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.

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.

Effect of a Probiotic-Enriched Diet on Sexual Competitiveness, Pheromone Emission, and Cuticular Hydrocarbons of Sterile and Fertile Anastrepha ludens (Diptera: Tephritidae).

The sterile insect technique has been used for the eradication or control of numerous tephritid fruit flies. However, mass-rearing and sterilization can affect the microbiota and sexual performance of male tephritid fruit flies. Despite the addition of postteneral protein food which contributes to the enhancement of the sexual performance of mass-reared males, in some cases, they are less competitive than their wild counterparts. Alternatively, the addition of probiotics may improve the sexual performance of mass-reared sterile males. In this study, we evaluated the effect of a postteneral Lactobacillus casei-enriched diet on the sexual competitivity, pheromone emission, and cuticular hydrocarbons of mass-reared sterile and fertile Anastrepha ludens (Loew) (Diptera: Tephritidae) males. Flies were fed either with sugar, standard diet (sugar and protein, 3:1), sugar + probiotic, or standard diet + probiotic. The addition of the probiotic improved the sexual competitivity of fertile and sterile males that were devoid of protein but led to a negative effect on males fed with a standard diet. As compared to males that were fed with the standard diet + probiotic/only sugar, the males fed with the standard diet or those fed on sugar + probiotic displayed a higher number of mating instances. Sterile males that fed on sugar + probiotic had a higher relative amount of anastrephine, epianastrephine, n-methyl octacosane, and 2-methyl triacontane than those fed on sugar only. Overall, these compounds were common in the treatments where males had the best sexual performance. Our results suggest that the probiotics offer nutritional advantages to males whose food lacks protein.