Ecotoxicological studies on the DI-31 in bees (Apis mellifera) orally administered

DI-31 is a brassinosteroid analogue obtained at the Chemistry Faculty of the Havana University. Brassinosteroids are a family of natural steroidal compounds from plants, which are able to improve yields and protect crops from abiotic and abiotic stresses (Krishna, 2003).Lack of toxicity of DI-31 for mammals has been previously reported (Pérez et al 1996), as well as the sensitivity of arthropods (microcrustaceans and insects) to DI-31 (Pérez et al 2007). Primary ecotoxicological studies with systemic focus in aquatic organisms were performed in 2007 (Pérez et al, unpublished).Since the contact safety of DI-31 for bees was recently demonstrated, the present study was aimed to the ecotoxicological evaluation by oral administration to the same species. The substance studied was supplied in the honey at a dose of 100 μg per bee. Three hundred and sixty bees of the species Apis mellifera, divided into three experimental groups, were used. The appearance of signs of toxicity and the mortality at 4, 24 and 48 hours after administration were scored (OECD, 1998). The bees treated did not present any sign of toxicity derived from the product assayed. These results take to the conclusion that DI-31 do not produce toxic effects by oral way in Apis mellifera.