Neonicotinoids: Spreading, Translocation and Aquatic Toxicity

Abstract

Various environmental and ecotoxicological aspects related to applications of neonicotinoid insecticides are assessed. Dosages of neonicotinoids applied in seed coating materials were determined and are compared to other applications (spray and granule). Environmental levels in soils and affecting factors in translocation are discussed. Excretion of neonicotinoids via guttation from coated maize seeds up to two months upon emergence, as well as cross-contamination of plants emerged from non-coated seeds or weeds nearby have been demonstrated. Contamination of surface waters is discussed in scope of a worldwide review and the environmental fate of the neonicotinoid active ingredients and the formulating surfactant appeared to be mutually affected by each other. Toxicity of neonicotinoid active ingredients and formulations on Daphnia magna completed with some investigations of activity of the detoxifying glutathione S-transferase enzyme demonstrated the modified toxicity due to the formulating agents. Electrophysiological results on identified central neurons of the terrestrial snail Helix pomatia showed acetylcholine antagonist (inhibitory) effects of neonicotinoid insecticide products, but no agonist (ACh-like) effects were recorded. These data also suggested different molecular targets (nicotinergic acetylcholine receptors and acetylcholine esterase enzyme) of neonicotinoids in the snail central nervous system.Before the approval of neonicotinoids in seed treatment, numerous insect pests were controlled with the use of in-furrow granular insecticides. Seed coating is regarded as a precise delivery method of pesticides, which is therefore more effective compared to other plant protection product (PPP) applications (e.g., spraying). Neonicotinoids persist long enough to provide an effective control on a broad spectrum of insects, which led to their increased adoption by growers. As for maize, an estimated annual average of 45% and 25% of the total crop cultivation in the US was treated with CLO and TMX, respectively (with annual maxima of 65% for CLO and 45% for TMX in any given year) [16], and corresponding average proportion of the use of seeds coated with CLO or TMX are 46%, 33%, 24% and 18% for sugar beet, cotton, sorghum and soybean, respectively [16]. In accordance with these maximum rates, nearly 100% of maize in the US and canola in Canada is cultivated from seeds coated with neonicotinoids [17] and often fungicides as well.One of the first signs of the environmental problem caused by neonicotinoids was detected in Germany in the spring 2008, when abrasion of active substance from treated seeds during sowing of maize led to mass poisonings incidents of bees [18]. Thereafter, substantial efforts were made to minimize the environmental impacts of these crop protection products. Improvements in seed coating technology (e.g., application of polymers) and modification of pneumatic planters have been introduced to reduce abrasion of the seed coating material during planting. Polymers in seed treatment not only i...

Evaluation of Systemic Imidacloprid and Herbicide Treatments on Flatheaded Borer (Coleoptera: Buprestidae) Management in Field Nursery Production

“…The remaining imidacloprid residues in soil are presumably lost to volatilization, microbial and chemical degradation, uptake by other plants, and lateral or vertical movement by leaching or on eroded soil particles ( Bonmatin et al 2015 , Botías et al 2015 ). Imidacloprid residues that are not removed by the maple trees could be a hazard to nontarget organisms like aquatic invertebrates or pollinators, since imidacloprid is commonly found outside of crop areas in surface and ground water or in other vegetation ( Krupke et al 2012 , Botías et al 2015 , Mörtl et al 2020 ). Since neonicotinoids can have soil half-lives >1,000 d ( Bonmatin et al 2015 ), the effective lower application rates in this study may help to reduce accumulation persistence and off-site movement.…”

“…Therefore, there is a need to identify systemic treatment options that can allow more trees per unit area to be treated. An added benefit of lower rates could be less cost to growers, lower active ingredient loads in soil resulting in reduced persistence and off-site movement in the environment, and reduced impacts on nontargets like pollinators ( Krupke et al 2012 , Bonmatin et al 2015 , Botías et al 2015 , Mörtl et al 2020 ).…”

“…Imidacloprid not removed by crop plants either remains in the soil or is lost to degradation, leaching, or uptake by other plants ( Sur and Stork 2003 , Bonmatin et al 2015 ). Because systemic insecticides are translocated by plants, other adjacent vegetation like weeds may compete with nursery tree crops for the same insecticide residues ( Krupke et al 2012 , Botías et al 2015 , Mörtl et al 2020 ). If so, then management of competing weed vegetation in nursery rows with herbicides may improve tree root access to insecticide residues in the soil.…”

Impacts of Neonicotinoids on Molluscs: What We Know and What We Need to Know

“…Imidacloprid and thiamethoxam, for instance, can be applied by numerous techniques including root drench to the soil, foliar sprays over ground plants, or as trunk injection to trees; however, the majority of all neonicotinoids are conveyed as seed/soil treatment in agricultural systems [ 41 , 47 ]. The application rate of neonicotinoids depends on several factors, including the crop type, method of application and the specific neonicotinoid and the country of used [ 48 ].…”

Analysis of Anopheles messeae s.l. intron gene polymorphism associated with imidacloprid resistance

“…The most commonly used neonicotinoid, imidacloprid, has a half‐degradation time of about a year in water (Mason et al 2013). Due to these properties, treating areas with imidacloprid caused rather high concentrations of neonicotinoids in the surrounding water bodies (Starner and Goh 2012, Mörtl et al 2020). This leads to the long‐term selection of the most resistant organisms and, as a consequence, changes the gene pool of populations as a whole.…”