<P> Resistance can be managed by reducing use of a pesticide . This allows non-resistant organisms to out - compete resistant strains . They can later be killed by returning to use of the pesticide . </P> <P> A complementary approach is to site untreated refuges near treated croplands where susceptible pests can survive . </P> <P> When pesticides are the sole or predominant method of pest control, resistance is commonly managed through pesticide rotation . This involves switching among pesticide classes with different modes of action to delay or mitigate pest resistance . The U.S. Environmental Protection Agency (EPA) designates different classes of fungicides, herbicides and insecticides . Manufacturers may recommend no more than a specified number of consecutive applications of a pesticide class be made before moving to a different pesticide class . </P> <P> Two or more pesticides with different modes of action can be tankmixed on the farm to improve results and delay or mitigate existing pest resistance . </P>

Explain how some insects develop resistance to pesticides in terms of natural selection