Environmental fate and exposure; neonicotinoids and fipronil

Abstract

Systemic insecticides are applied to plants using a wide variety of methods, ranging from foliar sprays to seed treatments and soil drenches. Neonicotinoids and fipronil are among the most widely used pesticides in the world. Their popularity is largely due to their high toxicity to invertebrates, the ease and flexibility with which they can be applied, their long persistence, and their systemic nature, which ensures that they spread to all parts of the target crop. However, these properties also increase the probability of environmental contamination and exposure of nontarget organisms. Environmental contamination occurs via a number of routes including dust generated during drilling of dressed seeds, contamination and accumulation in arable soils and soil water, runoff into waterways, and uptake of pesticides by nontarget plants via their roots or dust deposition on leaves. Persistence in soils, waterways, and nontarget plants is variable but can be prolonged; for example, the half-lives of neonicotinoids in soils can exceed 1,000 days, so they can accumulate when used repeatedly. Similarly, they can persist in woody plants for periods exceeding 1 year. Breakdown results in toxic metabolites, though concentrations of these in the environment are rarely measured. Overall, there is strong evidence that soils, waterways, and plants in agricultural environments and neighboring areas are contaminated with variable levels of neonicotinoids or fipronil mixtures and their metabolites (soil, parts per billion (ppb)-parts per million (ppm) range; water, parts per trillion (ppt)-ppb range; and plants, ppb-ppm range). This provides multiple routes for chronic (and acute in some cases) exposure of nontarget animals. For example, pollinators are exposed through direct contact with dust during drilling; consumption of pollen, nectar, or guttation drops from seed-treated crops, water, and consumption of contaminated pollen and nectar from wild flowers and trees growing near-treated crops. Studies of food stores in honeybee colonies from across the globe demonstrate that colonies are routinely and chronically exposed to neonicotinoids, fipronil, and their metabolites (generally in the 1–100 ppb range), mixed with other pesticides some of which are known to act synergistically with neonicotinoids. Other nontarget organisms, particularly those inhabiting soils, aquatic habitats, or herbivorous insects feeding on noncrop plants in farmland, will also inevitably receive exposure, although data are generally lacking for these groups. We summarize the current state of knowledge regarding the environmental fate of these compounds by outlining what is known about the chemical properties of these compounds, and placing these properties in the context of modern agricultural practices.

Chronic neonicotinoid pesticide exposure and parasite stress differentially affects learning in honeybees and bumblebees

“…The concentration used was chosen to reflect field-realistic values. Reported values of the maximum amounts of clothianidin residues found in the nectar of treated crops vary from 1 to 14 ppb with the average values ranging from 0.3 to 5.4 ppb [29,[37][38][39]. Fresh sugar water solutions (contaminated with clothianidin or not) were renewed every 2 -4 days, and the amount of sugar water collected was recorded by weighting the feeders.…”

Detection of Oxamyl and Imidacloprid Pesticide residues in Some Iraqi Vegetables

“…When temperature reach to 20 ºC, the rate of imidacloprid solubility in water increase 610 higher than other circumstances with aqueous photolysis reach to 0.2 faster and water-sediment reach to 129 slower than other condition, this also explain the reason for disappear imidacloprid from November samples [66].…”

“…So before the targeted plants harvested, the concentration of pesticide reduced to half the concentration when it apply to plant, that is another reason of disappearing oxamyl and imidacloprid active ingredients in all samples. According to reference [64], imidacloprid can bind with soil organic matter and that reduce potentially the ability of imidacloprid for leaching throw the soil, this explain the reason of high ability for decomposers for degrade the active ingredients of imidacloprid. The samples 29/8/2016, zucchini from Sulaimaniyah and 24/8/2016, eggplant from Al-Yusufiyah, showed no pesticide residues or pesticide bi-products residues, the investigation revealed that the kind of planting soil is sandy soil.…”

Pollinators and Global Food Security: the Need for Holistic Global Stewardship

“…Neonicotinoids are persistent in soil and water, remain in the environment for a long time, and spread quickly through surface water (Bonmatin et al 2015). Through systemic uptake it also contaminates wild flowers (Botías et al 2015).…”