Invasive alien species threaten agriculture and biodiversity in Africa: Study

Context

A recent study shows that Africa may lose about $3.66 trillion annually due to impact of Invasive alien species (IAS) on agriculture.

About

About Invasive alien species (IAS):

The International Union for the Conservation of Nature (IUCN) defines an alien species as a species introduced outside of its natural range.
They may be brought in by people accidentally or intentionally into regions where they do not exist.
An alien species becomes invasive once it threatens biological diversity, food and economic security, and human health and well-being.
They may lack natural predators in their new environments, allowing them to quickly increase their abundance and spread.
They can carry diseases, outcompete or prey on native species, alter food chains, and even change ecosystems by, for example, altering soil composition or creating habitats that encourage wildfires.
These impacts can lead to local or global extinctions of native species and eventual ecological devastation.

Impact in Africa:

Africa may lose about $3.66 trillion annually from the impact of the IAS on agriculture and other vital food production programmes.
Cassava in Ghana, for example, is a main staple crop and contributes about 22 per cent and 30 per cent to the agricultural gross domestic product and daily calories intake, respectively.
The crop can be at risk from cassava brown streak virus which can reduce yields by up to 70 per cent.
Maize lethal necrosis, a disease caused by co-infection of Maize chlorotic mottle virus and Sugarcane mosaic virus was first reported in Kenya in 2011 but has since been reported in Democratic Republic of Congo, Ethiopia, Rwanda, and Tanzania.

Zoological Survey of India Report on Invasive Species

The Zoological Survey of India (ZSI) has for the first time compiled a list of 157 alien invasive animal species. This list excludes the invasive microbe species.
Some commonly found alien species:
African apple snail (Achatina Fulica): The most invasive among all alien fauna in India, this mollusc was first reported in the Andaman and Nicobar Islands. It is now found across the country and is threatening the habitat of several native species.
Papaya Mealy Bug (Paracoccus marginatus): Native of Mexico and Central America, it is believed to have destroyed huge crops of papaya in Assam, West Bengal, and Tamil Nadu.
Cotton Mealy Bug (Phenacoccus solenopsis): Native to North America, it has severely affected cotton crops in Deccan
Amazon sailfin catfish (Pterygoplichthys pardalis): This species is responsible for destroying the fish population in the wetlands of Kolkata.
Invasive growth of the grass Paspalum distichum has changed the ecological character of large areas of the Keoladeo National Park, reducing its suitability for certain waterbird species including the Siberian Crane.
In the Kanjli Wetlands, the water hyacinth which was introduced is now invasive. From time to time it is removed using mechanical means.