Sexual competitiveness and compatibility of sterile, JH-treated, protein-fed Anastrepha fraterculus males and females

D.F. SEGURA; M.C. LIENDO; F. DEVESCOVI; M.E. UTGÉS; P.A. PERALTA; G. BACHMANN; L.Z. CARABAJAL PALADINO; S. ABRAHAM; V. YUSEF; P.G. CENDRA; J.P. BOUVET; F.H. MILLA; S.B. LANZAVECCHIA; M.C. GIARDINI; M. JURI; C. CONTE; M. HOJAK; A. PARREÑO; M.T. VERA; J.L. CLADERA

Pereybere, Mauricio

Workshop; Fourth Coordination Meeting of the FAO/IAEA Coordinated Research Project “Improving Sterile Male Performance In Fruit Fly SIT Programmes”; 2009

Previous studies have shown that JH topical application accelerates sexual maturation in A. fraterculus males under laboratory conditions. It was also shown that JH treatment massively applied by dipping the pupae in a methoprene solution produced the same effect. JH treatment was effective only when the adult diet contained a protein source, in our case MP Biomedical® hydrolyzed yeast (MP), at least in a 12:1 (sugar:protein) ratio. Under field cage conditions, 6 days-old JH topically treated males probed to be as competitive as mature untreated lab males. Here we addressed the sexual performance of young laboratory sterile males that were massively treated with methoprene and fed with a diet low in protein. Lab flies were gamma-irradiated (60Gy), 6 days-old, fed on a 12: 1 (sugar: MP protein) diet, and dipped in a 0.05mg/ml (methoprene/acetone) solution for 5 min 48hs prior to emergence. We compared the mating performance with 5 alternative treatments: 1) Mature untreated flies fed with 3:1 diet (sugar:MP); 2) 6 days-old flies topically treated with JH, fed with 12:1 diet (sugar:MP); 3) 6 days-old flies dipped in JH, fed with sugar only; 4) 6 days-old flies dipped in JH fed, with 3:1 diet (sugar:local brand hydrolyzed yeast) and 5) 6 days-old flies dipped in JH fed with a 3:1 diet (sugar:MP). The tests were carried out under field cage conditions and the laboratory males had to compete with wild sexually mature males for wild females, with one type of treated male being released in each cage. Given no genetic sexing strain (GSS) is available for this species, laboratory females were treated as males and released in the cages for evaluation of their sexual behavior. Laboratory male performance did not differ from that of wild males when laboratory flies were treated with methoprene (either by dipping the pupae or by topical treatment) and fed a diet containing MP (either in a 3:1 or a 12:1 sugar: protein ratio). In fact, 6 days-old laboratory males treated by dipping and fed a 12:1 diet performed as well as 10 days-old untreated laboratory males fed with a 3:1 diet. In contrast, JH treated laboratory males showed a reduced competitiveness when they were fed either a 3:1 diet supplied with hydrolyzed yeast from a local brand, or sugar only.  Young (6 days-old) laboratory females showed a significantly lower performance than wild females irrespectively on the JH treatment and diet they received, but mature (14 days-old) untreated laboratory females performed as well as wild females, showing that low young female mating propensity was not due to mating incompatibility issues. In sum, our results show a promising pre-release treatment for A. fraterculus males based on fast and massive method to apply JH and a diet with a small amount of high quality hydrolyzed yeast. As no GSS has been developed yet for this species, this treatment would be inevitably applied to females as well. However, our results showed no impact of such treatment (JH and diet) on female mating propensity. Moreover, this treatment increases the separation between sexual readiness peaks for males and females confirming the physiological sexing effect of methoprene previously found for A. fraterculus.