Answer:
Random variation in the population led to a population with a favorable adaptation
Explanation:
Insecticide resistance can be defined as an evolutionary process that causes a decreased susceptibility of an insect population to a particular insecticide. The evolution of the insecticide resistance occurs by the mechanism of natural selection, where most resistant insects survive and thus pass on their acquired heritable resistance to their offspring. Moreover, the evolutionary origins of the resistance trait may be associated with different processes: 1-de novo mutations (i.e., the emergence of beneficial genetic changes in the population), 2-standing variation in the original population which is selected under the selective agent (in this case, the pesticide), 3-migration of resistant specimens originally resistant to the pesticide, and 4-even interspecific transfer (i.e., horizontal transfer between different species).
