Soil Biodiversity: State-of-the-Art and Possible Implementation in Chemical Risk Assessment.

Protecting the structure and functioning of soil ecosystems is one of the central aims of current regulations of chemicals. This is, for instance, shown by the emphasis on the protection of key drivers and ecosystem services as proposed in the protection goal options for soil organisms by the European Food Safety Authority (EFSA). Such targets require insight into soil biodiversity, its role in the functioning of ecosystems, and the way it responds to stress. Also required are tools and methodologies for properly assessing biodiversity. To address these issues, the Society of Environmental Toxicology and Chemistry (SETAC) Europe 14th Special Science Symposium (SESSS14) was held 19 to 20 November 2019 in Brussels, Belgium. The central aim of the SESSS14 was to provide information on how to include soil biodiversity and soil functions as protection goal options in the risk assessment and quantification of the effects of chemicals and other stressors (including their respective regulations). This paper is based on the presentations and discussions at the SESSS14 and will give a brief update on the scientific state-of-the art on soil biodiversity, novel scientific developments, experimental and modeling approaches, as well as case studies. It will also discuss how these approaches could inform future risk assessment of chemicals and other stressors in the regulatory context of protecting soil ecosystems. Integr Environ Assess Manag 2021;17:541-551. © 2020 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Authors response on Schick et al. 2017 "An experiment of the impact of a neonicotinoid pesticide on honey bees; the value of a formal analysis of the data". Environ Sci Eur (2017).

Whilst a formal statistical analysis of any experimental data is always preferable in principle, in the case of Pilling et al. (PLoS ONE 8:e77193, 2013), it is hard to see how the results of any formal analysis-including those provided by Schick et al.-could be considered reliable. Regardless of the issue of statistical analysis, there was a wealth of valuable and novel biological and chemical residue data generated under field conditions of use in Pilling et al., which when taken into consideration alongside other relevant available published data and information (i.e. expert judgement) demonstrated a low risk to honeybees from thiamethoxam when used as a seed treatment on oilseed rape. Indeed, similar conclusions have been reported in subsequent published honeybee field studies using thiamethoxam seed-treated oilseed rape, thus supporting the original conclusions of Pilling et al.

Monitoring the effects of thiamethoxam applied as a seed treatment to winter oilseed rape on the development of bumblebee (Bombus terrestris) colonies.

BACKGROUND: The development of bumblebee (Bombus terrestris audax) colonies that had foraged for 5 weeks on flowering winter oilseed rape grown from seed treated with thiamethoxam (as Cruiser OSR) was assessed (two control, one treated field). Colony development was evaluated by monitoring the colony mass, forager activity was assessed, both at the hive and within the crop, and the contribution of oilseed rape to the pollen stored within the colony was analysed. RESULTS: Pollen collected from the treated crop contained residues of 1.0 µg thiamethoxam kg(-1) and 3.0 µg CGA322704 (metabolite likely equivalent to clothiandin) kg(-1) , and nectar contained residues of 1.8 µg thiamethoxam kg(-1) and no metabolite. No residues of thiamethoxam or CGA322704 were detected in samples from the control fields. Up to 93% of bumblebee collected pollen sampled from within the colonies originated from oilseed rape, and B. terrestris were observed actively foraging on all the fields. Colonies on all three fields showed similar rates of mass gain during the exposure phase and comparable production of gynes and drones. CONCLUSIONS: B. terrestris colonies placed adjacent to a field of flowering oilseed rape grown from thiamethoxam-treated seed developed at a comparable rate with colonies placed adjacent to oilseed rape grown from untreated seed. © 2015 Society of Chemical Industry.

Thiamethoxam: Assessing flight activity of honeybees foraging on treated oilseed rape using radio frequency identification technology.

The present study was designed to assess homing behavior of bees foraging on winter oilseed rape grown from seed treated with thiamethoxam (as Cruiser OSR), with 1 field drilled with thiamethoxam-treated seed and 2 control fields drilled with fungicide-only-treated seed. Twelve honeybee colonies were used per treatment group, 4 each located at the field edge (on-field site), at approximately 500 m and 1000 m from the field. A total of nearly 300 newly emerged bees per colony were fitted (tagged) with Mic3 radio frequency identification (RFID) transponders and introduced into each of the 36 study hives. The RFID readers fitted to the entrances of the test colonies were used to monitor the activity of the tagged bees for the duration of the 5-wk flowering period of the crop. These activity data were analyzed to assess any impact on flight activity of bees foraging on the treated compared with untreated crops. Honeybees were seen to be actively foraging within all 3 treatment groups during the exposure period. The data for the more than 3000 RFID-tagged bees and more than 90 000 foraging flights monitored throughout the exposure phase for the study follow the same trends across the treatment and controls and at each of the 3 apiary distances, indicating that there were no effects from foraging on the treated crop. Under the experimental conditions, there was no effect of foraging on thiamethoxam-treated oilseed rape on honeybee flight activity or on their ability to return to the hive.

Recalibration of the earthworm tier 1 risk assessment of plant protection products.

