BIOLOGY AND MORPHOMETRY OF TENEBRIO MOLITOR (COLEOPTERA: TENEBRIONIDAE) UNDER LABORATORY CONDITIONS

Abstract

The beetle Tenebrio molitor is a species of insect of the family Tenebrionidae, of the order Coleoptera. It is commonly known as the mealworm or mealworm. As it is a cosmopolitan species, a notorious pest of grains in storage and because it has a high protein value in its molecular composition, T. molitor can be understood as a species of great agronomic interest, being used in studies of pathogenicity of microorganisms and in the formulation of diets for animals. Therefore, the objective of this study was to determine the biological cycle of T. molitor in the laboratory, under a diet based on bran and corn feed. The initial rearing consisted of 120 first-instar larvae, housed in plastic boxes, under controlled conditions, fed with bran-based feed and corn feed. Growth in each phase of the biological cycle of the species was evaluated. Measurements were made by separating an aliquot of 30 individuals from the initial sample space whenever ecdysis was observed, confirming the passage of instar. The parameters evaluated were coloration, mass, length, dimensions of the thorax, wings and wingspan. The means were compared through statistical tests, nonparametric T and SNK (Student-Newman-Keuls). The results showed that adults had an average length of 14.5 ± 1.00 mm and 15.43 ± 0.85 mm and mass of 0.11 ± 0.01 g and 0.12 ± 0.01 g, for males and females, respectively, expressing notable sexual dimorphism for the species. Pupae also showed significant differences between sexes, with females having greater weight. As for larvae, marked growth was observed in the last instars; The life cycle of the species lasted, on average, 160 days for females and 156 days for males. Therefore, it can be concluded that, in addition to its agronomic and nutritional importance, the tenebrio beetle is a species that has a long life cycle and distinct sexual dimorphism, especially in the pupal and adult stages.