Honeybees

Ya en 2013 la EFSA emitió sus conclusiones sobre la peligrosidad de estos insecticidas para las abejas cuando utilizados en el tratamiento de semillas, lo que ha llevado a que se restringiese su uso en toda la Unión Europea, lo que fue un avance considerable. Más que confirmado. Confirmadísimo. La semana pasada la Autoridad Europea de Seguridad Alimentaria (EFSA) publicó un nuevo estudio que confirma una vez más la peligrosidad de tres insecticidas neonicotinoides (el imidacloprid y la clotianidina, producidos por Bayer, y el tiametoxam, producido por Syngenta) para las abejas. La conclusión es clara: “riesgos elevados fueron identificados o no pueden ser excluidos” cuando estos insecticidas son fumigados sobre los cultivos.

Nach Ansicht der Europäischen Behörde für Lebensmittelsicherheit (EFSA) stellt das Spritzen von neonikotinoidhaltigen Pflanzenschutzmitteln zur Blattbehandlung ein Risiko für Bienen dar. Das ergibt sich aus den vergangene Woche veröffentlichten Bewertungen der für Bienen bestehenden Risiken durch Clothianidin, Imidacloprid und Thiamethoxam. Berücksichtigt wurden dabei alle Anwendungen mit Ausnahme der Saatgutbehandlungen und von Granulat. Für die Fälle, in denen die Bewertung abgeschlossen werden konnte, ermittelte die EFSA entweder hohe Risiken oder will Risiken zumindest nicht ausschließen. In den übrigen Fällen sorgten Datenlücken für den Verzicht auf ein abschließendes Urteil.

Sublethal exposure to fungicides can affect honey bees (Apis mellifera L.) in ways that resemble malnutrition. These include reduced brood rearing, queen loss, and increased pathogen levels. We examined the effects of oral exposure to the fungicides boscalid and pyraclostrobin on factors affecting colony nutrition and immune function including pollen consumption, protein digestion, hemolymph protein titers, and changes in virus levels. Because the fungicides are respiratory inhibitors, we also measured ATP concentrations in flight muscle. The effects were evaluated in 3- and 7-d-old worker bees at high fungicide concentrations in cage studies, and at field-relevant concentrations in colony studies. Though fungicide levels differed greatly between the cage and colony studies, similar effects were observed. Hemolymph protein concentrations were comparable between bees feeding on pollen with and without added fungicides. However, in both cage and colony studies, bees consumed less pollen containing fungicides and digested less of the protein. Bees fed fungicide-treated pollen also had lower ATP concentrations and higher virus titers. The combination of effects we detected could produce symptoms that are similar to those from poor nutrition and weaken colonies making them more vulnerable to loss from additional stressors such as parasites and pathogens.

Center for Food Safety's (CFS) report, “Water Hazard: Aquatic Contamination by Neonicotinoid Insecticides in the United States,” shows widespread water contamination with neonicotinoid insecticides and threatening a range of aquatic invertebrates including crabs and insects. In particular, the report draws attention to the use of neonicotinoid seed coatings, up to 95 percent of which ends up in the environment, not the crop. Neonicotinoids are a class of insecticide known to have acute and chronic effects on honey bees and other pollinator species and are considered a major factor in overall bee population declines and poor health. The report examines representative case studies from Maryland, Iowa, and California, each of which is experiencing widespread neonicotinoid contamination exceeding recommended standards as determined by leading experts in aquatic species toxicology. The report also highlights contamination elsewhere, including New York, South Dakota, Texas, and Wisconsin. It describes the key roles of irrigation and field drainage and discusses the growing risks to aquifers, vulnerable wetlands and the valuable wildlife inhabiting those areas, such as migratory birds and sport fish.

Glyphosate (GLY) is a herbicide that is widely used in agriculture for weed control. Although reports about the impact of GLY in snails, crustaceans and amphibians exist, few studies have investigated its sublethal effects in non-target organisms such as the honeybee Apis mellifera, the main pollen vector in commercial crops. Here, we tested whether exposure to three sublethal concentrations of GLY (2.5, 5 and 10 mg l−1: corresponding to 0.125, 0.250 and 0.500 μg per animal) affects the homeward flight path of honeybees in an open field. We performed an experiment in which forager honeybees were trained to an artificial feeder, and then captured, fed with sugar solution containing traces of GLY and released from a novel site either once or twice. Their homeward trajectories were tracked using harmonic radar technology. We found that honeybees that had been fed with solution containing 10 mg l−1 GLY spent more time performing homeward flights than control bees or bees treated with lower concentrations. They also performed more indirect homing flights. Moreover, the proportion of direct homeward flights performed after a second release from the same site increased in control bees but not in treated bees. These results suggest that, in honeybees,exposure to levels of GLY commonly found in agricultural settings impairs the cognitive capacities needed to retrieve and integrate spatial information for a successful return to the hive. Therefore, honeybee navigation is affected by ingesting traces of the most widely used herbicide worldwide, with potential long-term negative consequences for colony foraging success.

A UK Government study by their agency Fera has been published today. The study contains three key results, it shows:-
• A clear relationship across regions between imidacloprid use (the commonest neonicotinoid used during the period of the study) and overwintering honeybee colony losses. • Neonicotinoid seed treatments (mainly imidacloprid) on Oilseed rape did not produce a consistent yield benefit - positive in three years, negative in one and no overall effect.
• Neonicotinoid use reduced insecticide spray use in the autumn only if the initial use of the neonicotinoid was ignored, but appeared to increase insecticide sprays the following spring – net effect circa 0.75 more insecticide uses per hectare. Government has been aware of this statistical link between imidacloprid use and honeybee colony loss since early 2013 – the minutes of their own Advisory Committee on Pesticides of 29th January 2013 contain extensive discussion about a “prepublication” analysis that revealed that once regional differences had been accounted for 7-8% of honeybee colony loss was associated with imidacloprid use “there was a clear signal from imidacloprid use despite this ‘noise’, from other factors”.