Slowing the Race by Slowing the Attack

Abstract

Though it may seem counterintuitive, we have seen that the more effective a pesticide is, the more likely it is to promote resistance. As a rule, the more intense the killing agent (i.e., pesticide), the greater the stress on the target organism and the greater the selective pressure favoring existing genetic variation that protects the target organism from that stress. This is no more than an extension of Darwin’s five postulates outlining the process of natural selection (as was discussed in chapter 3): most individuals in every population die before they reproduce, and those that survive have some adaptive trait that reduces the environmental stress below lethal levels and allows them to live long enough to reproduce. Adaptation is simply the rapid spread throughout a population of a genetic mutation that promotes survival in the face of the most potent stress. Thus, the greater the proportion of a population that a pesticide kills, the faster the resistant mutant allele will come to dominate the subsequent population, because most of the offspring of the survivors will possess the mutation. The Red Queen governs the process and is capable of shifting into hyperdrive when selective forces, such as pesticides, are very intense. The only way to beat the system using pesticides as the only environmental stress is to eliminate all individuals so that not a single resistant gene survives the chemical assault.