The Palmyra Atoll is a little known, small chain of islets a thousand miles south of Hawaii. Rats had invaded it while troops were there during World War II. Without natural predators, the rats thrived, devouring seabird eggs, native crabs, and whatever seeds and seedlings they could find. The rats eventually wiped out the native crabs and a number of ground-nesting seabirds. Fortunately, the rats on the atoll were eradicated in 2011 in a coordinated rat baiting project. Crabs and seabirds came back, as expected, but another, completely unexpected benefit resulted—mosquitoes stopped biting. A two-year survey was just completed, and it confirms this, having found not a single Asian Tiger mosquito there.
The Asian Tiger mosquito (a species that invaded the U.S. in 1985 and is now in 40 states), is capable of transmitting a number of dangerous diseases to humans. This mosquito feeds during the day, preferentially on mammals (including rats and people on the islet). Before the rats were eliminated these mosquitoes tormented the few people who were there. There are only from five to 30 scientists who live there at any one time.
Were the mosquitoes eliminated because their main host, rats, were eliminated, and there were not enough people and no other mammals to feed on? Perhaps, but that is not the whole story.
When the rats were there, they gnawed the fallen coconut shells in half so they could eat the succulent coconut flesh inside. These half-shells littered the atoll. The coconut shells would fill with rainwater and became ideal places for mosquito larvae to grow. With the rats gone, the main food source of the mosquitoes was gone, plus the mosquitoes had a harder time finding standing water to complete their life cycle.
The rats were not only causing problems themselves, they were also the reason dangerous mosquitoes thrived there!
- Posted by admin
- On May 22, 2021
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