Effectiveness of method improvements of OECD GD 75 – Evaluation by the ICP-PR Bee Brood Working Group
Abstract
Background: The OECD Guidance Document No. 75 (2007) is a method to investigate potential effects of plant protection products on the brood of honeybees (Apis mellifera L.), with the ‘brood termination rate’ (BTR, failure of individual eggs or larvae to develop) as the key endpoint. As in recent years a number of studies displayed a strong variability in BTRs, Pistorius et al. (2012) recommended some measures for improvements. First results in the season 2011 indicated that these measures led to lower BTRs and lower variability. The ICP-PR bee brood working group has evaluated the effectiveness of the recommended measures for improving the reliability of the method and the resulting BTRs and reports in this paper.Results: To evaluate the effectiveness of these measures a data analysis of a total of 62 studies was performed which were carried out in Germany and Switzerland between 2011 and 2014. Based on this analysis, the mean BTR in the control was 29.2% and this result did not display a distinct improvement compared to the historical data (34.7%) (Pistorius et al. 2012) and neither compared to the data of the bee brood ring-test (28.0%) (Schur et al. 2003). Moreover, the proportion of replicates (colonies) with BTRs ≤30% amounted to be 61.5% compared to 55.6% in the years before. And every 2nd study displayed BTRs >30% in two or more replicates. Also, the proportion of replicates (colonies) with BTRs ≤40% amounted to 76.9% compared to 68.3% in the years before and just 21.7% of the studies displayed BTRs >40% in two or more replicates.
Conclusion: Overall, these findings highlight that the test method according to the OECD Guidance document in 2007was not be considerably improved with the recommended measures. But although the reliability of the method and a reliable interpretation regarding potential effects of a plant protection product (PPP) on bee brood was not given in all studies, it currently remains the only available test method to address the potential risk of a plant protection product on honeybee larval development in realistic worst-case (semi-field) exposure conditions. Among other factors, it is assumed that the limitations are most likely due to the confined semi-field conditions. Further work should investigate potential additional improvements in semi-field conditions and also brood termination rates in field conditions.
Keywords: honeybees, bee brood test, OECD GD 75, brood termination rate
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2015-10-12
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Rubrik
Section II: Developments in laboratory, semi-field and field testing for honeybees
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