Combined effects of three insecticides with different modes of action on biochemical responses of the solitary bee Osmia bicornis.

Bees are simultaneously exposed to a variety of pesticides, which are often applied in mixtures and can cause lethal and sublethal effects. The combined effects of pesticides, however, are not measured in the current risk assessment schemes. Additionally, the sublethal effects of pesticides on a variety of physiological processes are poorly recognized in bees, especially in non-Apis solitary bees.

Mortality Pattern of Beetles after Repeated Topical Exposure to Insecticide─Stochastic Death or Individual Tolerance?

The mortality of organisms exposed to toxicants has been attributed to either stochastic processes or individual tolerance (IT), leading to the stochastic death (SD) and IT models. While the IT model follows the principles of natural selection, the relevance of the SD model has been debated. To clarify why the idea of stochastic mortality has found its way into ecotoxicology, we investigated the mortality of (Linnaeus, 1758) beetles from pesticide-treated oilseed rape (OSR) fields and unsprayed meadows, subjected to repeated insecticide treatments.

Effects of agricultural landscape structure and canola coverage on biochemical and physiological traits of the ground beetle Poecilus cupreus.

The intensifications in the agricultural landscape and the application of pesticides can cause adverse effects on the fitness of organisms in that landscape. Here, we investigated whether habitats with different agricultural pressures influenced acetylcholinesterase (AChE) activity - a biomarker for exposure to pesticides, respiration rate, and resistance to starvation in the ground beetle Poecilus cupreus. Two differently structured landscapes were selected for the study, one dominated by small (S) and another by large (L) fields.

Floral resources,energetic value and pesticide residues in provisions collected by Osmia bicornis along a gradient of oilseed rape coverage.

Pollinators in agricultural landscapes are facing global decline and the main pressures include food scarcity and pesticide usage. Intensive agricultural landscapes may provide important food resources for wild pollinators via mass flowering crops. However, these are monofloral, short-term, and may contain pesticide residues.

Homogeneity of agriculture landscape promotes insecticide resistance in the ground beetle Poecilus cupreus.

The intensification of agriculture leads to increased pesticide use and significant transformation from small fields towards large-scale monocultures. This may significantly affect populations of non-target arthropods (NTA). We aimed to assess whether the multigenerational exposure to plant protection products has resulted in the evolution of resistance to insecticides in the ground beetle Poecilus cupreus originating from different agricultural landscapes.

Physiological and biochemical response of the solitary bee Osmia bicornis exposed to three insecticide-based agrochemicals.

The physiological and biochemical stress induced by pesticides need to be addressed in economically and ecologically important non-Apis solitary bees, particularly at lower than field-applied concentrations. Thus, the aim of the present study was to analyse the physiological and biochemical changes in female adult Osmia bicornis bees upon continuous oral exposure to three insecticide-based agrochemicals - i.e.

Toxicokinetics of three insecticides in the female adult solitary bee Osmia bicornis.

The worldwide decline of pollinators is of growing concern and has been related to the use of insecticides. Solitary bees are potentially exposed to many insecticides through contaminated pollen and/or nectar. The kinetics of these compounds in solitary bees is, however, unknown, limiting the use of these important pollinators in pesticide regulations.

Effects of agricultural landscape structure, insecticide residues, and pollen diversity on the life-history traits of the red mason bee Osmia bicornis.

Agricultural landscapes have changed substantially in recent decades, shifting from the dominance of small fields (S) with diverse cropping systems toward large-scale monoculture (L), where landscape heterogeneity disappears. In this study, artificial nests of the red mason bee, Osmia bicornis, were placed in S and L landscape types on the perimeter of oilseed rape fields representing different oilseed rape coverages (ORC, % land cover). The local landscape structure around each nest was characterised within a 100, 200, 500, and 1000 m radius using ORC and 14 landscape characteristics, which were then reduced by non-metric multidimensional scaling (nMDS) to two axes: nMDS1 characterised the dataset primarily according to land fragmentation and the main crop, whereas nMDS2 captured the prevalence of more natural areas in the landscape.

Different effects of Zn nanoparticles and ions on growth and cellular respiration in the earthworm Eisenia andrei after long-term exposure.

