Amid rising cases of dengue cases, the Department of Environment and Natural Resources (DENR) on Tuesday warned the public against releasing frogs and fish to eliminate dengue-causing mosquitoes.
Natividad Bernardino, Biodiversity Management Bureau chief, said frogs and fish in stagnant water and swamps could disrupt the ecological balance of the surrounding environment.
To place frogs and fish is not an effective solution to eliminate dengue-causing mosquitoes as they have “diverse diet from plant materials to small invertebrates, she clarified.
“While adult frogs eat a variety of things, mosquitoes do not appear to be a major part of the diet of any adult frog or toad,” she stressed.
Citing a 2016 study by biologist Jodi Rowley on the effectiveness of frogs to combat the Zika virus, Bernardino said that “mosquitoes make up only less than 1 percent of the frog’s diet.”
The cane toad, known as Rhinella marina, which is being released by several local government units supposedly to combat dengue, is one of the worst invasive alien species in the world, she warned.
“When introduced to a new environment, non-native species of frogs and fishes may become invasive and alter the biodiversity of the area,” she said.
According to Bernardino, the Convention on Biological Diversity defines invasive alien species as “organisms that are non-native to an ecosystem, and which may cause economic or environmental harm or adversely affect human health.”
She added that invasive species can negatively affect human health by directly infecting humans with new diseases, serving as vectors for certain diseases, or causing wounds through bites, stings, allergens, or other toxins.
She said the proliferation of mosquitoes is largely attributed to environmental conditions that encourage the reproduction of disease vectors, such as dirty surroundings, stagnant man-made canals, and interference to natural water flows, and a decline in the quality of wetlands such as streams, creeks, rivers, swamps, and marshes due to solid wastes, invasive plants, and structures.