ABSTRACT Ceratitis capitata (medfly) is a globally important horticultural pest that can be controlled using the sterile insect technique (SIT), but the success of SIT depends on the sexual performance of mass-reared males when released into the field. We added “guarana” (Paullinia cupana) powder (derived from an Amazonian fruit that is considered to be a stimulant with aphrodisiac effects, capable of improving human physical stamina) to the diets of adult male medflies to determine whether it increased their sexual performance. The basic diet of a protein extract + sucrose (1:3) was enriched with guarana powder (3 % on a volume basis). Experiments examining sexual competitiveness were performed using lab-reared males fed with the enriched diet vs. lab-reared males fed on the basic diet (and lab-reared females fed on the basic diet), as well as lab-reared males fed with the enriched diet vs. wild males fed on the basic diet (and wild females fed on the basic diet). The results of both experiments indicated that males maintained on diets enriched with guarana powder showed higher copulation successes than males fed only with the basic diet. Guarana powder therefore contributed to the greater mating success of lab-reared males (probably because of its stimulant properties), and may represent a new and viable option for increasing SIT effectiveness.

Results of previous investigations trying to ascertain which physiological factors are more important to the mating success of medfly males are controversial. In part, this controversy owes to the fact that each factor was evaluated by an independent study using different experimental designs and populations. In the present study we compare the roles of age and nutritional status (immature and adult phases) on the mating competitiveness of Ceratitis capitata (Wiedemann, 1824) males. Three parameters were used to evaluate the male mating success: calling behavior (pheromone emission), lek participation and copulation (ability to be chosen by a female). Females gave preference to the males that were given a high protein diet in the larval phase. By contrast, females did not give preference to males that had been well-nourished in the adult phase only. The other parameters evaluated followed the same pattern: young males and males that had been fed a high protein diet during their immature phase had a greater participation in leks and called more often than older males and males that had been fed a diet poor in protein during their larval phase. Therefore, we conclude that the mating success of C. capitata males is determined both by age and nourishment during the immature stage.

Ceratitis capitata is one of the most important pests of fruits for exportation, and Sterile Insect Technique (SIT) has been the most efficient and environmental friendly technique used to control fruit fly populations around the world. A key goal in achieving a successful SIT program is a mass rearing system producing high quality insects at low cost. Providing adults with an artificial diet containing hydrolysed protein has been the major obstacle for bio-production facilities in Brazil, because it is expensive and has to be imported. Two other commercial products, autolysed yeast (AY) and yeast extract (YE), of domestic origin and low cost, were tested as substitutes of the imported hydrolyzed protein. To compare their efficiency we observed the female fecundity, adult survival and egg viability of flies raised on diets containing one of each of the different protein products. Flies reared on the domestic yeast products had equivalent or superior performance to the flies reared on imported protein. Both AY and YE can be a possible substitute for imported hydrolyzed protein for C. capitata mass-rearing, as they are cheaper and are readily available in the national market.

In this paper, we investigated the influence of protein ingestion during the early adult phase on the sexual behavior of males of Ceratitis capitata (Wiedemann, 1824). The following parameters were evaluated: mating success (ability to be chosen by females), number of copulations, and copula duration. Experiments were carried out using a fifteen-year old laboratory lineage with the occasional introduction of wild flies. Two groups of adult males fed a high-protein diet during their larval phase were given either a high-protein diet (based on Brewer's yeast, concentration = 6.5 g/100 ml) or a no-protein diet. Both groups of males were exposed to females fed either a high-protein diet or a no-protein diet and were subsequently evaluated for the parameters listed above. All experiments were conducted at 25ºC, 70% R.H. and with a photoperiod of L12:D12. The number of copulations was the only parameter affected by adult diet. Males fed a high-protein diet and exposed to females fed a no-protein diet had a greater number of copulations compared with males fed a no-protein diet.

