So, I guess our earlier DDT post was too lighthearted. Please bear with us; we’re learning. This is actually a very serious subject. I hate to see people in our bed bug community wasting their precious resources of energy and time on the idea that DDT could once again be a solution for bed bugs.
I understand why people yearn for it, and media reports are partly to blame, but entertaining the idea of ‘bringing back DDT’ is so disheartening, such a powerful distraction from the good work that can be done and that we should all consider.
So, for those who doubt that bed bugs are really resistant to DDT, here are some sources for your review.
Links below are PDF articles retrieved from the Armed Forces Pest Management Board’s excellent Literature Retrieval System (an amazing resource).
Bed Bugs [to download PDF enter accession:112924], World Health Organization, Vector Biology and Control Division, 1982:
Table: Insecticide Resistance in Bed Bugs in Countries or Areas (WHO, 1980)
C. lectularius is the particular bad guy we’re tracking in the table above, the common bed bug.
Insecticide Resistance of Medically Important Arthropods [to download PDF enter accession:23590], Report of the U.S. Army Environmental Hygiene Agency Medical Entomology Division, January 1962:
Table: Insecticide Resistance of Medically Important Arthropods
Note, in the earlier post I cited slightly different years for the first reports of observed resistance, 1947 for the Hawaii report and 1951 for Israel. The 1947 date is cited in various secondary sources and the 1951 date is from a WHO bulletin: A survey of bed-bug resistance to insecticides in Israel, Norman G. Gratz, 1959, 20, 835-840.
In a March 2008 Bedbugger interview, Texas A & M research scientist James W. Austin noted the continued resistance to DDT (emphasis added):
While screening multiple populations of bed bugs against various insecticides we have found virtually all populations were 100% resistant to DDT. This is not a surprise given that the first observances of DDT resistance were noted almost 50 years ago. It is a little surprising that they continue to be so completely resistant to DDT.
In 2007, Alvaro Romero, Michael F. Potter, and Kenneth F. Haynes, published their findings of insecticide resistance: Insecticide Resistance in the Bed Bug: A Factor in the Pest’s Sudden Resurgence? (Journal of Medical Entomology, Volume 44, Number 2, March 2007 , pp. 175-178). The July 2007 article in Pest Control Technology contains an additional table (on page 50) which outlines DDT susceptibility of 5 bed bug populations:
Three of the four pyrethroid-resistant populations we tested exhibited minimal mortality after five continuous days of exposure — suggesting that bed bug resistance to DDT may be common today, as was becoming the case a half-century ago when the pest was vanishing from this country.
It’s really not that difficult to find references to the history of DDT resistance in bed bugs. Here’s one, from a July 2001 New Yorker article by Malcolm Gladwell, The Mosquito Killer, where Dr. McWilson Warren (National Institute of Allergy and Infectious Diseases) remembers the challenges of malaria eradication work in Malaysia in the 50s and 60s:
“Then the Malaysians started to complain about bedbugs, and it turns out what normally happens is that ants like to eat bedbug larvae,” McWilson Warren said. “But the ants were being killed by the DDT and the bedbugs weren’t—they were pretty resistant to it. So now you had a bedbug problem.”
A bed bug problem is exactly what we have right now.
But DDT is a complete waste of mental space.
Update 9/1/10: I found the research article Dr. Austin was likely referring to and mentioned it elsewhere but neglected to write an update to this post:
Steelman, C. Dayton, Allen L. Szalanski, Rebecca Trout, Jackie A. McKern, Cesar Solorzano, and James W. Austin. 2008. Susceptibility of the Bed Bug Cimex lectularius L. (Heteroptera: Cimicidae) Collected in Poultry Production Facilities to Selected Insecticides. Journal of Agricultural and Urban Entomology 25(1): 41-51. doi:10.3954/1523-5475-25.1.41.
They tested three populations of bed bugs collected from broiler-breeder poultry facilities in Arkansas (they threw in DDT tests just because):
No previous history of organochlorine use was obtained for any of the facilities containing the three populations of bed bugs utilized in the present studies as all three facilities were constructed after the ban on organochlorine insecticides in the United States over 30 yr ago. However, we included DDT in these studies and found that the LC50s of all three populations were >100,000 ppm. It seems probable that all three of these bed bug populations had been exposed to DDT or other organochlorines at some previous time, and certainly before the infestations occurred in the broiler-breeder egg production facilities. High levels of resistance to DDT, effectively acting as 99% exposure, caused only 20% mortality after 96 h of continuous exposure.
LC50 = pesticide concentration to kill 50% of the exposed bed bugs (exposed for 24 or 48 h at 25dC in insecticide-treated vials).
Two years later and DDT for bed bugs is still the same powerful media-driven dream that will not die. I expect people will be clamoring for DDT 50 and 100 years from now. An interesting question is, if it worked, would it make a difference anyway? They can’t even approve propoxur, which does work, what makes anyone think they would even think of considering DDT, which doesn’t?