Context:
∙ Recently, Andhra Pradesh, Odisha, and Punjab have released mosquitofish into local water bodies to address a mosquito menace.
About Mosquitofish
∙ The biological control of mosquitoes, introducing mosquitofish in freshwater ecosystems to feed on mosquito larvae became a prominent way to control mosquito menace.
∙ It is a prominent alternative to chemical solutions like pesticides that have dire adverse effects on both human health and the ecosystem.
∙ Among mosquito predators were two species of mosquitofish, Gambusia affinis and Gambusia holbrooki.
∙ In 1928, Gambusia was first introduced in India during British rule. The idea of this scheme was that the newly introduced species would prey on or compete with mosquito larvae, reducing the latter’s population.
∙ The strategy was well-intentioned but it backfired, leading to severe ecological and environmental problems.
Major Concerns
∙ The mosquitofish began to proliferate with their populations eventually spreading far beyond their original habitats.
∙ These species of mosquitofish originated in the U.S. but today have become global inhabitants.
∙ They are notorious for their detrimental ecological impact, including, displacing and preying on native fauna,
∙ leading to the extinction of native fish, amphibians, and various freshwater communities.
∙ The authors who recently investigated the diversity of haplotypes and genotypes within Gambusia species in India, consider mosquitofish to be among the hundred most detrimental invasive alien species.
∙ Haplotypes are DNA variants likely to be inherited together; the genotype is an organism’s entire genetic material.
∙ Aside from their resilience, these fish also have voracious feeding habits and have demonstrated aggressive behaviour in habitats to which they are introduced.
∙ Studies conducted in other countries have consistently revealed the harmful consequences of the presence of Gambusia in water bodies.
∙ For example, in Australia, introduced mosquitofish have led to the local extinction of the red-finned blue-eye (Scaturiginichthys vermeilipinnis), an endemic fish species.
∙ In India, some reports have indicated a decline in Microhyla tadpoles following the introduction of Gambusia.
Steps Taken
∙ The World Health Organisation stopped recommending Gambusia as a mosquito control agent in 1982.
∙ In 2018, the National Biodiversity Authority of the Government of India also designated G. affinis and G. holbrooki as invasive alien species.
Way Ahead
∙ India’s Gambusia story thus underscores the importance of careful consideration, research, and monitoring when using biological control methods to manage pest species.
∙ At this time, more stringent enforcement measures are crucial to prevent the species from continuing to be introduced to freshwater ecosystems.∙ Alternatives to Gambusia should come from local solutions. Native fish species that are capable of controlling mosquito larvae need to be introduced.
