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West Nile mosquito spraying kills other insects

By Gary Bogue
Monday, October 9th, 2006 at 10:29 am in Mosquitoes, Pesticide, West Nile virus.

The following brief from the Associated Press appeared in today’s Contra Costa Times "Around The State" section:

"Sacramento — Mosquito spray deployed this summer in the Central Valley exterminated more than the targeted insect, killing ants, beetles, midges and other tiny creatures, according to field samplings by UC Davis.

"The Sacramento-Yolo Mosquito and Vector Control District hired pilots to spray the skies above Davis and Woodland for two nights in August. The EverGreen Crop Protection EC 60-6, a short-lived pesticide, was aimed at killing enough mosquitoes to break a cycle of West Nile virus infection that can move from bird to bug to human.

"The spraying spared larger insects such as dragonflies and butterflies. But Walter Boyce, co-director of the UC Davis Wildlife Health Center, said researchers should study the effects of the insecticide on threatened or endangered bugs."

I couldn’t agree more with Walter’s statement. It’s very important to do what we can to stop the spread of the West Nile virus in California and other states, and one immediate action that can be taken is to kill the mosquitoes that carry the virus. People are dying from this deadly disease.

But right now there’s a LOT of insecticide spraying going on throughout the state of California and it offers researchers a unique opportunity to study the secondary effects of this spraying on other non-target species of insects.(This is all the more important since I recall that there was some talk early on by a few mosquito and vector control districts that this spraying would only kill mosquitoes.)

Walter suggests they focus on threatened and endangered insects, but I think we should take a look at the effects on ALL species of insects.

Threatened and endangered bugs are important because their populations are already dangerously low. But common insects are also important because they are food sources for many species of birds, mammals, amphibians and reptiles. And maybe somewhere down the line, they also feed other threatened of endangered creatures.

These studies might also uncover a method of controlling the West Nile virus that doesn’t affect non-target species. That would be nice.

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4 Responses to “West Nile mosquito spraying kills other insects”

  1. Mike "troll" Dame Says:

    is EC 60-6 a synthetic pyrethroid? i didnt know other counties were useign things other than permethrin, sumithrin & resmethrin, silly me.
    ive been kinda expecting somethign like this after being told how ultra low volume spraying worked it seemed to me that anything close to the size of a mosquito out and about during treatment times could be effected.

  2. Gary Says:

    EC 60-6 is composed of pyrethrins (6%), piperonyl (60%), and petroleum distillates (5-15%).
    Yeah, I’ve been expecting this, too. You can’t spray poisons and not expect to kill things.

  3. Stuart Flashman, J.D., Ph.D. Says:

    I serve on the Board of trustees of the Alameda County Mosquito Abatement District. I wanted to comment on the question of specificity. Pyrethrins (like EC 60-6) are relatively non-specific. They kill pretty much any insect, as well as other arthropods, like spiders, mites, centipedes, etc. The main things affecting what gets killed are time and method of application. If sprayed at dusk and focused in areas where mosquitoes tend to collect (e.g., around water and wetlands), pyrethrins won’t hit a lot of non-target species, but others, such as gnats, that share mosquitoes’ behavior patterns, will definitely be affected. That said, more data on effects on non-target species is always good.

    On the question of other “sprays”, some earlier articles mistakenly equated helicopter application of BTI pellets with spraying. BTI (bacillus thuringensis israelensis) is a protein toxin produced by a bacterium that is an insect pathogen. It attacks the larval insect gut, and is extremely specific — affecting only mosquitoes and very closely related species. However, it’s a larvacide, and has no effect on any adult insects — only insect larvae that live in water.

    BTI is great for early control of mosquitoes, but won’t stop emerged adults from flying, biting, and laying eggs. If the adult population has already gotten out of control, adulticides like pyrethrins are the only way to get rid of them.

    Since no pest control is perfect, personal protection is always in order:

    1) avoid going out at dusk & dawn when mosquitoes tend to be most active;

    2) wear long sleeved shirts, long pants, and socks;

    3) use an effective mosquito repellant (DEET is the “gold standard”, but there are now a few other good ones like picardin.)

  4. repellent Says:


    I would never use any pesticides, I stick to Natural Mosquito Repellent or traps, I buy my at http://www.mosquitorepellent.EU if some are interested, I know they also look for retailers if some wants to sell there repellents or trap.

    well thats just my opinion, have a great day.

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