I

Anno 2 N. 2
Claudio Porrini [1], Anna Gloria Sabatini [2]

Honey bees and pesticides toxicity

[1] DiSTA - Area Entomolgia, Università di Bologna, Italy
[2] CRA - Istituto nazionale di apicoltura, Italy


Corresponding author: cporrini@entom.agrsci.unibo.it

For the introduction of plant protection products on the market, ecotoxicological studies, which are set out by the European Directive 91/414/CEE of July 15, 1991, are required. These regulations consider the effects of pesticides on the environment and on useful organisms, particularly on honey bees and other pollinators. Several international institutions, such as the EPPO (European and Mediterranean Plant Protection Organization) and the European Council, collaborated in order to harmonize the evaluation methods. A common protocol is available for all European Member States, but each country can choose autonomously which methodologies to adopt.

The European Directive mentioned above is based on the concept of risk which has replaced that of innocuousness, toxicity being a common property of all pesticides. Therefore, risk assessment of a pesticide can only be done after both laboratory and field trials have been conducted, which lead to classifying a product as of high, medium, low, and negligible risk to honey bees. The risk assessment procedure takes into account numerous factors, such as the applied doses, the method of application, the crop being treated, etc. Each stage of the procedure leads either to an assessment of the risk or to further tests.

Three parameters are relevant for determining the toxicity (in the laboratory) and the risk (in the field) of a plant protection product: the characteristics of the molecule, of the environment in which the product is being used, and of the test organism. Contrary to what occurs in the field, in the laboratory the molecule is protected from degradation, but the honey bees are stressed due to the confinement. Thus, when no toxicity effects are recorded in laboratory tests, in most cases the product can be considered harmless to honey bees. However, for reliable risk assessment, test conditions should resemble usual farming practices, but this would involve expensive and laborious procedures, difficult to get going, and sometimes the recorded data are of difficult interpretation. A combination of laboratory and field tests is a useful alternative. However, when laboratory and field data do not match, the latter should be considered more reliable than the former. The recent introduction on the market of new plant protection products that do not necessarily cause mortality effects in honey bees, but may affect the behaviour of adult bees and the development of bee larvae, induced researchers to develop new methods, taking into account also sublethal effects.