in the region.

Detection of Babesia, Borrelia, Anaplasma, and Rickettsia spp. in Adult Black-Legged Ticks (Ixodes scapularis) from Pennsylvania, United States, with a Luminex Multiplex Bead Assay.

Ixodes scapularis, the black-legged tick, harbors multiple organisms and transmits several pathogens to animals and humans. To determine the presence of tick-borne microorganisms carried by I. scapularis in Pennsylvania, 299 adult I. scapularis ticks were collected from across the state and tested with a multiplex bead panel targeting 20 microorganisms. The Luminex bead-based xMAP® MultiFLEX Mega Tick Panel detected microorganisms in these ticks, including Anaplasma spp. (1.7%), Borrelia spp. (45.8%), Babesia spp. (16.1%), and Rickettsia spp. (22.1%) at the genera level and identified Anaplasma phagocytophilum (1.7%), Babesia microti (0.7%), Borrelia burgdorferi sensu stricto (45.5%), Borrelia miyamotoi (0.3%), and Rickettsia parkeri (0.7%) at the species level. Babesia spp. reactivity was found to be due to Ba. odocoilei, and Rickettsia spp. reactivity was mainly due to rickettsial endosymbionts.

First Record of Aedes albopictus (Diptera: Culicidae) and Second Record of Aedes japonicus (Diptera: Culicidae) Parasitized by Water Mites (Acari: Hydrachnidiae) in North America.

The primary aim of this study was to determine if the Asian tiger mosquito (Aedes albopictus (Skuse)) (Diptera: Culicidae), that vectors a number of arboviruses, is parasitized by water mites (Acari: Prostigmata: Parasitengonina: Hydrachnidiae). Larval water mite parasitism of adult mosquitoes has been shown to reduce mosquito fecundity and life span in the laboratory, and impact some populations in the field. Water mites have been considered for biocontrol purposes and used to age-grade mosquito populations. Consequently, there is interest in water mite-mosquito associations from public health and integrated pest management perspectives. In 2016, the Pennsylvania Department of Environmental Protection West Nile Virus Control Program examined 146,607 mosquitoes representing 31 species for parasitic mites. Ten mosquitoes representing four species rarely or not previously known to be parasitized by mites were saved from destructive West Nile virus and Zika virus testing. Twelve parasitic mites were identified to the lowest taxonomic level possible. An Asian tiger mosquito and an Asian bush mosquito (Aedes japonicus) (Theobald) were each parasitized by a Parathyas sp. Lundblad (Hydryphantoidea: Hydryphantidae: Euthyadinae) water mite, and are the first and second records of these associations in North America, respectively. Two Culex restuans Theobald (Diptera: Culicidae) mosquitoes parasitized by either a Euthyas sp. Piersig (Hydryphantoidea: Hydryphantidae: Euthyadinae) or a Parathyas sp. water mite are new associations, and a Culex pipiens Linnaeus mosquito parasitized by a Parathyas sp. water mite represents a new record for this association in North America.

A decade of colonization: the spread of the Asian tiger mosquito in Pennsylvania and implications for disease risk.

In recent decades, the Asian tiger mosquito expanded its geographic range throughout the northeastern United States, including Pennsylvania. The establishment of Aedes albopictus in novel areas raises significant public health concerns, since this species is a highly competent vector of several arboviruses, including chikungunya, West Nile, and dengue. In this study, we used geographic information systems (GIS) to examine a decade of colonization by Ae. albopictus throughout Pennsylvania between 2001 and 2010. We examined the spatial and temporal distribution of Ae. albopictus using spatial statistical analysis and examined the risk of dengue virus transmission using a model that captures the probability of transmission. Our findings show that since 2001, the Ae. albopictus population in Pennsylvania has increased, becoming established and expanding in range throughout much of the state. Since 2010, imported cases of dengue fever have been recorded in Pennsylvania. Imported cases of dengue, in combination with summer temperatures conducive for virus transmission, raise the risk of local disease transmission.

First Record of Aedes stimulans from Louisiana.

The first confirmed collection of Aedes stimulans in Louisiana was made in St. Tammany Parish, LA. A single adult female was collected by a large-bore aspirator in March 2011, and identified by microscopic and molecular methods. Notes are provided on the morphology, location, habitat, and potential mosquito associates that may be found with Ae. stimulans.

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.

Annotated checklist of the mosquitoes of Pennsylvania including new state records.

A checklist of 62 species of mosquitoes found in Pennsylvania is presented. In addition, new state records for 9 species are as follows: Aedes aegypti, Anopheles earlei, Culiseta minnesotae, Ochlerotatus atlanticus/Oc. tormentor, Oc. dupreei, Oc. infirmatus, Oc. thibaulti, Psorophora howardii.