The more, the better? Effect of density on the growth of the lesser mealworm, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae)

Understanding the concept of larval density scaling in mealworm farming enables us to analyze and compare the growth patterns of these species and their overall productivity in terms of produced insect biomass. This paper explores the impact of larval density on the development of the lesser mealworm, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae). Seven different larval densities were examined in laboratory trials, ranging from 7.5 to 53 larvae per cm2, while the volumetric density per vial was consistent through the experiment at 10 larvae per cm3. The results showed a significant effect of larval density, restricted though to specific developmental traits of A. diaperinus larvae. Based on the results, the highest overall yield and biomass production was achieved at 53 larvae per cm2, however, this density resulted in prolonged development time and decreased larval growth and feed consumption metrics. It is suggested that a larval density of 30.3 larvae per cm2 could offer a favorable balance for achieving optimal biomass efficiency in terms of the time required for harvest, growth performance, feed utilization and economic feasibility. Nevertheless, to the best of our knowledge, this is the first work on the effect of larval density on the performance of A. diaperinus larvae and aims to contribute to the increase of the profitability of A. diaperinus mass-rearing production systems.