Insecticides

None flew over the cuckoo's nest: A world without birds

Could we be facing a future without birds? Our reliance on pesticides has cut a swathe through their numbers. We must act now, argues Kate Ravilious. It is nearly 50 years since Rachel Carson wrote Silent Spring, the book that warned of environmental damage the pesticide DDT was causing. Today, DDT use is banned except in exceptional circumstances, yet we still don't seem to have taken on board Carson's fundamental message. According to Henk Tennekes, a researcher at the Experimental Toxicology Services in Zutphen, the Netherlands, the threat of DDT has been superseded by a relatively new class of insecticide, known as the neonicotinoids. In his book The Systemic Insecticides: A Disaster in the Making, published this month, Tennekes draws all the evidence together, to make the case that neonicotinoids are causing a catastrophe in the insect world, which is having a knock-on effect for many of our birds.

Onrustwekkende achteruitgang van de boerenzwaluw in Europa en Noord Amerika door insectenschaarste

Het gaat niet goed met de boerenzwaluw Hirundo rustica in Vlaanderen. De populatie wordt nu geschat op 20 à 30.000 broedparen tegenover 200 à 300.000 in het begin van de jaren zeventig. Een dramatische achteruitgang van ongeveer 90 procent in 35 jaar. Volgens de Vogelbescherming is de Nederlandse broedpopulatie sinds 1980 ook met 50-75% geslonken. De schaalvergroting en intensivering van de landbouw is een belangrijke reden voor de achteruitgang van de boerenzwaluw in onze streken. Veel van de kleine gemengde familiebedrijven zijn gestopt en vervangen door industriële veehouderijen met moderne stallingen die veel minder geschikt zijn als broedplaats voor boerenzwaluw. Ook het gebruik van insecticiden is één van de redenen voor de steile achteruitgang van het aantal broedende boerenzwaluwen. Boerenzwaluwen zijn voor hun voeding en het grootbrengen van hun jongen immers volledig aangewezen op insecten.

Physiological and behavioural effects of imidacloprid on two ecologically relevant earthworm species

Earthworms play key roles in soils and sublethal effects of environmental toxicants on these organisms should be taken seriously, since they might have detrimental effects on higher ecological levels. Earthworms make important contributions to the breakdown of organic matter, soil fertility, and to the formation of soils. In laboratory experiments we have assessed sub-lethal effects of imidacloprid on two earthworm species commonly found in different agricultural soils (Lumbricus terrestris and Aporrectodea caliginosa). After 7 days of exposure in contaminated soil, a significant loss of body mass was found in both species exposed to imidacloprid concentrations as low as 0.66 mg kg-1 dry soil. These losses ranged from 18.3 to 39% for A. caliginosa and from 7.4 to 32.4% for L. terrestris, respectively. The detected sub-lethal effects were found close to the predicted environmental concentration (PEC) of imidacloprid, which is in the range of 0.33–0.66 mg kg-1 dry soil.

Fatal Imidacloprid Poisoning in Humans

Neonicotinoids, agonists at the nicotinic acetylcholine receptors (nAChRs), induce neuromuscular paralysis. The high selectivity for nAChRs (particularly the a4b2 subtype) in insects compared with mammals results in their favorable toxicological profile. We describe fatal toxicity with one such insecticide, imidacloprid, considered relatively safe. This patient manifested neurological dysfunction and rhabdomyolysis. The initial neurological dysfunction, probably due to central nicotinic stimulation, was compounded by ischemic and metabolic encephalopathy. This report of imidacloprid toxicity sensitizes clinicians to an emerging cause of poisoning and highlights the need for a careful review of its toxicity profile.

Marianne Thieme over het nieuwe boek "The Systemic Insecticides: A Disaster in the Making"

Afgelopen woensdag (3 november 2010) was er een rondetafelgesprek over gif - of gewasbescherming zoals de sector het zelf graag noemt - in de Tweede Kamer. Dr. Henk Tennekes, die onderzoek doet naar de relatie tussen neonicotinoiden – een heel giftige insecticide - en bijensterfte, was daar ook aanwezig als deskundige. Dr. Tennekes is lang bezig geweest met onderzoek naar kanker. Hij vertelde mij dat hij betrokken raakte bij het onderzoek naar bijensterfte, toen hij ontdekte dat insecticiden zoals imidacloprid op een vergelijkbare manier werken als kankerverwekkende stoffen. Toen hij zich realiseerde wat dit betekent voor het milieu en de biodiversiteit, heeft hij besloten hier werk van te maken. Om zijn zorgen over de effecten van neonicotinoiden met een wijder publiek te delen, heeft Dr. Tennekes ook een boek geschreven over dit onderwerp: The systemic insecticides: a disaster in the making. Voorafgaand aan het rondetafelgesprek bood Henk mij zijn nieuwe boek aan. Hij wilde mij daarmee bedanken voor het feit dat ik al in 2007 Kamervragen heb gesteld over dit onderwerp.

