Submitted to: Journal of Entomological Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/24/2009
Publication Date: 4/1/2010
Citation: Morales Ramos, J.A., Rojas, M.G., Shapiro Ilan, D.I., Tedders, W.L. 2009. Developmental plasticity in Tenebrio molitor (Coleoptera: Tenebrionidae): Analysis of Instar Variation in Number and Development Time under Different Diets. J. Entomol. Sci. 45(2):75-90. Interpretive Summary: The yellow mealworm is a commonly mass produced beetle that is currently sold in the United States as food for captive mammals, birds, reptiles, and amphibians. The yellow mealworm is different from most other insects in its ability to change the number of molts it goes through during development and the time it requires to complete development. A better knowledge of these mechanisms of stadia length and instar number variation in T. molitor could improve techniques to reduce the development time of this insect. Our research showed that nutritional supplements can be used to speed up development and improve survival. This could be advantageous for the commercialization of this insect by providing industry with the production flexibility to match changes in the demand of the product.
Technical Abstract: The variation in instar number and the pattern of sequential instar development time of Tenebrio molitor L. (Coleoptera: Tenebrionidae) was studied under 4 different diet regimes. Addition of dietary supplements consisting of dry potato or a mix of dry potato and dry egg whites significantly reduced the number of larval instars and total development time. The pattern of sequential stadia length showed regularity and low variability in instars 5 to 9. Stadia length continuously increased between instar 10 and the last instar before pupation (P-1). Instar number significantly impacted total development time and was also significantly correlated with stadia length. The length of each stadium was significantly reduced as the protein content in diets was increased. The length of the last stadium (P-1) was regular within food treatments regardless of sequential instar number, but P-1 was also significantly affected by nutrition in a similar way as all the sequential stadia. The pattern of instar variation is discussed in regard to the insertion of new instars based on variation of stadia length.