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

SEGURA, DF; MC. LIENDO; F DEVESCOVI; ME. UTGÉS; PA PERALTA; G BACHMANN; LZ. CARABAJAL PALADINO; S ABRAHAM; V YUSEF; PV GÓMEZ CENDRA; MC GIARDINI; FH MILLA; JP BOUVET; SILVIA LANZAVECCHIA; M HOJAK; M JURI; C CONTE; A PARREÑO; MT VERA; JL CLADERA

Mauritius

Workshop; 4th Research Coordination Meeting of the FAO/IAEA Coordinated Research Project “Improving Sterile Male Performance In Fruit Fly SIT Programmes; 2009

FAO/IAEA

Juvenile hormone (JH) topical applications have proven to accelerate sexual maturation of A. fraterculus males. It was shown later that JH could be applied massively by dipping pupae in a methoprene solution. JH was effective only when the adult diet included a protein source, in our case MP Biomedical® hydrolyzed yeast (MP), at least in a 12:1 (sugar:protein) ratio. In field cages, 6 days-old JH topically treated males proved to be as competitive as mature untreated lab males.             Here we addressed the sexual performance of sterile young males that were massively treated with methoprene and fed with a diet low in protein. Six-days-old laboratory flies were gamma-irradiated (70Gy), 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 emerge. We compared their mating performance after 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); 5) 6 days-old flies dipped in JH fed with a 3:1 diet (sugar:MP).             Tests were carried out in field cages and the laboratory males had to compete for wild females with sexually mature wild males, with one type of treated male being released in each cage. Because no genetic sexing strain (GSS) is available for this species, laboratory females received the same treatment as males and were released in the cages for evaluation of their sexual behavior.             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) laboratory male performance did not differ from that of wild males. 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 brewer's 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.             In sum, a pre-release treatment for A. fraterculus males based on a fast and massive method to apply JH and a diet with a small amount of high quality hydrolyzed yeast allowed 6 days-old males to compete with wild males. 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.