AUGMENTATIVE BIOLOGICAL CONTROL AND MASS REARING FOR BENEFICIAL AND PEST INSECTS
Location: Biological Control of Pests Research Unit
Title: Self-selection of two diet components by Tennebrio molitor (Coleoptera: Tenebrionidae) larvae and its impact on fitness
Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 22, 2011
Publication Date: July 1, 2011
Citation: Morales Ramos, J.A., Rojas, M.G., Shapiro Ilan, D.I., Tedders, W.L. 2011. Self-selection of two diet components by Tennebrio molitor (Coleoptera: Tenebrionidae) larvae and its impact on fitness. Environmental Entomology. 40(50): 1285-1294.
Interpretive Summary: Our efforts to improve the mass rearing capabilities of the yellow mealworm led us to study the ability of these insects to self-select food items according to their nutritional requirements. This ability has been demonstrated in other insects, which have been shown to consume individual diet components in ratios consistent with the optimal for growth and development. The results of our study confirmed that the yellow mealworm possesses this ability. This is an important advancement for the improvement of diets that would increase the growth of this insect and therefore the mass production capabilities. This knowledge will be useful for the existing mealworm producing industry, which currently supplies mealworms as feed for captive and wild birds and other pet animals. The results will also support our current efforts to utilize mealworms to mass produce biological control agents such as insect infecting nematodes.
We studied the ability of Tenebrio molitor L. (Coleoptera: Tenebrionidae) to self-select optimal ratios of two dietary components to approach nutritional balance and maximum fitness. Life table analysis was used to determine the fitness of T. molitor developing in diet mixtures comprised of four different ratios of wheat bran to dry potato flakes (9:1, 4:1, 7:3, and 3:2 = 10, 20, 30, and 40% potato, respectively). The four diet mixtures were compared to each other and a control diet of wheat bran only. In a separate experiment, relative consumption of the two diet components was determined among the four diet mixtures. Doubling time was significantly higher in groups consuming 9:1 and 4:1 diet mix ratios than the control and lower in groups feeding on 7:3 and 3:2 diet mix ratios. Consumption of individual diet components by T. molitor larvae deviated significantly from the expected ratios indicating non-random consumption. Mean percentages of dry potato consumed were 11.98, 19.16, 19.02, and 19.27% during the first 4wk and 11.89, 20.48, 24.67, and 25.97% during the next 3 wk period for diets with 10, 20, 30, and 40% potato, respectively. The self-selected ratios of the two diet components approached 4:1, which was the second best ratio for population growth. However, the shortest development time was observed at this ratio (4:1). Our findings fulfill the criteria for evidencing dietary self-selection behavior in T. molitor larvae. These findings may lead to new methods for optimizing dietary supplements for mass production of T. molitor.