4 plants for your garden to reduce West Nile virus risk

Culex pipiens
CC BY 2.0 Anton Zelenov

A new study discovers what plants Culex pipiens mosquitoes love and hate when it comes to where to lay eggs.

I love science, and I particularly love science when results in studies prove to be simple, sensible, and so easy to put to good use. Case in point: A new study from the University of Illinois at Urbana-Champaign that looks at how leaf litter in water influences the abundance of Culex pipiens mosquitoes.

How is this helpful? C. pipiens is the brand of mosquitoes responsible for transmitting West Nile virus to humans, pets, birds and other wildlife. The study found that different kinds of leaf litter in standing water influences where these mosquitoes decide to lay their eggs and whether or not the hatchlings thrive or flounder.

As it turns out, C. pipiens does a happy dance when it comes to standing water containing leaf litter from two non-native, invasive plants, Amur honeysuckle (Lonicera maackii) and autumn olive (Elaeagnus umbellata).

"The invasive honeysuckle was definitely the highest quality habitat in terms of the adult mosquito emergence rates, even when you had very high densities of the larvae," said graduate student Allison Gardner, who led the research with University of Illinois entomology professor Brian Allan and Illinois Natural History Survey entomologist Ephantus Muturi.

Less hospitable environments, they found, came courtesy of standing water littered with matter from the following:

1. Multiflora rose (Rosa multiflora)

Multiflora roseWikimedia Commons/CC BY 2.0
Multiflora rose was associated with a low numbers of eggs laid and low survival rate of the larvae. (Unfortunately, as our readers have pointed out since the publication of this post, multiflora rose is also an aggressive invasive species. So although the study shows it's not great for C. pipiens, it's also not great for native vegetation as well.)

2. Native blackberry (Rubus allegheniensis)

BlackberryWikimedia Commons/CC BY 2.0
This one was unexpected to the team, and the most exciting. Native blackberry encouraged C. pipiens to deposit a lot of eggs on the water's surface, which sounds bad. But very few of the resulting larvae survived to adulthood. A trap!

"Blackberry was a really poor habitat: It took the larvae a long time to develop and the adult mosquitoes that eventually emerged were small," Allan said. "What's exciting about this is that it suggests that blackberry functions as a kind of ecological trap, enticing mosquitoes to lay their eggs in a place where the larvae are unlikely to survive."

3. Elderberry (Sambucus canadensis)

ElderberrySB_Johnny/Wikimedia Commons/CC BY 2.0
Like blackberry, elderberry attracted mosquitoes looking for a place to lay their eggs, and the larval survival rates were low, but not as low as for blackberry. Still, can't hurt.

4. Serviceberry (Amelanchier laevis)

With serviceberry standing water, the mosquitoes deposited the lowest number of eggs, but the survival of the larvae was not bad at 62 percent; so a bit of a mixed bag, but still a good bet.

Future studies will explore whether blackberry leaves can be used to undermine the viability of disease-carrying mosquitoes, Allan said. How great is that? Science put to best poetic and practical use.

4 plants for your garden to reduce West Nile virus risk
A new study discovers what plants Culex pipiens mosquitoes love and hate when it comes to where to lay eggs.

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