Research Entomologist USDA Stoneville, Mississippi
The yellow mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae) is one of the most common industrialized insects produced as feed and food world-wide. The interest in T. molitor as a feed and food source has been increasing as new research confirms its suitability as a source of protein and lipid for monogastric livestock and cultured fish. One of the challenges to use T. molitor to produce insect protein is the length of its life cycle (3 to 10 months from egg to reproductive adult). Selecting for shorter larval development time would shorten the life cycle of T. molitor and selecting for larger size could increase biomass productivity. Recent studies have confirmed that larval development time and pupal weight have a significant genetic component and can be subject to selection. The objective of this study was to determine if different levels of larval development time and pupal weight could be simultaneously influenced by selection and to determine their effect on fecundity. Four combination levels (developmental classes) of larval development time (7 d range) and pupal weight (40 mg range) were established: 16 weeks and 180 mg; 18 weeks and 200 mg; 20 weeks and 220 mg; and 22 weeks and 240 mg. After 3 generations of selection, there were significant differences in development time and pupal weight between two developmental classes (220 and 240 mg). There were also significant differences among developmental classes in fecundity, egg viability and early instar survival.
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