[LUM#5] Dear Invaders

[LUM Magazine] - Published on March 14, 2017 in Science-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 bill is actually much higher...

It measures just a few millimeters, but costs us billions... Originally from 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 landed on American soil, the insect found a climate conducive to its development and gradually colonized this new territory. The problem is that this little wood-eating insect, which will devour anything to satisfy its insatiable appetite, wreaks havoc on homes. And the cost is steep: each year, the Formosan termite is estimated to cost the community $30 billion.

Like him, dozens of insect species are taking advantage of globalized trade to colonize new territories, transported in containers, cargo ships, and other goods. Once settled, these tiny stowaways can cause significant damage, eating away at houses and crops, or spreading new diseases. Invasive insects are costly, very costly... To assess the cost, a team of researchers including entomologists, ecologists, and economists reviewed 737 publications on the impact of the 10 main invasive insect species. Their verdict: the cost of the damage caused by these insects amounts to at least €69 billion per year (Massive yet grossly underestimated global costs of invasive insects, in Nature Communication, 2016).

Pest insects

While buildings pay a heavy price for Formosan termites, agriculture is also a sector that is heavily impacted by invasive species. "Insects as a whole consume 40% of crops," says 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 virulent pests is the cabbage moth, an invasive insect that feeds on all kinds of cruciferous plants and causes nearly €4.1 billion in damage each year.

Another sector affected is healthcare. "The total cost attributable to invasive insects in this area exceeds €6.1 billion per year," says Frédéric Simard. The main culprits are mosquitoes. Aedesmosquitoes, which carry dengue fever, including the tiger mosquito now present in the region. "And this amount only takes into account direct costs, such as the price of care and hospitalizations. It does not take into account indirect costs," warns the entomologist. For example, the absence from work of a sick employee or any lasting effects, or "the cost of training doctors to treat this disease," adds Jean-Michel Salles, an economist at Lameta and also co-author of the study.

The tip of the iceberg

So these little creatures cost us more than $69 billion? "Much more!"admit the experts, who confess that this figure is only the tip of the iceberg. "There are many species for which we have no data and many regions that have not been studied. Most of the studies we have found mainly concern the United States and, to a lesser extent, Europe. There are none in Africa and very few in South America and Asia," points out Frédéric Simard. "There are also parameters that are very difficult to quantify, such as the consequences for local ecosystems and the knock-on effects of the arrival of invasive species," adds Jean-Michel Salles.

The latter can eliminate competing species and reshape the ecosystem in which they have taken up residence. Take, for example, the Asian hornet, which devours bees at the entrance to hives. However, 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. This service is provided free of charge, but it translates into hard cash.

In a study published in 2009, Jean-Michel Salles assessed the economic impact of pollinator decline. "35% of plant-based foods come from crops that depend in part on pollinators," explains the economist, "and their contribution to the world's main crops has been estimated at €153 billion." This figure is based on 2005 agricultural prices and would therefore "certainly be revised upwards" today .

Investing in prevention

If we added up all the costs not taken into account in the study, researchers estimate that the real cost of invasive species could amount to several hundred billion euros. How can we reduce this bill? "Prevention policies must be put in place to limit the arrival and spread of invasive insects ," say the researchers. This approach involves increased monitoring, but also the development of environmentally friendly methods of elimination or control, such as less polluting insecticides. "We also need to conduct more studies. What we have done here is merely an assessment of the situation, which allows us to evaluate the scale of the phenomenon, but also highlights the extent of our knowledge gaps on the subject. Further studies are needed to gain a more accurate picture," advise the researchers.

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