Fenitrothionis a phosphorothioate (organophosphate) insecticide; cheap and widely used worldwide. In experiments fenitrothion at sublethal doses affected the motor movement of marsupials, and at acute dose levels it reduced the energy of birds. In chronic (low) dose tests, unexpectedly only the lowest concentration (0.011 microgram/liter) of fenitrothion depressed the growth of an algae, though all of the chronic dose levels used were toxic in other ways to the algae. Just half of fenitrothion's minimally effective dose altered the thyroid structure of a freshwater murrel (the snakehead fish). In an unusual demonstration of resistance to pesticides, 8% of insects in farm fields were found to carry a symbiotic gut microbe that can metabolize and detoxify fenitrothion; after in-vitro tests showed that the microbe significantly increased the survival of fenitrothion-treated insects.
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