The Zika virus epidemic, transmitted by the mosquito Aedes aegypti, has caused fear in populations of the affected areas, and some are taking advantage of this to make money. Accordingly, the idea that toads and frog in the home can control mosquitos has spread, and the sales of amphibians as pets has soared.
In Argentina, for example, where there have only been five confirmed cases of Zika, online sales of amphibians have multiplied since the authorities announced that the vector mosquitos are resistant to fumigation.
However, the reality is that, although amphibians are voracious consumers of a wide variety of insects, the strategy of having them at home as pets to fight mosquitos is far from effective.
Amphibians are fundamental in food chains, being both prey and predators. However, the mechanics by which amphibians control mosquito populations, and those of other insects in the ecosystem, are very complex. The effects of amphibian predation on insects takes place at the level of natural communities, which are made up of thousands and millions of individuals of different species in different states of development. Actually, most of the consumption of mosquitos by amphibians happens in the aquatic environment, where amphibian larvae prey on mosquito larvae. Additionally, the most notable aspect of amphibian predation on insects is the enormous variety of insects they consume as prey, which makes it difficult to evaluate their effect on just one individual species. Therefore, although amphibians can severely alter insect communities, the effect of this cannot be described in simplistic terms.
A good example of the risks of using amphibians as agents of biological control is the cane toad (Rhinella marina), which was introduced in many countries as a way to fight agricultural pests. In Australia, since their introduction in the 1930s, the population of cane toads has not stopped growing exponentially. Unfortunately, the desired effect of reducing the insect population in Australia was not achieved, and in the end they went back to using insecticides, and the cane toad became an extraordinary pest that threatens the local biodiversity.
We are very concerned about the commercial sale of amphibians and the possession of these animals by people who do not know the risks of introducing the foreign species into the environment. Even worse, the most widely known damage that these introduced species can trigger, the predation on, and competition with, local species, is child’s play compared to their role as potential vectors of other infectious diseases.
Translated by Nate Stein