Effect of the interaction between Lactobacillus casei and hydrolyzed yeast on the sexual competitiveness, survival, and fecundity of Anastrepha obliqua (Diptera: Tephritidae).

Abstract

Enriching the diets of sterile fruit flies with bacterial species prior to their release has been shown to improve their survival and sexual competitiveness. However, most of the bacteria associated with fruit flies are enterobacteria, and some species have been classified as opportunistic pathogens. On the other hand, in diets that include hydrolyzed yeast, the effect of bacteria has been counterproductive, which could be due to the protein content in the diet being too high. Therefore, our aim here was to evaluate the effect of Lactobacillus casei, interacting with different contents of hydrolyzed yeast in the diet, on the performance of Anastrepha obliqua adults. In sexual competitiveness tests, the highest proportion of matings was achieved by males fed on a standard diet (3 : 1 sugar : yeast) plus L. casei. However, the differences with the 3 : 1 sugar : yeast diet was not significant. In survival tests, the 3 : 1 diet, without L. casei, showed the highest survival. The group fed with sugar plus L. casei showed the lowest survival. Females fed the 3 : 1 diet showed the highest fecundity, followed by those fed the 3 : 1 diet plus L. casei. Enriching the standard 3 : 1 diet with L. casei did not lead to significant improvements in male sexual performance, survival of either sex, or fecundity, compared to flies fed the standard diet alone. However, given that Lactobacillus is harmless to both humans and flies, further research into its potential application in the sterile insect technique (SIT) is recommended. Future studies should explore alternative formulations, varying concentrations, and other species within the Lactobacillus genus that may exert more pronounced effects on the biological traits of this fruit fly.