In this study, the effects of zinc nanoparticles (ZnO-NPs) and ions (ZnCl) on the mortality, growth, maturation, and cellular respiration of the earthworm Eisenia andrei were assessed. Earthworms were individually exposed for 98 days, starting from the juvenile stage, to soils contaminated with either ZnO-NPs or ZnCl (125, 250, 500 and 1000 mg Zn kg dry weight (dw)). Exposure to the highest-concentration ionic treatments (500 and 1000 mg kg) caused 100% mortality, while for other treatments, mortality did not exceed 15% at the end of exposure.

The development of the solitary bee Osmia bicornis is affected by some insecticide agrochemicals at environmentally relevant concentrations.

Solitary bees provide essential pollination services for many arable crops, but are prone to global decline. Agricultural intensification, which is connected with pesticide usage, is among major threats to bees and, thus, to the food security and ecosystem stability. As it may not be possible to cease pesticide usage currently because of the growing demand for food, it is crucial to understand the pesticide toxicities to bees for better protection of pollinator populations.

Supporting non-target arthropods in agroecosystems: Modelling effects of insecticides and landscape structure on carabids in agricultural landscapes.

Intensification of agricultural practices is one of the most important drivers of the dramatic decline of arthropod species. We do not know, however, the relative contribution to decline of different anthropogenic stressors that are part of this process. We used high-resolution dynamic landscape models and advanced spatially-explicit population modelling to estimate the relative importance of insecticide use and landscape structure for population dynamics of a widespread carabid beetle Bembidion lampros.

Unravelling the ZnO-NPs mechanistic pathway: Cellular changes and altered morphology in the gastrointestinal tract of the earthworm Eisenia andrei.

A major uptake route of nanoparticles (NPs) occurs via the gastrointestinal (GI) tract. When GI tract cells are exposed, NPs cytotoxic effects are observed that subsequently adversely affect the GI tract morphology and have consequences for the whole organism. The aim of this study was to understand the mechanism of effects caused by ZnO-NPs compared to Zn ions on the earthworm Eisenia andrei.

Effects of Cadmium Bioavailability in Food on Its Distribution in Different Tissues in the Ground Beetle Pterostichus oblongopunctatus.

In most laboratory studies with oral exposure of terrestrial invertebrates to metals an artificial food, which is easy to handle, is used. The bioavailability of metals from this artificial food may, however, be much higher than from more field relevant food sources. Such differences may affect toxicokinetic processes in different tissues.

Energy reserves and respiration rate in the earthworm Eisenia andrei after exposure to zinc in nanoparticle or ionic form.

The energy budget is an indicator of an organism's overall condition. Changes in energy reserves and/or energy consumption have been used as biomarkers of toxic stress. To understand the effects of different forms and concentrations of Zn and the costs of effective Zn regulation by the earthworm Eisenia andrei, we performed a toxicokinetic experiment in which individuals were sampled over time to determine the available energy reserves (total carbohydrate, protein, and lipid content), energy consumption (measured at the cellular level and as the whole-animal respiration rate), and internal Zn concentration.

Effect of cadmium bioavailability in food on its compartmentalisation in carabids.

Metals assimilated by organisms are sequestered in various compartments and some forms are more stable than others. Sequestration mechanisms used by invertebrates to detoxify metals and prevent interaction with important biomolecules include metal binding to proteins and other ligands, and storage in inorganic granules. The rate and extent at which metal concentrations in different compartments respond to metal concentrations in food and food characteristics has not received much attention, despite being of great relevance.

Ground beetle communities in a mountain river subjected to restoration: The Raba River, Polish Carpathians.

Effects of passive restoration of mountain rivers on the organisms inhabiting exposed riverine sediments are considerably less understood than those concerning aquatic biota. Thus, the effects of a recovery of the Raba River after abandonment of maintenance of its channelization scheme on ground beetle (Coleoptera: Carabidae) communities were investigated by comparing 6 unmanaged cross-sections and 6 cross-sections from adjacent channelized reaches. In each cross-section, ground beetles were collected from 12 sampling sites in spring, summer, and autumn, and 8 habitat parameters characterizing the cross-sections and sampling sites were determined.

Toxicokinetics of zinc-oxide nanoparticles and zinc ions in the earthworm Eisenia andrei.

The toxicokinetics of zinc in the earthworm Eisenia andrei was investigated following exposure for 21 days to ionic zinc (ZnCl) or zinc oxide nanoparticles (ZnO-NPs) in Lufa 2.2 soil, followed by 21 days elimination in clean soil. Two concentrations were tested for both ZnCl (250 and 500μg Zn g) and ZnO-NPs (500 and 1000μg Zn g), corresponding to EC and EC for effects on reproduction.

