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In addition to other assessments, the EFSA bee guidance document (2013) requires the risk assessment of plant protection products on honey bee larvae. At the time the EFSA GD was finalized, no data on honey bee larvae were available due to absence of suitable methods. That is why in 2013 the European Crop Protection Association (ECPA) perfomed an impact analysis of the new EFSA risk assessment, using extrapolated endpoints derived from acute oral honey bee endpoints. Today, a number of honey bee larvae toxicity studies (138 active substances or formulated products) have been conducted according to the newly developed testing methods for single exposure (OECD TG 237) repeated exposure studies until the end of the larval development (D7/D8) and repeated exposure testing (OECD GD 239) until adult hatch (D22). These experimental data have been used to determine the ‘pass rates’ for 215 worst case uses (72 fungicide spray and solid uses, 91 herbicide spray uses, incl. 8 PGR uses and in total 52 insecticide spray and solid uses, incl. 2 nematicide and 3 IGR uses) according to the EFSA Bee GD and to compare with the original ECPA impact analysis. As standardized test methods for non- Apis bees larvae were not available, risk assessment according to EFSA for bumblebees and solitary bees based on the honey bee endpoint as surrogate corrected by a safety factor of 10. Morevoer, the sensitivity of the NOEDs at D8 and D22 in repeated exposure (D 22) studies were analysed. Overall, the toxicity of fungicides and herbicides to honey bee larvae (expressed as means and medians of NOED and LD50 values) was moderate to low, while insecticides as expected displayed stronger toxicity. Moreover, the endpoints for herbicides were on average a factor of 2 higher than fungicides which ranges within the normal biological variability (factor of 3). In addition, it is unclear, if the difference is related to a slightly higher toxicity or other factors like different physical chemical properties (e.g. lower solubility). For insecticides, toxicity was about 125 (based on medians) and 6 to 8 (based on means) times higher than herbicides. In the screening risk assessment according to EFSA Bee GD the majority of fungicide (83.3%) and herbicide (95.6%) uses passed the risk assessment for larvae; whereas, for all insecticide uses thr pass rate was about 29%. In the Tier 1 risk assessment, these pass rates slightly increased and were even higher in the ‘treated crop’ and ‘weed in the field’ scenarios for fungicide and herbicide uses, almost being 100%. Pass rates for insecticide uses did not improve very much and amounted to be about 42% for both scenarios. When basing the risk assessment of bumblebee and solitary bee larvae on 1/10th of the honey bee larval endpoint, the majority of active substances and their respective products will fail the screening (overall about 96%) and Tier 1 risk assessment (overall about 90%). Alternative risk assessment approaches proposed by ECPA (e.g. following the EPPO approach; ECPA Option 1 using refinement options and more representative assumptions) or comparing an assummed exposure concentration to the NOEC (ECPA Option 2) led to a slight increase (Option 1) or even no differences in the pass rates (Option 2a) compared to EFSA Tier 1 risk assessment. Thus both, the standard risk assessment according to the EFSA Bee GD as well as the alternative ECPA Option 1 and 2 result in a clear distinction between products with high toxicity (insecticides) vs. non-toxic products (herbicides and fungicides) for the honey bee risk assessment. The sensitivity analysis of repeated exposure studies according OECD GD 239 indicated that in most cases toxicity did not increase during the pupation period between D8 and D22. Thus, the larval growing period between D3 and D8 represents the most sensitive period of the pre-imaginal development.

A preliminary data evaluation was conducted by ECPA companies to compare the sensitivity of bumblebees (Bombus terrestris) with the sensitivity of honeybees (Apis mellifera). For the evaluation about 70 data sets were available for contact exposure and about 50 data sets for oral exposure. The data sets comprised insecticides, fungicides, herbicides in about equal numbers plus a few other substances. The preliminary ECPA company data evaluation of LD 50 values indicates lower or similar contact sensitivity of bumblebees vs. honeybees. Similarly, lower or similar oral sensitivity of bumblebees vs. honeybees was determined with one exception for an insecticide that indicated higher acute oral bumblebee sensitivity compared to honeybees. For this insecticide, higher tier data indicates no negative impact on bumblebees at the maximum intended use rate. Overall, the ECPA company data evaluation indicates that bumblebees are not more sensitive than honeybees based on acute toxicity assessment.

