Hol­loway study re­veals bees are en­dan­gered by pes­ti­cides

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EX­PO­SURE to a com­mon pes­ti­cide makes bum­ble­bees less able to start colonies, ac­cord­ing to new re­search – and with­out new colonies ‘bum­ble­bees could die out com­pletely’.

Re­searchers from Royal Hol­loway, in Egham, and the Uni­ver­sity of Guelph have found that ex­po­sure to thi­amethoxam, a com­mon pes­ti­cide, re­duced the chances of a bum­ble­bee queen start­ing a new colony by more than a quar­ter.

Build­ing on field stud­ies, the re­searchers used math­e­mat­i­cal mod­els of bum­ble­bee pop­u­la­tions which showed that thi­amethoxam ex­po­sure sig­nif­i­cantly in­creases the like­li­hood that wild bee pop­u­la­tions could be­come ex­tinct.

“Queens ex­posed to the pes­ti­cide were 26% less likely to lay eggs to start a colony,” said Dr Gemma Baron, from the School of Bi­o­log­i­cal Sci­ences at Royal Hol­loway. “Cre­at­ing new bee colonies is vi­tal for the sur­vival of bum­ble­bees. If queens don’t pro­duce eggs or start new colonies it is pos­si­ble that bum­ble­bees could die out com­pletely.”

Pro­fes­sor Vin­cent Jansen, also from Royal Hol­loway, said: “We used math­e­mat­i­cal mod­els to show that this re­duc­tion in colony found­ing is a very real threat to the sur­vival of wild bum­ble­bees.

“Neon­i­coti­noids are the most widely used class of pes­ti­cide in the world. It is vi­tal that we un­der­stand the ef­fects of these pes­ti­cides on our wildlife be­fore al­low­ing their con­tin­ued use.”

The EU has is­sued a tem­po­rary ban on the use of thi­amethoxam, as well as two other neon­i­coti­noid pes­ti­cides.

Neon­i­coti­noids have long been im­pli­cated in the de­cline of bees, but­ter­flies and other species, and there is cur­rently global de­bate about their us­age.

Pro­fes­sor Nigel Raine from the Uni­ver­sity of Guelph said: “This re­search shows that these pes­ti­cides can have a dev­as­tat­ing ef­fect on bees, and we ur­gently need to know more about how pes­ti­cides could be af­fect­ing other species.”

Bum­ble­bee queens al­ready face a hugely chal­leng­ing task if try to start new colonies. They must first sur­vive the win­ter, which can cause them to lose up to 80% of their fat re­serves, and then sur­mount the threats posed by, par­a­sites, preda­tors, bad weather, and a lack of re­sources.

Pro­fes­sor Mark Brown, also of Royal Hol­loway, said: “Our work is a ma­jor step for­ward in un­der­stand­ing how pes­ti­cides may im­pact bum­ble­bees and other pol­li­nat­ing species.”

The study, pub­lished in Na­ture Ecol­ogy & Evo­lu­tion, was funded by a BBSRC-DTG stu­dentship, and the In­sect Pol­li­na­tors Ini­tia­tive.

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