A Spinosad-Based Formulation Reduces the Survival and Alters the Behavior of the Stingless Bee Plebeia lucii.

The decline in bee populations worldwide has been associated with the use of pesticides in crop systems where these insects forage. The use of biopesticides, like spinosad, is preferred as an alternative method to control pests, because it is considered safer to non-target insects. In this study, we evaluated the lethal and sublethal effects of the spinosad-based formulation Tracer® on foragers of the stingless bee Plebeia lucii Moure (Apidae: Meliponini). Groups of bees were fed a pure diet (negative control) or a diet at different concentrations of spinosad. Positive control groups consisted of bees orally exposed to a diet with the neonicotinoid imidacloprid. Next, flight behavior, body mass, and respiration rate were evaluated in surviving bees. The results showed that bees´ survival was reduced by all concentrations of spinosad, when compared with the negative control. Bee locomotion-walking and flight-was reduced in accordance with the increase in spinosad concentrations; however, body mass and respiration rate were not altered. Our results show that the use of Tracer® in ecosystems visited by P. lucii can reduce forager bee survival and reduce their locomotion, generating a negative impact on pollination services provided by these bees.

Application of urea dosing for alkalinity supply during anaerobic digestion of vinasse.

Pushed by demand for renewable energy, the ethanol industry in Brazil is expanding. However, production of 1 m(3) of ethanol generates around 13 m(3) of liquid residues (vinasse), so this expansion results in an increasing need for a more adequate destination of these residues. Nowadays the vinasse is dispersed on the sugar cane fields in the practice of fertirrigation, but anaerobic digestion of this residue may be a better solution, additionally offering an alternative source of energy, able to complement hydroelectric power supply in the dry season. However, when trying to digest vinasse at reduced hydraulic retention times, complications arise from its strong tendency toward acidification, upsetting the fragile balance of transformations normally occurring under anaerobic conditions. For successful operation of an anaerobic treatment process with acceptable hydraulic residence times, increasing alkalinity levels inside the reactor is neces-sary. In the present work we show that pH regulation by means of urea dosing, in spite of the risk posed by ammonia toxicity towards methanogenic biomass, can be a viable alternative to avoid vinasse acidification. The ammonia formed in urea conversion remains in solution, rather than escaping to the biogas, and so its use as fertiliser can offset its cost of application in the process.