Jütte, Tobias

Pistorius, Jens

Steinigeweg, Charlotte

English

JKI Open Journal Systems (Julius Kühn-Institut)

10th Young Scientists Meeting, Siebeldingen, Germany, November 08-10, 2017 Steinigeweg et al. Exposure by nesting material? – Method development of a suitable design for higher tier studies with solitary bees Charlotte Steinigeweg1, Tobias Jütte2 and Jens Pistorius2 1Technical University Braunschweig, Institute of Geoecology, Braunschweig 2Julius Kühn-Institut, Institute for Bee Protection, Braunschweig E-mail of corresponding author: ch.steinigeweg@arcor.deThe registration processes and risk as-sessment of plant protection products on bees resulted in an increasing need for experiments with non-apis pollina-tors to assess potential side effects of plant protection products on this rela-tively new group of test organisms. Re-cently, numerous studies have been performed but there is still a wide range of ongoing challenges. One of the chal-lenges is the risk from insecticide expo-sure to solitary bees, especially at their larval stages, by contaminated nesting material (e.g. mud partitions – mason bees). In 2017, an experiment was performed under modified field conditions with the horn-faced mason bee Osmia cornuta (Hymenoptera, Megachilidae) with 6 replicates per treatment group at two comparable locations in Southeast Lower Saxony, Northern Germany. The aim of the experiment was to develop a suitable test method for higher tier risk assessments with solitary wild bees ex-posed to treated nesting material. The potential effect of the insect growth regulator (IGR) Diflubenzuron to bees and their brood was examined. The IGR was applied at two concentrations (T1: 1ppm, T2: 5ppm) directly into the pollen mass and on the mud wall. The results in both treatments were compared to a water treated control (C). The reproduction capacity and brood termination rate were observed in the study as endpoints. Furthermore, hatching success and flight activity were recorded as additional information at several occasions. Other observations and surrounding flowering plants in the nearby environment were also docu-mented and considered. The present results provide no evidence that the exposure by Diflubenzuron has an effect on the development during the larval stages of Osmia cornuta, neither in pollen mass nor in the nesting mate-rial. It remains to be seen whether the results can be confirmed at the end of our experiment in next spring, when further parameter like completion of development, phenotypical changes, hatching and fitness will be evaluated.  The developed method initially seems to be suitable but it is still prone to various sources of errors which have to be ex-cluded by some modifications. For ex-cluding those errors and uniting labora-tory regulations and natural conditions of the field experiments, probably semi-field experiments might be more appro-priate. Semi-field test designs would investigate the exposure of adult bees as well as their brood to field-realistic pes-ticide quantities and ensure a collecting only of contaminated pollen/nectar and nesting material.  72 Berichte aus dem Julius Kühn-Institut 192

Exposure by nesting material? – Method development of a suitable design for higher tier studies with solitary bees

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Exposure by nesting material? – Method development of a suitable design for higher tier studies with solitary bees

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