Insecticides

Neonicotinoid insecticide travels through a soil food chain, disrupting biological control of non-target pests and decreasing soya bean yield

Neonicotinoids are the most widely used insecticides world-wide, but their fate in the environment remains unclear, as does their potential to influence non-target species and the roles they play in agroecosystems. We investigated in laboratory and field studies the influence of the neonicotinoid thiamethoxam, applied as a coating to soya bean seeds, on interactions among soya beans, non-target molluscan herbivores and their insect predators. In the laboratory, the pest slug Deroceras reticulatum was unaffected by thiamethoxam, but transmitted the toxin to predaceous beetles (Chlaenius tricolor), impairing or killing >60%. In the field, thiamethoxam-based seed treatments depressed activity–density of arthropod predators, thereby relaxing predation of slugs and reducing soya bean densities by 19% and yield by 5%. Neonicotinoid residue analyses revealed that insecticide concentrations declined through the food chain, but levels in field-collected slugs (up to 500 ng g−1) were still high enough to harm insect predators. Our findings reveal a previously unconsidered ecological pathway through which neonicotinoid use can unintentionally reduce biological control and crop yield. Trophic transfer of neonicotinoids challenges the notion that seed-applied toxins precisely target herbivorous pests and highlights the need to consider predatory arthropods and soil communities in neonicotinoid risk assessment and stewardship.

Het Ctgb in Wageningen plaatst zich boven onze volksvertegenwoordiging

Na een publicatie in Nature in juli 2014 heeft staatssecretaris Dijksma van Economische Zaken direct aan het College voor de toelating van gewasbeschermingsmiddelen en biociden (Ctgb) gevraagd om te reageren op het onderzoek en te bezien of er consequenties zijn voor de toelating van imidacloprid. Een dergelijk verzoek aan het Ctgb is te beschouwen als de eerste stap in een 'regulier traject' voor nationaal ingrijpen in de toelating van een gewasbeschermingsmiddel. Wanneer zich in de toekomst een vergelijkbaar geval voordoet, zal Dijksma het Ctgb zal opnieuw vragen te beoordelen of ingrijpen in de toelating tot de mogelijkheden behoort. Dat schrijft de staatssecretaris aan de Tweede Kamer.

A multi-year field study to evaluate the environmental fate and agronomic effects of insecticide mixtures

A mixture of insecticides used in corn production was monitored over a three-year period in a field study to determine how long each persists in the environment, where each insecticide travels within the corn field, and the efficacy of using soil-applied insecticides with genetically modified corn. The genetically modified corn contained the insecticidal Cry1Ab and Cry3Bb1 proteins (Bt corn) and the Cry1Ab protein was found to persist only during the corn growing season in soil, runoffwater, and runoff sediment with highest concentrations measured during pollination. Very low concentrations of Cry1Ab proteins were measured in soil collected in the non-Bt corn field, and no Cry1Ab proteins were detected in shallow groundwater or soil pore water. Clothianidin, a neonicotinoid insecticide used as a seed coating, was detected in all matrices and remained persistent throughout the year in soil pore water. Tefluthrin, a pyrethroid insecticide applied at planting to control corn rootworm larvae (Diabrotica spp., Coleoptera: Chrysomelidae) populations, was consistently detected in soil, runoff water, and runoff sediment during the corn growing season, but was not detected in groundwater or soil pore water. Tefluthrin did not have an effect on root damage from corn rootworm larvae feeding to Bt corn, but did prevent damage to non-Bt corn. A slight reduction in grain yield was observed in the non-Bt, no tefluthrin treatment when compared to all other treatments, but no significant difference in grain yield was observed among Bt corn treatments regardless of soil insecticide application. In the current study, the use of tefluthrin on Bt corn did not significantly affect crop damage or yield, and tefluthrin may travel off-site in runoff water and sediment.

Meer dan 100 wetenschappers doen een beroep op de Pollinator Health Task Force van president Barack Obama om actie te ondernemen tegen de neonicotinoïden

In een brief aan het Witte Huis refereren meer dan 100 wetenschappers uit diverse disciplines (daaronder de Nederlandse toxicoloog Henk Tennekes) naar de groeiende hoeveelheid bewijsmateriaal dat de neonicotinoïden en andere systemische pesticiden ernstige schade toevoegen aan bijen en andere bestuivers. Deze wetenschappers doen een beroep op de leiders van de Pollinator Health Task Force van president Barack Obama om actie te ondernemen tegen pesticiden ter bescherming en bevordering van een gezonde populaties van bijen en andere bestuivers.

100+ Scientists Call on Obama’s Bee Task Force to Take Action on Pesticides

In a letter submitted for today’s White House “listening sessions” deadline, over 100 scientists from diverse disciplines (including Dutch toxicologist Henk Tennekes) cited the growing body of evidence that neonicotinoids and other systemic pesticides harm bees. These scientists called on leaders of President Barack Obama’s Pollinator Health Task Force to take action on pesticides to protect and promote healthy populations of bees and other pollinators.

