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Nutritional and chemical composition of different life stages of Tribolium castaneum (Herbst)

Publication . Duarte, S.; Limão, J.; Barros, G.; Bandarra, N.M.; Roseiro, L.C.; Gonçalves, H.; Louro Martins, Luisa; Mourato, Miguel; Carvalho, Maria Otilia

Tribolium castaneum can survive in extremely dry environments and be one of the major insect pests of broken and processed grains or other stored dried foods. Additionally, this species has demonstrated resistance to some classes of insecticides. The objective of this work was to evaluate the nutritional and chemical composition of T. castaneum, reared on maize flour, and compare protein, lipids and fatty acids profile, amino acids and mineral contents, of different developmental stages: larvae, pupae and adults. In general all stages were rich in protein (15.3% for larvae and 17.0% for adults, wet body weight). Disparities among developmental stages regarding amino acids and fatty acids content were found. Essential amino acids were most abundant in T. castaneum; a different essential amino acid was prevalent on each developmental stage: larvae - valine; pupae - lysine; adults - histidine. Tribolium castaneum is rich in phosphorus, potassium and sulphur; larvae had a significantly higher content of phosphorus, potassium, sulphur and zinc, while adults showed significantly lower content of potassium and zinc. Larvae and pupae showed higher values of SFA (heptadecanoic and stearic acid) and PUFA (α-linolenic and linolenic acids), while MUFA showed the reverse tendency, with adults having the highest contents of hypogeic, palmitoleic and oleic acids. The nutritional differences among different developmental stages identified are due to specificities of each stage (level of chitinization, motility, energy requirements and food intake habits), as the diet offered to the insects was the same. This study can thus be considered a first step towards future directions of investigation, to a better understanding of this pest nutritional preferences and alternatives to achieve a more sustainable management of infested stored products

2021Journal article

Open access

The Interaction between Tribolium castaneum and Mycotoxigenic Aspergillus flavus in Maize Flour

Publication . Duarte, Sónia; Magro, Ana; Tomás, Joanna; Hilário, Carolina; Alvito, Paula; Ferreira, Ricardo Boavida; Carvalho, Maria Otilia

Tribolium castaneum is one of the most common insect pests of stored products. Its presence makes cereals more susceptible to the spread of the fungi Aspergillus flavus, which may produce mycotoxins. The aim of this work was to evaluate the influence of T. castaneum adults on the development of a mycotoxigenic A. flavus strain in maize flour as well as the influence of this fungus on the insects. Maize flour was exposed to T. castaneum, spores of A. flavus or to both. The results revealed an interaction between T. castaneum and A. flavus as the flour exposed to both organisms was totally colonized by the fungus whereas almost all the insects were killed. Aflatoxin B1 (AFB1) revealed a significantly higher concentration in the flour inoculated with both organisms (18.8 g/kg), being lower when exposed only to A. flavus, suggesting that the presence of insects may trigger fungal development and enhance mycotoxin production. The ability of these organisms to thrive under the same conditions and the chemical compounds they release makes the interaction between them a subject of great importance to maintain the safety of stored maize. This is the first work evaluating the interaction between T. castaneum and A. flavus mycotoxin production

2021Journal article

Open access