Studies on the nutritional biology of Anastrepha fraterculus for the development of artificial rearing protocols.

OVIEDO, A.; ABRAHAM, S.; WILLINK, E.; NESTEL, D.; CHANG, CH.L.; PAPADOPOULOUS, N.; VERA, M. T.

Pereybere, Isla Mauritius

Workshop; Final RCM on Development of Mass Rearing for New World (Anastrepha) and Asian (Bactrocera) Fruit Fly Pests in Support of Sterile Insect Technique (SIT); 2009

IAEA

In nature, fruit fly adults can compensate from deficient diets by balancing nutrient intake among different diets while for larvae, even in those species that are polyophagous, individual development will be restricted to the quality of the host the female chose for oviposition. This reflects the fact that nutritional requirements and feeding behaviour should be considered to develop artificial rearing protocols, particularly when it is desirable to reduce rearing costs. Aiming at maximizing fitness components of Anastrepha fraterculus rearing, we evaluated adult diets of different nutritional values and delivery schedules as well as larval development in different larval diets. Adult individual intake was measured daily for two weeks following adult emergence as a direct indicator of food consumption and ability to select and discern nutrients. Five options of sugar and protein supply were evaluated. Then, we set up cohort cages were two food sources (sugar or the standard diet) were provided either alone or in a combined form in two delivery plates. Based on the diet given and the period of food exposure we established six treatments. The first set of experiments revealed that, for both sexes, survival and the cumulative sugar intake was higher for flies which were offered sugar and protein in separate plates compared to those were the nutrients were given in combination (same plate). In cohort cages, flies provided with the standard diet and complemented with an additional source of sugar lived longer than control cages. Fecundity was reduced in flies deprived from a protein source from day 0 to 4. Females offered the two food sources on different delivery plates exhibited increased fecundity, twice as much as those of the control cages. With respect to larval diets, in a first step, three different supports were assessed: agar, sugar cane bagasse and cloth sponge (liquid diet). Once conditions adjusted, different nutrients (sugar, wheat germ and brewer's yeast) proportions were investigated. For each case, several replicates were performed with 0.5 ml of eggs each. The variables used to evaluate diet performance were larval survival, pupal weight, adult emergence and sex ratio. In the first step, the conditions that rendered the highest recovery values were those using the sponge cloth. Then, and using the sponge cloth, it was found that diets that contained a sugar, wheat germ and protein ratio of 2:1:1 had higher recovery values than the diet that is used currently and has a 1:1:1 ratio. Our results suggest that adult physiological needs drive food selection. Providing them one diet with sugar and protein in an unbalanced proportion resulted detrimental for both fecundity and longevity. We propose that complementing the diet with an additional sugar source may increase production and reduce the amounts of protein used at the rearing facilities. With regards to larval diets, the need to find a single balanced diet with the optimal sugar to protein ratio was reflected. It seems possible to implement a diet reducing the current quantities of protein.