How do invasive species relate to the mosquito population in Illinois? The University of Illinois has made strides in understanding how land management of invasive species has affected the population of the West Nile-carrying mosquito, Culex pipiens.

Research has revealed that the fallen leaves of some of the most detested invasive plants help mosquitoes thrive. Mosquito larvae eat microbial flora that live on leaf litter in standing water. The type of leaf litter can affect where they deposit their eggs, how quickly their larvae grow, and whether they survive to adulthood.

Graduate student Allison Gardener, along with entomology professor Brian Allan and Illinois Natural History Survey entomologist Ephantus Muturi, have said that invasive honeysuckle and autumn olive provide high-quality habitat for larvae to grow and yielded large numbers of adult mosquitoes.

The team also identified native blackberry as a possible ecological trap. The leaves are very attractive for mosquitoes to lay their eggs, but is poor in producing adult mosquitoes. The native blackberry is Rubus allegheniensis. This common blackberry is primarily found in the northern two-thirds of the state and grows in a wide range of habitats.

A study conducted by postdoctoral student researcher Andrew Mackay and entomology professor Brian Allan found that mowing two invasive species of cattails and phragmites in storm basins actually produces a larger population of larvae and adult mosquitoes.

This is bad news for land managers, as mowing is one of the tools they use to reduce these invasive plants. Most people believe tall grasses are mosquito magnets, but they are not.

The scientists are part of the stormwater and mosquito project at the University of Illinois. The group believes that green infrastructure technology dealing with stormwater and manipulation of aquatic habitat for larvae growth can inhibit growth of the mosquito population.

Key to reducing the populations is eliminating standing water in your landscape, but personal protection is still important for Illinoisans to prevent getting bitten by female mosquitoes and thus preventing the transfer of the West Nile virus.

Use personal bug sprays. The Illinois Department of Public Health recommends DEET as the most effective chemical to use to combat mosquitoes. DEET, in a concentration of 40 percent, is effective for four to six hours.

DEET confuses the mosquito and blocks the females’ ability to detect carbon dioxide, heat, moisture and human sweat. The product should be sprayed liberally on uncovered skin but should not be used on children younger than 2. A 10 percent DEET product for children will last around two hours. Long sleeves, long pants, socks, gloves and hats also can help prevent mosquito bites.

Kelly Allsup is the University of Illinois Extension horticulture educator in Livingston, McLean and Woodford counties.


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