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VIII SIMPOSIO INTERNAZIONALE ICPBR HAZARDS
OF PESTICIDES TO BEES Effetti di Pesticidi sui bombi e su altri apoidei An extended laboratory test to evaluate the effects of pesticides on bumblebees Francesca Incerti (1), Laura Bortolotti (2), Claudio Porrini (3), Anna Micciarelli Sbrenna (1) and Giovanni Sbrenna (1) (1) Dipartimento
di Biologia, Università di Ferrara, Via Borsari 46, 44100, Ferrara,
Italy. E-mail: sbr@unife.it Bombus terrestris is considered an important pollinator both for cultivated crops and wild plants. Although it is widely used in agriculture, studies of the effects of pesticides on bumblebees are few, and results are often drawn from already existing data on honeybees. Nevertheless the morphological and biological differences between the species make it necessary to study the toxicological effects also on bumblebees. The misuse of pesticide can threaten their existence and decrease their beneficial effects upon the agriculture. Recent laboratory tests regarding the toxicity of pesticides on bumblebees have been conducted, according to the methods proposed by ICPBR, in the AMA Project, with the thirty most widely used pesticides in agriculture. Data on the toxicity of pesticides on bumblebees, in semi-field and field-tests, is still not unavailable due to only a small amount of research having been conducted. One of the aims of the AMA Project was the development of an extended laboratory bioassay to evaluate the effects of insecticides and acaricides on bumblebees. Special boxes were built which contained plants, and permitted insects a wide flight area, but also allowed operations to be controlled. The base of the box (plywood) measured 0,5x0,5 meters, while walls (plastic) were 1 meter in height, with openings to allow the introduction of insects and plants. Boxes were supplied with an irrigation system. The plants used were cucumbers (Cucumis sativus) on which, during the flowering period, different pesticides were sprayed. In each cage were placed two plants which were sprayed with 25 ml of pesticide solution, according to the quantity usually utilised in the field. Different types of pesticides were tested, such as phosphorganics (chlorpyrifos-methyl, dichlorvos, dimethoate, heptenophos and quinalphos), azotorganics (ethionfencarb, imidacloprid) and pyrethroids (acrinathrin, bifenthrin). Thirty bumblebees were put into contact with the plants in each box 1 hours after the treatment. Every 24 hours for the next three days temperature, abnormal behaviour and bumblebee mortality were recorded. In the second trial the introduction of the bumblebees into the cage was delayed for 24 hours after treatment; behaviour and mortality were checked over the next two days. The first results showed that phosphorganics have the highest level of toxicity, especially dimethoate and quinalphos, whereas the lowest hazard was found for pyrethroids, heptenophos and ethionfencarb. Imidacloprid did not lead to high mortality rate but it was able to stop insect activity for several hours. Delayed
introduction showed a significant hazard decrease only for phosphorganics.
The method seemed to provide reproducible and useful results for the
evaluation of pesticide toxicity; in addition it could be interesting
to combine the results with those gained from usual laboratory administrations
(contact and oral). In order to standardise this testing method, it
must be improved, in particular to minimise the difference in temperatures
and photoperiod due to seasonal differences. Also a repellence effect
of some of the pesticides should be investigate.
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