Introducing the INSIGNIA project: Environmental monitoring of pesticide use through honey bees

Abstract

As a starting point, we performed toxicological studies with the N -cyano-substituted neonicotinoid insecticide thiacloprid and N -nitro-substituted compound imidacloprid to identify the reason(s) for the over 500-fold higher intrinsic toxicity of N -nitro-substituted compounds to the honey bee ( Apis mellifera ). Radioligandbinding assays revealed that both, thiacloprid and imidacloprid, display a similar nanomolar binding affinity to their target, the postsynaptic nicotinic acetylcholine receptor (nAChR). However, thiacloprid is significantly faster degraded by hydroxylation compared to imidacloprid providing evidence that cytochrome P450 monooxygenases (P450s) facilitate oxidative metabolism of this chemical class. Subsequently, a honey bee P450 expression library compromising all 27 clade 3 P450s was established and P450s belonging to CYP9Q-subfamily were identified to be involved in the rapid turnover of thiacloprid, mainly driven by CYP9Q3, but with a low turnover of imidacloprid. Beside the honey bee CYP9Q-family, we also identified in collaboration with external partners at Rothamsted Research and Exeter University the orthologous P450s CYP9Q4-6 in the bumblebee ( Bombus terrestris ) and CYP9BU1-2 in the red mason bee ( Osmia bicornis ) as key determinants of neonicotinoid selectivity. The knowledge obtained from this interdisciplinary approach is of high value to mechanistically understand the interaction of pesticides and bees beyond guideline studies and is further extended to gain insights in the molecular mechanism underlying bee-sensitivity in other pollinator species, i.e. the alfalfa leafcutter bee Megachile rotundata . Moreover, the established molecular and biochemical tools are ready to be applied to address questions of fundamental research as well as in the targeted design of intrinsically bee-friendly insecticides. Abstract INSIGNIA aims to design and test an innovative, non-invasive, scientifically proven citizen science environmental monitoring protocol for the detection of pesticides by honey bees. It is a 30-month pilot project initiated and financed by the EC (PP-1-1-2018; EC SANTE). The study is being carried out by a consortium of specialists in honey bees, apiculture, statistics, analytics, modelling, extension, social science and citizen science from twelve countries. Honey bee colonies are excellent bio-samplers of biological material such as nectar, pollen and plant pathogens, as well as non-biological material such as pesticides or airborne contamination. Honey bee colonies forage over a circle of 1 km radius, increasing to several km if required, depending on the availability and attractiveness of food. All material collected is accumulated in the hive. Abstract The ICP-PR Bee Brood Working Group (WG) was founded at the 9 th Symposium held at York, UK, in 2005. It was chaired by Roland Becker (BASF) until the 13 th Symposium in 2017 in Valencia, Spain; the WG is currently chaired by Verena Tänzler (Ibacon)), Lukas Jeker (Agroscope) and Selwyn Wilkins (Fera). The first WG meeting following Valencia was held in Amsterdam in March 2018. The first task was to identify WG priorities given recent regulatory developments and data requirements on higher-tier bee brood studies i.e . semi-field and field testing. The aim was to continue the previous work of the group toward improving and harmonizing the OECD 75 1 and Oomen et al . 1992 2 methods. A full review of the available test methods was undertaken, looking at the strengths and limitations of the semi-field and full-field brood testing methods. Additionally, one of the major issues noted was lack of a clear structure or guidance for progressing through the testing methods and under what circumstances should a particular test be considered? Based on this initial meeting and discussions, three subgroups were formed each working separately on their tasks and coming together at joint WG meetings to discuss their progress.