Results of Ring-Testing of a Semifield Study Design to Investigate Potential Impacts of Crop Protection Products on Bumblebees (Hymenoptera, Apidae) and a Proposal of a Potential Test Design

Abstract

In Europe, the risk assessment for bees at the European Union or national level has always focussed on potential impacts on honeybees. During the revision of the European Food Safety Authority bee guidance it was explicitly stated that bumblebees and solitary bees should be considered as well and consequently concerns were raised regarding the representativeness of honeybees for these other bee species. These concerns originate from differences in size as well as differences in behavioral and life history traits of other bee species. In response to this concern, the non-Apis working group of the International Commission for Plant-Pollinator Relationships initiated a ring-test of a semifield tunnel study design using the bumblebee Bombus terrestris. Nine laboratories participated, validating and improving the proposed design over a 2-year period. The intention of the ring-test experiments was to develop and if possible, establish a test protocol to conduct more standardized semifield tests with bumblebees. In the present study, the results of the ring-tests are summarized and discussed to give recommendations for a promising experimental design. Environ Toxicol Chem 2022;41:2548-2564. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Keywords: Bumblebee; Crop protection products; Ecotoxicology; Non-Apis; Risk assessment; Test design.

Figure 1

Bumblebee life cycle. Life cycle of Bombus terrestris: hibernating queens start foraging in spring and initiate a new bumblebee colony; the foundress queen starts building a brood nest and starts laying eggs; the foundress queen is still foraging and takes care of the brood; as soon as the first workers emerge, they take over the brood care and start foraging, the eusocial phase in the life cycle starts, and the foundress queen stays in the brood nest; the colony grows and produces workers; in the reproduction phase males and gynes are produced; the foundress queen dies and the young queens and males start foraging; gynes are mating; mated queens search for a place to overwinter and hibernate.

Figure 2

Box plot of the number of exiting and entering bumblebees per 10 min during the exposure phase in 2016 and 2017 (only the results of the valid tests are shown). The median, and first and third quartiles are presented, and whiskers represent minimum and maximum values.

Figure 3

Box plot of the number of dead worker bees in hives during the exposure phase in 2016 and 2017 (only the results of the valid tests are shown). The median, and first and third quartiles are presented, and whiskers represent minimum and maximum values.

Figure 4

Box plot of the total colony weight development of bumblebee colonies during the whole exposure phase in 2016 and 2017 (only the results of the valid tests are shown). The median, and first and third quartiles are presented, and whiskers represent minimum and maximum values.

Figure 5

Box plot of the total number of bumblebee queen stages (sum of emerged gynes, queen larvae, and queen pupae) produced in 2016 and 2017 (only the results of the valid tests are shown). The median, and first and third quartiles are presented, and whiskers represent minimum and maximum values.

Figure 6

Daily weight increase in control colonies during the exposure phase in 2016 and 2017 (tests observed with statistically significant lower number of bumblebee queen stages produced marked in gray).