Asymmetry of the frontal bristles and postocular setae was studied in samples from natural populations and laboratory colonies of Anastrepha sp. 1 aff. fraterculus, of A. sp. 2 aff. fraterculus, and in F1 hybrids obtained from laboratory reciprocal crosses. Natural populations were sampled in a zone of sympatry and in two geographically distant regions with different climatic conditions. Asymmetry was scored as the differences between the number of bristles and of setae on the right and left sides of the head, males and females analyzed independently. The two traits exhibited variability according to the model of fluctuating asymmetry (FA). No significant differences among samples were found in the FA of frontal bristles. A significant FA was observed for the postocular setae of A. sp. 1 males from a southern population (Vacaria, RS) as compared to the asymmetry exhibited by males and females of some other samples. No significant differences in FA were observed among the interspecific hybrids and the laboratory samples of both parental species. The higher FA found in the males from Vacaria was attributed to climatic conditions prevailing in that region. The absence of a higher FA in hybrids may be related to the relatively recent evolutionary history of the two species.

The sterile insect technique (SIT) is widely utilized in the biological control of fruit flies of the family Tephritidae, particularly against the Mediterranean fruit fly. This study investigated the interaction between mating success and morphometric variation in the wings and the production of acoustic signals among three male groups of Ceratitis capitata (Wiedemann): (1) wild males, (2) irradiated with Co-60 (steriles), and (3) irradiated (steriles) and treated with ginger oil. The canonical variate analysis discriminated two groups (males irradiated and males wild), based on the morphological shape of the wings. Among males that emit buzz signals, wild males obtained copulation more frequently than males in Groups 2 and 3. The individuals of Group 3 achieved more matings than those in Group 2. Wild males displayed lower pulse duration, higher intervals between pulses, and higher dominant frequency. Regarding the reproductive success, the morphological differences in the wings' shape between accepted and nonaccepted males are higher in wild males than in the irradiated ones. The present results can be useful in programs using the sterile insect technique for biological control of C. capitata.

The state of Rio Grande do Norte is an important fruit-producing and exporting area in northeastern Brazil. The success of this industry depends on fruit fly population control, especially in fly-free exporting zones. However, many fruits are not exported because of quarantine restrictions imposed by importing countries. A survey in the state has detected a considerable increase of the fruit fly, Anastrepha zenildae Zucchi (Diptera: Tephritidae), probably a result of the introduction of irrigated guava orchards that make fruit available all year. Knowledge of the sexual behavior of Tephritidae has great importance to pest control programs, particularly those that employ the Sterile Insect Technique. In order to characterize the reproductive behavior of A. zenildae, 32 individuals (16 males; 16 females) in each of six generations were submitted to an artificial 12:12 L:D cycle (750: < 1 lux, lights on 07:00–19:00) and observed over their lifetimes. The courtship and copulation occurred in leks and the episodes varied with the time of day, courtship being most frequent between Zeitgeber time (ZT) 3 and ZT 7, peaking at ZT 5–6. Copulations occurred between ZT 2 and ZT 8, with a higher frequency between ZT 5–7 and a peak at ZT 6. Mean duration was 0.28 ± 0.03 min/male (range: 5–163 min). Males in the leks attempted to copulate mainly between ZT 3 and ZT 7 with a peak at ZT 6, and males outside leks peaked at ZT 7. The different timing of sexual behaviors among related sympatric species, including A. zenildae, may contribute to species isolation.

ResumoMachos de Anastrepha sexualmente ativos formam grupos e exibem comportamento de corte para atrair as fêmeas, formação típica da estratégia de lek. As fêmeas escolhem um macho para copular, provavelmente utilizando parâmetros morfológicos e comportamentais. Este estudo teve por objetivo identificar o papel dos caracteres morfológicos na seleção sexual de A. zenildae. As observações do comportamento de cópula foram realizadas em unidades experimentais (16 machos e 16 fêmeas virgens) durante a fotofase por três dias consecutivos. Machos que acasalaram foram marcados. Para as análises morfométricas dos machos foram utilizados cinco caracteres: comprimento da asa direita, comprimento do tórax, largura da cabeça, largura da face e número de cerdas da placa frontal. As medidas foram feitas a partir das imagens capturadas utilizando o programa Motic Imagens Plus 2.0. Para a maioria das características, os machos que obtiveram sucesso de cópula apresentaram valores médios mais elevados do que aqueles que não obtiveram sucesso. As variáveis comprimento do tórax, comprimento de asa e o módulo da diferença entre cerdas da placa frontal mostram-se alvos da seleção sexual, sugerindo que fêmeas podem discriminar os machos por tamanho durante a interação que ocorre na estratégia de lek. Palavras-chave: Assimetria flutuante; Caracteres morfométricos; Cerdas frontais; Seleção sexual AbstractChoice of sexual partners in Anastrepha zenildae (Zucchi, 1979, Diptera: Tephritidae): role of the morphological traits. Sexually active Anastrepha males form groups and display courting behavior to attract females, a typical form of the lek strategy. Females choose a male to copulate with, perhaps using morphological and behavioral parameters. This study aimed to identify the role of morphological traits on the sexual selection of A. zenildae. Observations on the copulation behavioral were conducted at experimental units (16 virgin males and 16 virgin females) during the photophase for three consecutive days. The males which mated were marked. Five traits were used for morphometric analysis of males: right wing length, thorax length, head width, face Biotemas, 26 (2): 113-120, junho de 2013 ISSNe 2175-7925 doi: 10.5007/2175 Revista Biotemas, 26 (2) width, and number of bristles on the front plate. The measurements were made through images captured using the software Motic Images Plus 2.0. For most traits, the males which were successful regarding copulation showed higher mean values than those which weren't successful. The variables thorax length, wing length, and the difference module between front plate bristles show to be sexual selection targets, suggesting that females can discriminate males by size during the interaction occurring in the lek strategy.