Honeybees

Much attention has been given to the plight of bees because of their importance as pollinators of major crops. But there is growing evidence that butterflies and moths – many of which have suffered dramatic declines in recent years – play an important role as specialist pollinators of some of our favourite wild flowers. A Swedish study recorded pollen on the bodies of three-quarters of butterfly species examined with some individuals carrying up to 350 grains.

Bees and butterflies are experiencing widespread population decline, creating public concern in recent years. Data collected in Germany suggest that it’s not just bees and butterflies at risk: insect populations overall have plummeted by more than 75 percent since 1989. Scientists have known about the population decline for several years. However, they didn’t know how many species were declining, and they didn’t expect it to be happening so fast.

The decline of pollinators worldwide is of growing concern and has been related to the use of plant protecting chemicals. Most studies have focused on three neonicotinoid insecticides, clothianidin, imidacloprid and thiamethoxam, currently subject to a moratorium in the EU. Here we focus on thiacloprid, a widely used cyano-substituted neonicotinoid thought to be less toxic to honey bees and of which use has increased in the last years. Honey bees (Apis mellifera carnica) were exposed chronically to thiacloprid in the field for several weeks at a sublethal concentration.

Honey bees provide key ecosystem services. To pollinate and to sustain the colony, workers must walk, climb, and use phototaxis as they move inside and outside the nest. Phototaxis, orientation to light, is linked to sucrose responsiveness and the transition of work from inside to outside the nest, and is also a key component of division of labour. However, the sublethal effects of pesticides on locomotion and movement to light are relatively poorly understood. Thiamethoxam (TMX) is a common neonicotinoid pesticide that bees can consume in nectar and pollen.

The UK will back a total ban on insect-harming pesticides in fields across Europe, the environment secretary, Michael Gove, has revealed. The decision reverses the government’s previous position and is justified by recent new evidence showing neonicotinoids have contaminated the whole landscape and cause damage to colonies of bees. It also follows the revelation that 75% of all flying insects have disappeared in Germany and probably much further afield, a discovery Gove said had shocked him.

L'enquête qui vient d'être rendue publique par l'UNAF dresse un bilan alarmant concernant les néonicotinoïdes. Cette année encore, plus de 6 millions d'hectares de cultures ont été traités par ces pesticides tueurs d'abeilles. Alors que cinq néonicotinoïdes doivent prochainement être interdits, une autre substance pose problème : le sulfoxaflor. Ce pesticide serait également un néonicotinoïde.

In his book, Dutch toxicologist Henk Tennekes (2010) makes the case that the contamination of surface water by neonicotinoids is so widespread in the Netherlands (and possibly elsewhere in Europe), that loss of insect biomass on a continental scale is behind many of the widespread declines that are being seen, be they of marsh birds, heath or meadow birds or even coastal species. This suggests that we should be looking at possible links between neonicotinoid insecticides and birds, not on a farm scale, but in the context of whole watersheds and regions.

A previous study reported by Cresswell et al. (2014) claimed a differential behavioural resilience between spring or summer honey bees (Apis mellifera) and bumble bees (Bombus terrestris) after exposure to syrup contaminated with 125 µg L−1 imidacloprid for 8 days. The authors of that study based their assertion on the lack of body residues and toxic effects in honey bees, whereas bumble bees showed body residues of imidacloprid and impaired locomotion during the exposure. We reproduced the experiments of Cresswell et al.

Le miel nord-américain, y compris le miel québécois, est le plus contaminé aux pesticides néonicotinoïdes au monde, d’après une analyse internationale qui s’inquiète des effets cumulatifs sur la santé. Les néonicotinoïdes sont les pesticides les plus répandus au monde. Depuis quelques années, scientifiques et apiculteurs les accusent de décimer les colonies d’abeilles et de menacer la santé humaine. On retrouve des traces de ces substances dans la plupart des fruits et légumes, mais aussi dans les céréales et dans l’eau.