DDT is an insecticide that was used extensively in agriculture in the mid-1900s to kill many insect pests, including the boll weevil (pictured below), another pest of commercial cotton. DDT was initially effective at controlling boll weevil outbreaks, but after about a decade DDT became much less effective, because many populations of boll weevil had evolved resistance to DDT. Required:
Which conditions would biologists say was required for the evolution of DDT resistance in a population of boll weevils?