In addition to other assessments, the 2013 EFSA bee guidance document requires the risk assessment of plant protection products on honey bee larvae. At the time the EFSA document was finalized, no data on honey bee larvae were available. In 2013 ECPA (the European Crop Protection Association) perfomed an impact analysis of the (then) new EFSA risk assessment and the reliability of the outcomes, using estimated endpoints derived from acute oral honey bee tests together with the usual extrapolation factors. Today, a number of honey bee larvae toxicity studies have been conducted according to the newly developed testing methods for single exposure (OECD TG 237) and repeated exposure testing (OECD GD 239). These experimental data have been used to update the ECPA impact analysis. Data on 114 active substances or formulated products were used, covering 166 worst case uses; (58 herbicides, 53 fungicides, 47 insecticides and 8 PGRs). The “pass” rates were determined according to the EFSA Bee guidance document and compared with the original outcome of the impact analysis from 2013 and with adult chronic toxicity data. When the findings of the impact analysis based on experimental data from 22 day larval tests was compared with the impact analysis from 2013 based on extrapolated data the two gave very similar results, thus indicating that the original assessment using acute data and extrapolation factors was suitably predictive.

A data evaluation was conducted to compare the acute sensitivity of the bumblebee Bombus terrestris L. with that of the honey bee Apis mellifera L. to plant protection products. For the evaluation 97 data sets were available for oral toxicity and 108 data sets for contact toxicity. For data sets with unbound honey bee LD50 values the data indicated similar or lower sensitivity of bumblebees versus honey bees by contact or oral exposure for all fungicides and herbicides. Likewise, similar or lower contact sensitivity of bumblebees than honey bees was found for all insecticides with definite honey bee endpoints. For oral exposure, this was also the case except for 5 active substances. Overall, the data supports for a wide range of chemistry that the honey bee is a sensitive surrogate test species for bumblebees. Therefore, routine application of a standard safety factor on honey bee endpoints in context of plant protection product risk assessment to cover bumblebee sensitivity is not justified. At present, honey bees seem to be an appropriate surrogate species to cover acute bumblebee sensitivity. [ABSTRACT FROM AUTHOR]

Abstract: There has been increasing interest in the effects of neonicotinoid insecticides on wild bees. In solitary bee species the direct link between each individual female and reproductive success offers the opportunity to evaluate effects on individuals. The present study investigated effects of exposure to winter oilseed rape grown from thiamethoxam‐treated seed on reproductive behavior and output of solitary red mason bees (Osmia bicornis) released in 6 pairs of fields over a 2‐yr period and confined to tunnels in a single year. After adjustment to the number of females released, there was significantly lower production of cells and cocoons/female in tunnels than in open field conditions. This difference may be because of the lack of alternative forage within the tunnels. Under open field conditions, palynology of the pollen provisions within the nests demonstrated a maximum average of 31% oilseed rape pollen at any site, with Quercus (oak) contributing up to 86% of the pollen. There were no significant effects from exposure to oilseed rape grown from thiamethoxam‐treated seed from nest establishment through cell production to emergence under tunnel or field conditions. Environ Toxicol Chem 2018;37:1071–1083. © 2017 SETAC [ABSTRACT FROM AUTHOR]

Abstract: Neonicotinoid insecticides have been used globally on a wide range of crops through seed treatment as well as soil and foliar applications and have been increasingly studied in relation to the potential risk to bees because of their detection in pollen and nectar of bee‐attractive crops. The present article reports the results of laboratory studies (10‐d adult and 22‐d larval toxicity studies assessing the chronic toxicity of thiamethoxam to adult honey bees and larvae, respectively) and a colony feeding study, with 6 wk of exposure in an area with limited alternative forage, to provide a prewintering colony‐level endpoint. The endpoints following exposure of individuals in the laboratory (10‐d adult chronic no‐observed‐effect concentration [NOEC] for mortality 117 μg thiamethoxam/kg sucrose solution, 141 μg thiamethoxam/L sucrose solution; 22‐d larval chronic NOEC 102 μg thiamethoxam/kg diet) are compared with those generated at the colony level, which incorporates sublethal effects (no‐observed‐adverse‐effect concentration [NOAEC] 50 μg thiamethoxam/L sucrose solution, 43 μg thiamethoxam/kg sucrose solution). The data for sucrose‐fed honey bee colonies support the lack of effects identified in previous colony‐level field studies with thiamethoxam. However, unlike these field studies demonstrating no effects, colony feeding study data also provide a threshold level of exposure likely to result in adverse effects on the colony in the absence of alternative forage, and a basis by which to evaluate the potential risk of thiamethoxam residues detected in pollen, nectar, or water following treatment of bee‐attractive crops. Environ Toxicol Chem 2018;37:816–828. © 2017 SETAC [ABSTRACT FROM AUTHOR]

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. Environ Toxicol Chem 2016;35:385-393. © 2015 SETAC [ABSTRACT FROM AUTHOR]