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Un estudio publicado en el Boletín de Insectología en Estados Unidos, confirma la sospecha de investigadores de la relación entre los pesticidas y el problema del colapso de colonias, conocido como CCD. Para encontrar al culpable de la muerte de millones de abejas en muchas regiones de los Estados Unidos y Europa, los científicos estudiaron 18 colonias en tres locaciones de Massachusetts durante el año 2012 y 2013. Los investigadores encontraron que dos pesticidas utilizados regularmente en la agricultura eran los responsables directos por el abandono y muerte de varias colmenas. Para el estudio se expuso un tercio de las colonias a bajas dosis del pesticida Imidacloprid, mientras que el otro tercio fue expuesto al pesticida Clotianidina, los dos pertenecientes a la clase Neonicotinoide que actúa sobre el sistema nervioso de los insectos y es utilizado por los agricultores. El tercio restante no recibió ningún pesticida como método de control.

Some of the honeybees were lying on their backs, trembling and twitching. Others were crawling slowly on the ground, unable to fly. Many were motionless, lying dead in piles. Many more had simply disappeared, apparently unable to find their way back to their hives. This was the gruesome scene commercial beekeeper Steve Ellis came upon on the morning of May 7, 2013.
The sight stunned Ellis, who has owned and operated Old Mill Honey Company in Barrett, Minnesota for 35 years. "Normally in the spring, we typically expect bees to build up and get stronger," he recalled. "For a beekeeper to watch his bees be devastated in the springtime — it's like watching a little child get extremely sick and debilitated. It takes a real mental toll on you."
But almost immediately, Ellis discovered the culprit: That morning, a farmer had planted corn in a field directly adjacent to his bee yard, which housed roughly 1,300 hives at the time. He was well aware that most corn seeds are treated with a pesticide called neonicotinoids. And that day, the wind was blowing from the cornfield toward Ellis' bees, the beekeeper wrote in an incident report he sent to the US Environmental Protection Agency. The bees' only sources of food were nearby willow trees, which, Ellis surmised, had become coated with pesticide-contaminated dust. "We took a close look to see how the bees were behaving when they were trying to forage them. It was shocking what we found," Ellis said in a video he took that day documenting the massacre. "Bees literally incapacitated when they come in contact with the flowers."

We have recently been surveying what chemicals the local farmers in East Sussex use each year. Chemicals applied to two fairly typical fields, one with winter oilseed rape, one with winter wheat, in a single growing season (2012/13). I should stress that these are perfectly normal farms; not especially intensive, situated on the edge of the South Downs, an area of gentle hills, hedgerows and wooded valleys. Beautiful, rural England; Constable would have liked it here. But let’s look at it from a bee’s perspective, focussing on the oilseed rape, since this is a crop they will feed on when it flowers: firstly, the crop is sown in late summer with a seed dressing containing the insecticide thiamethoxam. This is a systemic neonicotinoid, with exceedingly high toxicity to bees. We know it is taken up by the plant, and that detectable levels will be in the nectar and pollen gathered by bees in the following spring. In November, despite the supposed protection of the neonicotinoid, the crop is sprayed with another insecticide, the charmingly named Gandalf. Gandalf contains beta-cyfluthrin, a pyrethroid. Pyrethroids are highly toxic to bees and other insects, but there should be no bees about in November so that is probably OK. The following May, when it is flowering, the crop is sprayed with another pyrethroid, alpha-cypermethrin. Less than three weeks later, the crop is blitzed with three more pyrethroids, all mixed together, a real belt-and-braces approach. Why use one when three will do? The crop is still flowering at this point (it was a late year), and would be covered in foraging bumblebees and other pollinators. In between, the crop is also treated with a barrage of herbicides, fungicides, molluscicides and fertilizers – 22 different chemicals in total.

Current bee population declines and colony failures are well documented yet poorly understood and no single
factor has been identified as a leading cause. The evidence is equivocal and puzzling: for instance, many
pathogens and parasites can be found in both failing and surviving colonies and field pesticide exposure is
typically sublethal. Here, we investigate how these results can be due to sublethal stress impairing colony
function. We mathematically modelled stress on individual bees which impairs colony function and found
how positive density dependence can cause multiple dynamic outcomes: some colonies fail while others
thrive. We then exposed bumblebee colonies to sublethal levels of a neonicotinoid pesticide. The dynamics
of colony failure, which we observed, were most accurately described by our model. We argue that our
model can explain the enigmatic aspects of bee colony failures, highlighting an important role for sublethal
stress in colony declines.

Il Centro di Riferimento Tecnico per l’Apicoltura Problematiche Ambientali e Nutrizionali di Unaapi ha sviluppato negli anni una più che proficua ollaborazione con tutti gli enti, soggetti istituzionali e scientifici che si sono variamente impegnati per rimediare alle cause che provocano il collasso di api e impollinatori. Vai riconosciuta alla ricerca scientifica italiana – perché significativamente pubblica e non condizionata? - una notevole capacità di monitoraggio e d’indagine. Grazie anche all’insieme di ricerche italiane si sono affermate alcune semplici, ma determinanti, modalità di studio, quali: l’insensatezza della traslazione all’alveare della dose letale 50 manifestata dalle singole api; la distinzione fra mortalità invernali e in stagione attiva; l’impatto ambientale della contaminazione in epoca di semina con concianti sistemici; la considerazione della possibilità che sia: “la goccia prodotta dall’uomo che fa traboccare il vaso”; le variegate vie di posizione “abitualmente” non considerate ecc… Il CRT Unaapi ha quindi ritenuto indispensabile proporre una disamina dello stato delle conoscenze sui comprovati e possibili effetti dei pesticidi sulle api, per:
• Denunciare infondatezza e falsità delle rassicurazioni sulla: “certa assenza di conseguenze”.
• Evidenziare quanti e quali sono gli aspetti non considerati rispetto ai possibili effetti dei pesticidi (puntuali o
ancor peggio: cronici) su api, impollinatori e vivente.
• Invitare apicoltori e cittadinanza tutta ad andare oltre la vaga lamentela, documentandosi adeguatamente.
Ringrazio i ricercatori che hanno redatto tale imponente e istruttiva, complessa ma fruibile, rassegna. A quanti si misureranno con la lettura l’auspicio di far tesoro di tale mole di accertamenti scientifici…

A very interesting paper has been issued under the aegis of the UK Royal Society, which however seems highly selective and biased in its ‘interpretations’. While this ‘appears’ to be a neutral assessment of the existing evidence on neonicotinoids and bee deaths, it is in my opinion a government/ science establishment project designed to justify/ bolster the UK government’s position. The involvement of Tjeerd Blacquiere from Wageningen in Holland makes one immediately suspect a rat - as does the involvement of anyone from Rothamsted Research - whose so-called ’scientists’ have served as the shock-troops for the advancement of GM technology, systemic pesticides and the industrialisation of farming in the UK. There are two scientists here from NERC -funded (National Environmental Research Council) research bodies; this is synonymous with UK government. The paper will undoubtedly be used to justify the UK government’s continued support for neonics and for their opposition to a Europe-wide ban.

This spring most Canadian corn and soybean growers will be planting another crop of pesticide-coated seeds, even as researchers raise new warnings that the practice may have deadly side effects for bees and other wildlife. The heated debate around the use of the neonicotinoid-coated seeds, developed by Bayer CropScience and introduced here about a decade ago, has divided farmers, beekeepers and scientists, and turned Canada into a kind of environmental battlefront.