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  • Compositional profile of food supplements for honeybees
    Publication . Chaabane, Ines; Falcão, Soraia; Vilas-Boas, Miguel; Essid, Faten
    Honeybees (Apis mellifera L.) are the main pollinating agents for numerous plants and fruit trees and, hence, play a key role in agriculture and more generally in the maintenance of ecological biodiversity. Like the most of organisms, honeybees need a diverse diet consisting of minerals, carbohydrates (sugars), fats, and amino acids (proteins) to survive and reproduce. An adult honey bees carbohydrate requirement is satisfied by the nectar produced in flowers and also occasionally from extra floral nectarines or honeydew secreted by plant-feeding insects, while, flower pollen is the main source of amino acids, protein building blocks, largely used to feed developing larvae and young bees to provide structural elements of muscles, glands and other tissues. Bee-population declines are linked to nutritional shortages caused by land-use intensification, which reduces diversity and abundance of plant species. Together with the deficiency caused by adverse climatic changes and with the need to reduce colony mortality and particularly to ensure good nutritional/health status of bees in specific production moments, artificial supplementation of honeybee colonies became a major issue in beekeeping, and now is a common and growing practice within Portuguese beekeepers. This practice, in association with the reduced regulation in this area is leading to the proliferation of commercial products based on carbohydrates, protein and other substances of diverse origins and compositions. The impact of these products on hives may enable the beekeeper to remedy colony imbalances resulting from adverse or beekeeping conditions, but also may pose risks to the bee’s health and the bee products quality, depending on the used raw materials and the presence of harmful substances. The present work, inserted within the project ApisCibus - Artificial food for honeybees: quality survey, digestibility and performance on the bee hive, will have as main objective to evaluate the quality of commercial honeybee artificial supplementation through composition analysis of commercial supplements. The quality parameters evaluated are: minerals quantified through atomic absorption spectroscopy, fatty acids analyzed by gas chromatography coupled to mass spectrometry (GC-MS) and amino acids which are analyzed by ultra-performance liquid chromatography coupled with electro spray ionization mass spectrometry (UPLC-ESI-MS). Food supplements that are analyzed are largely used by beekeepers without knowing if they are benefic or not, toxic or not on the health of bees. Furthermore the results of the analysis shows that what is represented on the labels of products could be not exactly the same amounts of the real product inside the package. It shows also that some products may be considered as benefic or as toxic depending on the amount of these micronutrients. To continue this work in order to confirm these hypothesis, in vitro tests could be done on honeybees using these products analyzed in this thesis. Through the obtained results we could observe that the high amount of free amino acids presented in the studied supplements does not necessarily reflect a good source of nutrients, considering that for the bee it is important to have access to a diverse set of amino acids. Bee's nutritional requirements require 10 essential amino acids (Arg, Phe, His, Ile, Leu, Lys, Met, Thr, Trp and Val). The supplement P12 appears as the richest and most balanced, followed by P05. The C08 supplement, although containing an adequate proportion in most amino acids, has an excessive amount of Arg, which may cause adverse effects. Regarding fatty acids, the samples presented several compounds, among which the most abundant were hexanoic acids, 9-octadecenoic acid (oleic acid) and 9,12-octadecadenoic acid (linoleic acid). Although the role of fatty acids in bee nutrition is not yet fully understood, compounds such as linoleic acid, linolenic acid, myristic acid and dodecanoic acid appear to play an important role in inhibiting some microorganisms that affect bees, as Paenibacillus larvae larvae (American foulbrood). For this reason the sample P05 appears as the one with the highest nutritional quality, since it presented a higher number of fatty acids. In the analysis of minerals, it was observed that protein foods are significantly richer in micronutrients. In this work, the most common elements were potassium, sodium, calcium and magnesium, while copper and manganese appeared in some foods in small quantities. Cadmium, often an associated element with heavy metal contamination appeared in only one of the products, P05, but in very small quantities, lead was not detected in any of the supplements. In general, there were discrepancies between the results obtained and the description available on product labels, making clear the need for further quality control of these commercial products.
    2021Dissertação de mestrado Acesso aberto Ver mais