1. Borneo – An Example of Human Impact
A food web is representation of all of the feeding relationships within an ecosystem. A food web is a complex and interconnected unit. This becomes clear to us when human actions have unexpected effects. An example of this is evident in the events on the Southeast Asian island of Borneo. In 1955 the World Health Organization used the pesticide DDT to kill mosquitoes that carry the disease malaria (characterized by severe fever and sweats). The DDT killed the mosquitoes and relieved the malaria, but it caused an undesirable chain reaction on the island

2. Borneo – Human Impact
First, the thatched roofs of many of the homes on the island started collapsing. What could this have to do with DDT? The DDT had not only killed the mosquitoes, but also the wasps that ate thatch-eating caterpillars. Without the wasps, the caterpillars multiplied and devoured the thatch roofs.

3. Borneo – Human Impact
Second, the DDT was killing cockroaches, as well as mosquitoes and wasps. Island lizards then ate the cockroaches. The pesticide in the cockroaches damaged the nervous systems of the lizards. This caused the lizard’s movements and reflexes to slow considerably. Because they now moved so slowly, most of them were caught and eaten by house cats. After eating the lizards, the cats suffered the effects of the DDT and died in great numbers.

4. Borneo – Human Impact
Without cats in the village, rats from the forest moved in. The rat’s fur carried fleas. The fleas were infected with the bacteria that causes plague. Plague is a devastating disease that can wipe out large populations. Finally, officials were forced to parachute crates of healthy cats into Borneo to control the rat population and rid the island of plague.

5. Borneo – Human Impact
The chain of events on Borneo occurred because the organisms on Borneo were connected to each other in a food web. When one part of the web was disturbed other parts were also affected.