Why some insects resist low-oxygen atmospheres in grain storage
Insects have a vital need for oxygen, and research into the risk of populations developing resistance to oxygen-poor modified atmospheres - and a fortiori, atmospheres in which the oxygen and nitrogen in the air are partially replaced by CO₂ has shown that while significant levels of tolerance to oxygen depletion were achieved after selection in 40 successive generations of Tribolium castaneum exposed to atmospheres modified by nitrogen or carbon dioxide, it is impossible for this recurrent selection to occur in practice on the same insect colony.
If a few insects manage to survive anoxia or the dehydrating effect of CO₂, they are eliminated at the time of processing (the hermetic enclosure is completely emptied and no insects remain in the container, unlike in conventional silos) and no progeny of insects more tolerant to asphyxia are possible. This absence of risk of the emergence of inert-gas-resistant populations is a clear advantage over conventional insecticides or phosphine, whose regular and repeated use over time has led to the emergence of insect populations resistant to the recommended insecticide doses in all major cereal-producing countries.