What is it about?

Aggressive predatory species that are intentionally or sometimes accidentally introduced to regions where they are not naturally found, can cause severe environmental damage. Islands tend to have communities of co-adapted species that in many cases have evolved in isolation. Therefore these ecosystems are extraordinarily susceptible to the introduction of new animals and plants, because the island organisms often lack defenses. This is the case for the Jackson's chameleon, an African predatory lizard that lives in trees and is popular in the pet trade. Our research group recently discovered that this lizard is consuming rare native species in the rain forest where it has spread, and to date, no method has been found to successfully control it.

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Why is it important?

Ecosystems provide a multitude of important functions to human society including basic services which we might take for granted, like clean water, clear air, and pollination of plants including crops. One of the principle threats to intact ecosystems today comes in the form of invasive species. Prevention of further introductions is extremely important, because once a plant or animal becomes established it is very difficult and expensive to control and often impossible to eradicate. We hope the method we have tested here can one day be implemented in the field to reduce the population of jackson's chameleons in places where it is a pest, such as the Hawaiian Islands.


I first learned of the use of Tylenol (acetaminophen) to control the invasive brown tree snake on the US territorial island of Guam about 4 years ago while conducting rare candidate endangered tree surveys for Environmental Impact Studies. This gave me the initial inspiration to test this form of chemical control on invasive chameleons in Hawaii. We showed the chemical toxicity is effective in this application, and demonstrated to precise dosage necessary to achieve lethal effects, but the challenge is in how to apply this, or how to get it into the predators. We also presented an idea based on their predatory ecology, for how to trick them into eating empty snail shells laced with the chemical.

Dr Brenden Holland
Hawaii Pacific University

Read the Original

This page is a summary of: Chemical control of the invasive Jackson's chameleon (Trioceros jacksonii xantholophus) in Hawaii, International Journal of Pest Management, October 2017, Taylor & Francis, DOI: 10.1080/09670874.2017.1386334.
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