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Invasive species: solutions to the economic burden

Christophe Diagne
Christophe Diagne
Post-doctoral researcher in Dynamics of Biodiversity and Macroecology at Université Paris Saclay
Boris Leroy
Boris Leroy
Senior Lecturer at the National Museum of Natural History (MNHN)

To date, there are 544 species list­ed as inva­sive in France. Among them, the Asian hor­net dec­i­mates domes­tic bees, the tiger mos­qui­to spreads dengue fever and chikun­gun­ya, the prim­rose wil­low caus­es the dis­ap­pear­ance of aquat­ic plants that are close to it… This phe­nom­e­non is called ‘bio­log­i­cal inva­sion’ and these species have cer­tain char­ac­ter­is­tics in com­mon. First, they have been dis­placed by humans, often as unex­pect­ed pas­sen­gers in the trans­port of goods and peo­ple. Once intro­duced, they have sur­vived in their new envi­ron­ment, spread, and had var­i­ous impacts, such as elim­i­na­tion of local species, spread of dis­eases, alter­ation of ecosys­tems or dev­as­ta­tion of crops. 

Inva­sive species are not only a threat to bio­di­ver­si­ty, but also a major eco­nom­ic bur­den. We have recent­ly demon­strat­ed this by sum­maris­ing all exist­ing glob­al eco­nom­ic costs due to inva­sions since 1970, which total $1,288bn1. This is only a tiny frac­tion of the actu­al costs, as it is only what has been esti­mat­ed and pub­lished. As such, the major­i­ty of the costs have not as yet been assessed. This fig­ure has been grow­ing steadi­ly, tripling every ten years until it reached an esti­mat­ed $163 bil­lion in 2017 alone. A new study just pub­lished in France specif­i­cal­ly shows that inva­sions cost between 1.1 and 10.2 bil­lion euros between 1993 and 20182.

These costs are asso­ci­at­ed with many socio-eco­nom­ic sec­tors (agri­cul­ture, health, tourism, real estate…), and thus affect a vari­ety of pri­vate and pub­lic actors. The bur­den of bio­log­i­cal inva­sions there­fore appears to be sys­temic and requires a strong and con­cert­ed pol­i­cy rather than one-off efforts. Below, we present three ways of tack­ling this burden.

1. Concerted research as a first line of defence

The eco­nom­ic costs gen­er­at­ed by inva­sive species can be divid­ed into dam­age costs (loss of agri­cul­tur­al yields, tourism rev­enues, etc.) and man­age­ment costs (con­trol or erad­i­ca­tion of inva­sive pop­u­la­tions, etc.). All stud­ies show that invest­ment in pre­ven­tive mea­sures is the most cost-effec­tive and effi­cient strat­e­gy against bio­log­i­cal inva­sions. For exam­ple, ear­ly detec­tion and rapid erad­i­ca­tion of new inva­sions is much less cost­ly and has a much high­er suc­cess rate than late action, which often amounts to dam­age control.

It is there­fore essen­tial to strength­en ear­ly detec­tion and mon­i­tor­ing pro­grammes for alien species, so that an effec­tive response can be ini­ti­at­ed at the first sign of neg­a­tive impacts. The vari­ety of these impacts cou­pled with the com­plex­i­ty of imple­ment­ing research rec­om­men­da­tions requires inter­dis­ci­pli­nary and inter­sec­toral approach­es – still too rare – involv­ing ecol­o­gists, econ­o­mists, ana­lysts, soci­ol­o­gists and stake­hold­ers (e.g. bio­di­ver­si­ty managers). 

2. Prevention at the individual level through education

To raise aware­ness of bio­log­i­cal inva­sions among the gen­er­al pub­lic and pri­vate and pub­lic stake­hold­ers. It is cru­cial to raise aware­ness of pub­lic and pri­vate stake­hold­ers who are respon­si­ble for the translo­ca­tion of liv­ing organ­isms on an international/regional scale (e.g. activ­i­ties linked to trade or live­stock farm­ing) and/or who are vic­tims of their effects (e.g. farm­ers). It is also essen­tial to raise aware­ness among the gen­er­al pub­lic through var­i­ous media and edu­ca­tion­al chan­nels (e.g. in school cur­ric­u­la). Empow­er­ing con­sumers by pro­vid­ing infor­ma­tion on the ori­gin and risks of the organ­isms they buy, for exam­ple in the orna­men­tal trade [i.e. trade in exot­ic ani­mals or plants], would be an excel­lent way to reduce the risks of uncon­trolled intro­duc­tions into the wild.

