Biological control Biological control is a method of controlling a certain population of organisms. It makes use of the prey -predator interaction, parasitism or competition relationship est control is a major issue, especially in agriculture. Excessive use of pesticides costly, causes pollution and increases the resistance of the pests. Resistance develops when some pests escape from death by receiving a lower dose of pesticides or are able to tolerate pesticides better than others. These pests tend to survive and increase in the population as long as the same pesticide is used. The resistant pests reproduce and eventually, a large percentage of the population is able to withstand the pesticide. Biological control is a more effective way to control pests. For example, a plantation owner uses owls and snakes to reduce the number of rats in an oil palm estate because owls and snakes are natural predators of rats.