Acclimatization and Foraging of Native Brazilian Stingless Bees in Arenas with Covering Materials of Different Spectral Properties

The use of Meliponini for crop pollination in protected environments is practically non-existent. One of the reasons is the difficulty of acclimatizing Meliponini to the temperature and light conditions inside greenhouses. We investigated how covering materials used in greenhouses, which filter different intensities of ultraviolet (UV) light, affect the foraging behaviors, flight orientation, attraction to walls and ceilings, and mortality of Scaptotrigona cf. postica (Letreille), Frieseomelitta varia (Lepeletier), and Melipona quadrifasciata (Lepeletier). The experiments were conducted in 5.3 m3 arenas covered with four types of plastic films that do not polarize sunlight, with UV transmittance levels ranging from 0.1 to 54%, compared to a transparent glass control. The temperature inside the arenas varied between treatments, from 27 ± 3°C to 31 ± 2°C. All three species collected resources and returned to the colony, regardless of the covering material. However, the proportion of this behavior, the number of bees attracted to the ceiling and wall, and mortality varied among treatments and/or throughout the confinement days for each species. Melipona quadrifasciata and F. varia acclimatized better to the confined environments than S. cf. postica and showed consistent resource collection behavior throughout the confinement days in all tested materials, except for the one that filtered around 90% of UV. In all three species, the mortality gradually decreased throughout the confinement days. The results indicate that the choice of covering material, considering its optical characteristics, can be crucial to ensure greater effectiveness of the pollination services provided by stingless bees in protected systems.

Validation of an Innovative Chromatographic Method for Hypericin Quantification in Nanostructured Lipid Carriers

BACKGROUND

Hypericin (HYP) is a natural compound widely used as a food supplement. The encapsulation of HYP into nanosystems, such as nanostructured lipid carriers (NLC), is a promising strategy for delivering this lipophilic molecule and protecting it from degradation.

OBJECTIVE

This study aims to develop and validate an analytical method to quantify the encapsulation efficiency of HYP in NLC.

METHOD

A reverse-phase high-performance liquid chromatography (HPLC) method was developed and validated according to the International Conference on Harmonization (ICH) guide Q2 (R1). NLC was prepared through the ultrasonication method, and HYP encapsulation efficiency was evaluated using the validated method.

RESULTS

Separation was achieved using an isocratic mobile phase composed of acetonitrile, methanol, and ammonium acetate buffer (10 mM, pH 5.0) (54:36:10, v/v/v) and a reverse stationary phase. The specificity, linearity, precision, accuracy, and robustness of the method were assessed and confirmed during the validation. Furthermore, the validated method was able to determine the encapsulation efficiency of HYP in NLC.

CONCLUSIONS

The HPLC method was validated, and the results indicated the ability of NLC to deliver HYP compounds for further application as a food supplement.

HIGHLIGHTS

HYP is used as a food supplement and for photodynamic therapy (PDT). The developed method was specific, linear, precise, accurate, and robust. NLCs showed a high ability to encapsulate HYP.

The gut microbiota of insecticide-resistant insects houses insecticide-degrading bacteria: A potential source for biotechnological exploitation

The exploration of new niches for microorganisms capable of degrading recalcitrant molecules is still required. We hypothesized the gut microbiota associated with insect-resistant lines carry pesticide degrading bacteria, and predicted they carry bacteria selected to degrade pesticides they were resistant to. We isolated and accessed the pesticide-degrading capacity of gut bacteria from the gut of fifth instars of Spodoptera frugiperda strains resistant to lambda-cyhalothrin, deltamethrin, chlorpyrifos ethyl, spinosad and lufenuron, using insecticide-selective media. Sixteen isolates belonging to 10 phylotypes were obtained, from which four were also associated with the susceptible strain. However, growth of gut bacteria associated with larvae from the susceptible strain was not obtained in any of the insecticide-based selective media tested. Growth of isolates was affected by the concentration of insecticides in the media, and all grew well up to 40 μg/ml. The insecticide-degrading capacity of selected isolates was assessed by GC or LC-MS/MS analyses. In conclusion, resistant strains of S. frugiperda are an excellent reservoir of insecticide-degrading bacteria with bioremediation potential. Moreover, gut-associated bacteria are subjected to the selection pressure imposed by insecticides on their hosts and may influence the metabolization of pesticides in insects.