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How can they develop a resistance to something that physically destroys their exoskeleton? It acts as an abrasive. >Boric acid also has the reputation as "the

How can they develop a resistance to something that physically destroys their exoskeleton? It acts as an abrasive. >Boric acid also has the reputation as "the gift that keeps on killing" in that cockroaches that cross over lightly dusted areas do not die immediately, but that the effect is like shards of glass cutting them apart. This often allows a roach to go back to the nest where it soon dies. edit: found the article, >All of the tested resistance intervention strategies selected for increased resistance to all AIs applied in field treatments except boric acid....Our results also showed non-significant, but nonetheless elevated cross-“tolerance” towards boric acid in some instances.[0] So it's probably noise in the data. Boric acid is different from the rest of the substances studied. It may not be all that effective however, according to the paper, is my take. [0] https://www.nature.com/articles/s41598-019-44296-y https://www.nature.com/articles/s41598-019-44296-y

orblivion 7y ago
> How can they develop a resistance to something that physically destroys their exoskeleton? It acts as an abrasive. Broadly speaking, couldn't they just develop a change to the structure of their exoskeleton? I can see how it might be less likely than a chemical resistance, but it still seems possible.
- CriticalCathed 7y ago
  I'm sure it's possible, but it's like a human being developing a resistance to a hammer to the skull. It would take much more than few generations of selective pressure to do that.
  - perfmode 7y ago
    how many generations will roaches have passed through within the space of one year? tens? hundreds? thousands?
    - graywh 7y ago
      American cockroaches take 6 months to a year to reach reproductive maturity
  - dmitrygr 7y ago
    Your skull IS such an adaptation. Not hammer, but it does protect your CNS from many physical harms, and was evolutionarily gifted to you back in the days of early vertebrates
    - CriticalCathed 7y ago
      I'm not saying it's not an adaptation. Think about the scale of time you just referenced and compare it to the frame of time of the study and my comment. Read my comment again. Thank you.
      - dmitrygr 7y ago
        The speed of evolution is mainly a function of the length of a generation (and also of the amount of pressure from the environment). Consider how long human generations are compared to cockroaches, and how little evolutionary pressure humans face today. Read my comment again. Thank you
        CriticalCathed 7y ago
        I did read your comment. You're wrong. A few generations (1.5 years) would not plausibly have this effect. I doubt even a hundred generations would be able to select for something so significant since it's a weakness that all exoskeleton insects have. Insects have remained largely the same for millions of years. I never said it wasn't possible, I said it wasn't plausible for it happen on short scales of time such as this study. You're being pedantic, but you're still wrong.
  - Teever 7y ago
    Different humans have skulls of different thicknesses and if there was a situation where hammer skullings became major cause of death I'm sure that over time those with thicker skulls or other features that made them less susceptible to skullings would survive and flourish.
    - deleted 7y ago
      [deleted]
logfromblammo 7y ago
I get the sense that someone has confused boric acid with diatomaceous earth, and spread their confusion to Wikipedia. For an insect with a waxy cuticle over their exoskeleton, walking over diatomaceous earth is basically like John McClane in Die Hard, running in bare feet over broken glass. Except instead of bleeding to death from the lacerations, the water in their hemolymph diffuses out at a faster rate through the scratches in their cuticle, and they dehydrate to death. The glasslike skeletons of diatoms are hard, sharp, and insoluble in water at neutral pH. Boric acid has to be ingested. It's a chemical poison. It works fine when added to bait. Sprinkling it as a powder won't work as well, as the insect would have to be dusted with it over their body, and then groom themselves shortly thereafter to remove the powder. Walking through it just dusts the ends of the legs. It works especially well with ants, who will carry poisoned baits back to the colony, but only if you add it to sugar or peanut butter. As boric acid is softer than glass, and soluble in water, I wouldn't count on it as an insect-killing abrasive. We can all blame Wikipedia user Rfc1394, who added the text to the Boric Acid article at 10:05, 23 June 2017, apparently with a citation to the EPA R.E.D. factsheet, which does not contain anything remotely close to the text added.
- CriticalCathed 7y ago
  I think you're mistaken. There are many other independent sources that talk about its action as an abrasive. You may be the one spreading confusion. Here's one of many. This one is from the National Pesticide Information Center which operates out of Oregon State University in partnership with the EPA (OSU has a large focus on agricultural research.) > It can also scratch and damage the exterior of insects. http://npic.orst.edu/factsheets/boricgen.html http://npic.orst.edu/factsheets/boricgen.html
  - logfromblammo 7y ago
    I'd take a source that has been peer-reviewed by entomologists containing the evidence of independently repeatable measurements. The falsifiable hypothesis is that crystalline boric acid can kill an insect without being ingested, by a purely mechanical action. Sassolite (boric acid) has a Mohs hardness of ONE. Please understand why I might be skeptical of its supposed reputation for killing things by scratching them. Minerals with low Mohs hardness, like graphite, talc, and yes, also boric acid, are used as lubricants.[0] I also question whether those multiple sources in support are truly independent, as I have seen several search results that quote the Wikipedia article verbatim. [0] http://nersp.nerdc.ufl.edu/~wsawyer/boricWear2006.PDF http://nersp.nerdc.ufl.edu/~wsawyer/boricWear2006.PDF

