Feed particle size matters for the larval growth of Alphitobius diaperinus (Panzer) but not for Tenebrio molitor L. (Coleoptera: Tenebrionidae)

The effect of the particle size of the feed on the larval growth and feed utilization parameters of two mealworm species, Alphitobius diaperinus (Panzer) and Tenebrio molitor L. (Coleoptera: Tenebrionidae), was examined under laboratory conditions. Wheat bran of four different particle sizes (100–250, 500–650, 850–1000 and >2000 μm) was provided as feed to larvae of both species. The larval growth and survival, as well as time to pupation and the amount of feed consumed, were monitored to determine differences among the wheat bran particle sizes within each insect species. Our research results suggest that a finely ground feed with a particle size below 650 μm significantly impact the growth and development of A. diaperinus, as opposed to a feed containing particles larger than 850 μm. Contrariwise, the larvae of T. molitor exhibited no discernible response to the various feed particle sizes that were evaluated. Overall, it was observed that the two mealworm species did not exhibit identical responses for the tested feed particle size, suggesting that this factor is species dependent.