Protein Feeding Attenuates Attraction of Mexican Fruit Flies (Diptera: Tephritidae) to Volatile Bacterial Metabolites

We tested the hypothesis that Mexican fruit flies [Anastrepha ludens (Loew)] are attracted to odor of tryptic soy broth cultures of Staphylococcus aureus (Rosenbach) because they are hungry for protein. First, we demonstrated that attraction to the odor was attenuated by feeding on a relatively complete diet containing sugar, protein, fats, vitamins, and minerals compared to feeding on sugar only; second, we showed that feeding on a diet of casein hydrolysate and sugar in which the percentage of protein was equal to that in the complete diet attenuated attraction to the same degree as the complete diet; and third, we showed that attraction to bacterial odor decreased as percentage of protein increased in a diet containing casein hydrolysate and sugar. Results of the three experiments support the hypothesis that flies are attracted to odor of S. aureus cultures largely to find protein. Dietary vitamins, minerals, fats, and percentage of protein as amino acids had no effect.