Question

Q4.15. 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. Which of the following conditions would biologists say was required for the evolution of DDT resistance in a population of boll weevils? Boll weevils in the population learned to adapt to the high levels of DDT in the environment. The boll weevil population needed to evolve DDT resistance in order to avoid extinction. A few boll weevils in the population were resistant to DDT before it was ever used. Exposure to DDT caused specific, nonrandom mutations for DDT resistance within the population.