Certified Crop Advisor Practice Exam

Which of the following increases the possibility of genetic resistance developing in a pest?

1. High population diversity

2. Single gene inheritance of resistance

3. Multiple gene inheritance

4. Natural predation

The correct answer is: Single gene inheritance of resistance

The development of genetic resistance in a pest can often be linked to the mechanisms of inheritance involved. When resistance is determined by a single gene, it often means that only a small number of individuals in the pest population may possess that resistance trait. As a result, if a pesticide is used and some individuals survive because of that single resistance gene, these survivors can reproduce and pass on their resistance to the next generation. This leads to a more rapid increase in the proportion of resistant individuals in the population. In contrast, if multiple genes are responsible for resistance, it generally requires a more complex set of genetic changes to confer the same level of resistance. This necessitates a broader selection pressure and may slow down the process of resistance becoming prevalent in the population, as multiple genes would need to be simultaneously selected for. Additionally, high population diversity can dilute the presence of a resistant allele, and natural predation often reduces pest populations before significant resistance can become established. Thus, single gene inheritance creates a scenario where resistant traits can quickly become widespread, making it more likely for genetic resistance to develop in pest populations.