Bees of genus Apis are the main crop pollinators; however, the use of pesticides in agriculture may intoxicate them during foraging. In this study, we evaluated the toxic eff ects caused by difenoconazole (fungicide), fenpyroximate (acaricide) and mineral oil (adjuvant) used alone and associated (pesticide + adjuvant) on workers of Apis mellifera L. Bees were exposed to product doses recommended by manufacturers, orally and in contact on a contaminated surface in a controlled environment. All products presented low lethality, both in isolation and combination (except for difenoconazole via contact), however, they all showed toxic effects. The results showed that combination of pesticides with adjuvant augmented toxic eff ects.

The conservation of the fauna of bees inhabiting the Brazilian savanna is threatened due to changes in land use in the last decades. We investigated the composition, species richness and abundance of a bee assemblage in the vicinity of the Chapada Diamantina National Park. In addition, we compiled data on composition and diversity from another bee assemblage located in the same portion of the Cerrado, which was previously investigated by one of us almost 30 years ago, in order to produce a more complete panorama on beta diversity of bees in this region. We used a non-metric multidimensional scaling ordination analysis (NMDS) to compare composition of bee assemblages from diff erent types of open vegetation. We recorded 77 bee species (H’ = 2.95; J = 0.68), 42% of them were singletons. We collected slightly more than half of the species and 60% of the genera recorded in the bee assemblage studied three decades ago. H’ was signifi cantly lower in our area than in the previous study (t = 8.588, p <0.001), but equitability (J) was very similar. Several factors may contribute to these diff erences, including local diff erences in bee assemblage composition, diff erences in the probability of capturing the diff erent species (many rare species), factors affecting the sampling itself, and perhaps species loss over the three decades separating the two studies. The magnitude of species loss is difficult to assess because the two studies were not carried out exactly in the same area and there were differences in sampling time and sampling effort.

In this study we investigated the group of floral resources that support bee populations from a bee assemblage in a savanna, and the way in which bee species use these food resources, with an emphasis on the breadth and overlap of trophic niches. The interactions between 75 species of bees and 62 species of plants visited to obtain floral resources were recorded on a Brazilian savanna site. The bee species explored a diverse set of plant species, but concentrated the collection of resources in a few plant species. The distribution of the samples over a long period favored a robust characterization of the food niche of the bee populations. Byrsonima sericea, Serjania faveolata, and Stigmaphyllon paralias were the plant species with the highest number of links with bees. In general, the trophic niche overlap was low, with 75% of pairs of bee species having a niche overlap (NO) less than 0.33. Only four pairs showed high overlap (NO>0.70) and all cases were related to the exploitation of floral resources provided by B. sericea, a key resource for the maintenance of the local bee fauna, an oil and pollen provider.

Introdução: O controle postural depende da ação integrada dos sistemas sensoriais e motores, e uma maior demanda atencional em situações de dupla-tarefa possivelmente acarreta maior oscilação postural. Objetivo: comparar a influência de tarefas cognitivas sobre o equilíbrio estático de indivíduos saudáveis. Materiais e métodos: estudo transversal realizado com 20 participantes adultos saudáveis. Os participantes foram submetidos a avaliação estabilométrica (olhos abertos e fechados) durante a execução de tarefas cognitivas (Stroop Test e contagem regressiva) e na situação controle (sem tarefa). Os deslocamentos do centro de pressão foram coletados e analisado. Resultados: Houve diferença significante dos efeitos obtidos na execução da tarefa matemática em comparação às demais situações (aumento da área de deslocamento e oscilações do centro de pressão). As demais comparações do tamanho do efeito não demonstraram significância. Conclusão: A execução de tarefas cognitivas influenciou o equilíbrio estático dos participantes. A tarefa matemática demonstrou maior influencia sobre o equilíbrio estático.

The ideal cavity dimensions for neotropical cavity-nesting bees with the potential to be managed as pollinators have not been getting proper attention. We investigated whether the occupancy of trap-nests by Centris analis Fabricius and Tetrapedia diversipes Klug, and other nesting aspects, are affected by different trap-nest length. The used trap-nests were cardboard tubes 5, 10, 15 and 20 cm in length, and Ø 8 mm. Occupation rates of 10-cm trap-nests by C. analis was higher than that of the 5-cm ones (χ2=11.17, gl=1, p<0.001). On the other hand, there was not difference between the occupation rates of 10 and 15-cm long trap-nests (χ2=0.51, gl=1, p=0.48), and between the ones measuring 15 and 20 cm long (χ2=1.36, gl=1, p=0.24). T. diversipes occupied a smaller number of 5-cm trap-nests than the 10-cm ones (χ2=1.52, gl=1, p=0.22), as well as that the 15-cm ones were more occupied than the 10-cm trap-nests (χ2=4.23, gl=1, p=0.04); moreover, there was not difference between the occupation of 15 and 20-cm trap-nests (χ2=0.28, gl=1, p=0.59). Both species showed higher rates of dead immatures in nests set in the shortest trap-nests, whereas these mortality rates were lower in the longest ones. By taking into consideration that there was not significant difference in many of the assessed parameters in comparison to values recorded for 15 and 20-cm long trap-nests, it seems likely to recommend the adoption of 10-cm long trap-nests for C. analis reproduction in agricultural sites that depend on the pollination service provided by this bees species.