Host interactions of Aedes albopictus, an invasive vector of arboviruses, in Virginia, USA

Abstract

Background As an invasive mosquito species in the United States, Aedes albopictus is a potential vector of arboviruses including dengue, chikungunya, and Zika, and may also be involved in occasional transmission of other arboviruses such as West Nile, Saint Louis encephalitis, eastern equine encephalitis, and La Crosse viruses. Aedes albopictus feeds on a wide variety of vertebrate hosts, wild and domestic, as well as humans. Methodology/Principal findings In order to investigate blood feeding patterns of Ae. albopictus, engorged specimens were collected from a variety of habitat types using the Centers for Disease Control and Prevention light traps, Biogents Sentinel 2 traps, and modified Reiter gravid traps in southeast Virginia. Sources of blood meals were determined by the analysis of mitochondrial cytochrome b gene sequences amplified in PCR assays. Our aims were to quantify degrees of Ae. albopictus interactions with vertebrate hosts as sources of blood meals, investigate arboviral infection status, assess the influence of key socioecological conditions on spatial variability in blood feeding, and investigate temporal differences in blood feeding by season. Analysis of 961 engorged specimens of Ae. albopictus sampled between 2017–2019 indicated that 96%, 4%, and less than 1% obtained blood meals from mammalian, reptilian, and avian hosts, respectively. Domestic cats were the most frequently identified (50.5%) hosts followed by Virginia opossums (17.1%), white-tailed deer (12.2%), and humans (7.3%), together representing 87.1% of all identified blood hosts. We found spatial patterns in blood feeding linked to socioecological conditions and seasonal shifts in Ae. albopictus blood feeding with implications for understanding human biting and disease risk. In Suffolk Virginia in areas of lower human development, the likelihood of human blood feeding increased as median household income increased and human blood feeding was more likely early in the season (May-June) compared to later (July-October). Screening of the head and thorax of engorged Ae. albopictus mosquitoes by cell culture and RT-PCR resulted in a single isolate of Potosi virus. Conclusion and significance Understanding mosquito-host interactions in nature is vital for evaluating vectorial capacity of mosquitoes. These interactions with competent reservoir hosts support transmission, maintenance, and amplification of zoonotic agents of human diseases. Results of our study in conjunction with abundance in urban/suburban settings, virus isolation from field-collected mosquitoes, and vector competence of Ae. albopictus, highlight the potential involvement of this species in the transmission of a number of arboviruses such as dengue, chikungunya, and Zika to humans. Limited interaction with avian hosts suggests that Ae. albopictus is unlikely to serve as a bridge vector of arboviruses such as West Nile and eastern equine encephalitis in the study region, but that possibility cannot be entirely ruled out.

The Effects of Host Availability and Fitness on Aedes albopictus Blood Feeding Patterns in New York

“…8,11,13,15 Similarly, the fourth most common host, opossum, has been reported in five previous studies, also at lower levels, with the exception of Virginia. [9][10][11]14,16 Long Island Aedes albopictus fed less frequently on dogs compared with the representative proportion in numerous other studies. 8,10,11,[14][15][16][17] Notably absent from the Long Island blood meals were cows, deer, and birds, all of which were present on at least one site in our study and have been detected in at least six previous blood meal studies.…”

“…The proportion of human blood meals (32.2%) identified in Long Island was lower than reported in many other locations worldwide, 5,6,[12][13][14][15][16][17][19][20][21][22][23] but was higher than in some other studies from the United States (Hawaii, Missouri, North Carolina, Maryland, and Virginia). [7][8][9][10][11] More Ae. albopictus fed on cats in our study on Long Island than in any other location previously reported, with the exception of Virginia.…”

“…albopictus fed on cats in our study on Long Island than in any other location previously reported, with the exception of Virginia. 9 The third most common host for this mosquito species on Long Island, the horse, has only been detected in four of 18 previous Ae. albopictus blood meal studies and at lower levels.…”

“…In some parts of the United States, human feeding frequency was much lower, such as at a tire dump in Missouri (6.5%), urban Baltimore, MD (13.6%), urban and rural sites in Hawaii (18.1%) and Virginia (7.3%), and suburban North Carolina (20%). [7][8][9][10][11] Additional studies have reported moderate human feeding rates such as in urban and peripheral sites in Brazil, urban and suburban Japan, and suburban New Jersey. [12][13][14] Of those populations that did not feed predominantly on humans, most fed on a diverse array of animals, with the exception of Baltimore, where a striking number of Ae.…”

“…albopictus to feed primarily on mammals compared with birds and reptiles. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] About half of studies report feeding on birds at low rates (1.7% to 25.6% of all blood meals). 8,[10][11][12][13]15,17,20,22 A tendency to feed even sporadically on birds is particularly important because of their role as amplifying hosts of arboviruses such as West Nile and Eastern equine encephalitis.…”