I discovered that bed bug evolution–specifically resistance to pesticides–was also the subject of the National Evolutionary Synthesis Center‘s podcast this month.  A FASCINATING interview with one of the grand old men of evolutionary genetics, James Crow.  He worked on DDT resistance back in the late 40s and 50s.

There is also a wonderful accompanying article at Understanding Evolution.  And, they repeat something that I’ve tried to explain in the past:

“Like pyrethrums, DDT kills insects by acting on the sodium pores in their nerve cells — and it just so happens that many of the same mutations that protect an insect against DDT also happen to protect it from pyrethrums. When DDT was first introduced, such mutations were probably extremely rare. However, with the widespread use of DDT in the 1950s and 60s, such mutations became much more common among bed bugs through the process of natural selection. Though DDT is rarely used today because of its environmental effects, these mutations have stuck around and are still present in modern bed bug populations. Because of the action of natural selection in the past (favoring resistance to DDT), many bed bug populations today are primed with the right sort of genetic variation to evolve resistance to pyrethrums rapidly.”

Posted by Gwen Pearson

Entomologist. Educator. Writer. NERD.


  1. […] BugGirl helpfully points us to some excellent new resources on bed bugs and pesticide resistance. […]

  2. […] yes, you’re right:  DDT stopped working against bedbugs in the 1950s (see Bug Girl’s recent post).  That doesn’t stop the publicists from defending the movie at the movie’s blog.  […]

  3. Interesting, I would not of expected DDT-resistance to provide cross-resistance to pyrethrums. I remember when many people were claiming that there would never be resistance to BT. I always thought that moronic, especially since the endotoxin occurs in nature, and it didn’t take long to find out I was right. I wonder what BT-resistance confers cross resistance to?

    Pyrethrum is extracted from a composite and I know many birds will dress their nest with plants that are alleged to have a negative effect on their parasites, including the bloody house sparrows that ravaged my only expensive variety of Achillea millefolium. I wonder if the bed bug genes conferring resistance to DDT originated in response to composites in bird nest cimicids or even to our ancestors’ tendency to spread smelly plants around the house?

  4. As for resistance you are correct? but we find they are not resistant to Thrins/throids as a whole, yet! Deltamethrin is becoming rapidly ineffective on them but other products such as cyfluthrin still work to control bed bugs, especially when combined with imidacloprid. DE (diatomaceous earth) is great for long term residual control and unfortuantely it being sold on the internet as “Cheap Way to Get Rid of Bed Bugs!” to disasterous effect. As a pest control proivder we have layered our attack and have achieved about 90% elimination on the first treatment. Our layer is
    1. Steam Treatment of entire room, furniture, carpet, bed, carpet…..you get the picture
    2. Encasement of infected mattress after treatment.
    3. chemical treatment

  5. Dave–it’s really more of a biochemical accident–the ion pathway that is blocked is similar, and changes in proteins confer resistance to both, or at least partial resistance.

    And I agree, anyone who thinks there will never be resistance to something is moronic :)

  6. JD–correct, and there is =huge= geographic variation in resistance of populations as well, which is really interesting.

  7. The Bed Bugs Bite October 9, 2010 at 3:58 am

    Fascinating stuff Bug Girl! Light years ahead of the normal “bed bugs are coming” pablum spouted by most blogs. Any Pro/Con argument on DDT is always interesting, couple that with natural selection and you have a cutting edge bed bug blog in our web site’s opinion!

  8. Eeeek i’m not liking the bugs!

  9. […] Our internet’s best expert in bedbugs, Bug Girl, recently featured another post relating how DDT drove evolution of bedbugs, so that bedbugs are no longer susceptible to DDT.  You should go read what Bug Girl said. […]

  10. DDT resistance due to natural selection? Really? And here my landlord told us that he really couldn’t do a lot about the immense population of bedbugs he’d allowed to become established in our building because the meddling socialists in government wouldn’t let risk-taking entrepreneurs like him use DDT.
    Jeez, who to believe…

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