Neonicotinoid contamination of global surfacewaters and associated risk to aquatic invertebrates: A review

Neonicotinoids, broad-spectrum systemic insecticides, are the fastest growing class of insecticides worldwide and are now registered for use on hundreds of field crops in over 120 different countries. The environmental profile of this class of pesticides indicate that they are persistent, have high leaching and runoff potential, and are highly toxic to a wide range of invertebrates. Therefore, neonicotinoids represent a significant risk to surface waters and the diverse aquatic and terrestrial fauna that these ecosystems support. This review synthesizes the current state of knowledge on the reported concentrations of neonicotinoids in surface waters from 29 studies in 9 countries world-wide in tandem with published data on their acute and chronic toxicity to 49 species of aquatic insects and crustaceans spanning 12 invertebrate orders. Strong evidence exists that water-borne neonicotinoid exposures are frequent, long-term and at levels (geometric means = 0.13 μg/L (averages) and 0.63 μg/L (maxima)) which commonly exceed several existing water quality guidelines.

Henk Tennekes vertelt over zijn werk over neonicotinoïden tijdens afsluiting project de Honingbank in Den Haag

De Honingbank is een kunstproject dat is bedacht door het Franse collectief Parti Poétique (‘Poetische Partij’) en in samenwerking met Stroom Den Haag werd ontwikkeld. Dit project bood een instrument om bijen te sparen: De Bijenspaarrekening. Stroom heeft ervoor gekozen met de Honing Bank te stoppen, waarvoor de organisatorische, financiële en praktische belasting die het project vereist, de belangrijkste redenen zijn. Op vrijdag 14 november 2014 werd het Honing Bank project feestelijk afgesloten. Tijdens deze bijeenkomst vertelde toxicoloog Henk Tennekes over zijn onderzoek naar neonicotinoiden dat hij heeft gedaan m.b.v. een extra bijdrage die de Honing Bank via crowdfunding binnenhaalde.

Miskenning van het aerotoxisch syndroom door de KLM oogst heftige kritiek van gerenommeerde neurologen

Een Boeing 737 gezagvoerder van KLM heeft verleden jaar zijn werkgever aangeklaagd na 'chronische vergiftiging' in de cockpit. De KLM-vlieger meldde zich van tijd tot tijd ziek. De klachten kwamen steeds terug als hij weer aan het werk ging. In 2011 werd hij opgenomen in het ziekenhuis. De advocaat van de man vermoedt dat er sprake is van ernstige ziekteverschijnselen door giftige lucht in de cabine en cockpit. De werkgever van de piloot stelde dat er geen bewijs is voor de relatie tussen de lichamelijk ongemakken en de mogelijkheid van giftige dampen in het vliegtuig en maande de piloot vergeefs weer aan het werk te gaan. Sinds vorige maand krijgt hij geen salaris meer. De discussie rond de mogelijkheid van aerotoxisch syndroom wordt door KLM afgehouden aangezien er nog steeds geen bewijs is. De maatschappij meldt structureel dat er geen officiële gevallen bekend zijn van aerotoxisch syndroom binnen de bemanning. Wel is er een werkgroep binnen de maatschappij die onderzoek doet naar de mogelijke gevolgen voor het vliegend personeel van de lucht die via de motoren van de vliegtuigen de cabine in komt. Een recente publicatie van deze werkgroep in het vaktijdschrift Neurotoxicology waarin het aerotoxisch syndroom wordt ontkend leidde tot heftige kritiek van gerenommeerde neurologen (bijlage).

Time dependent sorption behavior of dinotefuran, imidacloprid and thiamethoxam

In this research study, time-dependent sorption behavior of Dinetofuran (DNT), imidacloprid (IMD) and thiamethoxam (THM) in vineyard soil was studied. Sorption kinetics studies were conducted over a period of 96 hours with sampling duration varying from 0, 2, 4, 8, 12, 24, 60 and 96 hours. All three neonicotinoids exhibited very low sorption potential for the soil investigated. Overall percent sorption for all three neonicotinoids was below 20.04 ± 2.03% with highest percent sorption being observed for IMD followed by DNT and THM. All three neonicotinoids are highly soluble with solubility increasing with IMD < THM < DNT. Although, DNT has the highest solubility among all three neonicotinoids investigated, it exhibited higher percent sorption compared to THM, indicating factors other than solubility influenced the sorption kinetics. Low sorption potential of neonicotinoids indicates greater leaching potential with regard to groundwater and surface water contamination.

Evaluation of leaching potential of three systemic neonicotinoid insecticides in vineyard soil

In this study, the leaching behavior of Dinotefuran (DNT), imidacloprid (IMD), and thiamethoxam (THM) was investigated in soils collected from an active AgriLife Research Extension Center (AREC) vineyard. A series of column experiments were conducted to evaluate the leaching potential of insecticides under two experimental scenarios: a) individual pulse mode, and b) mixed pulse mode. In both scenarios, the breakthrough pattern of the insecticides in the mostly acidic to neutral vineyard soil clearly demonstrates medium to high leachability. Of the three insecticides studied for leaching, DNT has exhibited high leaching potential and exited the column with fewer pore volumes, whereas IMD was retained for longer, indicating lower leachability. Relative differences in leaching behavior of neonicotinoids could be attributed to their solubility with the leaching pattern IMD < THM < DNT showing strong correlation with increasing aqueous solubility 610 mg/L < 4100 mg/L < 39,830 mg/L. Triplicate column study experiments were conducted to evaluate the consistency of the breakthrough pattern of these insecticides. The repeatability of the breakthrough curves shows that both DNT and IMD are reproducible between runs, whereas, THM shows some inconsistency. Leaching behavior of neonicotinoid insecticides based on the leachability indices such as groundwater ubiquity score, relative leaching potential, and partitioning between different environmental matrices through a fugacity-based equilibrium criterion model clearly indicates that DNT may pose a greater threat to aquatic resources compared to IMD and THM.