Invasive species that are knowingly or unknowingly introduced into new habitats by humans endanger existing ecosystems in many places. But not only that: As a new study shows, they also represent an enormous economic burden. Between 1970 and 2017, invasive species caused costs of at least 1.288 trillion US dollars, and the trend is rising. The amount is due on the one hand to control measures, but above all to direct and indirect damage, for example from eaten crops.
If an animal or plant species succeeds in spreading in a region in which it is not actually native, it often causes great damage: Since natural enemies and competitors are often lacking, it can reproduce excessively and thereby displace or displace native species endanger, for example, by feeding. Introduced species are therefore one of the most important reasons for species extinction. In addition, they are responsible for massive economic losses: Invasive weeds make agriculture more inefficient, introduced insects and small animals eat crops and the tourist attractiveness of a region can also suffer due to invasive species.
The costs of introduced species are increasing
In order to find out how big such damage actually is, a team led by Christophe Diagne from the Université Paris-Saclay in France has evaluated and summarized thousands of published cost estimates. On this basis, the researchers calculated that invasive species caused costs of at least 1.288 trillion US dollars worldwide between 1970 and 2017. “The global cost of alien species is so massive that we spent months reviewing our models and this overall estimate to make sure we weren’t overdoing it,” says Diagne. “Instead, as it turns out, our approach is a massive underestimation of the real economic costs.”
Since 1970, the reported costs have increased year on year. According to Diagne and colleagues, on the one hand, this may be related to the fact that the economic losses caused by invasive species have become more widely known and have therefore been recorded more intensively. However, since it can also be observed that invasive species are spreading more and more worldwide, the authors assume that not only the costs reported have increased, but also the actual costs. “We found that the cost doubles about every six years, a pattern that mimics the continued increase in the number of alien species around the world,” said co-author Corey Bradshaw of Flinders University in Australia.
Invasive insects as the biggest cost factor
The rise in costs can be explained by a combination of factors: “The continuing intensification of global trade and transport creates more and more opportunities for animals and plants to invade new areas,” the authors explain. “In addition, the increasing land grabbing of the planet’s surface, for example through the expansion of agriculture and infrastructure, makes our societies sensitive to the effects of these introductions.”
According to the evaluated data, invertebrates are responsible for the largest share of the damage, especially insects. They can jeopardize crops, require more costly crop protection, and spread disease to humans and livestock. In second place are mammals such as rats. According to the evaluation, however, invasive plant species are only responsible for a small part of the economic losses. The authors point out, however, that this assessment can be distorted by the fact that damage caused by invasive plants is comparatively rarely recorded and reported, while insect damage, for example, is more widely recognized.
Consider the effects of transnational projects
In addition to direct and indirect economic damage, Diagne and colleagues also recorded the costs that arise from control and preventive measures. “The cost of damage from invasive species was about 13 times higher than the cost of all countermeasures,” they report. “In addition, the damage costs rose much faster.” In view of the massive ecological and economic effects, the authors call for increased international commitment to prevent the spread of invasive species. “We need international political agreements that aim to reduce the burden of invasive species,” said Bradshaw.
The researchers believe that the unintended costs of biological invasion should also be taken into account when deciding on transnational projects. They cite China’s “New Silk Road” as an example, where China is opening up new global trade routes, but at the same time creating new ways for animals and plants to spread to foreign regions. “The unintended effects – including costs – that are likely to arise for all affected countries should be factored into the estimated net revenues of this commercial initiative,” said the researchers.
Source: Christophe Diagne (Université Paris-Saclay, France) et al., Nature, doi: 10.1038 / s41586-021-03405-6