Gentrol may make bed bugs worse
By nobugsonme on Mar 26, 2007 in bed bugs, bedbugs, gentrol, pesticides, treatment
Hi all,
An anonymous entomologist and PCO who reads the blog has clarified for me the issues around Gentrol (an Insect Growth Regulator commonly used against bed bugs, by PCOs: IGRs are supposed to halt growth, which should cut off reproduction). We have heard before that Gentrol isn’t
But my source tells me this:
In recent research, the results seem to indicate that the
use of Gentrol is at best not producing the
expectd positive results in regard to overall
bed bug reduction. In fact in this study it seems
that the use may result in a long term increase.But again this is one study and the unexpected
outcome itself still needs to be studied.
It hadn’t occurred to me that Gentrol could be not just ineffective, but might also make your bed bug problems worse. Still, the jury is still out, and we need more information.
content rss
jessinchicago | Mar 26, 2007 | Reply
As a side note, I recently read something (cannot remember where or what) that indicated Gentrol might actually cause bedbugs to increase activity and lay more eggs, at least directly following initial exposure. This was explained as a normal effect of the product, as the stimulation of procreation actually leads to more bugs exposed to the intended effects in a shorter amount of time- before the product is rendered ineffective over time. Also, I believe I read that Gentrol stimulates the behavior of roaches and other targeted insects as a method of control as explained above. I wonder if this is what the expert is referring to, or if it’s something else altogether? Interesting…
S. | Mar 27, 2007 | Reply
My PCO had been to a conference where a study like this was shared. I don’t recall the details either, but it was a similar outcome - at best, nothing happens; at worst, they actually reproduce more. I still think the theory of an IGR is sound, but maybe Gentrol isn’t quite ready for prime time.
I hope the ‘anonymous expert’ will keep us posted if this changes!
willow-the-wisp | Mar 30, 2007 | Reply
I had heard thet growth regs didn’t work on bb’s, then I heard they prevent adult state of bed bug.
naybe this is whewr I should have put it:
who knows
nobugsonme | Mar 30, 2007 | Reply
Willo,
The intention is to prevent their growth from nymph to adult. But the study says this may not happen. It may not be effective, and may have the opposite effects.
Hopefully more studies will follow.
anonymous | Mar 8, 2008 | Reply
The study was never officially published, but here is an excerpt from it dated December 2007. Note, the study was actually supported by Zoecon (the company that manufacturers gentrol IGR)! Below is the excerpt from the study. Please understand that since the study has yet to be “published”, I must keep my anonymous status at this point in time…
The following paper was presented at the Annual Meeting of the Entomological Society of America on 13 December, 2006: The effects of hydroprene (9%) on the common bed bug (Cimex lectularius (L.) development by David J. Moore, Dini M. Miller (VPI).
Note: the study was supported by Zoecon.
Summary of the study:
The study was targeted at third instar nymphs of bed bugs using the labeled rate of Gentrol. The third instar stage was selected because this stage was supposedly the most susceptible to the effect of hydroprene. Gentrol was applied to filter paper strips, which were placed into small glass vials containing third instar bed bugs. Three filter paper strips (one treated and two untreated) were placed into each vials for the Gentrol treatment whereas the control treatment received three untreated paper strips. After 2 weeks of continuous exposure, one untreated filter paper strip was replaced with a fresh Gentrol treated paper to mimic application recommendation by Zoecon in the Gentrol treatment.
No developmental effects were evident in the nymphs until the commencement of nymph-to-adult molt. Sixteen percent of bed bugs died during mid-molt and an additional 18% died due to incomplete sclerotization of the adult cuticle. Surviving adults were examined for morphological defects. Males exposed to Gentrol showed a 25% reduction in the length of the male genitalia and the deformation of female genetalia was also observed. Potential reproductive effect of Gentrol exposure was examined by paired crosses of the survivors (control vs. treated) by sex. Treated females mated with treated males produced ~15.3 eggs, treated males mated with untreated females produced ~11.5 eggs whereas untreated males mated with untreated females produced ~7.9 eggs. Egg viability was > 95% in all crosses. The study showed that exposure to Gentrol significantly improves the fecundity of bed bugs, and thus the effect of Gentrol on the overall level of control is actually negative.
mangycur | Mar 8, 2008 | Reply
Anonymous, that is fantastic. Where can we get a copy of the full study? Can I find it by googling?
persona-non-bugga | Mar 9, 2008 | Reply
Anonymous, thank you so much for sharing this.
Do you expect the study will eventually get published?
To any entos: are there other insect growth regulators that have been shown to be effective against bedbugs? Thanks in advance for any responses.
Natalie | Apr 1, 2008 | Reply
i was treated with Gentrol and 5 days later I have found several BB’s on my person AND a ton of Roaches that were in hiding before!!!
nobugsonme | Apr 1, 2008 | Reply
Natalie,
The jury is still out on whether Gentrol helps or makes bed bug infestations worse.
I think I can say, though, that whatever negative effects it might have would not have occurred within five days.
It is more likely that something your PCO used to treat (perhaps a flushing agent) drove bed bugs and roaches out of hiding. This does not mean their population has increased, but rather means you have a better shot at killing them. Hiding bugs do not die from pesticides. Coming out and crossing poison is the way they will be hit.
So, sorry this is unpleasant, but don’t assume the treatment was bad. If you want more feedback, come to the forums (button above). In any case, make sure your PCO re-treats in about 2 weeks.