Chemical signatures in the developmental stages of Protopolybia exigua.

The chemical signature of social insects is very important for communication, and specific signs of each colony and its individuals are acquired throughout their development. This chemical signature can also be related to the composition of the materials employed during nest construction. Furthermore, the venom also contains important chemicals required for the maintenance of wasp colonies. Therefore, the objective of this study was to evaluate the chemical composition of the wasp Protopolybia exigua along its different development stages, including the nest substrate and the venom of adult worker at different ages. To achieve this, gas chromatography coupled to mass spectrometry was used. The results show that the chemical cuticular compounds present in different stages of development, and in the nest of P. exigua, are qualitatively similar, but quantitatively different, demonstrating that these compounds can be used as signals for the identification of co-specific individuals within the colonies. However, there was no significant variation in these compounds between different colonies, which may be related to the parental level between the colonies and due to them sharing the same resources. The non-polar compounds of the venom vary significantly according to the age of the workers, probably due to their different roles within the colony, and there was a clear increase in the complexity of the compounds as the wasps aged. Older wasps perform higher-risk activities, such as foraging, and therefore need to make more use of venom.

Use of cerrado plants as an alternative in the control of bacterial contamination in the alcoholic fermentation process.

Bacterial contamination causes irreparable losses in the performance of alcoholic fermentation. Antibiotics are used to control these microorganisms, but they generate residues and cause microbial resistance. Today the only commercial product used by the mills is hops, but it is very expensive. As an alternative, the objective of this work was to evaluate the feasibility of using extracts from plants grown in the Cerrado for antimicrobial control during an alcoholic fermentation to replace antibiotics. Hydraethanolic extracts of leaves and essential oil of the following species were tested: Schinus terebinthifolius Raddi, Serjania erecta, Serjania marginata, Campomanesia adamantium and Syzygium cumini. Only the extract of Serjania marginata did not show any activity against the bacterium Bacillus sp. Both the essential oils as well as the hydroalcoholic extracts of S. terebinthifolius and C. adamantium and the extract of S. erecta showed antibacterial activity without harming the yeast, with potential to replace the hops.