Insecticides

There has been recent interest in the threat to bees posed by the use of systemic insecticides. One concern is that systemic insecticides may translocate from the soil into pollen and nectar of plants, where they would be ingested by pollinators. This paper reports on the movement of two such systemic neonicotinoid insecticides, imidacloprid and thiamethoxam, into the pollen and nectar of flowers of squash (Cucurbita pepo cultivars “Multipik,” “Sunray” and “Bush Delicata”) when applied to soil by two methods: (1) sprayed into soil before seeding, or (2) applied through drip irrigation in a single treatment after transplant.

The European Food Safety Authority was asked by the European Commission to assess the scientific information on some neonicotinoids (i.e. thiamethoxam, clothianidin and imidacloprid) and fipronil gathered by the Italian authorities with a funded project named “APENET” and to identify whether this new scientific information might require a change in the assessment of these substances as regards their effects on bees. APENET is a multidisciplinary monitoring and research project, mainly aimed at evaluating the bee health status, the dust dispersal during the sowing of maize coated seeds with thiamethoxam, clothianidin, imidacloprid and fipronil, the lethal effects on bees exposed to this dust, and homing behaviour and orientation effects. Potential synergism between clothianidin and bee pathology was also considered. EFSA evaluated in particular the scientific information as reported in the project report from 2011 (APENET, 2011), which was brought to the attention of the European Commission.

To determine whether environmentally realistic levels of imidacloprid are capable of making a demographic impact on bumble bees, we exposed queenless microcolonies of worker bumble bees, Bombus terrestris, to a range of dosages of dietary imidacloprid between zero and 125 μg L−1 and examined the effects on ovary development and fecundity. Microcolonies showed a dose-dependent decline in fecundity, with environmentally realistic dosages in the range of 1 μg L−1 capable of reducing brood production by one third. In contrast, ovary development was unimpaired by dietary imidacloprid except at the highest dosage. Imidacloprid reduced feeding on both syrup and pollen but, after controlling statistically for dosage, microcolonies that consumed more syrup and pollen produced more brood. We therefore speculate that the detrimental effects of imidacloprid on fecundity emerge principally from nutrient limitation imposed by the failure of individuals to feed.

Ilse Aigner hat Post von den Grünen bekommen: Eine sog. Kleine Anfrage zum Thema Pestizide und Bienen mit dem Schwerpunkt Neonicotinoide. Der Abgeordnete Harald Ebner hat zusammen mit weiteren Kollegen auf sieben Seiten 31 Fragen an die Bundesregierung zur Verwendung der Neonicotinoide gestellt (Beilage). Sie bzw. ihre Antworten sollen einem späteren Antrag zum Verbot der Neonicotinoide dienen. Dabei beziehen sich die Abgeordenten auf eine ganze Reihe wissenschaftlicher Untersuchungen. Antwort der Bundesregierung in der Beilage. Zur Beantwortung erklärt Harald Ebner: "Die Bundesregierung setzt Bienen unnötigen Risiken durch Neonicotinoide aus und lässt Imker im Regen stehen. Weder existieren umfassende Schutzmaßnahmen oder Monitorings, noch werden die Imker ausreichend über den Einsatz von bienengefährlichen Pestiziden informiert. Und statt wie in Frankreich giftige Rapsbeizmittel zu verbieten, lässt Aigner seit Jahren Ausnahmegenehmigungen für Neonicotinoide zu. Unbequeme Forschungsergebnisse hört und liest die Bundesregierung ungern. Anstatt sich mit kritischen Studien auseinanderzusetzen, wischt sie deren Ergebnisse mit nicht nachvollziehbaren Vorwürfen wie methodische Mängel vom Tisch. Pestizidbelastungen, insbesondere durch Neonicotinoide, sind Alarmzeichen, die uns nachdenklich machen müssen. Mit ihrer jetzt erneut bestätigten Ignoranz gegenüber möglichen Risiken von Pestiziden setzt die Bundesregierung in verantwortungsloser Weise die biologische Vielfalt und die Existenz von Hobby- und Berufsimkern aufs Spiel" (Beilage).

For most of 1961, the American biologist Rachel Carson had locked herself in her cottage in Colesville, Maryland, to complete her book, Silent Spring. Serialised in the New Yorker during the summer of 1962, Silent Spring was published that September. It remains one of the most effective denunciations of industrial malpractice ever written and is widely credited with triggering popular ecological awareness in the US and Europe. At the Women's National Press Club, Rachel Carson denounced the links that had been established between science and industry. "When a scientific organisation speaks," she asked, "whose voice do we hear – that of science or of the sustaining industry?" The question remains as pertinent today as it did in 1962. Nor have matters improved. Neonicotinoids, insecticides used in seed dressing, have been linked to colony collapse disorder in honeybees, a condition that saw 800,000 hives wiped out in the US in 2007 alone. As Carson wrote: "Chemical war is never won and all life is caught in its violent crossfire." Attached is an article on the influence of Bayer Cropscience on Dutch policy makers (which appeared in the magazine "Vrij Nederland" on April 4, 2012)

Biologists at the University of California at San Diego (UCSD) have discovered that a small dose of the commonly used neonicotinoid crop pesticide imidacloprid turns honey bees into “picky eaters” and affects their ability to recruit their nestmates to otherwise good sources of food. The results of the experiments, detailed in this week’s issue of the Journal of Experimental Biology, shed light on one of the main culprits suspected to be behind the recent declines in honeybee colonies and detail the particular ways that the substance impedes the functions of the colony.

Native stingless bees (Hymenoptera: Apidae: Meliponinae) are key pollinators in neotropical areas and are threatened with extinction due to deforestation and pesticide use. Few studies have directly investigated the effects of pesticides on these pollinators. Furthermore, the existing impact studies did not address the issue of larval ingestion of contaminated pollen and nectar, which could potentially have dire consequences for the colony. Here, we assessed the effects of imidacloprid ingestion by stingless bee larvae on their survival, development, neuromorphology and adult walking behavior. Increasing doses of imidacloprid were added to the diet provided to individual worker larvae of the stingless bee Melipona quadrifasciata anthidioides throughout their development. Survival rates above 50% were only observed at insecticide doses lower than 0.0056 µg active ingredient (a.i.)/bee. No sublethal effect on body mass or developmental time was observed in the surviving insects, but the pesticide treatment negatively affected the development of mushroom bodies in the brain and impaired the walking behavior of newly emerged adult workers. Therefore, stingless bee larvae are particularly susceptible to imidacloprid, as it caused both high mortality and sublethal effects that impaired brain development and compromised mobility at the young adult stage. These findings demonstrate the lethal effects of imidacloprid on native stingless bees and provide evidence of novel serious sublethal effects that may compromise colony survival.