Use of nutrient self selection as a diet refining tool in Tenebrio molitor (Coleoptera: Tenebrionidae)

Authors: Morales Ramos, Juan; Rojas, Maria - Guadalupe; Shapiro Ilan, David; TEDDERS, WALKER - Southeastern Insectaries, Inc

Submitted to: Bulletin of Entomological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/6/2013
Publication Date: 7/1/2013
Citation: Morales Ramos, J. A., Rojas, M. G., Shapiro Ilan, D. I., Tedders, W. L. 2013. Use of nutrient self selection as a diet refining tool in Tenebrio molitor (Coleoptera: Tenebrionidae). Bulletin of Entomological Research. 48(3):206-221.

Interpretive Summary: The yellow mealworm is being produced and sold commercially to mass produce insect killing nematodes in the southeastern United States to control the small hive beetle, one of the most important honey bee pests in the U.S. One of the main objectives of this project was to improve the mealworm mass rearing methods to reduce the costs of production of insect killing nematodes. Improving nutrition through the development of better diets reduces mealworm mortality, shortens the development time, and increases fecundity. Production is more efficient with fewer losses and shorter production cycle. Developing improved diets requires extensive studies to obtain optimal combinations of suitable ingredients. In this research we follow the “self-selection” approach, which consists of allowing the larvae of mealworms to choose themselves the optimal ratios of 7 dietary ingredients. The ratios chosen by the mealworm larvae were then used to prepare a new diet formulation. The self-selected diet was then compared to previously developed formulations and a control using wheat bran alone. Wheat bran is used to produce mealworms commercially. The self-selected diet reduced mortality and shortened the time required by the mealworms to complete development as compared to the control and to a diet consisting of dry potato and wheat bran. Most significant was the improvements in fecundity observed in the self-selected diet as compared to control and other previously developed diets. The self-selected diet formulation increased survival from 65 to 91% as compared to the control; reduced development time by one month; required half as much diet to complete development; and increased fecundity by three fold as compared to the control. This new diet will benefit the mealworm industry by reducing the costs of mealworm production.

Technical Abstract: A new method to refine existing dietary supplements for improving production of the yellow mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae), was tested. Self selected ratios of 6 dietary ingredients by T. molitor larvae were used to produce a dietary supplement. This supplement was compared to existing supplement formulations mixed with wheat bran at 1:4 ratio and a control consisting of wheat bran alone for food utilization efficiency, larval growth, development time, immature survival, and fecundity. Ingredients of dietary supplements included dry potato as a source of carbohydrate; dry egg white and soy protein as a source of protein; and peanut, canola, and salmon oil as a source of lipid. A supplement consisting of dry potato alone significantly improved food utilization, growth, development time, survival, and fecundity compared to the wheat bran only control group. The addition of protein to the supplement significantly shortened development time and improve food conversion efficiency and fecundity compared to the supplement with potato alone. The addition of lipid did not provide any significant improvements. The supplement derived from self selected ratios of the basic ingredients provided a significant increase in fecundity compared to previously developed supplements and the control. Self selected ratios of the basic ingredients by T. molitor larvae had an effect on the adult stage that resulted in significantly higher progeny production.