The European regulatory framework (Directive 91/414/EEC, Regulation 1107/2009/EC) requires data to evaluate the risk of pesticides on the honey bee brood. Beside the possibility to run studies under laboratory conditions, there are 2 publications available to run higher tier studies (e.g. semi-field and field) in order to evaluate the potential impact of a pesticide on the honey bee brood development.
The “in-hive field test” published by Oomen et al. (1992), is carried out with free-flying bee colonies, which are fed with contaminated sugar solution. One litre of sugar solution is mixed with a certain amount of pesticide and offered to the bee colonies over a short time period. The brood development is followed by weekly assessments of individual marked brood cells. Such kinds of tests are qualitative test methods or screening tests in order to evaluate the question, whether PPPs are causing harmful effects on the bee brood or not.
A quantitative test method closer to the real field scenario is the semi-field brood test according to the OECD Guidance Document 75 (OECD, 2007). Within this test design a PPP is sprayed directly on a flowering crop and the bee colonies are forced to forage for nectar and pollen in tunnel tents. Thus the bee brood contacts contaminated food and the development of the bee brood in single cells is followed regularly over one complete brood cycle from an egg to a worker bee.
A third possibility to evaluate the risk of PPPs to the bee brood under field conditions is a honey bee field study based on the EPPO 170 (EPPO, 2010a) guideline in combination with detailed brood assessments according to the OECD Guidance Document 75. In the following paragraphs the main focus will be directed to the test method under semi-field conditions.