In­va­sive in­sects cause $77 bil­lion in dam­age

Re­searchers look at the im­pact of non-na­tive species

Kuwait Times - - HEALTH & SCIENCE -

PARIS: In­va­sive in­sects cause at least $77 bil­lion (69 bil­lion eu­ros) in dam­age ev­ery year, ac­cord­ing to a study re­leased Tues­day that says this fig­ure is “grossly un­der­es­ti­mated” be­cause it cov­ers only a frac­tion of the globe. Cli­mate change is on track to boost the area af­fected by nearly 20 per­cent be­fore mid-cen­tury, the au­thors re­ported in the jour­nal Na­ture Com­mu­ni­ca­tions.

Can­vass­ing more than 700 re­cent sci­en­tific stud­ies, re­searchers looked at the im­pact of non­na­tive species on goods and ser­vices, health­care and agri­cul­tural out­put. Most of these stud­ies ap­plied to North Amer­ica and Europe, which means the dev­as­ta­tion wrought by crop-chomp­ing and dis­ease-car­ry­ing bugs from afar has not been ad­e­quately mea­sured, the au­thors said.

The most de­struc­tive of the in­sects can­vassed was the Formosan subterranean termite, which lives in huge colonies and feasts on wooden struc­tures and liv­ing trees. It has in­fested large swathes of the United States and has proven im­pos­si­ble to erad­i­cate. The di­a­mond­back moth, which orig­i­nated in the Mediter­ranean re­gion, has also spread world­wide and is a vo­ra­cious con­sumer of so-called cru­cif­er­ous crops: broc­coli, cau­li­flower, bok choy and es­pe­cially cab­bage.

Also in the rogues’ gallery of in­va­sive in­sects are the brown spruce longhorn beetle (which rav­ages ever­green trees, es­pe­cially in Canada), the gypsy moth (tree de­fo­li­a­tion) and the Asian long-horned beetle (which at­tacks tem­per­ate forests). In­sects are “prob­a­bly the costli­est an­i­mal group to hu­man so­ci­ety,” a team of re­searchers led by Franck Cour­champ from France’s Na­tional Cen­tre for Sci­en­tific Re­search con­cluded. The global health bill at­trib­ut­able to in­va­sive in­sects tops six bil­lion dol­lars (5.4 bil­lion eu­ros), in large mea­sure due to the im­pact of Dengue fever, a trop­i­cal dis­ease spread by mos­qui­toes. The es­ti­mate does not in­clude the im­pact of malaria, the Zika virus or eco­nomic losses in tourism or pro­duc­tiv­ity, the re­searchers said.

Pes­ti­cides ‘not the so­lu­tion’

Global warm­ing-which has seen av­er­age sur­face tem­per­a­tures climb one de­gree Cel­sius (1.8 de­grees Fahren­heit) in the last 150 years-has pushed plants and an­i­mals towards the poles, es­pe­cially north­ward. “The dis­tri­bu­tion of many in­va­sive species is to­day lim­ited by tem­per­a­ture bar­ri­ers, and cli­mate change could al­low them to in­vade re­gions that were in­hos­pitable up to now, said Cour­champ. There are some 2.5 mil­lion in­sect species in the world. Only a tiny per­cent­age-some 2,200 - have col­o­nized new ter­ri­to­ries, but they have man­aged to wreak havoc all the same. Only a tenth of in­sect species that wind up in an­other part of the world be­come es­tab­lished, and only ten per­cent of these qual­ify as in­va­sive, the study notes.

The best way to com­bat this grow­ing threat­spread mainly through in­ter­na­tional com­mer­ceis not more pes­ti­cides, said Cour­champ. “We’ve see how well that worked,” he said. Nor is it ge­netic ma­nip­u­la­tion such as gene drive, a tech­nol­ogy that makes it pos­si­ble to en­gi­neer lo­cal ex­tinc­tions by re­leas­ing males into the wild that pro­duce only male off­spring. “The so­lu­tion is bet­ter ‘bio-se­cu­rity’,” said Cour­champ. “This in­cludes in­spec­tion of ship and air cargo from cer­tain re­gions, leg­is­la­tion to en­sure that high­risk im­ports must be treated and rapid erad­i­ca­tion of new in­cur­sions.”

All in­sects, in­clud­ing those in their na­tive habi­tat, take a heavy toll on agri­cul­ture, con­sum­ing 30 to 40 per­cent of global har­vests-enough to feed a bil­lion peo­ple. Mos­quito-borne dis­eases, es­pe­cially malaria, claim hun­dreds of thou­sands of lives ev­ery year. The In­ter­na­tional Union for the Con­ser­va­tion of Na­ture (IUCN) main­tains a data­base of in­va­sive species with nearly 900 species cur­rently listed, in­clud­ing plants, an­i­mals, bac­te­ria and fun­gus. The UN Con­ven­tion on Bio­di­ver­sity has said that “pri­or­ity” in­va­sive species should be “con­trolled or erad­i­cated” by 2020.

— AP

In this photo, a rhino grazes in the bush on the edge of Kruger Na­tional Park in South Africa.

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