They flourish there because all of their natural predators are removed during the initial forest clearing. Traditionally, snakes and other potential predators are systematically eliminated if they make any attempt to recolonise the oil palm plantations.
Rat problems - try owls & snakes!
Once established, rats are very difficult to remove from plantations. In the past oil palm plantation managers used poisons indiscriminately to eliminate them. This indiscriminate use also poisoned other animals that were attempting to recolonise the plantations.
Today, more enlightened companies raise and release owls and other predators to control rats on the plantations. They also instruct workers not to kill pythons and other snakes that eat rats. The use of other pesticides on plantations is rather minimal, with a few notable exceptions. For example, the Oryctes rhinoceros beetle, Ganoderma, stem rot, other beetles and even bagworms can require treatment.
Some herbicides are still used, however, particularly when plantations are being established. Once the trees grow and produce a canopy that shades the ground, the use of herbicides is greatly reduced.
Credits
Extracts from "World Agriculture & Environment" by Jason Clay - buy the book online from Island Press
Environmental Impacts: Use of Pesticides
Rats are the most common mammals found within oil palm plantations. Rats are attracted to the plantations because they feed on the oil palm seeds.
