Biologia de Tenebrio molitor L. (Coleoptera: tenebrionidae) em diferentes dietas alimentares

Abstract

Tenebrio molitor L. (Coleoptera: Tenebrionidae), commonly known as the mealworm, has enormous potential to replace commonly used protein sources in human and animal diets. Given the importance of this insect as an alternative and sustainable source for food production due to its nutritional value and ease of rearing, the objective of this research was to study the biology of T. molitor on different diets and the impacts on its larval and reproductive development, with the perspective of obtaining quality larvae and a shorter development cycle. The experiment was conducted in the entomology laboratory at the State University of Maranhão under controlled conditions of temperature (25-26°C), humidity (60-70%), and a 12-hour photoperiod from October 23, 2024, to June 17, 2025. The design was completely randomized with four treatments (T1 - Control – 50% wheat bran and 50% cornmeal; T2 - 100% cornmeal; T3 - 100% wheat bran; T4 - 100% oat bran). The body length, greatest width, and weight of the insects at different stages (larva, pupa, and adult) and biological parameters such as the duration of the egg, larval, pupal, adult, and total cycle stages were evaluated. The results indicated that diet has a direct and significant influence on the biology of T. molitor. Biometric analyses showed that, although there were no differences in the initial stages, distinctions became evident from the third and fourth instars. The corn-based and control diets consistently produced larvae, pupae, and adults with greater body length, width, and weight. Notably, adults from the corn diet showed greater length and width than those from the other treatments. In contrast, the oat diet resulted in smaller individuals. The life cycle duration also varied with diet. The fastest development was observed in insects fed wheat bran, which completed the cycle in 214 days. The corn and control diets showed intermediate durations of 218 and 223 days, respectively. The oat bran diet was less efficient, prolonging the cycle to 236 days. Adult longevity was also affected, being highest on the corn diet (73 days) and drastically lower on the oat diet (37 days). It is concluded that the cornmeal diet is effective for optimizing biomass gain in T. molitor rearing, being ideal for production focused on volume and weight. To achieve a faster development cycle, wheat bran is the best option. The selection of the substrate is, therefore, a strategic decision that depends on production objectives.