Tag Archives: toxin

Alternative lawns sign for Mosquito Shield

If you give presentations on the non-target effects of pyrethroid mosquito sprays, here are some modified lawn signs to download and use. I’ve based them on an actual sign from Mosquito Shield, below.

Mosquito Shield lawn sign

First, here’s a sign that simply has an additional part that shows the name and molecular structure one of the two chemicals used by Mosquito Shield (they also use cyfluthrin). It would be nice to have signs like this because it educates neighbors on what is actually in these types of sprays (the companies don’t like to disclose).

Mosquito Shield lawn sign with active ingredient listed

Here’s a mocked-up sign that informs neighbors that the homeowner has also eliminated his/her butterfly and moth problem.

Butterfly Shield lawn sign

Here’s a Firefly Shield sign. It’s really the only beetle people care about and, unfortunately, the numbers of fireflies is plummeting. There are thousands of other beetle species in a typical backyard and none deserves to be dosed with a neurotoxin.

Firefly Shield lawn sign

Spiders are also killed by Mosquito Shield sprays. I suspect many people would see this is a plus but spiders are likely important predators of mosquitoes … and spiders are not hurting humans.

Spider Shield lawn sign

Many bird species depend on insects and spiders to feed themselves and their young, so when you hire Mosquito Shield to nuke your yard you are indirectly reducing the numbers of birds that can survive in an area. I think few homeowners realize this, and Mosquito Shield (and other companies) are unlikely to spell out that consequence.

Bird Shield lawn sign

Finally, pyrethroids get washed into nearby bodies of water and end up killing fish. This might be rare in towns where there is just one person who subscribes to Mosquito Shield … but if everyone in town decided to get sprayed the fish would really take a hit.

Fish Shield lawn sign

More details here.

Using mosquitoes’ sweet tooth to control Zika transmission

Now that everyone wants to kill mosquitoes that transmit Zika virus, can somebody please make a transgenic plant that expresses mosquitocidal Bti (Bacillus thuringiensis subsp. israelensis) toxins? Just stick the Bti gene behind a phloem-specific promoter so that the protein gets pumped into the nectar. Then when males and female mosquitoes drink (and almost all do), they die.

White-footed woods mosquito (Psorophora ferox) nectaring on goldenrod flowers.

You could then plant acres of the modified plant nearby towns to protect people from Zika (and anything else transmitted by mosquitoes). The beauty of this method is that you could reduce populations of mosquitoes from an area without spraying, and do so for generations if you modified nectar-producing perennials. I know it’s trendy to dislike GMOs (like vaccines), but I think many people would support them under these circumstances.

And yes, apparently Bti toxins can kill adult mosquitoes (including Aedes aegypti), not just larvae. Klowden and Bulla 1984 demonstrated it, for example. And yes, Aedes aegypti drinks nectar (and probably fruit juice).

Of course, even if somebody had the incentive to make such a plant, it could take a decade to wade through the red tape involved in getting non-regulated status from governments. So if you want to do something today, leave out containers of sugar water (10%) that is laced with Bti (e.g., Mosquito Dunks, which you can buy online or at hardware stores). Maybe add something floral to attract them, too. (A review of olfactory cues suggests that imitation cherry and apple can work. If you don’t have those sitting around, I’d wager a few drops of jasmine flavoring or rose water would work, and those are easily found at local stores.) Even if the Bti doesn’t immediately kill the adult, adults sucking up a big sugar meal can transfer the bacteria to water where they lay eggs, and thus eventually cause the death of any larvae that develop. Note that bees and ants might get interested in your sugar water, but the Bti is completely harmless to them.

And if you don’t want to use Bti, there are plenty of articles on using sugar baits laced with insecticides (e.g., Qualis et al. 2013, Junilla et al. 2015). They really can work: mosquitoes absolutely love sugar and will drink up poisons in the process. These are great if you don’t want to use crop dusters to destroy all insects in the area.

If you have kids and want to entertain them, add food dyes to the sugar bait and then challenge them to find mosquitoes with bellies full of sugar water. For older kids that might be amused by actual science, use two dyes to test attractiveness of two different volatiles (or different sugars). It’s probably rare to recapture one right after a nectar meal, but when distended they reveal gut contents nicely.

FYI, white-footed woods mosquito (Psorophora ferox) doesn’t transmit Zika, but illustrates to the unbelieving that mosquitoes do drink nectar.