Which mosquito is suspected to be a major vector of eastern equine encephalitis in humans and horses?

The correct answer is Aedes sollicitans, as this species is known to be a significant vector for eastern equine encephalitis (EEE) in both humans and horses. Aedes sollicitans is primarily recognized for its role in transmitting EEE due to its habitat preferences and biting behavior. This mosquito typically thrives in coastal areas and wetlands where the virus is amplified in bird populations, particularly in areas that are suitable for breeding.

In contrast, while Aedes vexans, Culex tarsalis, and Anopheles punctipennis are all mosquitoes that can be involved in disease transmission, they are not specifically identified as the major vectors for eastern equine encephalitis. Aedes vexans is more of a generalist mosquito that can transmit various pathogens but is not the primary vector for EEE. Culex tarsalis is mainly associated with West Nile virus in some regions, and Anopheles punctipennis is primarily known for its role in malaria transmission rather than being a significant vector for EEE. Therefore, Aedes sollicitans stands out as the key mosquito implicated in the epidemiology of eastern equine encephalitis.