Mike Coulson

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.

Thiamethoxam: Assessing flight activity of honeybees foraging on treated oilseed rape using RFID 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.

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.

Occurrence and distribution of earthworms in agricultural landscapes across Europe with regard to testing for responses to plant protection products

PurposeWithin the regulatory framework for authorisation of plant protection products (PPPs) (EU Directive 91/414/1991/EEC replaced by Regulation (EC) 1107/2009), higher tier risk assessments and earthworm field tests are conducted in different countries across Europe. This paper describes dominant earthworm species for regulatory and biogeographical regions in agricultural landscapes across Europe and examines regional differences in earthworm communities and densities and their respective response to a toxic reference.Materials and methodsFor the assessment of earthworm abundance and species distribution, data of untreated control plots from 30 earthworm field studies were analysed; each conducted according to the ISO 11268–3 (1999) guideline by European Crop Protection Association member companies in the context of registration of PPPs. For the evaluation of the response to PPPs under different regional and climatic conditions, the effect on earthworm abundance was assessed by comparing plots treated with toxic references with untreated control plots. Additionally, a comparative literature review was included providing an overview of earthworm species composition and densities in agricultural crops from 14 European countries.Results and discussionThe assessment of earthworm field studies from six different European countries revealed that common earthworm species of anecic and endogeic ecological groups are present at most field sites. Dominant species groups of endogeic and anecic earthworms can be defined that are abundant in all assessed countries. These are the endogeic species Aporrectodea caliginosa, Aporrectodea rosea and Allolobophora chlorotica, and the anecic species Lumbricus terrestris (Northern and Central Europe) and Lumbricus friendi (Southern Europe). Taking into account the high variability in total earthworm abundances, it can be concluded that the variability within regions was larger than the variability between regions.ConclusionsAnalysis of the earthworm community and data of toxic references lead to the conclusion that testing in different zones is not considered necessary.

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.

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.

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.

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.

Semi-field and field testing on the honey bee working group

Findings of high concentrations of bee-toxic compounds in guttation drops from crop plants treated with a neonicotinoid seed dressing gave rise to concerns about a potential risk to honeybee colonies. As bee colonies seem to prefer water sources in the near surroundings, several field trials were set up, aimed to investigate if setting minimal distances of bee colonies to a frequently guttating seed-treated field could be a method to minimize the potential risk of water collecting bees ingesting contaminated guttation drops. The experiments were conducted in 2011 and 2012 on conventional managed maize, wheat and oilseed rape fields near Braunschweig (Lower Saxony, Germany). Every experimental field consisted of two plots; one planted with a neonicotinoid treated seed batch and one adjacent plot with an untreated seed batch. The bee hives were placed in the untreated plot before or immediately after emergence with a 0 m to maximal 85 m distance to the adjacent treated plot. The entrance of every hive pointed toward the treated plot. At each distance a minimum of three bee colonies containing approximately 11.000 20.000 bees were set up. During the whole experiment climatic conditions, growth stage of the crop plants and presence of guttation, rain and dew drops were recorded. If guttation occurred, droplets were sampled. Furthermore, colony development (Liebefelder method) and mortality (Gary-dead bee traps) were assessed. After completion of the field experiment residue analyses of guttation drops and dead bees were conducted. Guttation occurred frequently during the experimental phase. Residues in guttation droplets were detected during the entire experiment from BBCH 10 up to a maximum of BBCH 59, depending on the investigated crop. However in most cases the number of dead bees per colony was at a normal level, regardless of the tested crop and the distance between the bee colony and the treated field. The only exception was a slightly increased number of dead bees in tests with oilseed rape which was occasionally observed at 0 m distance to the treated crop. Furthermore, in some dead bees residues of the seed treatment were detected but without link between mortality and residues. However, no long term effects on bee brood and honey bee colony strength and development were observed independently from the distance and tested crop. Taking into account the results of all experiments there were no indications of an unacceptable risk for bee colonies from contaminated guttation drops in our trials. However, results of individual samples from the dead traps suggest that individual honeybees occasionally use guttation droplets as water source. Therefore, to maintain a certain distance between beehives and insecticide-treated fields of 60 m could be a potentially useful measure to further reduce the potential risk although the applicability and practicability of such a mitigation measure may be questioned. In many cases, it is neither for beekeepers nor growers possible to move the apiary or the field. It is possible that such a mitigation measure could further complicate the discussions between beekeepers and farmers in real life.Dust drift during sowing of maize seeds treated with neonicotinoids has led to several severe honey bee poisoning incidents in the past. Studies have been conducted to assess the abrasion potential of treated seeds, the influence of different sowing machines, and effects on honey bees in semi-field and field conditions. In the JKI a number of field and semi-field trials with sowing of treated seeds assessing effects on honey bees and also with manual application of small amounts of dusts were conducted. Several trials were conducted with sowing of winter oil seed rape (4 trials) and maize (3 trials) and an adjacent flowering crop, either winter oil seed rape or mustard both downwind and upwind of the sown area. Sowing was conducted when wind direction was at the achievable optimum. Residue samples from petri dishes for 2-D and gauze collectors for 3– D drift of dust drift were taken as well as samples from the adjacent flowering crop. Honey bee colonies were placed both upwind and downwind of the sowing area and served as treated variant and respective control. As sowing was conducted during bee flight activity, hive entrances of colonies in the semi-field experiments were closed from early morning until end of sowing. Thus a worst case scenario was obtained for exposure of bees to dusts deposited on flowers, nectar and pollen. The high number of the trials conducted between 2009 and 2014 allows a detailed insight of the correlation between Heubach a.i. values, 2-D and 3-D exposure and effects on honey bees after sowing of different crops.152 Julius-Kühn-Archiv, 450, 2015 2.16 Semi-field and field testing on the honey bee working group Frank Bakker, Heino Christl, Mike Coulson, Axel Dinter, Hervé Giffard, Nicole Hanewald, Gavin Lewis, Mark Miles, Jens Pistorius, Job van Praagh, Marit Randall, Christine Vergnet, Connie Hart, Christoph Sandrock, Thomas Steeger 1Eurofins, 2Tier 3, 3Syngenta, 4DuPont, 5Testapi, 6BASF, 7JSC, 8BCS, 9JKI, 10ICPPR, 11Norwegian FSA, 12ANSES, 13Health Canada, 14IES, 15US EPA