Pesticide resistance – a new development

  • That bugs become resistant to pesticides over time is well known, however, while this resistance develops over multiple generations, bacteria can go through several generations in one day. New research has shown that some bacteria have evolved to be able to digest the toxins in insecticides, but also have the ability to live inside the gut of insects, providing them with resistance.
  • The phenomenon requires several factors to coincide:
    • The pesticide observed was one of the most commonly used organophosphorus insecticides in the world (fenitrothion), which has been so widely deployed that bacteria have evolved to use it as a feed source.
    • Many of these bacteria inhabit the soil where the pesticide is used, simply cutting down the level of insecticide present. One particular species however, Burkholderia, also has the ability to inhabit the gut of insects.
  • Within the experiment, a pot of soil treated with fenitrothion was found to boost the bacterial population and that 80 per cent of the bacteria grown were able to digest the toxin. When plants were grown in both sets of soil and an agricultural pest introduced, those that were on the insecticide treated soil ended up with bacteria in their mid-gut that could digest the pesticide. This also appeared to provide the bugs with protection from surface exposure to the insecticide.

The research is important in that it shows that where previously it was thought that pests selected for resistance over multiple generations, the presence of bacteria in their gut means this can happen in the space of a day. However, the researchers found that in this case, where fenitrotion was used sparingly, the resistance doesn’t seem to occur because if the bacteria can’t guarantee its presence, they won’t evolve the ability to digest it. Future research may be needed to test the effects of smaller applications, and up skill the farming community to help them to tackle pesticide resistance.

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About Julia Chatterton

Systems modeller with a particular expertise in food, farming and agricultural systems. Working with life cycle assessment methods for over 4 years to assess and analyse the environmental burdens associated with food and other production systems.
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