What Is Biological Rat Control?

Biological controls were defined in a paper titled "Prospects for biological control of rodent populations" written by Kazimierz Wodzicki in 1973 as "an attempt to reduce the population density of a pest species by increasing predation, manipulating conditions of the habitat, introducing or stimulating epizootics, or by application of antifertility agents." The basic principle of biological control is killing or reducing the birth rate of rats by natural agents rather than chemical poisons. It relies on some of the same factors of population control that occur in the natural world without the interference of man.

  1. Parasites

    • According to the Royal Society of Chemistry, rats are susceptible to several parasites. Finding a parasite that causes damage to the rats while not harming any other species is the challenge. The parasites also vary from continent to continent and from region to region within the continent. Parasites often weaken the rat making it more susceptible to other causes of death.

    Predators

    • Rats are hunted by a variety of predators depending on the location. In Asia and South America various snakes often feed on rats. Other predators include the mongoose, owls and other birds of prey, monitor lizards and ferrets. Any activity that increases the number of rat predators will decrease the number of rats.

    Cats as Predators

    • According to Wodzicki cats have been used longer than any other species of animal for vermin control. His study reported that cats are often useful in situations where the rat population has been thinned by poisoning or other form of control.

    Disease

    • Research has been conducted looking for the perfect "rat virus," a disease that causes the death of the rat without harming any other species. This was a common form of rat control in Europe between the early 1900s and about 1959. At that time the use was restricted because of concerns the diseases would spread to non-intended species.

    Biological Control Success

    • According to the Alabama Cooperative Extension Service, biological controls have a low success rate. Predators such as snakes, birds of prey and cats often do as much damage to beneficial species such as songbirds as they do to the rat population.