The temporal pattern of mating behavior of the fruit fly, Anastrepha zenildae in the laboratory.

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.

Influence of different light intensities on the daily grooming distribution of common marmosets Callithrix jacchus.

The daily distribution of autogrooming was evaluated in adult marmosets submitted to different illumination intensities in the light phase of the light-dark cycle. Autogrooming and locomotor activity were monitored and the faecal cortisol level assessed as a stress indicator. The distribution of autogrooming showed two distinct tendencies: when the light intensity varied from 500 to 200 lux, a slight increase in frequency and duration was observed, while a significant decrease in both variables occurred at 10 lux. Varying light intensities did not inhibit rhythm synchronization. The daily profile of autogrooming was mainly unimodal with an acrophase in the first half of the light phase. Faecal cortisol levels tended to increase in animals submitted to 100 and 10 lux, but these results are not conclusive. We suggest keeping captive marmosets in light intensities of at least 200 lux in the light phase, allowing animals to maintain autogrooming levels in order to reduce the discomfort caused by captivity and isolation.

Circadian activity rhythm in pre-pubertal and pubertal marmosets (Callithrix jacchus) living in family groups.

In marmosets, a phase advance was observed in activity onset in pubertal animals living in captivity under semi-natural conditions which had stronger correlation with the times of sunrise over the course of the year than the age of the animal. In order to evaluate the effect of puberty on the circadian activity rhythm in male and female marmosets living in family groups in controlled lighting conditions, the activity of 5 dyads of twins (4 ♀/♂ and 1 ♂/♂) and their respective parents was continuously monitored by actiwatches between the 4th and 12th months of age. The families were kept under LD 12:12 h with constant humidity and temperature. The onset of puberty was identified by monitoring fecal steroids. Juveniles showed higher totals of daily activity and differences in the daily distribution of activity in relation to parents, in which the bimodal profile was characterized by higher levels in evening activity in relation to morning activity. Regarding the phase, the activity onset and offset, occurred later in relation to parents. After entering puberty, the activity onset and offset occurred later and there was an increase in total daily activity. On the other hand, when assessing the effect of sex, only females showed a delay in the activity offset and an increase in total daily activity. Therefore, the circadian activity rhythm in marmosets has peculiar characteristics in the juvenile stage in relation to the total of daily activity, the onset and offset of the active phase, and the distribution of activity during this phase. Besides, the entering puberty was associated with a phase delay and increase on total daily activity, with differences between sexes, possibly due to hormonal influences and/or social modulation on rhythm.

Influence of seasonality on circadian motor activity rhythm in common marmosets during puberty.

The effect of puberty on circadian rhythmicity in nonhuman primates has been little studied, even though it has been demonstrated that puberty-related changes in circadian activity rhythm occur in a number of species, including humans. To characterize the motor activity rhythm during puberty in common marmosets (Callithrix jacchus), six animals was continuously monitored by actimeters between their 5th and 12th months of age. The animals were housed with their families in outdoor cages under seminatural conditions. Onset of puberty was determined from fecal estrogen and progesterone levels in females and androgen levels in males. The spectral power of the circadian component stabilized later in the last two animals to enter puberty. The bimodal characteristic of the active phase in this species became progressively more apparent over the course of the months in which the mean temperature was highest, irrespective of the animal's age. Although the onset of activity advanced after entry into puberty, this parameter showed a strong correlation with sunrise, indicating that seasonality influences this variable. Neither age nor climatic factors included in the regression model influenced the differences in phase angles between sunrise and onset of activity, and between sunset and offset of activity. Total activity was the only parameter influenced by age in the regression model, showing an increase after entry into puberty. Despite the evidence of pubertal influence on both the circadian component and total activity, under seminatural conditions seasonal factors may have a more important effect on motor activity rhythm in common marmosets.