Larval Rearing and Nutrition of the Polyphagous Tephritid Pest Anastrepha ludens on Artificial Diets with Calcium Alginate, Agar, or Carrageenan as Gelling Agents at Various Concentrations and across Extreme Larval Density Conditions.

Simple Summary: Artificial diets are one of the most critical components in insect mass-rearing facilities worldwide. Research on artificial diets to rear pestiferous tephritid flies dates back to the 1950s but is still a topic of great relevance, as fruit flies represent one of the ten most important pests of fruit in temperate and tropical regions of the world. In the past 15 years, much research has been performed to develop liquid- or gel-based diets more closely resembling the rearing environment a wild fruit fly larva experiences inside a fruit in nature. To identify new gelling agents that could perform better than already established ones such as agar and carrageenan, we assessed the performance of calcium alginate, a gelling agent widely used in the food industry, that had not been tested in the case of fruit fly mass rearing. We also examined larval density in gel diets as a critical factor that affects insect-rearing systems. Our results show that agar and carrageenan diets outperformed calcium alginate diets broadly and that the effects of larval density depended on the gel type used. We believe that the applications of calcium alginate in tephritid rearing should be analyzed in more depth in future studies. Research on larval rearing and nutrition of tephritid flies on artificial diets is key for the sterile insect technique. Here, we examined the effects of the type of gel (calcium alginate, agar, or carrageenan), at varying percentages in artificial diets for the polyphagous pest Anastrepha ludens, on the physicochemical and nutritional traits of the diets, and the effects of the type of gel, the gel content and the larval density (larvae/g of diet) used in production, quality parameters for mass-reared tephritids, diet removal (an indirect estimation of diet consumption), and nutritional traits of flies. Regardless of the gel content, calcium alginate diets were firmer and more resistant to penetration than the agar and carrageenan diets. The larval recovery, pupation, pupal weight, and flight ability of A. ludens were lower in calcium alginate diets than in agar and carrageenan diets. Diet removal was higher in calcium alginate diets; however, low levels of ammonium and high levels of uric acid in excretions from larvae on these diets suggest an alteration in protein metabolism. The firmness and penetration resistance characteristics of calcium alginate diets may have limited movement and feeding of larvae, but this could be overcome by the collective feeding of large groups of larvae. Our findings provide insights into the mechanism governing gel-diet rearing systems for A. ludens. [ABSTRACT FROM AUTHOR]