Dr. Khurshid Ahmad Tariq
The World Biodiversity Day was celebrated on 22nd of May under the auspices of the United Nations Organization to increase awareness about the issues, importance, sustainable use, managemen tand conservation of biological diversity throughout the world. The aim behind this essay is to highlight and understand the relation between parasite species extinction due to man enforced eradication programmes and its effects on biodiversity.
Biodiversity or biological diversity is the variety of life (microorganisms, plants, animals) in terms of number and variety of species and levels of diversity (species diversity, genetic diversity and ecosystem diversity) on this earth. The theme for this year’s day shall be “Celebrating 25 Years of Action for Biodiversity”. In the year 1993, the UN general assembly designated the Convention on Biological Diversity (CBD) for the management and conservation of diversity of life after the CBD was adopted at Earth Summit in Rio de Janeiro in 1992. The convention was based on three objectives: conservation of biodiversity, sustainable use of biodiversity, fair sharing and deriving equitable benefits from the use of genetic diversity.
Parasites have a very high diversity in the world occupying every possible ecosystem on earth. About half of the biological species are parasites and more than three-fourths of the food webs involve parasites. Parasites are not inherently bad and dangerous as we perceive them but are very crucial for the healthy growth of our ecosystems and for the wellbeing of other life on the earth. They are good monitors of ecosystem health and have enabled us to understand the best ecological principles governing the life on this planet. Some of the parasites have been reported with ecosystem buffering roles because they absorb heavy metals and other pollutants from their hosts thereby detoxifying the latter. Therefore, parasites are good ; not bad.
Naturally parasites never want to destroy their host species. Both parasite and its host obey a density dependent ecological principle which naturally stops the extinction process in the host due to ultimate dependence of a parasite on its host. Therefore, it has never been the aim of a parasite to eliminate or be the reason behind the extinction of its host.
The phenomenon of parasite species eradication is an unnatural offshoot of human greed and selfishness at the cost of human betterment. As soon as parasites were found as the causative agents of many plant, animal and human diseases, human beings started developing the means and ways to destroy parasites by introducing many parasite eradication programmes like vaccination, genetic engineering, sterilization and vector elimination. A species extermination being done deliberately by man is not tolerated by nature and it can have devastating effects on our ecosystems. For example, the pathogenic parasites responsible for causing rinderpest in cattle and small pox in human have been eradicated. The eradication programmes of parasites like Screw worm, Hypoderma, Cochliomyia, Echinococcus, Wuchereria, Amblyomma, Tsetse fly, and so on are ongoing in different parts of the world. Similarly, the eradication is almost complete for parasite species Dracanculusmedinensis causing Guinea worm disease. But, the question to be asked is that the absence of these parasite species can lead to ecological imbalances, altered population dynamics, altered food webs and energy cycles, loss of certain ecosystem services and alteration of species interaction in their respective ecosystems of which they form a part.
The word extinction can be of ordinary meaning for a common man but it sends red waves across the minds of a parasitologist. Eradicating any parasite can have some economic gains for man but it has serious consequences for ecosystem functioning.Therefore, the parasite eradication programmes are now challenged by the parasitologists and ecologists because the existence of living organisms on this earth is based on the chain of relationships between the organisms. For example, a parasite that is recognized as the pathogen is itself ultimately host of some other parasite/s which in turn can act as the host for some other parasite, the relationship called as hyper-parasitism sustains so many food chains and energy cycles in an ecosystem. In that instance if one parasite is altered or irritated or eliminated it means the destruction of so many other biological objects.
This certainly challenges the human intentions in eradicating various parasites from the planet. This phenomenon of parasite elimination and eradication ultimately leads to co-extinction (loss or endangerment of other species) that depends on it. In simpler terms the co-extinction means the loss of biological diversity, irreparable loss of co-evolution of species, irreplaceable ecosystem services, loss of food web dynamics, etc. Therefore, we humans need to rethink over it as we have already been recognized as the sole reason behind the sixth mass extinction of biological life from this planet. We need to adopt realistic paths for effective protection of parasite diversity with coordinated efforts of policy makers and public because parasites are well worth to be protected and not eradicated.
—The writer is Assistant Professor of Zoology at the Islamia College of Science and Commerce, Srinagar. He can be reached at: firstname.lastname@example.org.