Her­bi­cide boost for tad­poles: Study

Kuwait Times - - HEALTH & SCIENCE -

Ma­ligned as a bee-killer and pos­si­bly cancer-caus­ing, a com­mon her­bi­cide has turned out to be a boon for tad­poles mak­ing them more toxic to preda­tors, re­searchers said yes­ter­day. Com­mon toad lar­vae ex­posed to glyphosate, used in the well-known her­bi­cide Roundup, con­tained higher doses of bu­fa­dieno­lides-life-sav­ing nat­u­ral chem­i­cals found in some plants and an­i­mals. Bu­fa­dieno­lides taste bad to put off po­ten­tial tad­pole din­ers, and can kill in large quan­ti­ties.

“That en­vi­ron­men­tal pol­lu­tion can in­duce changes in bu­fa­dieno­lide pro­duc­tion is rel­e­vant not only for toads but also for their preda­tors,” said study co-au­thor Veronika Bokony of the Hun­gar­ian Academy of Sciences. While some toad species are de­clin­ing, she pointed out, oth­ers such as the Aus­tralian cane toad are in­vad­ing new ar­eas and dis­turb­ing es­tab­lished ecosys­tems.

“Thus, if some pes­ti­cides make toads more poi­sonous, this might al­ter preda­to­ryprey dy­nam­ics and the struc­ture of nat­u­ral com­mu­ni­ties in fresh­wa­ter habi­tats,” Bokony told AFP. Toads with more bu­fa­dieno­lides in their bod­ies are more toxic. Large Aus­tralian preda­tors like croc­o­diles, for ex­am­ple, die from eat­ing cane toads which are a large species and there­fore con­tain more tox­ins.

For the ex­per­i­ment, Bokony and a team raised com­mon toad lar­vae in wa­ter pol­luted with a glyphosate-based her­bi­cide, and noted that the amount of bu­fa­dieno­lides in their tiny bod­ies were el­e­vated. “So these tad­poles be­came a more ‘con­cen­trated’ source of bu­fa­dieno­lides com­pared to their sib­lings that were raised in clean wa­ter,” said Bokony.

Glyphosates are widely used in agri­cul­ture, and pol­lute fresh­wa­ter bod­ies that re­ceive runoff from farms. The Euro­pean Union will de­cide in De­cem­ber whether to re­new the li­cence for glyphosate, which is pro­duced by US agro-chem­i­cals gi­ant Mon­santo. Last year, Europe lim­ited use of the her­bi­cide for re­search, over fears that it causes cancer. The EU’s chem­i­cal agency said glyphosate should be not be clas­si­fied as cancer-caus­ing.

But this is chal­lenged by sci­en­tists and en­vi­ron­men­tal­ists who point to a find­ing by the In­ter­na­tional Agency for Re­search on Cancer that glyphosate is “prob­a­bly car­cino­genic”. The study was pub­lished in Pro­ceed­ings of the Royal So­ci­ety B.—AFP

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