Landscape and land use affect composition and nutritional values of bees' food.

Bees are primary pollinators across various terrestrial biomes and rely heavily on floral resources for sustenance. The composition of landscapes can influence bee foraging behavior, while human activities can directly affect both the composition and nutritional value of bee food. We aimed to assess how landscape structure and land use practices can impact the composition and nutritional value of food sources for two generalist social bee species, Apis mellifera and Scaptotrigona postica. Food samples were collected from twenty-five colonies of A. mellifera and thirteen of S. postica to examine how food composition and nutritional value may vary based on the extent of human land use and the composition of landscapes surrounding beekeeping sites. The pollen composition and nutritional value of A. mellifera were influenced by both land use practices and landscape heterogeneity. The number of patches determined total sugar and lipid content. Landscape heterogeneity affected pollen composition in S. postica, primarily due to the number of patches, while total sugar was affected by landscape diversity. Pollen nutritional value in S. postica was linked to land use, mainly meadow and vegetation, which influenced total sugar and dry matter. S. postica showed a higher sensitivity to land use changes compared to A. mellifera, which was more affected by landscape heterogeneity. Assuring landscape heterogeneity by preserving remaining forest patches around apiaries and meliponaries is crucial. Thoughtful land use planning is essential to support beekeeping activities and ensure an adequate quantity and quality of bee food resources.

Sublethal doses of imidacloprid and pyraclostrobin impair fat body of solitary bee Tetrapedia diversipes (Klug, 1810).

Solitary bees present greater species diversity than social bees. However, they are less studied than managed bees, mainly regarding the harmful effects of pesticides present in agroecosystems commonly visited by them. This study aimed to evaluate the effect of residual doses of imidacloprid and pyraclostrobin, alone and in combination, on the fat body (a multifunctional organ) of the neotropical solitary bee Tetrapedia diversipes by means of morphological and histochemical evaluation of oenocytes and trophocytes. Males and females of newly-emerged adults were submitted to bioassays of acute topical exposure. Experimental groups were essayed: control (CTR), solvent control (ACT), imidacloprid (IMI, 0.0028 ng/µL), pyraclostrobin (PYR, 2.7 ng/µL) and imidacloprid + pyraclostrobin (I + P). The data demonstrated that the residual doses applied in T. diversipes adults are sublethal at 96 h. Both oenocytes and trophocytes cells responded to topical exposure to the pesticides, showing morphological changes. In the IMI group, the bee oenocytes showed the greatest proportion of vacuolization and altered nuclei. The pyraclostrobin exposure increased the intensity of PAS-positive labeling (glycogen) in trophocytes. This increase was also observed in the I + P group. Changes in energy reserve (glycogen) of trophocytes indicate a possible mobilization impairment of this neutral polysaccharide to the hemolymph, which can compromise the fitness of exposed individuals. Also, changes in oenocytes can compromise the detoxification function performed by the fat body. This is the first study to show sublethal effects in neotropical solitary bees and highlight the importance of studies with native bees.

Morpho-anatomic characterization of vegetative organs of Cattleya walkeriana Gardner (Orchidaceae) - DOI: 10.4025/actascibiolsci.v26i1.1664 / Caracterização morfo-anatômica dos órgãos vegetativos de Cattleya walkeriana Gardner (Orchidaceae) - DOI: 10.4025/actascibiolsci.v26i1.1664

The epiphytic orchids species have singular morpho-anatomic adaptations, which enable them to stay in places where water and nutrients scarcity are frequent, such as trees branch and trunk. The tissues specialized in water reservation are common in these species, as much as in leaves, roots and pseudobulbs. This study aimed to distinguish morpho-anatomically the vegetative organs of ,em>Cattleya walkeriana Gardner. Their leaves are coriaceous-fleshy in texture, covered by thick cuticle, hypostomatic and their mesophyll tends to the dorsal-ventral. In the pseudobulbs, the cuticle and some underlying cell layers waterproof the fundamental parenchyma, formed by big cells that reserve water and grains of starch. The vascular bundles are collateral, and the longest ones have sclerenchyma cap in both conductor tissue poles. In the roots, the velamen and the cortical tissue are formed by several cell layers, although both exoderm and endoderm are not very thick

As espécies de orquídeas epífitas possuem adaptações morfo-anatômicas singulares e que as tornam aptas a ocuparem ambientes onde a escassez de água e de nutrientes é freqüente, como os ramos e troncos das árvores. Nelas são comuns os tecidos especializados para a reserva de água, tanto nas folhas quanto nas raízes e nos pseudobulbos, tendo este estudo o objetivo de caracterizar morfo-anatomicamente os órgãos vegetativos de Cattleya walkeriana Gardner. As folhas são coriáceo-carnosas, revestidas com espessa cutícula, hipostomáticas e com mesofilo tendendo para a dorsi-ventralidade. Nos pseudobulbos, a cutícula e algumas camadas de células subjacentes impermeabilizam o parênquima fundamental, formado por grandes células que reservam água e carboidratos na forma de grãos de amido. Os feixes vasculares são colaterais, tendo os maiores, calotas de fibras em ambos os polos de tecidos condutores. Nas raízes o velame e o tecido cortical estão formados por várias camadas de células, embora tanto a exoderme quanto a endoderme mostrem-se pouco espessadas