orblivion 7y ago

> How can they develop a resistance to something that physically destroys their exoskeleton? It acts as an abrasive. Broadly speaking, couldn't they just develop a change to the structure of their exoskeleton? I can see how it might be less likely than a chemical resistance, but it still seems possible.

CriticalCathed 7y ago
I'm sure it's possible, but it's like a human being developing a resistance to a hammer to the skull. It would take much more than few generations of selective pressure to do that.
- perfmode 7y ago
  how many generations will roaches have passed through within the space of one year? tens? hundreds? thousands?
  - graywh 7y ago
    American cockroaches take 6 months to a year to reach reproductive maturity
- dmitrygr 7y ago
  Your skull IS such an adaptation. Not hammer, but it does protect your CNS from many physical harms, and was evolutionarily gifted to you back in the days of early vertebrates
  - CriticalCathed 7y ago
    I'm not saying it's not an adaptation. Think about the scale of time you just referenced and compare it to the frame of time of the study and my comment. Read my comment again. Thank you.
    - dmitrygr 7y ago
      The speed of evolution is mainly a function of the length of a generation (and also of the amount of pressure from the environment). Consider how long human generations are compared to cockroaches, and how little evolutionary pressure humans face today. Read my comment again. Thank you
      - CriticalCathed 7y ago
        I did read your comment. You're wrong. A few generations (1.5 years) would not plausibly have this effect. I doubt even a hundred generations would be able to select for something so significant since it's a weakness that all exoskeleton insects have. Insects have remained largely the same for millions of years. I never said it wasn't possible, I said it wasn't plausible for it happen on short scales of time such as this study. You're being pedantic, but you're still wrong.
- Teever 7y ago
  Different humans have skulls of different thicknesses and if there was a situation where hammer skullings became major cause of death I'm sure that over time those with thicker skulls or other features that made them less susceptible to skullings would survive and flourish.
  - deleted 7y ago
    [deleted]

logfromblammo 7y ago

I get the sense that someone has confused boric acid with diatomaceous earth, and spread their confusion to Wikipedia. For an insect with a waxy cuticle over their exoskeleton, walking over diatomaceous earth is basically like John McClane in Die Hard, running in bare feet over broken glass. Except instead of bleeding to death from the lacerations, the water in their hemolymph diffuses out at a faster rate through the scratches in their cuticle, and they dehydrate to death. The glasslike skeletons of diatoms are hard, sharp, and insoluble in water at neutral pH. Boric acid has to be ingested. It's a chemical poison. It works fine when added to bait. Sprinkling it as a powder won't work as well, as the insect would have to be dusted with it over their body, and then groom themselves shortly thereafter to remove the powder. Walking through it just dusts the ends of the legs. It works especially well with ants, who will carry poisoned baits back to the colony, but only if you add it to sugar or peanut butter. As boric acid is softer than glass, and soluble in water, I wouldn't count on it as an insect-killing abrasive. We can all blame Wikipedia user Rfc1394, who added the text to the Boric Acid article at 10:05, 23 June 2017, apparently with a citation to the EPA R.E.D. factsheet, which does not contain anything remotely close to the text added.

CriticalCathed 7y ago
I think you're mistaken. There are many other independent sources that talk about its action as an abrasive. You may be the one spreading confusion. Here's one of many. This one is from the National Pesticide Information Center which operates out of Oregon State University in partnership with the EPA (OSU has a large focus on agricultural research.) > It can also scratch and damage the exterior of insects. http://npic.orst.edu/factsheets/boricgen.html http://npic.orst.edu/factsheets/boricgen.html
- logfromblammo 7y ago
  I'd take a source that has been peer-reviewed by entomologists containing the evidence of independently repeatable measurements. The falsifiable hypothesis is that crystalline boric acid can kill an insect without being ingested, by a purely mechanical action. Sassolite (boric acid) has a Mohs hardness of ONE. Please understand why I might be skeptical of its supposed reputation for killing things by scratching them. Minerals with low Mohs hardness, like graphite, talc, and yes, also boric acid, are used as lubricants.[0] I also question whether those multiple sources in support are truly independent, as I have seen several search results that quote the Wikipedia article verbatim. [0] http://nersp.nerdc.ufl.edu/~wsawyer/boricWear2006.PDF http://nersp.nerdc.ufl.edu/~wsawyer/boricWear2006.PDF