Insecticides

The European Food Safety Authority (EFSA), which carries out risk assessment on plant protection products, is currently reviewing recent scientific literature with regard to the effects of pesticides, and in particular of neonicotinoids, on bees. In its conclusions on imidacloprid and fipronil, EFSA has identified the toxicity to bees (and other non-target organisms) as a critical area of concern.

Honey bees provide important pollination services to crops and wild plants. The agricultural use of systemic insecticides, such as neonicotinoids, may harm bees through their presence in pollen and nectar, which bees consume. Many studies have tested the effects on honey bees of imidacloprid, a neonicotinoid, but a clear picture of the risk it poses to bees has not previously emerged, because investigations are methodologically varied and inconsistent in outcome. In a meta-analysis of fourteen published studies of the effects of imidacloprid on honey bees under laboratory and semi-field conditions that comprised measurements on 7073 adult individuals and 36 colonies, fitted dose–response relationships estimate that trace dietary imidacloprid at field-realistic levels in nectar will have no lethal effects, but will reduce expected performance in honey bees by between 6 and 20%. Statistical power analysis showed that published field trials that have reported no effects on honey bees from neonicotinoids were incapable of detecting these predicted sublethal effects with conventionally accepted levels of certainty. These findings raise renewed concern about the impact on honey bees of dietary imidacloprid.

Global pollinators, like honeybees, are declining in abundance and diversity, which can adversely affect natural ecosystems and agriculture. Therefore, we tested the current hypotheses describing honeybee losses as a multifactorial syndrome, by investigating integrative effects of an infectious organism and an insecticide on honeybee health. We demonstrated that the interaction between the microsporidia Nosema and a neonicotinoid (imidacloprid) significantly weakened honeybees. This provides the first evidences that interaction between an infectious organism and a chemical can also threaten pollinators, interactions that are widely used to eliminate insect pests in integrative pest management. An independent American study by Pettis et al. recently confirmed these results.

De actualiteit over de toelating van gewasbeschermingsmiddelen op basis van neonicotinoïden is voor Bart Bosveld, directeur van het College voor de toelating van gewasbeschermingsmiddelen en biociden (Ctgb), reden om nogmaals uiteen te zetten dat het Nederlands toelatingsbeleid zorgvuldig en veilig is. Wanneer een middel op basis van een neonicotinoïde toegelaten wordt in Nederland is aangetoond dat het gebruik van dát middel niet leidt tot een gevaarlijk hoge blootstelling van bijen, zegt Bosveld op 11 maart 2011 (zie bijlage). In een reactie zegt toxicoloog Henk Tennekes dat er inmiddels overduidelijke aanwijzingen zijn dat chronische blootstelling van bijenvolken aan neonicotinoïden (door besmetting van stuifmeel en nectar) betrokken is bij de verhoogde bijensterfte (zie bijlage). Bovendien is er sinds 2004 sprake van een compleet falende handhaving van kwaliteitsnormen voor het oppervlaktewater. De groteske normoverschrijdingen van imidacloprid in het oppervlaktewater, die sinds 2004 worden veroorzaakt door de glastuinbouw, fruit-, boom- en bloembollenteelt en in de akkerbouw, en die een dodelijke bedreiging voor niet-doelwit insecten vormen, worden door het Ctgb tot op de dag van vandaag niet bestreden. Met de recent besloten handhaving van de toelating van het middel Merit Turf (ter bestrijding van engerlingen en emelten in openbare grasvegetatie en graszodenteelt) heeft het Ctgb te kennen gegeven geenszins van plan te zijn toepassingen van imidacloprid in te perken om oppervlaktewater verontreiniging te bestrijden. Dit ondanks het feit dat ook de zogenaamde 'spuitschadecommisie' al in 2009 bij de toenmalige minister van LNV zijn zorg over de aanwezigheid van imidacloprid in het oppervlaktewater heeft uitgesproken, aldus Tennekes (zie bijlage).

Beekeepers across the United States have reported higher than average overwintering losses since at least 2006. Scientists are investigating various pathogens, parasites, environmental stresses – including the impacts of pesticides – and management issues as likely contributors to the widespread die-offs. While scientists and beekeepers have been puzzling over the cocktail of factors that could be driving the die-offs, Colorado beekeeper Tom Theobald suspects that a group of pesticides called neonicotinoids, which attack insects’ central nervous systems, paralyzing and killing them, play a key role. To date, much of the research into the potential effects of neonicotinoids on honeybees has focused on clothianidin’s cousin and Bayer’s top selling seed treatment, imidacloprid – sold under the trade name Gaucho – which works in a similar way. Attached is an article on the influence of Bayer Cropscience on Dutch policy makers (which appeared the magazine "Vrij Nederland" on April 4, 2012).

A mixture of chemicals found in modern pesticides may be killing bee colonies around the world, according to a United Nations report. The report says that the highly toxic chemicals in the insecticides, collectively known as neonicotinoids, can cause loss of the sense of direction and memory on which bees rely to find food. The United Nations Environment Programme (UNEP) report says that when neonicotinoids are combined with certain fungicides, the toxicity becomes a thousand times stronger. It says that the loss of nature’s most important plant pollinators could undermine efforts to feed the world’s growing population. The report finds that tens of thousands of plant species could be lost in coming years unless conservation efforts are stepped up.