Effects of adult-diet composition and irradiation on longevity of male and female Anastrepha fraterculus

MARÍA E. UTGÉS; DIEGO F. SEGURA; MARÍA T. VERA; VERÓNICA YUSEF; JORGE L. CLADERA; JUAN C. VILARDI

Salvador de Bahia, Brasil.

Congreso; 7th International Symposium on Fruit Flies of Economic Importance.; 2006

The detrimental impact of protein on survival as well as its importance on sexual maturation has been documented for several species of fruit flies. This is of particular concern for the success of the sterile insect technique (SIT), were males have to be able to survive until sexual maturation and mate in the field were they are expected to have limited food resources. Any pre-release action to enhance the sterile male insemination success in the field will be reflected in an improved pest control. In the case of Anastrepha fraterculus, substantial efforts are being invested to develop SIT. In this work, we analyzed the effect of protein provided in the adults’ diet and irradiation, on fly longevity. Laboratory flies from EAOC (Tucumán) were used in the three experiments conducted at IGEAF, INTA (Castelar). Male and female longevities were measured as number of days the flies survived after emergence. In Experiment 1, males and females were offered food for five days after emergence. Two diets were compared: sugar plus protein plus vitamins (TUC, from EEAOC); and brown sugar (S). In Experiment 2, the effect of a combination of diets on male longevity was evaluated. Four treatments were compared: 1) S-S, fed for 6 days on S; 2) TUC-TUC, fed for 6 days on TUC; 3) S-TUC, fed on S for 4 days and 2 days on TUC thereafter; and 4) TUC-S, fed on TUC for 4 days and 2 days on S thereafter. In Experiment 3 males and females were evaluated. They had access to food for 4 days. One group of each sex was irradiated with 72.4 Gy as pupae, 48 hours before emergence. Irradiated (I) and non-irradiated (NI) flies were subdivided into two groups of diet: brown sugar (S/S, in two containers for control); one portion of TUC and another of brown sugar (TUC/S, in separate containers). In all experiments longevity was measured in 3 L flasks containing 10 newly emerged individuals of only one sex. Ten replicates (flasks) were randomly assigned to each treatment. Water was supplied ad libitum throughout the whole experiment. All experiments concluded with the death of the last fly. The number of dead flies was registered every day. We used ANOVA (or nested ANOVA), Tukey contrasts and Survival Analysis (Kaplan-Meier) to examine the data. Experiment 1 showed that flies fed with S (14.42 ± 0.37 days) lived longer than the ones fed with TUC (10.88 ± 0.24 days) (p<0.001). In Experiment 2 survival was as follows: TUC-TUC (11.42 ± 0.19) < TUC-S (13.27 ± 0.31) < S-TUC (14.84 ± 0.40) < S-S (17.12 ± 0.57) (for all comparisons p<0.03). Experiment 3 showed that flies fed with S/S (13.16 ± 0.38) lived longer than the ones fed TUC/S (10.13 ± 0.25) (p<0.001). Irradiated flies lived as long as non-irradiated. Males’ and females’ longevity showed no significant differences. In all assays, sugar-fed flies achieved maximum survivorship. These experiments, should be interpreted in the context of protein influence on courtship and mating, and complemented with studies on the effect of diet on sexual maturation, so that a diet formulation that enhance sexual maturity but has the minimum impact on survival can be applied prior to sterile releases.