Question

Describe the four categories of natural, or biological, pest control. Cite examples of each and discuss their effectiveness.

Short answer

The four categories of natural pest control are predation, parasitism, herbivory, and pathogens. Each involves a different method of controlling pest populations. The effectiveness of each method varies with predation and pathogens generally being the most effective, although pathogens can have detrimental effects on beneficial insects as well.

Step-by-step solution

Identify and Describe the Four Categories

The four categories of natural or biological pest control are: Predation, Parasitism, Herbivory, and Pathogens. Predation refers to when one organism, the predator, hunts and consumes another organism, the prey. This method helps in controlling the prey population. Parasitism involves an organism living in or on another organism, the host, and causing it harm. This method aids in controlling the host population. Herbivory pertains to the eating of plants by animals. This method helps in controlling plant population. Pathogens are disease-causing organisms which can control the host population by causing illness and sometimes death.

Cite Examples for Each Category

For Predation, an example would be ladybugs eating aphids. In case of Parasitism, a parasitic wasp laying eggs inside aphids can be taken as an example. A typical example of Herbivory is deer eating tree leaves. Lastly, for Pathogens, we can cite the use of Bacillus thuringiensis, a bacterium, to control caterpillar pests.

Discuss the Effectiveness of Each Category

Predation is highly effective, but needs specific predators for specific pests and is dependent on correct environmental parameters. Parasitism can also be effective but may require larger numbers of parasites to be introduced into the environment. Herbivory is generally less effective as it can lead to overgrazing and other ecological issues. Pathogens are largely effective but may not discriminate between beneficial insect species and pests, and thus can be harmful to beneficial insects.