Explain how a mutation causing resistance to pyrethrins and pyrethroids would spread through a population of bed bugs that are being treated with the pesticide. a) in a population of bed bugs, variation exists. some variation provides resistance to the pesticides. those bed bugs survive to reproduce, passing the resistance on to offspring. eliminate b) mutations happen randomly to change the gene pool of a population. the mutations are favored when a population of organisms winds up in an environment in which the mutations happen to be useful. c) when a population of insects, like bed bugs, is subjected to pesticides, some of the bed bugs alter their genetic make-up and they are able to survive. they then pass the new genes on to offspring. d) in any population of organisms, sexual reproduction provides for variation in the gene pool. such variation allows some insects to be resistant to pesticides. when sexual reproduction occurs again, the resistance is passed to offspring.