Interactions between the imperiled West Indian manatee, Trichechus manatus, and mosquitoes (Diptera: Culicidae) in Everglades National Park, Florida, USA

Abstract

Arthropod-borne viruses (arboviruses), including those vectored by mosquitoes, have recently been cited as potential emerging health threats to marine mammals. Despite the fully aquatic habits of cetaceans, immunologic exposure to arboviruses including West nile virus and eastern equine encephalitis virus has been detected in wild Atlantic bottlenose dolphins, and captive orcas have been killed by West nile virus and St. Louis encephalitis virus. currently, there is no evidence of direct interactions between mosquitoes and marine mammals in nature, and it remains unknown how wild cetaceans are exposed to mosquito-vectored pathogens. Here, we report the first evidence of direct interactions between an aquatic mammal, the West indian manatee, a federally threatened species, and mosquitoes in nature. observations of manatees in everglades national park, florida, USA, indicate that mosquitoes of three genera, Aedes, Anopheles, and Culex are able to locate and land on surface-active manatees, and at minimum, penetrate and probe manatee epidermis with their mouthparts. Whether mosquitoes can successfully take a blood meal is not known; however, an arbovirus-infected mosquito can inoculate extravascular host tissues with virus-infected saliva during probing. these observations suggest that it is possible for marine mammals to be exposed to mosquito-vectored pathogens through direct interactions with mosquitoes. The importance of mosquitoes to domesticated animal and human health, as the vectors of disease-causing pathogens, is widely recognized. Less well understood is the importance of mosquitoes in ecosystems and their impact on wildlife health 1. Female mosquitoes of most species require a blood meal, taken from another animal, in order to obtain proteins necessary to complete egg development 2. This requirement can facilitate the transmission of diverse pathogens, particularly viruses, protozoa, and helminths, between vertebrate hosts. The host-use patterns of mosquitoes vary by species. Mosquitoes take blood from all major terrestrial vertebrate classes: Amphibia, Aves, Mammalia, and Reptilia, and at least one is an invertebrate specialist of Annelida hosts 3. Most mosquitoes specialize on particular types (e.g., endo-or ectothermic animals) or classes of host animals, with a few mosquito species that are relative generalists. Mosquitoes are well known to take blood from host animals that are amphibious or primarily aquatic. Some mosquito species are host specialists of frogs, including ranids that are closely associated with aquatic habitats 4-6 , and fishes, e.g., mudskippers, other gobies, and eels 7,8. Crocodilians 9,10 , and semi-aquatic snakes and turtles (e.g., Agkistrodon piscivorus, Python bivittatus, and Trachemys scripta) often serve as hosts for opportunistic mosquitoes 11-13. There is no direct evidence of interactions between mosquitoes and marine mammals in nature, however, mosquito-vectored viruses (e.g., West Nile virus, Eastern equine encephalitis virus, St. Louis encephalitis virus, and Venezuela...

Everglades virus: an underrecognized disease-causing subtype of Venezuelan equine encephalitis virus endemic to Florida, USA

“…Dolphins from South Carolina were seronegative for VEEV. That marine mammals are bitten by mosquitoes was demonstrated by Reeves et al (2020), who photographed Culex ( Melanoconion ) sp., Aedes sp., and Anopheles sp. biting manatees in the Everglades.…”