JUVENILE HORMONE TREATMENT AND PROTEIN SUPPLY IN ADULT DIET: THE CASE OF ANASTREPHA FRATERCULUS

SEGURA, DIEGO F.; VERA, M. TERESA; LIENDO, M. CLARA; DEVESCOVI, FRANCISCO; UTGÉS, M. EUGENIA; ABRAHAM, SOLANA; PERALTA, PATRICIA1; CARABAJAL PALADINO, LEONELA; BACHMANN, GUILLERMO; MILLA, FABIÁN; TEAL, PETER; CLADERA, JORGE

Congreso; VIII Symposium on Fruit Flies of economic Importance; 2010

Anastrepha fraterculus is a major fruit pest in South America. Our research focuses on obtaining baseline data for the implementation of the Sterile Insect Technique. In this species, males have a long pre-copulatory period, increasing the needs to develop methods to shorten it. We studied the effect of treating A. fraterculus with a juvenile hormone analogue, methoprene, which accelerates maturation in other Anastrepha. Because sexual development is tightly associated to protein intake, methoprene effects were analyzed under several nutritional regimes. In laboratory, we found that methoprene treatment allowed a faster sexual maturation of A. fraterculus fertile as well as sterile (gamma-irradiated) males. Further studies showed no differences in transferred sperm between methoprene-treated males and mature, untreated males. Protein-fed, methoprene-treated males reached sexual maturity earlier than treated males that fed on sugar, or untreated males fed on sugar plus protein. However, this was not the case for every protein source; hydrolyzed yeast showed the highest percentage of matured males. We found that a 12:1 (sugar:hydrolyzed yeast) diet is enough for methoprene to shorten the pre-copulatory period. Under an SIT program, methoprene must be delivered to millions of males at once. Dipping pupae in a methoprene solution allowed males to mature as fast as topically treated males. Including methoprene in adult diet also induced an accelerated development, but it relies on methoprene solubility in water. In field cages, we found that 6 days-old laboratory males treated with methoprene (by dipping pupae in methoprene) and fed sugar and hydrolyzed yeast (12:1 ratio) were able to courtship, to attract of females, to mate, to transfer sperm and to induce a mating refractory period in females as well as sexually mature wild males fed on a 3:1 diet. Young laboratory females showed lower performance (only 5% mated) than wild females irrespectively on the fact that they were treated with methoprene and fed a diet containing protein. Sexual maturation of A. fraterculus sterile males can be accelerated by treating the flies with methoprene, but protein is needed for methoprene to act. Methoprene and protein allow laboratory males to compete for wild females in field cages. Massive delivery of methoprene is possible through feeding and dipping, and future studies should focus on massive delivery of protein and sugar. In the absence of a genetic sexing system, the fact that females do not respond as males to methoprene acts as a physiological sexing effect.