The United Nations proclaimed May 22 as ‘The International Day for Biological Diversity’ to increase understanding and awareness of biodiversity issues. This year’s theme for the International Day for Biological Diversity is ‘Invasive Alien Species’. The theme seeks to highlight one of the greatest threats to biodiversity, by raising awareness of the issue, identifying and implementing solutions to effectively tackle the problem.

Invasive alien species are plants, animals, and other organisms that are non-native to an ecosystem. They adversely impact biodiversity, apart from causing economic hardships.

Centre of Biological Diversity estimates that since 17th century, invasive alien species have contributed to nearly 40% of all animal extinctions. Movement of plants and animals across ecosystems is a natural process. But, human travel and trade are factors contributing to presence of invasives far from their native lands. While they have been transported deliberately in some cases, most of the time, their movement has been by accident. Increased global trade has accelerated their movement.

Invasive species compete with their native counterparts for survival. Invasive species enter into a ecosystem aggressively and stamp their monopoly on survival resources. Since two species cannot occupy the same space, at the same time, invasive species usually displace the natives. An exception would be when the invasive survives in a space where the native cannot tolerate the conditions. Invasive can change the structure of ecosystems, and disrupt its balance causing harmful effects on plants and animals.
India is one among the several countries in the world battling the problem of invasive species.

Parthenium weed was accidentally introduced into India around 1956 and since then has spread all over the country. Initially present in waste lands, it is now intruding into farmlands. It is known to cause asthma, bronchitis, dermatitis, and hay-fever in humans, and livestock.

Giant African snail was introduced into India around 1857 in Bengal. With over 500 different plant species included in their diet, they have created havoc as far as Kerala. Farmers have been affected the most as they have lost their crops.

These are just a couple of examples of invasive species in India. More plant and animal species exist in India that fall under the ‘invasive’ category and cause adverse effects. It is difficult to quantify the monetary loss caused by invasive species in India, due to lack of data. We will never know how many people had health problems attributed to Parthenium, nor how many acres of cultivated lands were lost due to infestation of Giant African Snail.

Following link provides a list of some of the other invasive alien species in India. http://isebindia.com/05_08/07-07-2.html
Owing to the increased social and economic risks posed by the invasive alien species, it is imperative to address the issue in a focused manner. Control measures including mechanical, chemical, and biological methods have so far proved less effective. National Centre for Integrated Pest Management has been established to cater to the emerging plant protection needs.

While the troubles of invasive alien species are many, the negatives are only part of the picture. A complete balance sheet would list some invasive species as being economically beneficial and able to maintain diversity in the ecosystems. To see the invasive species issue as a choice between native species and alien species is myopic. Impending results should not be measured on the yardstick of how many native species are restored in our ecosystem. The widely believed notion, that ‘native species’ is always better than the alien species is incorrect. Answer may lie in formulating a way of managing the various tradeoffs of living in today’s global economy.

‘War’ against the ‘invasion’ of invasive alien species has created a common ground for farmers, non-government organizations, and research institutions across India. More research, and policy implementation is required to combat this invasion effectively.