Results of 2‐Year Ring Testing of a Semifield Study Design to Investigate Potential Impacts of Plant Protection Products on the Solitary Bees Osmia Bicornis and Osmia Cornuta and a Proposal for a Suitable Test Design

Abstract

There are various differences in size, behavior, and life history traits of non-Apis bee species compared with honey bees (Apis mellifera; Linnaeus, 1758). Currently, the risk assessment for bees in the international and national process of authorizing plant protection products has been based on honey bee data as a surrogate organism for non-Apis bees. To evaluate the feasibility of a semifield tunnel test for Osmia bicornis (Linnaeus, 1758) and Osmia cornuta (Latreille, 1805), a protocol was developed by the non-Apis working group of the International Commission for Plant-Pollinator Relationships, consisting of experts from authorities, academia, and industry. A total of 25 studies were performed over a 2-yr period testing a replicated control against a replicated positive control using either a dimethoate or diflubenzuron treatment. Studies were regarded to be valid, if ≥30% of released females were found to occupy the nesting units in the night/morning before the application (establishment). Thirteen studies were regarded to be valid and were analyzed further. Parameters analyzed were nest occupation, flight activity, cell production (total and per female), cocoon production (total and per female), emergence success, sex ratio, and mean weight of females and males. Dimethoate was a reliable positive control at the tested rate of 75 g a.i./ha, once >30% females had established, displaying acute effects such as reduction in flight activity, increase in adult mortality (shown by nest occupation), and reproduction ability of the females (total cell and cocoon production). On the other hand, no effects on larval and pupal development were observed. The growth regulator diflubenzuron had statistically significant effects on brood development, causing mortality of eggs and larvae at a rate of approximately 200 g a.i./ha, whereas fenoxycarb did not cause any significant effects at the tested rates of 300 and 600 g a.i./ha. In conclusion, the ring-test protocol proved to be adequate once the study comprised a well-established population of female Osmia bees, and the results improved in the second year as the laboratories increased their experience with the test organism. It is noted that the success of This article includes online-only Supplemental Data. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

How much pollen do solitary bee larvae consume? : Or establishing realistic exposure estimates of solitary bee larvae via pollen for the use in risk assessment

“…in south-west Germany (Limburgerhof). All locations were provided with artificial nest sites and the similar to the methods reported for Osmia field testing (Franke, Elston et al 2021). After one initial week of acclimatization we checked the nest sites twice a week for newly built cells and removed the pollen provisions before the larvae had hatched and stored them in individual Eppendorf® tubes at -20°C till analysis.…”

Bee Tracker—an open‐source machine learning‐based video analysis software for the assessment of nesting and foraging performance of cavity‐nesting solitary bees

“…Behavioral data can contribute to the understanding of behavior‐mediated impacts of environmental stressors on reproduction of solitary bee species (Artz & Pitts‐Singer, 2015). Pesticide exposure, for example, can impair orientation and memory (Siviter et al, 2018) and cause a reduction in nest recognition or foraging activity (Artz & Pitts‐Singer, 2015; Franke et al, 2021). Flight duration may also be increased by habitat degradation or food competition, which can cause increased flight distances to food sources (Gathmann & Tscharntke, 2002).…”

Establishing realistic exposure estimates of solitary bee larvae via pollen for use in risk assessment

“…Log pollen provision dw mg 0.92 log bee dw mg 0.44. (EPPO, 2010;Franke et al, 2021;OECD, 2014). All locations were provided with artificial nest sites and were similar to the methods reported for Osmia field testing (Franke et al, 2021).…”