DENR warns against releasing frogs, fish to fight dengue

The Department of Environment and Natural Resources (DENR) warned the public against releasing frogs and fish into swamps and stagnant water to eliminate mosquitoes causing dengue, saying that it is “not an effective solution” and can threaten ecological balance.

DENR - Biodiversity Management Bureau director Natividad Bernardino said that frogs and fish have a “diverse diet, from plant materials to small invertebrates.”

“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,” Bernardino said in a statement on Tuesday.

Citing a study from Australian biologist Jodi Rowley on the effectiveness of frogs to fight Zika virus, Bernardino said mosquitoes make up only less than 1 percent of a frog’s diet.

Bernardo said the cane toad Rhinella marina, which is being released by some local government units to combat dengue, “is one of the worst invasive alien species in the world.”

“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.

The DENR-BMB director said 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.”

According to the Conventional on Biological Diversity, the invasive alien species are defined as  “organisms that are non-native to an ecosystem, and which may cause economic or environmental harm or adversely affect human health.”

Bernardino said the proliferation of mosquitoes is largely attributed to environmental conditions that encourage the reproduction of disease vectors.

“These conditions include dirty surroundings, stagnant man-made canals and interference to natural water flows and decline in the quality of wetlands such as streams, creek, rivers, swamps and marshes due to solid wastes, invasive plants, and structures,” she said.

“The existence of natural predators in these wetland ecosystems, given that they are kept in their natural state or properly maintained, should also help control population of mosquitoes and invasive alien species should never be an option,” she added.

The Department of Health (DOH) on Monday said 92,343 dengue cases have been recorded in the country in the period from January to July 23, a 118-percent increase from the same period a year earlier.

The DENR, together with the DOH, advised the public to keep surroundings clean, maintain unobstructed water flows of water ways, and keep freshwater ecosystems healthy to remove possible breeding grounds of mosquitoes, seek early medical consultation, and support fogging or spraying in hotspot areas. — Richa Noriega/BM, GMA News