MANILA, Philippines – Scientists from the University of the Philippines Diliman's Institute of Biology (UP-IB) on Wednesday, September 11, condemned the recent release of invasive fish and toad species to quell mosquito populations, calling the measure "a recipe for ecological disaster."
As a response to the dengue outbreak, around 6,000 mosquitofish stocks were released in Dagupan City, Pangasinan, last August by the National Integrated Fisheries Technology Development Center-Bureau of Fisheries and Aquatic Resources.
Local barangay officials of Barangay Matandang Balara, Quezon City, led the release of more than 1,000 "bullfrogs," which were later identified as the invasive and highly toxic cane toad species Rhinella marina. (READ: Oops? QC barangay goofed in releasing cane toads to estero)
However, both the mosquitofish and cane toad are on the list of the top 100 worst invasive species worldwide.
'Ineffective mosquito control agent'
Citing numerous studies, the UP-IB said that contrary to what its name suggests, the mosquitofish is not the most effective combat against mosquito larvae.
"Because of its broad diet and ability to outcompete many fish, invertebrate, and vertebrate larvae, the negative impacts of introduced mosquitofish on native fauna is much greater than its intended use as a mosquito control agent," the UP-IB said.
Likewise, the UP-IB pointed out that cane toads are not effective in controlling mosquito populations.
"The fact is that they do not consume significantly enough to control mosquito populations," the UP-IB said, citing a study that found that mosquitos constituted less than 1% of a frog's diet.
The UP-IB added that cane toads are poisonous in all its life stages, from egg, tadpole, froglet, to adult. Human deaths have even been recorded following ingestion of cane toad eggs or adults.
Due to the cane toad's highly invasive nature, the scientists also raised alarm over the proximity of the release site to the UP Diliman campus, one of the last remaining green spaces in Metro Manila. The university has stressed their support of the plethora of native and endemic wildlife.
"These wildlife can very well disappear, disrupting the ecosystem functions they provide if their habitat is overrun with cane toads." the UP-IB said.
Against the law
The UP-IB also pointed out that the irresponsible release of the two invasive species violated Republic Act No. 9147 or the Wildlife Resources Conservation and Protection Act, which requires that a careful study and public consultation be conducted prior to the releases.
"Violators of RA 9147 could potentially result in imprisonment of up to 8 years and a fine of up to 5 million pesos," the UP-IB said.
The UP-IB said that the most effective combat against dengue is keeping your surroundings clean, removing possible breeding grounds for mosquito larvae, and applying mosquito repellent often.
The scientists called for a halt to the release of invasive species in the Philippines. They also recommended that further studies be conducted on both the dengue outbreak and the impact of invasive species. – Rappler.com
Nicolas Czar Antonio is a Rappler intern who studies psychology at the University of the Philippines Diliman. He tweets at @Nicolas_Czar.