The healthy maintenance of insects reared under laboratory conditions requires strategies to retain the natural characteristics of their life-histories traits. Rearing strategies include artificial selection to laboratory conditions, hybridization with compatible strains, and supplying the colony with wild individuals. We compared behavioral as well as life-history aspects of two laboratory strains of Ceratitis capitata Wiedemann (Diptera, Tephritidae) that had either been reared for 15-20 years under laboratory conditions with or without introducing wild specimens (Lab-Pop and Hybrid-pop, respectively). The parameters evaluated were: performance and food ingestion of immatures, adult size and longevity, female oviposition preference and fecundity, egg viability, and mating choice. Analyses of these parameters were conducted under laboratory rearing conditions. The largest differences observed between the two strains were related to behavioral components: food ingestion rate at the larval stage and oviposition behavior. In general, Lab-Pop individuals were less selective and more adapted to the artificial diet than Hybrid-Pop individuals (diet consumption), but there were no significant differences between the two strains in terms of percentage of emergence, egg viability, adult size, fecundity, and mating choice. It is suggested that the use of hybrid strains is more appropriate than the use of strains without the incorporation of wild individuals, especially in studies that involve behavioral parameters, as hybrid strains behave very similarly to wild populations, according our previous studies.

El mantenimiento saludable de insectos criados en condiciones de laboratorio requiere estrategias que conserven características naturales de sus historias de vida. Las estrategias en cría de insectos incluyen selección, hibridación con linajes compatibles y suministro a la colonia con individuos silvestres. Para investigar este último punto, comparamos los aspectos comportamentales así como los aspectos de las historias de vida de dos colonias de laboratorio de Ceratitis capitata Wiedemann (Diptera, Tephritidae) que han sido criadas entre 15 y 20 años en condiciones de laboratorio sin introducir ejemplares silvestres (Lab-Pop), o con introducciones ocasionales (Hybrid-Pop). Los parámetros evaluados fueron: el desempeño y la tasa de ingesta larval, el tamaño y la longevidad de los adultos, la preferencia de oviposición y fecundidad de la hembra, la viabilidad del huevo, y la elección para el apareamiento. Se realizaron análisis de estos parámetros bajo condiciones de cría con una dieta artificial. Las mayores diferencias entre individuos de las dos colonias se registraron en variables comportamentales: tasa de ingesta larval y comportamiento de oviposición. En general, la colonia Lab-Pop fue menos selectiva y más adaptada a la dieta artificial que la colonia Hybrid-Pop (consumo de la dieta), pero no hubo ninguna diferencia significativa entre las dos poblaciones en el porcentaje de emergencia, la viabilidad del huevo, el tamaño de los adultos, la fecundidad, y éxito en el apareamiento. Se sugiere que el uso de colonias híbridas es más apropiado al uso de colonias a las que no se les incorporan ejemplares silvestres, sobre todo en estudios que involucran parámetros comportamentales, dado que las colonias híbridas se comportan como las poblaciones silvestres, de acuerdo con estudios anteriores.

The influence of four host fruits, orange (Citrus sinensis L.), papaya (Carica papaya L.), mango (Mangifera indica L.) and apple (Malus domestica Borkh) on oviposition behavior of Ceratitis capitata (Wiedemann, 1824) was evaluated. Experiments were carried out on two C. capitata laboratory-reared populations: one with artificial diet for 10 years with periodic introduction of wild flies and other reared with artificial diet for 20 years without wild flies introduction. In acceptance experiments two pieces of a single fruit type were exposed to a group of 10 females; after 48 hours, these were changed by two new pieces of the same fruit type, and, in the end of the fourth day, the experiments were concluded. In preference experiments, two pieces of different fruits were offered to the females. These experiments were driven under the same conditions of the acceptance ones. Acceptance and preference experiments for both populations showed the following choice hierarchy: papaya > mango > orange > apple. The acceptance experiments showed no differences in the number of eggs/female/day laid in the first 48 hours and in the last 48 hours of the experiments. The amount of eggs in the two pieces of fruits offered to the females was similar. In spite of the two populations present similar behavior in relation to host hierarchy, the number of laid eggs was different, being larger for the population reared without wild flies introduction.

Experiments concerning oviposition preference were carried out on Ceratitis capitata to determine whether females are able to preferentially oviposit on natural hosts in which the larvae develop better. The results indicated that the females do not preferentially oviposit on hosts of better nutritive value for the larvae.