Insecticides

Imidacloprid, the largest selling insecticide in the world, has received particular attention from scientists, policymakers and industries due to its potential toxicity to bees and aquatic organisms. The decline of aquatic macro-invertebrates due to imidacloprid concentrations in the Dutch surface waters was hypothesised in a recent paper by Van Dijk, Van Staalduinen and Van der Sluijs (PLOS ONE, May 2013). Although we do not disagree with imidacloprid's inherent toxicity to aquatic organisms, we have fundamental concerns regarding the way the data were analysed and interpreted. Here, we demonstrate that the underlying toxicity of imidacloprid in the field situation cannot be understood except in the context of other co-occurring pesticides. Although we agree with Van Dijk and co-workers that effects of imidacloprid can emerge between 13 and 67 ng/L we use a different line of evidence. We present an alternative approach to link imidacloprid concentrations and biological data. We analysed the national set of chemical monitoring data of the year 2009 to estimate the relative contribution of imidacloprid compared to other pesticides in relation to environmental quality target and chronic ecotoxicity threshold exceedances. Moreover, we assessed the relative impact of imidacloprid on the pesticide-induced potential affected fractions of the aquatic communities. We conclude that by choosing to test a starting hypothesis using insufficient data on chemistry and biology that are difficult to link, and by ignoring potential collinear effects of other pesticides present in Dutch surface waters Van Dijk and co-workers do not provide direct evidence that reduced taxon richness and abundance of macroinvertebrates can be attributed to the presence of imidacloprid only. Using a different line of evidence we expect ecological effects of imidacloprid at some of the exposure profiles measured in 2009 in the surface waters of the Netherlands.

Single dose of imidacloprid (IMI-20 mg/kg bodyweight) was orally administered in female rats. Its disposition along with two metabolites 6-chloro nicotinic acid (6-CNA) and 6-hydroxy nicotinic acid (6-HNA) was monitored in organs (brain, liver, kidney, and ovary) and bodily fluids (blood, urine) at 6, 12, 24 and 48 h and faeces at 24 and 48 h. Maximum concentration (Cmax) of IMI and metabolites in each organ and bodily fluid occurred after 12 h. Area under curve (AUC) of IMI ranged from 35 to 358 μg/ml/h; 6-CNA: 27.12–1006.42 μg/ml/h and 6-HNA: 14.98–302.74 μg/ml/h in different organs and bodily fluids. Clearance rate of IMI was maximum in ovary followed by kidney, liver, brain, faeces, blood and urine. Percent inhibition of acetyl-cholinesterase (AChE) was comparable in brain and Red Blood Cells (RBC) at 6–48 h which suggests the RBC-AChE as valid biomarker for assessing IMI exposure. It is evident that IMI was absorbed, metabolized, and excreted showing increased level of serum enzymes like Glutamic oxaloacetic transaminase (GOT), Glutamic pyruvic transaminase (GPT) and biochemical constituents like billirubin and Blood Urea Nitrogen (BUN) at 48 h. These data suggest that IMI is widely distributed, metabolized and induced toxicology effects at 20 mg/kg bodyweight to female rats.

Changes in food uptake by detritivorous macroinvertebrates could disrupt the ecosystem service of leaf litter breakdown, necessitating the study of shredding under anthropogenic influences. The impact of the neonicotinoid insecticide imidacloprid on the feeding rate of individual Gammarus pulex was measured at a daily resolution both during and after a 4-d exposure period. The authors found that imidacloprid inhibits feeding of G. pulex during exposure at concentrations ≥30 µg/L and that there was no recovery in feeding on transfer into clean media for 3 d. Exposure to imidacloprid at concentrations ≥0.81 µg/L and ≤9.0 µg/L resulted in increased feeding after exposure even though there was no significant effect on feeding during the exposure itself. Comparison with the literature shows that concentrations found to influence feeding lie within the range of estimated and measured environmental concentrations. Additionally, effects on feeding rate were observed at concentrations 2 orders of magnitude lower than those causing mortality. The lethal concentration for 50% of test organisms after 4 d of exposure (270 µg/L, literature data) and the effect concentration for a reduction in feeding by 50% (5.34 µg/L) were used for this comparison. The present study discusses the potential that effects on feeding may evoke effects at the population level or disturb leaf litter breakdown in the environment.

In the cold winter of 2012-13, 29% of honeybee colonies in the UK died, with only Belgium suffering a higher rate of losses (34%) of the 17 countries surveyed. By contrast, only 5% of colonies in Italy were lost. Summer losses of colonies were also high in the UK, at 9.7%, with only France (14%) exceeding this. The Epilobee study surveyed 31,800 colonies and is the first pan-European assessment of the rate of colony deaths. It provides a valuable baseline for future research but does not indicate the relative effects of factors such as disease, habitat loss and pesticide use in honeybee decline. Neither does it examine why some countries are worse affected.

Der Verein "natur & ëmwelt" und Greenpeace Luxemburg präsentierten am Dienstmorgen in Kockelscheuer ihre Öffentlichkeitskampagne zum Schutz der Bienen im Großherzogtum. Mit verschiedenen Aktionen wollen die beiden Vereinigungen in den kommenden Wochen auf die Lage der Bienen aufmerksam machen. Seit den späten 1990er-Jahren berichten weltweit Imker von einem plötzlichen und unerklärlichen Rückgang der Bienenvölker und einer ungewöhnlich hohen Sterberate von Honigbienen-Völkern, so Lea Bonblet von "natur&ëmwelt". Laut den beiden Vereinigungen starben im Großherzogtum in der Zeitspanne zwischen Herbst 2010 und Frühling 2013 rund 40 Prozent des Bienenbestandes. Die Zahl der Bienenvölker sank in dieser Zeit von 5.580 auf 3.258 Einheiten. Schuld an dem Bienensterben seien u.a. die Pestizide, so die Vertreter der beiden Vereinigungen. Im Mai 2013 wurden die drei schlimmsten Neonicotinoide in allen 27 EU-Mitgliedstaaten zum Teil verboten. Zwei Jahre lang dürfen die Stoffe Thiamethoxam und Clothianidin nicht mehr zur Schädlingsbekämpfung verwendet werden. Doch auch die konventionelle Landwirtschaft sowie der schrumpfende Lebensraum und der Mangel an geeigneten Lebensräumen tragen zum Bienensterben bei.

Zu diesem Ergebnis kommt eine neue Studie des NABU im Auftrag des Umweltbundesamtes (UBA). Viele Vogelarten, darunter Rebhuhn, Feldlerche und Goldammer, finden durch den Chemikalieneinsatz weniger Nahrung, weil mit den Schädlingen auch Futtertiere wie Schmetterlingsraupen und andere Insekten getötet werden. Herbizide beseitigen außerdem Wildkräuter auf den Äckern, auf denen Insekten leben und die Kleinsäugern und Jungvögeln Schutz bieten. „Es ist dringend nötig, in der Agrarlandschaft mindestens zehn Prozent Vorrangflächen ohne Spritzmittel einzurichten, wenn die Biodiversitätsziele der EU für 2020 noch erreicht werden sollen“, sagte NABU-Präsident Olaf Tschimpke.