Effect of wheat germ in the diets of larvae and adults on the sexual display of males of the South American fruit fly, Anastrepha fraterculus, (Wiedemann)

Abstract

One of the goals of the sterile insect technique is to maximize male performance. For this, much of the effort is allocated to determine the role of plant derived volatiles exposure and the incorporation of protein in the pre-release adult diet on male sexual performance as well as the use of growth accelerators to shorten the time of sexual maturation. However, little attention is paid to the effect of the presence of certain nutrients in the larval diets. The objective of this work was to evaluate the effect of providing wheat germ on the diet of larvae and the diet of adults on the sexual performance of males. We worked with A. fraterculus flies from a laboratory colony corresponding to the Brazilian-1 morphotype. Two larval diets and two adult diets were evaluated whose main difference was the presence or absence of wheat germ. Larval diets consisted of sugar and brewer's yeast with and without wheat germ in equal proportions (1:1:1 or 1:0:1) while adult diets consisted of yeast and sugar hydrolysate, also with and without wheat germ (1:3:1 and 1:3:0 ratios respectively). The larval diet was prepared on a gel matrix with 100 fresh eggs over 20 ml of diet. The pupae obtained were maintained until the adults emerged. The newly emerged males were placed in glass jars (600 ml) in groups of 10 and were assigned one of the two adult diets. From the fifth day of emergence and fed with their corresponding diet, the number of males performing sexual display during the first hours of the morning, in coincidence with the daily peak of maximum sexual activity for this species, was recorded. Data were analyzed using linear models where the diet of larvae and adults were the fixed factors and the number of males performing sexual display, the response variable. The number of males who performed sexual display was higher in males fed as a larva in a diet with wheat germ than in males fed as a larva in a diet without wheat germ. The presence of wheat germ in the adult's diet did not show a significant effect on the sexual display of males. These results suggest that it is possible to develop diets for larvae that maximize male sexual performance.