Ochlerotatus Japonicus Aka: Asian Rock Pool or Asian Bush Mosquito – Another Asian Arrival!

If you have been reading our blogs, you are familiar with the Asian Tiger mosquito.  Two particularly unique characteristics of the Asian Tiger mosquito are its aggressiveness and its habit of biting during the day.  Other mosquitoes in Central Mass are most active at dusk and dawn while resting in shaded places during the day.

Ochlerotatus Japonicus or the Asian Rock Pool mosquito was confined to Asia and Russia prior to the late 1990’s.  It has traveled the world since, appearing briefly in the Netherlands and France but failed to establish itself in these countries.  It is now established in Germany, Switzerland and four other European countries.  In 1998, scientists in the US identified the first established colony of this mosquito in the eastern US.  The Asian Bush Mosquito is now in Central Mass and every state east of the Mississippi River, except two.  It also now inhabits two US Pacific Coast states.  Researchers believe the international tire trade from Asia is responsible for the expansion of this mosquito.  Its eggs are desiccation-tolerant.  This ability for eggs to survive dry periods without being in water makes this mosquito survive well during its long travel by ship.

The common names Asian Rock Pool and Asian Bush mosquito are an indication of the environment this mosquito favors.  Eggs of the mosquito are often found in rock pools and compete with another US mosquito, Aedes Atropalpus.  Due to the longer time required for Aedes Atropalpus eggs to hatch, the Asian Rock Pool mosquito seems to be taking over pools where both specie exist.  That’s unfortunate for us because A. Atropalpus is a mosquito that does not require a blood meal from humans to lay eggs and survive.

Although Ochlerotatus Japonicus prefers rock pools, tires, tree-holes, birdbaths, roof gutters and drinking fountains as a breeding pool, it will use any container with a small amount of water.  Its ability to adapt allows it to thrive in urban environments, especially near forested or brushy areas.  Along with being a day feeder, it prefers humans and mammals for its blood meal.  Research published in Parasites and Vectors and the National Institutes of Health (NIH) indicates it will also choose other mammals and birds for its blood meal.  Possums, deer, chipmunks, horses, birds and humans are all candidates for this mosquito’s blood meal.  Discovering that birds are on its menu concerns scientists.  Infecting birds will allow Ochlerotatus Japonicus to distribute West Nile virus across a far wider geographic area.

In addition to West Nile, Ochlerotatus Japonicus transmits St. Louis encephalitis, Japanese encephalitis, La Crosse virus and Eastern Equine encephalitis (EEE).  Yes, other mosquitoes transmit these viruses as well.  However, this mosquito’s ability to use polluted water sources like storm water drains and containers with high levels of pollutants means it has an edge on other mosquito species in an urban environment in distributing these diseases.

When any mosquito specie establishes itself, it’s difficult to eradicate it.  Our best defense is to reduce their numbers and our exposure to them.  As Ochlerotatus Japonicus continues to establish itself in Central Mass, eliminating them in in the outdoor environments we use will only become more difficult.