Bedbugs are a pest that has been a nuisance throughout human history. In the 1940s, the widespread introduction of the pesticide DDT allowed people to effectively kill bedbugs at home. However, a mutation in the gene that codes for sodium channels in these insects provided resistance to DDT in some bedbugs. DDT was banned in 1974, but most bedbugs today are still resistant to DDT. What could be an explanation for why most bedbugs still have resistance to DDT?
The mutation that provides resistance to DDT also provides resistance to other commonly used pesticides.
Bedbugs have retained resistance in case DDT is used in the future.
The large amount of DDT used before 1974 bred for exceptionally high levels of resistance, meaning resistance is unlikely to wear off for a very long time.
Once a trait has been selected for, a trait will remain in the population going forward.
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