In the first step of earthworm risk assessment for plant protection products (PPPs), the risk is assessed by comparing the no-observed effect levels (NOELs) from laboratory reproduction tests with the predicted exposure of the PPP in soil, while applying a trigger value (assessment factor [AF]) to cover uncertainties. If this step indicates a potential risk, field studies are conducted. However, the predicted environmental concentration in soil, which can be calculated, for example, for different soil layers (ranging from 0-1 cm to 0-20 cm), and the AF determine the conservatism that is applied in this first step. In this review paper, the tier 1 earthworm risk assessment for PPPs is calibrated by comparing the NOEL in earthworm reproduction tests with effect levels on earthworm populations under realistic field conditions. A data set of 54 pairs of studies conducted in the laboratory and in the field with the same PPP was compiled, allowing a direct comparison of relevant endpoints. The results indicate that a tier 1 AF of 5 combined with a regulatory relevant soil layer of 0 to 5 cm provides a conservative tier 1 risk assessment. A risk was identified by the tier 1 risk assessment in the majority of the cases at application rates that were of low risk for natural earthworm populations under field conditions. Increasing the conservatism in the tier 1 risk assessment by reducing the depth of the regulatory relevant soil layer or by increasing the tier 1 AF would increase the number of false positives and trigger a large number of additional field studies. This increased conservatism, however, would not increase the margin of safety for earthworm populations. The analysis revealed that the risk assessment is conservative if an AF of 5 and a regulatory relevant soil layer of 0 to 5 cm is used. Integr Environ Assess Manag 2016;12:643-650. © 2015 SETAC.

Authors' response on Hoppe et al. (2015) "Effects of a neonicotinoid pesticide on honey bee colonies: a response to the field study by Pilling et al. (2013)". Environ Sci Eur (2015) 27-28.

The published Commentary by Hoppe et al. (Environ Sci Eur 27-28, 2015) makes a number of strong criticisms of Pilling et al. (PLoS One 8:e77193, 2013), which this authors' response will show are either wrong, inaccurate or misleading. A selection of these misrepresentations include a claim that technical thiamethoxam was used rather than the commercial product. This is not true. Pilling et al. (PLoS One 8:e77193, 2013) clearly state that formulated commercial products were used which also included fungicides. It is claimed that there was a failure to quantify colony losses in winter. Again this is not true. These data were readily extractable from the original paper. It is claimed that 70 % of the colonies did not survive. For a multiple year study this is very misleading. The annual colony loss rate was 14.8 % for treated colonies and 16 % for control colonies, well within background colony loss rates reported by the EC Epilobee EU monitoring programme. Concerns are also raised regarding the PLOS One reviewing process. The reality is that Pilling et al. (PLoS One 8:e77193, 2013) was extensively reviewed by five referees during the original review process, followed by a second post-publication editorial review. These inaccurate and misleading statements are then used to infer that the data, methodology and conclusions of low risk to honeybees from Pilling et al. (PLoS One 8:e77193, 2013) are untruthful and misleading. This inference is both absolutely untrue and inappropriate. Pilling et al.'s (PLoS One 8:e77193, 2013) paper is a summary of one the most comprehensive set of field studies ever conducted on honeybees, a fact recognised within both the second review by PLOS One and within the published EFSA Evaluation of Thiamethoxam.

A four-year field program investigating long-term effects of repeated exposure of honey bee colonies to flowering crops treated with thiamethoxam.

Neonicotinoid residues in nectar and pollen from crop plants have been implicated as one of the potential factors causing the declines of honey bee populations. Median residues of thiamethoxam in pollen collected from honey bees after foraging on flowering seed treated maize were found to be between 1 and 7 µg/kg, median residues of the metabolite CGA322704 (clothianidin) in the pollen were between 1 and 4 µg/kg. In oilseed rape, median residues of thiamethoxam found in pollen collected from bees were between <1 and 3.5 µg/kg and in nectar from foraging bees were between 0.65 and 2.4 µg/kg. Median residues of CGA322704 in pollen and nectar in the oilseed rape trials were all below the limit of quantification (1 µg/kg). Residues in the hive were even lower in both the maize and oilseed rape trials, being at or below the level of detection of 1 µg/kg for bee bread in the hive and at or below the level of detection of 0.5 µg/kg for hive nectar, honey and royal jelly samples. The long-term risk to honey bee colonies in the field was also investigated, including the sensitive overwintering stage, from four years consecutive single treatment crop exposures to flowering maize and oilseed rape grown from thiamethoxam treated seeds at rates recommended for insect control. Throughout the study, mortality, foraging behavior, colony strength, colony weight, brood development and food storage levels were similar between treatment and control colonies. Detailed examination of brood development throughout the year demonstrated that colonies exposed to the treated crop were able to successfully overwinter and had a similar health status to the control colonies in the following spring. We conclude that these data demonstrate there is a low risk to honey bees from systemic residues in nectar and pollen following the use of thiamethoxam as a seed treatment on oilseed rape and maize.

Effects of solvent on the toxicity of dimethoate in a honey bee in vitro larval study.

BACKGROUND: There is increasing interest in the toxicity of pesticides to honey bee larvae. The solubility of pesticides in the artificial diet used to dose larvae is a key issue. There has been no full evaluation of the use of solvents to dissolve pesticides in the larval toxicity test system. RESULTS: Data generated for the toxicity of dimethoate to larvae using 5 and 10% acetone solvent in the diet were similar and close to the toxicity data for adults (LD50 0.1-0.3 µg bee(-1)). With only 1.5% acetone as a vehicle, the toxicity (LD50 0.6-1.14 µg larva(-1)) was lower and closer to published validation data of 1.5-3.1 µg larva(-1) (with some reported data as high as 8.8 µg larva(-1)) generated using dimethoate dissolved in water. This suggests that the solubility of the pesticide in the diet is a key factor in determining its toxicity. CONCLUSIONS: Consideration of the solubility of the toxic reference and test items when designing studies is important. The use of higher rates of acetone in the present study more closely represents the true exposure of larvae to pesticides that are not highly soluble in diet. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.