Organisatie - 19 april 2012

Bee review still holds water

The doses used in the Science studies ‘were not realistic'.

The recent headline-grabbing bee studies published in Science do not change the conclusions reached in Tjeerd Blacquière's bee review, says the Wageningen researcher. In the two studies, neonicotinoids are expressly named as the main suspect in relation to the global epidemic of mysterious bee deaths. Blacquière and his colleagues concluded that there was no evidence for this.
Both the new publications are about field studies. In one study, bumble bees showed clear signs of slowed growth after being fed a menu of pollen containing imidacloprid. What is more, they almost stopped producing queen bees. A ‘worst case scenario', says Blacquière. Such a study gives a measurable effect, but is not realistic enough. Blacquière: ‘Out in the natural world, they would also be able to land on unpolluted flowers outside the field.'
In another experiment, bees exposed to nectar containing thiamethoxam (another neonicotinoid) could no longer find their way back to the hive. Blacquière says the doses involved were not realistic. ‘The amount of thiamethoxam the bees got at one go was 18 times as much as they would absorb with nectar. That is very close to a fatal dose.' Only if you observe these kinds of negative effects at doses 10 or 20 times lower than this do you really have a point. Then there would be implications for our review.' Blacquière did the review for the ministry of EL&I. The board that authorizes plant protection products has already indicated that it does not consider the Science publications to have serious implications.