[LUM#5] Dear Invaders

[LUM Magazine] - Published on March 14, 2017 in Science and Society

69 billion euros. That is the annual cost of damage caused by invasive insects worldwide. A figure that is significantly underestimated, according to researchers, who argue that the actual cost is much higher…

It measures just a few millimeters, yet it costs us billions… Native to Asia, the Formosan termite arrived in the United States at the end of World War II, hidden in the wooden crates of GIs returning home. Once it reached the American continent, the insect found a climate conducive to its growth and gradually colonized this new territory. The problem: this tiny wood-boring insect, which will eat anything to satisfy its insatiable appetite, is wreaking havoc on homes. And the bill is steep: each year, the Formosan termite is estimated to cost the public 26.7 billion euros.

Like it, dozens of insect species are taking advantage of global trade to colonize new territories, spreading through the transport of containers, cargo, and other goods. Once established, these tiny stowaways can cause significant damage, gnawing away at homes and crops or spreading new diseases. Invasive insects that come at a high, very high cost… To assess the bill, a team of researchers comprising entomologists, ecologists, and economists reviewed 737 publications on the impact of the top 10 invasive insect species. Verdict: the cost of the damage caused by these insects is estimated to be at least 69 billion euros per year (Massive yet grossly underestimated global costs of invasive insects, in Nature Communications, 2016).

Pest insects

While buildings suffer greatly from the Formosan termite, agriculture is also a sector heavily impacted by invasive species.“Insects as a whole consume 40% of crops,” explains Frédéric Simard, director of the Mivegeclaboratory and co-author of this study. That’s 40% of agricultural production—enough to feed a billion people. Among the most destructive pests is the cabbage moth, an invasive insect that feeds on all types of cruciferous vegetables and causes nearly 4.1 billion euros in damage each year.

Another affected sector: healthcare.“The total cost attributable to invasive insects in this sector exceeds 6.1 billion euros per year,” notes Frédéric Simard. The main culprits: mosquitoes Aedes, vectors of dengue fever, including the tiger mosquito now present in the region.“And yet this figure only accounts for direct costs—the cost of medical care and hospitalizations, for example. It does not account for indirect costs,” warns the entomologist. Such as, for example, an employee’s absence from work due to illness or potential long-term effects, or “the cost of training doctors to manage this disease,” adds Jean-Michel Salles, an economist at Lameta and also a co-author of the study.

The tip of the iceberg

So these little critters would cost us more than 69 billion?“Much more!”admit the experts, who acknowledge that this figure is just the tip of the iceberg.“There are many species for which we have no data and many regions that haven’t been studied; most of the studies we’ve found focus primarily on the United States and to a lesser extent on Europe, with nothing in Africa and very little in South America and Asia,” notes Frédéric Simard.“There are also factors that are very difficult to quantify, such as the consequences for local ecosystems and the cascading effects associated with the arrival of invasive species,” adds Jean-Michel Salles.

These species can indeed eliminate competing species and reshape the ecosystem in which they have made their home. Take the Asian hornet, for example, which preys on bees at the entrance to hives. Yet these same bees belong to the large family of 2,500 species of pollinating insects that contribute to the sexual reproduction of flowering plants, and are therefore essential to many food crops. A service provided free of charge, yet one that translates into hard cash.

In a study published in 2009, Jean-Michel Salles assessed the economic impact of the decline in pollinators.“35% of plant-based foods come from crops that depend in part on pollinators,” explains the economist. “Their contribution to the world’s major crops has been estimated at 153 billion euros.” This figure is based on 2005 agricultural prices and would therefore “certainly be higher” today .

Investing in prevention

If we were to add up all the costs not accounted for in the study, the researchers estimate that the actual cost of invasive species could amount to several hundred billion euros. How can we reduce this cost?“We need to implement prevention policies to limit the arrival and spread of invasive insects ,” the researchers urge. This approach involves increased monitoring as well as the development of environmentally friendly elimination or control methods, such as less polluting insecticides. “We also need to conduct more studies; what we’ve done here is merely an assessment that allows us to gauge the scale of the phenomenon, but it also highlights the extent of our gaps in knowledge on the subject. Further studies are needed to gain a more precise understanding,” the researchers advise.

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