Honey bee risk assessment: new approaches for in vitro larvae rearing and data analyses

Abstract

Summary1. To sustain the vital ecosystem service of pollination, new methodical developments are needed for research on the underlying factors of globally observed bee losses. In particular, robust laboratory methods for assessing adverse effects on honey bee brood are required. In addition, from a statistical point of view, the shared origin of test individuals must be considered when analysing ecotoxicological data.2. To improve honey bee in vitro rearing, we adopted a nongrafting method to collect honey bee larvae without direct manipulation. Linear mixed effects model to evaluate LD50, larvae survival and prepupae weights integrated the colony background of larvae as a random factor into the statistical analyses. The novel rearing approach and appropriate statistical tools for data analyses are illustrated in an in vitro case study on acute oral dimethoate toxicity.3. We recommend our honey bee larvae collection approach for in vitro larvae‐rearing applications, because of (i) a mere 3% background mortality upon the prepupae stage, (ii) a high quantitative capacity and (iii) because of robustness of performance which are great benefits for standardization.4. The analyses indicate clear adverse effects of dimethoate by a significant survival reduction and prepupae weight reduction. For second instars, the acute 48‐h LD50 was 1·67 μg dimethoate per larva.5. We conclude that both our larvae collection method and the applied statistical approaches will help to improve the quality of environmental risk assessment studies on honey bees, to secure honey bee pollination and to sustain biodiversity.