Comparative Study of Laboratory Diets for Piophila casei: Beneficial Effects of Infant Formula

In integrated pest management (IPM), the mass rearing of insects is crucial for applications in agriculture and stored-product protection. The use of artificial diets for insect rearing enables control over insect quality, ensures a continuous insect supply, and provides logistical advantages. However, optimized diets are still lacking for the hosts of parasitoids used in the biological control of stored product pests, such as Piophila casei Linnaeus (Diptera: Piophilidae). In previous research, fly development was obtained using a whole powder milk-based artificial diet. However, a comprehensive evaluation of this diet's efficacy in sustaining feeding, development, growth, and reproduction across continuous generations had not yet been conducted. To fill this gap, this study aimed to investigate the effect of a diet based on infant formula on the development time, longevity, fecundity, and population growth parameters of P. casei, compared to the whole powder milk diet and to dry-cured ham. The results indicate that dry-cured ham (which is protein-rich) accelerated development, while the infant formula-based diet (which is carbohydrate-rich) enhanced longevity and improved population growth parameters. Among the artificial diets, the infant formula-based diet was the most effective in maximizing the number of individuals, making it suitable to produce P. casei as a host for parasitoid rearing, whereas the whole powder milk diet showed the poorest performance.