Why might an organism display resistance to a pesticide?

An organism may display resistance to a pesticide primarily due to overexposure to the chemical. When an organism is repeatedly exposed to a specific pesticide, those individuals that happen to possess traits that confer some level of tolerance or resistance are more likely to survive. This selective pressure leads to a higher proportion of resistant individuals in subsequent generations.

As a result, the population evolves to include more individuals that can withstand the effects of the pesticide, ultimately rendering the chemical less effective. This process is a form of natural selection, where the organism's traits adapt to enable survival in an environment where a particular pesticide is frequently applied.

While genetic modifications could contribute to resistance, they typically involve intentional alteration of the organism's genetic material, which is different from the natural selection process described. Nutrient deficiencies and habitat changes may influence an organism's health or behavior but are not directly linked to the development of pesticide resistance.