A recent study has shown that as many as 10 invasive alien species, out of the 330 that are known to be invasive in India, have cost the economy $127.3 billion in the last 60 years, according to report by Mongabay-India.

The study points to glaring knowledge gaps in costs incurred by these species to the Indian economy. As many as 330 species are declared invasive out of more than 2000 alien species in India and the costs of $127.3 billion as documented in the study comes from only 10 of these 330 species, making India the second topmost invasion-cost bearing country after the United States. These costs are likely to be a “gross underrepresentation” of the actual costs based on the authors’ global analysis of 112 countries, says the Mongabay-India report.

The study adds that the costs of IAS in India are severely underestimated – by anywhere between 20 and 10,000 times less – compared to what would be expected considering all other countries with invasion costs. Highly-fragmented data and wide knowledge gaps, which contribute to the underestimated costs, mainly arise because many invasive species, regions and affected sectors are underrepresented. The costs were pooled from Google Scholar for peer-reviewed literature and Google Search for popular articles, news items and official documents, and through dialogue with 20 researchers and stakeholders across the country who have been working on invasive species.

The analysis finds that invasions by semi-aquatic and aquatic taxa have been causing a greater monetary burden to the economy compared to taxa inhabiting terrestrial ecosystems. The semi-aquatic costs were driven solely by a single species, the yellow fever mosquito, reflecting the substantial human healthcare costs associated with this taxon. While there are synergies in tackling the spread of invasives with climate action, the researchers call for simple tweaks in national policies, for example, the need to include certification, quarantine, post-entry monitoring and early response programmes in national policies and guiding principles. They were also gravely concerned over the “unexplored and silent impact” of invasive species in central India, east India and northeast India’s biodiversity-rich regions for which not even a single cost report is available.

As for the sectors impacted by such invasive species, the study says that more than 99% of costs are attributed to multiple sectors without a proper break-up. Among the one per cent costs which specify afflicted sectors, most costs come from anthropocentric sectors such as fisheries, agriculture, health, social welfare, and administration. The costs related to forests and other non-anthropocentric ecosystems are almost absent. Because of these knowledge gaps, the study states that it is unsure “who the worst offenders are in terms of their economic impacts and the geographic regions where they are causing maximum economic offense and the ecosystems that require urgent attention.” While an economic lens is applied to measure climate impacts, the same treatment for taking stock of the impacts of invasive species is still underexplored. Additionally, the effects of climate change are more tangible than invasive species and both issues are often lumped together. However, researchers point out that synergies do exist between climate action and tackling the spread of invasives.

Another report by Mongabay-India warns that scientists have said that climate change will worsen the spread of invasive species that tend to show a robust resilience to warming and spread across landscapes. The report highlights the research carried out by a team from the Institute of Forest Productivity, Ranchi, India, that analyzed the dispersion dynamics of two invasive plant species. The researchers used computer modelling to examine the present and future (2050) distribution of the two plants in central and eastern India. The study area included Jharkhand, Chhattisgarh and West Bengal. Their results, that the two plants showed robust resilience to climate change, provide valuable information on sensitive sites prone to future invasion. Such prior information helps develop prevention and control measures to contain the infestation.

Invasive species are emerging as a severe threat, especially to natural and agricultural landscapes, according to the researchers. Their presence promotes wildfires in natural landscapes, hinders the regeneration and expansion of native species and their natural habitats; and reduces natural resources for the tribal people living in forest fringe areas and depending on numerous non-timber forest produce. Another threat is transportation, especially in tourist hotspots, which, along with wind, birds and wildfires, drive the dispersal of invasive species that mostly spread along roadsides, agriculture fields and across natural landscapes.