Combined effects of chlorpyriphos, copper and temperature on acetylcholinesterase activity and toxicokinetics of the chemicals in the earthworm Eisenia fetida.

In polluted environments organisms are commonly exposed to a combination of chemicals with different modes of action, and their effects can be additionally modified by natural abiotic conditions. One possible mechanism for interactions in mixtures is via toxicokinetics, as chemicals may alter the uptake, distribution, biotransformation and/or elimination of each other, and all these processes can be affected by temperature. In this study, the effect of temperature (T) on the toxicokinetics of copper (Cu) and chlorpyriphos (CHP), applied either singly or in binary mixtures, was studied in the earthworm Eisenia fetida.

Metal toxicokinetics and metal-driven damage to the gut of the ground beetle Pterostichus oblongopunctatus.

Toxicokinetics makes up the background for predicting concentrations of chemicals in organisms and, thus, ecological risk assessment. However, physiological and toxicological mechanisms behind toxicokinetics of particular chemicals are purely understood. The commonly used one-compartment model has been challenged recently, showing that in the case of metals it does not describe the pattern observed in terrestrial invertebrates exposed to highly contaminated food.

Subcellular partitioning of cadmium and zinc in mealworm beetle (Tenebrio molitor) larvae exposed to metal-contaminated flour.

By studying the internal compartmentalization of metals in different subcellular fractions we are able to better understand the mechanisms of metal accumulation in organisms and the transfer of metals through trophic chains. We investigated the internal compartmentalization of cadmium (Cd) and zinc (Zn) in mealworm beetle (Tenebrio molitor) larvae by breeding them in flour contaminated with either Cd at 100, 300 and 600mgkg(-1), or Zn at 1000 and 2000mgkg(-1). We separated the cellular components of the larvae into 3 fractions: the S1 or cytosolic fraction containing organelles, heat-sensitive and heat-stable proteins, the S2 or cellular debris fraction and the G or metal-rich granule fraction.

Concentration dependent toxicokinetics of copper in the red flour beetle Tribolium castaneum (Coleoptera: Tenebrionidae).

To predict internal metal concentrations in animals under specific environmental exposures, the relationship between the exposure concentrations and values of toxicokinetic parameters must be known. At high exposure levels, the availability of carriers transporting metal ions through cellular membranes may become limited, thereby decreasing the assimilation rates (k A ). Furthermore, increased metal concentrations in food may result in greater damage to the gut and reduce the assimilation efficiency and/or increase the elimination rate (k E ).

Regulation of body metal concentrations: Toxicokinetics of cadmium and zinc in crickets.

Previous studies indicated that essential and xenobiotic metals differ substantially in terms of their toxicokinetics. Whether these differences are due to different assimilation rates, different elimination rates, or both, and whether all metals are regulated in a similar manner but with different efficiency remains unclear. To compare the mechanisms responsible for the regulation of different metals, parameters for toxicokinetic models have to be tested under exposures to the identical molar concentration of those metals.

Using toxicokinetic-toxicodynamic modeling as an acute risk assessment refinement approach in vertebrate ecological risk assessment.

Recent guidance identified toxicokinetic-toxicodynamic (TK-TD) modeling as a relevant approach for risk assessment refinement. Yet, its added value compared to other refinement options is not detailed, and how to conduct the modeling appropriately is not explained. This case study addresses these issues through 2 examples of individual-level risk assessment for 2 hypothetical plant protection products: 1) evaluating the risk for small granivorous birds and small omnivorous mammals of a single application, as a seed treatment in winter cereals, and 2) evaluating the risk for fish after a pulsed treatment in the edge-of-field zone.

Toxicokinetics of metals in terrestrial invertebrates: making things straight with the one-compartment principle.

In this analysis, we first performed a critical review of one-compartment models used to describe metal toxicokinetics in invertebrates and found mathematical or conceptual errors in almost all published studies. In some publications, the models used do not represent the exact solution of the underlying one-compartment differential equations; others use unrealistic assumptions about constant background metal concentration and/or zero metal concentration in uncontaminated medium. Herein we present exact solutions of two differential-equation models, one describing simple two-stage toxicokinetics (metal toxicokinetic follows the experimental phases: the uptake phase and the decontamination phase) and another that can be applied for more complex three-stage patterns (toxicokinetic pattern does not follow two phases determined by an experimenter).