In this con­text, build­ing bridges between sci­ence and soci­ety is there­fore the key ele­ment. These bridges include (i) the for­mal­i­sa­tion of inter­sec­toral net­works ded­i­cat­ed to research and man­age­ment of bio­log­i­cal inva­sions, (ii) the organ­i­sa­tion of dis­cus­sion work­shops and spe­cif­ic and con­tin­u­ous train­ing, and (iii) the devel­op­ment of par­tic­i­pa­to­ry sci­ence pro­grammes, which rep­re­sent a major asset due to their triple edu­ca­tion­al, sci­en­tif­ic and man­age­ment role. For exam­ple, there is now an appli­ca­tion devel­oped by Europe (Inva­sive Alien Species Europe3) that allows any cit­i­zen to send pho­tos of new pre­sumed species with a view to deploy­ing rapid respons­es in terms of man­age­ment. Despite its inter­est, this appli­ca­tion is not wide­ly publicised. 

There is also great poten­tial in par­tic­i­pa­to­ry sci­ence tools based on arti­fi­cial intel­li­gence to iden­ti­fy species, such as the Pl@ntNet appli­ca­tion, which is a great tool for the ear­ly detec­tion of inva­sions4, but is large­ly under-exploit­ed at present. We there­fore empha­sise the need for deci­sion-mak­ers to be involved to achieve con­cert­ed and effi­cient man­age­ment of these bio­log­i­cal invasions. 

3. A legislative response proportional to the magnitude of the economic burden

Despite the increase in nation­al and inter­na­tion­al laws to com­bat bio­log­i­cal inva­sions, the mag­ni­tude of their dam­age con­tin­ues to accel­er­ate, which sug­gests that these laws remain insuf­fi­cient. There is a need to strength­en species black­lists by rapid­ly updat­ing them once impacts are proven, and to con­sid­er a shift in the legal par­a­digm towards whitelists, i.e. the delib­er­ate intro­duc­tion of new alien species must be autho­rised in advance on the basis of an inva­sion risk assess­ment. Those respon­si­ble for delib­er­ate intro­duc­tions should be held crim­i­nal­ly liable as a deterrent. 

Biose­cu­ri­ty, which con­sists of the inter­cep­tion of alien species pri­or to their intro­duc­tion, is the most effec­tive and cost-effi­cient tool to com­bat the impacts of bio­log­i­cal inva­sions. For exam­ple, some coun­tries severe­ly affect­ed by bio­log­i­cal inva­sions, such as New Zealand and Aus­tralia, have put in place high­ly effec­tive biose­cu­ri­ty pro­to­cols for both tourism and inter­na­tion­al trade. These mea­sures require sub­stan­tial staffing, par­tic­u­lar­ly for the imple­men­ta­tion of sur­veil­lance, quar­an­tine and dis­in­fec­tion pro­to­cols; but they offer insur­ance and a very sig­nif­i­cant net ben­e­fit com­pared to the exces­sive­ly high costs of dam­age and man­age­ment of invasions. 

In France, this legal frame­work and biose­cu­ri­ty mea­sures still appear to be lack­ing, as sug­gest­ed by the recent his­to­ry of inva­sions in France such as the Asian hor­net5, the tiger mos­qui­to6, the mug­wort7, gar­den flat­worms8, or the Xylel­la fas­tidiosa bac­teri­um9. As island sys­tems are even more frag­ile to inva­sions than con­ti­nen­tal ones, rein­forced biose­cu­ri­ty mea­sures should be imple­ment­ed, par­tic­u­lar­ly in the French over­seas ter­ri­to­ries, includ­ing trav­el between over­seas territories.


Bio­log­i­cal inva­sions cause enor­mous eco­nom­ic loss­es for soci­ety. This loss of earn­ings that we have esti­mat­ed is only the hid­den face of an ice­berg whose total amount is cur­rent­ly unquan­tifi­able, giv­en the diver­si­ty and scale of the impacts of inva­sions – and we are only talk­ing about the mon­e­tary cost here, ignor­ing the irrepara­ble eco­log­i­cal and health costs. Nev­er­the­less, we do have the keys to fight this bur­den since the prob­lem does not lie with the dis­placed species, but rather with our activ­i­ties that cause these dis­place­ments, over which we do have control.



Christophe Diagne

Christophe Diagne

Post-doctoral researcher in Dynamics of Biodiversity and Macroecology at Université Paris Saclay

Christophe Diagne’s research concerns the relationship between biodiversity and global change. He began his research on the contemporary evolutionary ecology of host-parasite interactions in small mammal communities in changing socio-ecosystems. In his current work, Christophe Diagne is interested in the ecological, health and socio-economic implications of biological invasions at various scales. He is also developing an integrative approach integrating interdisciplinary knowledge (ecology, social sciences, computer modelling).

Boris Leroy

Boris Leroy

Senior Lecturer at the National Museum of Natural History (MNHN)

Boris Leroy’s research focuses on the geographical distribution of biodiversity and on the factors that explain this distribution: climate, environment, history. He is interested in the alteration of the natural geographical distribution of biodiversity by global changes (climate change, invasive alien species, habitat destruction). His research also focuses on the methods used in ecology, biogeography and macroecology, and he makes his work available through the development and publication of free software.

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