Effect of two NeemAzalTM formulations on honeybees under semi-field conditions

Abstract

The effects of NeemAzalTM formulations: NeemAzalTM T/S (1% azadirachtin) and NeemAzalTM granules (1% azadirachtin) on honeybees, <i>Apis mellifera</i> L., were studied under semi-field conditions. Three plots at 15 m<sup>2</sup> each were sown with spring rape seeds Brassica napus cultivar Likolly (Brassicaceae/Cruciferae). In the first plot NeemAzal granules were added with the seeds during sowing. The second plot was sprayed with NeemAzal T/S during full flowering; GreemaxTM was used as a wetting agent. The third one was sprayed with water only during full flowering as a control. For each treatment one tunnel tent (3 × 5 × 2 m) was used during the flowering period. Small bee colonies were exposed to the treated plants for 7 days. Evaluation was carried out by comparing the results in the treatments to the control and, furthermore, by comparing the pre- and post-application. The mortality in the tunnels and the flight activity were checked before, as well as after the treatment. The development of the bee brood was evaluated by using transparent acetate sheets to mark single cells in brood combs with their contents on different assessment dates. The time schedule of the assessment dates was chosen in order to check the bee brood at different expected stages during the development. The development of the bee brood was evaluated by calculation of brood termination rates in percentage and brood indices. The results show that residues of NeemAzal granules did not adversely affect bee mortality, foraging activity or brood development. By contrast, it was noticed that NeemAzal T/S caused some reduction in foraging activity and brood development.