Mosquito trapping started in Dane County and the Madison area last week. With all the rain in May and warmer temperatures, the mosquito season got off to a strong start. We trapped the highest overall numbers ever for this week, with an average of 1826 mosquitoes per trap. This compares with 300 per trap, the previous record for these trap locations. Use personal protection, including a good repellent, to reduce risks.
This summer the UW-Madison Medical Entomology Lab is partnering with local public health offices from over a dozen locations (additional partners may yet be added) in southern Wisconsin counties to look for potential vectors of the Zika virus. If the Asian tiger mosquito (Aedes albopictus) — one of the types of mosquito known to be capable of carrying and transmitting Zika virus — is living in Wisconsin, it would likely be found near the southern border of the state (this map shows the estimated Aedes albopictus range according to the CDC).
The Asian tiger mosquito is a mosquito that evolved in forested areas to oviposit (lay it’s eggs) in small, water-filled areas such as holes in trees. This is a trait that is well adapted for oviposition in small man-made containers, and in fact some of the most important habitats for this mosquito in urban and suburban environments are areas with accumulations of used tires. We will use a trapping method known as “ovitrapping” that takes advantage of this egg-laying behavior. Each of our public health partners will set out cups partially-filled with water and including an “egg stick” — a setup that is ideal for these container breeders to lay eggs. Egg sticks will be checked each week for mosquito eggs (pictured below), and sent to our lab in Madison if any eggs have in fact been left. Because the Asian tiger mosquito is not the only container breeder that may visit one of our traps, eggs will be hatched, and the larval mosquitoes will be identified (larval Aedes aegypti pictured below). Any potential vectors of Zika virus found this summer will be reported to local public health offices, and if needed, further prevention methods will be pursued.