Which species has dog heartworm as a vector but is not a major vector of encephalitis viruses?

• A. Ochlerotatus canadensis
• B. Ochlerotatus taeniorhynchus
• C. Aedes vexans
• D. Aedes albopictus

Answer: (B)

Understanding which mosquitoes are important for which diseases comes from looking at feeding habits and ecological roles. Some species are known primarily for transmitting certain parasites like dog heartworm, while others are key vectors for encephalitis viruses such as West Nile or Eastern Equine encephalitis.

Ochlerotatus taeniorhynchus is a mammal‑feeding floodwater mosquito that efficiently transmits the dog heartworm parasite (Dirofilaria immitis) to dogs. However, it is not regarded as a major transmitter of encephalitis viruses in most settings. The other species listed are more commonly implicated in spreading encephalitis viruses in various regions, making taeniorhynchus the best fit for a mosquito that vectors dog heartworm but is not a major encephalitis virus vector.