Effect of Population Density on Development Time of Tenebrio molitor

Mealworms are used as food, so it is preferable if the larval stage lasts longer. On the other hand, to accelerate the population growth of mealworms, it is preferable if the larvae become adults quickly. The purpose of this study is to explore the effects of population density on development time of mealworms. We used a container size of 7 cm at the top, 5 cm at the bottom, and 3 cm in height. Mealworms lived in the containers at densities of 1, 2, 5, 10, and 20 per container. The containers were bedded with 1 g of wheat bran and formed two groups, fed and not fed, at each density levels. The experiments were performed three times. In all of the experiments, higher population densities resulted in shorter transformation times from larva to pupa, but the time from pupa to imago was not significantly different. In addition, given the same density, the presence of food accelerated the time to transformation to pupa, but not to imago. The data supported that a lower density is needed to prolong the larval stage, and if adults are needed at a faster rate, the density should be higher. Therefore, we conclude that the development time of mealworms can be controlled by the density which is useful information for mealworm farmers.