[LUM#5] Dear invaders

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

69 billion euros. This is the annual cost of damage caused by invasive insects worldwide. A figure that is clearly underestimated, according to researchers who claim that the bill is actually much higher...

Just a few millimeters long, it's costing us billions... Originally from Asia, the Formosan termite arrived in the United States at the end of the Second World War, lurking in the wooden crates of returning GIs. Once on the American continent, the insect found a climate conducive to its development and gradually colonized this new territory. The problem: this little wood-eating beetle, which will use any wood to satisfy its insatiable appetite, is ravaging homes. And the bill is high: every year, the Formosan termite is estimated to cost the community 26.7 billion euros.

Like them, dozens of insect species are taking advantage of the globalization of trade to colonize new territories conquered through the transport of containers, cargo and other goods. Once established, these little stowaways can cause major damage, nibbling away at homes and crops, or spreading new diseases. Invasive insects are expensive, very expensive... To assess the bill, a team of researchers including entomologists, ecologists and economists reviewed 737 publications on the impact of the 10 main invasive insect species. The verdict: the cost of damage caused by these insects is estimated at at least 69 billion euros per year(Massive yet grossly underestimated global costs of invasive insects, in Nature communication, 2016).

Insect pests

While buildings take a heavy toll 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 Mivegec laboratory and co-author of the study. 40% of agricultural production, enough to feed a billion human beings. Among the most virulent pests is the cabbage maggot, an invasive insect that feeds on crucifers of all kinds, causing some 4.1 billion euros worth of damage every year.

Another sector impacted: health. " The global cost attributable to invasive insects in this field exceeds 6.1 billion euros per year," explains Frédéric Simard. Main culprits: mosquitoes Aedesmosquitoes, vectors of dengue fever, including the tiger mosquito now present in the region. " And this figure only takes into account direct costs, such as the cost of care and hospitalization. But it does not take into account indirect costs ", warns the entomologist. For example, the absence from work of a sick employee or the possible after-effects, or "the cost of training doctors to deal with this disease ", adds Jean-Michel Salles, economist at Lameta and also co-author of the study.

The tip of the iceberg

So these little beasts are costing us over 69 billion? " The specialists admit that this figure is just 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 concern the United States and a little Europe, nothing in Africa, and very little in South America and Asia," Frédéric Simard points out. " There are also parameters that are very difficult to quantify, such as the impact on local ecosystems and the cascading effects of the arrival of invasive species ", adds Jean-Michel Salles.

They can eliminate competing species and reshape the ecosystem in which they make their home. Like the Asian hornet, for example, which devours 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 indispensable to many food crops. A service provided free of charge, but which can be converted into hard cash.

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

Investing in prevention

If we were to add all the sums not taken into account in the study, the researchers imagine that the real cost of invasive species could amount to several hundred billion euros. What can be done to reduce the bill? " Preventive policies must be put in place to limit the arrival and spread of invasive insects ", the researchers claim. This involves not only increased surveillance, but also the development of environmentally-friendly elimination or control methods, such as less polluting insecticides. "We also need to carry out more studies; what we've done here is no more than an assessment of the scale of the phenomenon, but it also highlights the extent of our shortcomings on the subject. We need to carry out further studies to get a clearer picture," the researchers advise.

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