Question

A woman is trying to get rid of weeds in her garden. She sprays them with a pesticide (chemical) and kills most of the weeds. After 2 weeks the garden is again filled with weeds. She sprays them again, but this time only half of the weeds die. What is most likely the reason for this?

Answer 1

The reduced effectiveness of the pesticide is most likely due to the development of resistance among the weed population, a process known as microevolution.

Step-by-step explanation:

The most likely reason for the reduced effectiveness of the pesticide on the weeds is the development of resistance among the weed population. This is an example of microevolution, where a small change in the population results in the ability to withstand chemical treatments that were previously effective.

When the woman initially sprayed her garden with a pesticide, it killed most of the weeds due to their susceptibility to the chemical. Over time, however, the few weeds that survived the initial spraying were likely those with some form of genetic resistance to the pesticide. As these resistant weeds reproduced, they passed on their resistant traits to the next generation. When the woman sprayed the pesticide a second time, it was less effective because a larger proportion of the weed population now possessed resistance to the chemical.

This phenomenon is a well-known challenge in the use of pesticides for weed control. It necessitates the need for other management strategies, such as rotating herbicides with different mechanisms of action, supplementing chemical control with cultural and biological practices, or using more targeted, selective herbicides. These alternative measures can help to prevent or slow down the development of resistance and maintain the effectiveness of pesticides.