Neues Buch „A disaster in the making“ über die Ursachen des europaweiten Bienen- und Vogelsterbens

Am 1. November 2010 erschien das Buch „A disaster in the making“ des holländischen Toxikologen Dr. Henk Tennekes über die Ursachen des europaweiten Bienen- und Vogelsterbens. Das Buch wird mit ganzseitigen Bildern des Künstlers Ami-Bernard Zillweger illustriert. Dr. Tennekes legt darin dar, dass der drastische Rückgang zahlreicher Vogelpopulationen, unter anderem Spatzen Bachstelzen, Stare, Kiebitze oder Feldlerchen, mit der Dezimierung von Insekten in Zusammenhang steht. Käfer, Fliegen, Schmetterlinge und Motten, die den Vögeln als Nahrung, werden vor allem durch die Anwendung von Pestiziden, sogenannten Neonicotinoiden, reduziert.

A Disaster in the Making: A new book on the hazards of imidacloprid

A 72-page 2010 publication raises new and troubling questions about a widely used insecticide's potential for harm to bees, beneficial insects, and bird populations. Using imidacloprid as an example, Dutch toxicologist Dr. Henk Tennekes reports on the hazards of imidacloprid to insects and birds. Imidacloprid is a neonicotinoid chemical, and has systemic action in plants. Other European researchers have linked this insecticide to significant risks for honey bee populations, including possible links to Colony Collapse Disorder.

Dr. Tennekes' findings indicate that imidacloprid (and possibly other neonicotinoid-type insecticides) can bind irreversibly to critical receptors in an insect's nervous system. If these receptors are permanently blocked, the insecticide would not follow a typical dose-response curve. He provides evidence that long term low level to imidacloprid exposure can lead to neurological problems and eventual death of insects.

Studies have shown imidacloprid to be highly persistent in the environment (RCC Compendium of Pesticide Information). In his book, Tennekes presents data showing that imidacloprid has contaminated most of the waterways in the Netherlands.

Systemic activity in plants combined with long-term persistence in the environment and toxicity at low concentrations can be a dangerous combination. Many vulnerable species over large areas could be exposed to this insecticide on land, in surface water following runoff from treated areas and in groundwater due to its potential for leaching through certain soil types.

Several previous studies have shown that imidacloprid is highly toxic to various forms of wildlife, including honey bees, certain beneficial insects, upland game birds, and crustaceans

Tennekes further suggests that imidacloprid has led to a general decline in the insect populations in the Netherlands, and this lack of food in turn has been responsible for declines in bird populations.

Potential risks of systemic imidacloprid to parasitoid natural enemies of a cerambycid attacking Eucalyptus

A community of insect herbivores has established on eucalyptus species in California following their introduction from Australia. A number of the species are under complete or partial biological control. A response to introduction of additional pest species into the complex has been the application of systemic insecticides to infested trees. Natural enemies that have been introduced to control the various pest species feed on the nectar of treated trees, and thus may be affected by these pesticides. In this study, Eucalyptus rudis trees were treated at label rates with the neonicotinoid systemic insecticide imidacloprid and nectar sampled at 5 months post-treatment during the spring bloom. The insecticide appears to be concentrating in the nectar at higher levels than reported from other plant species and at concentrations exceeding the LC50 for two important parasitoids. If tree treatments become widespread as a result of continual introductions of new eucalypt herbivores, established biological control programs could be at significant risk.

Assessing Toxicity of the Insecticide Thiacloprid on Chironomus riparius (Insecta: Diptera)

Since data documentation on neonicotinic toxicity to nontarget organisms should be enhanced, the effects of thiacloprid, a novel neonicotinoid insecticide, on the sediment-dwelling nontarget insect Chironomus riparius were investigated. C. riparius was impacted starting at concentrations of 0.5 μg/L, a concentration that can be considered environmentally relevant. Larval mortality, behavior, emergence, and Hsp70 protein level were sensitive indicators for the toxic effect of thiacloprid, whereas gender ratio and mouthpart morphology were not affected.

Neonicotinoid insecticides disrupt predation on the eggs of turf-infesting scarab beetles

Turfgrass applications of imidacloprid were previously shown to suppress the abundance of certain soil arthropods. To ascertain whether those impacts harbor functional consequences, the effect of neonicotinoids on Japanese beetle (Popillia japonica Newman) predation was examined in three experiments that measured removal of eggs implanted into non-irrigated field plots. A first experiment confirmed that a single imidacloprid application reduced the abundance of nontarget fauna and the rate of egg removal. A second experiment compared the impacts of imidacloprid with those of three other neonicotinoids, while a third measured the impact of imidacloprid when applied in July, August or September. Egg removal declined 28.3–76.1% in imidacloprid-treated plots across all studies. Effects were detected as early as one week after treatment (WAT) and persisted as long as four WAT. The extent of suppression did not vary across month of application. Clothianidin, dinotefuran and thiamethoxam also suppressed egg removal, and the effects were similar among them and with imidacloprid. There was no discernible association between variation in rainfall and treatment effects, but this was not explicitly tested. Results support the hypotheses that a single neonicotinoid application can suppress predation on pest populations and that the effect does not vary with respect to active ingredient or season of application. Neonicotinoid application at the time of beetle oviposition puts intended effects (mortality of neonates) in conflict with unintended effects (disruption of egg predation).