Zoological Survey of India (ZSI) for the first time compiled a list of alien invasive animal species, totalling 157. This number excludes invasive microbe species.
This compilation was announced on the sidelines of National Conference on Status of Invasive Alien Species in India organised by the ZSI and Botanical Survey of India (BSI).
Alien invasive species
Alien species become ‘invasive’ when they are introduced deliberately or accidentally outside their natural areas, where they out-compete native species and upset ecological balance. Invasive animal species pose a threat to biodiversity and human well-being. They harm agriculture and biodiversity.
Common characteristics of invasive species are rapid reproduction and growth, high dispersal ability, ability to survive on various food types and in a wide range of environmental condition and ability to adapt physiologically to new conditions (phenotypic plasticity).
Of the total 157 listed species by ZSI, 58 are found on land and in freshwater habitats, while 99 are found in marine ecosystem. The 58 invasive species found on land and in freshwater comprises 19 species of fish, 31 species of arthropods, 3 of molluscs and birds, 1 of reptile and 2 of mammals.
Among alien invasive marine species, genus Ascidia accounts for maximum number of species (31), followed by Arthropods (26), Annelids (16), Cnidarian (11), Bryzoans (6), Molluscs (5), Ctenophora (3), and Entoprocta (1).
Some of alien species are
Achatina fulica (African apple snail): It is most invasive among all alien fauna in India. It is mollusc and was first reported in Andaman and Nicobar Islands. Now it is found all across country and is threatening habitats of several native species.
Paracoccus marginatus (Papaya Mealy Bug): It is native to Mexico and Central America. It is believed to have destroyed huge crops of papaya in Assam, West Bengal and Tamil Nadu.
Phenacoccus solenopsis (Cotton Mealybug): It is native of North America. It has severely affected cotton crops in the Deccan.
Pterygoplichthys pardalis (Amazon sailfin catfish): It is responsible for destroying fish populations in the wetlands of Kolkata.