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Fabio Sgolastra, Simone Tosi, Piotr Medrzycki, Claudio Porrini and Giovanni Burgio

Abstract

In this paper we assessed, under laboratory conditions, the toxicity of an active substance on solitary bee larvae of Osmia cornuta (Hymenoptera: Megachilidae). A field-realistic dose of the systemic insecticide spirotetramat was applied to the mass provisions. The insecticide’s effects on several life-cycle parameters were studied in males and females. Our results showed a significantly shorter post-emergence longevity in bees exposed to spirotetramat during the larval stage, compared to the control. The observed reduction in longevity was 18 and 15%, respectively, in males and females. Mortality rate and other biological traits (larval and spinning duration, emergence time, food/body conversion rate) did not show significant differences between the two treatments. The method described in this study can be used to test the effects of toxic substances (i.e. agrochemicals) on bees. Moreover, it can constitute a basis for the development of a standardised protocol in the first tier of the Environmental Risk Assessment for solitary bees.

Open access

Ida Conti, Piotr Medrzycki, Francesca V. Grillenzoni, Francesca Corvucci, Simone Tosi, Valeria Malagnini, Martina Spinella and Mauro G. Mariotti

Abstract

Pollen collected from flowers by forager bees is the only natural protein source for the hive. This nutritional compound is fundamental for the nurse bee and brood development, and for the queen activity. Pollen has a strong influence on colony health. It is also known that the pollen quality, in terms of the amino acid profile and total protein content, varies significantly according to the floral origin. For this reason, the palynological diversity assessed in corbicular pollen is a good measure of the quality of the environment the bees live in, in terms of available food.

An international research initiative “C.S.I. Pollen” aims to elaborate a pollen diversity map for all of Europe, carried out by beekeepers. Chromatic assessment of pellet colours will be used as a method. In our study, we wanted to validate this idea, through the comparison between the two methods: chromatic assessment of the diversity of pollen pellet colours and palynological assessment of the real pollen type diversity. In other words, we wanted to verify whether the pellet-colour profile reflects the palynological one.

We found a significant correlation between results obtained from the two methods but some improvements are also proposed in order to increase the determination coefficient and to reduce the differences given by the two answers.