The objective of this study was verify the best waist:height ratio (WHtR) cut-off points for the prediction of insulin resistance (IR) according to stage of sexual maturation in Brazilian adolescents. Data were analysed from 37 759 adolescents between 12 and 17 years of age, of both sexes, participating in the ERICA study on cardiovascular risk factors in adolescents (‘Estudo de Riscos Cardiovasculares em Adolescentes – ERICA’). The following variables were included sex, age and sexual maturity according to the Tanner stage, waist circumference, height, WHtR, fasting insulin and fasting blood sugar so as to obtain the homeostasis model assessment-estimated insulin resistance (HOMA-IR). We constructed an Receiver Operating characteristic (ROC) curve for each group in order to determine the best WHtR cut-off points for the sample stratified by sex and stratified by sex and sexual maturation stage. The female sex corresponded to 60% of the sample, with a mean age of 14·7 years (sd ± 0·08 years) and 13·1 % had IR. The prediction of IR through the WHtR indicator was better for boys, where all the areas under the ROC curve were superior to 0·70. When stratifying by sex alone, the best WHtR cut-off points found were equal to 0·45 for girls and 0·44 for boys. When stratifying by Tanner maturation stages, the cut-off points were reduced with advancing sexual maturation in the male group, while the opposite occurred in the female group. Among Brazilian adolescents, WHtR is a good predictor of IR evaluated by HOMA-IR, but different cut-off points should be adopted according to sex and sexual maturation stage.

Nutritional geometry (NG) is a novel dietary analysis approach that considers nutrient balance, rather than single nutrient effects, on health and behaviour. Through NG, recent animal experiments have found that lifespan and reproduction are differentially altered by dietary macronutrient distribution. Epidemiological research using NG reports similar findings for human ageing. Yet, the relation of macronutrient balance to human reproduction, especially reproductive maturation, remains undefined. We studied the impact of childhood macronutrient intake on pubertal maturation, by applying NG to an Australian longitudinal adolescent dataset. Food records, collected at age 8 years from 142 pre-pubertal children (females, 92; males, 50), were analysed for absolute energy, percentage energy and energy-adjusted residuals from protein, carbohydrate and fat. Pubertal stage change (assessed at 8, 13 and 15 years) was modelled to obtain individual mathematical estimates of pubertal timing and tempo. Timing of menarche was recorded. The association of macronutrients to pubertal timing/tempo was assessed via NG, involving generalised additive models and heat maps to aid interpretation. Results showed lower dietary protein (relative to carbohydrate and fat) in girls consistently predicted earlier pubertal timing and menarche, and was related to faster pubertal tempo (all P < 0·05). No significant associations were identified in boys for both timing and tempo. Results suggest a role of non-protein macronutrients in facilitating female maturation; corroborating feeding and reproductive behaviour patterns observed in earlier NG studies of primates. Application of NG to other adolescent datasets is required to confirm the present findings. Such work would advance understanding of how nutrient balance shapes human development and health.

Animal and cross-sectional epidemiological studies suggest that prenatal lead exposure is related to delayed menarche, but this has not been confirmed in longitudinal studies. We analyzed this association among 200 girls from Mexico City who were followed since the first trimester of gestation. Maternal blood lead levels were analyzed once during each trimester of pregnancy, and daughters were asked about their first menstrual cycle at a visit between the ages of 9.8 and 18.1 years. We estimated hazard ratios (HRs) and 95% confidence intervals (CI) for probability of menarche over the follow-up period using interval-censored Cox models, comparing those with prenatal blood lead level ⩾5 µg/dl to those with prenatal blood lead <5 µg/dl. We also estimated HRs and 95% CI with conventional Cox regression models, which utilized the self-reported age at menarche. In adjusted analyses, we accounted for maternal age, maternal parity, maternal education, and prenatal calcium treatment status. Across trimesters, 36−47% of mothers had blood lead levels ⩾5 µg/dl. Using interval-censored models, we found that during the second trimester only, girls with ⩾5 µg/dl prenatal blood lead had a later age at menarche compared with girls with prenatal blood lead levels <5 µg/dl (confounder-adjusted HR=0.59, 95% CI 0.28–0.90; P=0.05). Associations were in a similar direction, although not statistically significant, in the conventional Cox regression models, potentially indicating measurement error in the self-recalled age at menarche. In summary, higher prenatal lead exposure during the second trimester could be related to later onset of sexual maturation.

The Artocarpus fruit fly, Bactrocera umbrosa (Fabricius) (Diptera: Tephritidae), is an oligophagous fruit pest infesting Moraceae fruits, including jackfruit (Artocarpus heterophyllus Lamarck), a fruit commodity of high value in Malaysia. The scarcity of fundamental biological, physiological and ecological information on this pest, particularly in relation to behavioural response to phytochemical lures, which are instrumental to the success of many area-wide fruit fly control and management programmes, underpins the need for studies on this much-underrated pest. The positive response of B. umbrosa males to methyl eugenol (ME), a highly potent phytochemical lure, which attracts mainly males of many Bactrocera species, was shown to increase with increasing age. As early as 7 days after emergence (DAE), ca. 22% of males had responded to ME and over 50% by 10 DAE, despite no occurrence of matings (i.e. the males were still sexually immature). Male attraction to ME peaked from 10 to 27 DAE, which corresponded with the flies’ attainment of sexual maturity. In wind-tunnel assays during the dusk courtship period, ME-fed males exhibited earlier calling activity and attracted a significantly higher percentage of virgin females compared with ME-deprived males. ME-fed males enjoyed a higher mating success than ME-deprived males at 1-day post ME feeding in semi-field assays. ME consumption also promotes aggregation behaviour in B. umbrosa males, as demonstrated in wind-tunnel and semi-field assays. We suggest that ME plays a prominent role in promoting sexual communication and enhancing mating performance of the Artocarpus fruit fly, a finding that is congruent with previous reports on the consequences of ME acquisition by other economically important Bactrocera species.

Heliothis viriplaca (Hüfnagel) (Lepidoptera: Noctuidae) is an important polyphagous pest of beans, cotton, maize, and alfalfa worldwide. H. viriplaca is a long-distance migrant, and if so, what pattern of seasonal migration this species exhibits in northern China remains unknown. In this study, in order to determine the seasonal migration of H. viriplaca in northern China, the combination of searchlight trapping and ovarian dissection was carried out on an isolated small island in the center of the Bohai Strait during 2003–2014. The results confirmed that H. viriplaca undertakes long-distance migration on the prevailing winds of the East Asian monsoon airflows. This species exhibited a regular pattern of seasonal migration across the sea from May to October, but there was considerable yearly and monthly variation in the trapped numbers, with the majority being trapped in summer (67.99 ± 6.54%). The mean period when migration was detectable at the island was 116.5 ± 5.6 days from 2003 to 2014, with the shortest time span of 74 days in 2013 and the longest of 144 days in 2005. Trapped females in May and June showed a relatively higher mating rates and some degree of ovarian development when compared with July, August and September, suggesting the migration of this species is not completely bound by the ‘oogenesis-flight syndrome’. These findings will be helpful to improve the forecasting system and managing strategies of H. viriplaca.

The rice leaf roller, Cnaphalocrocis medinalis (Guenée), is a serious insect pest of rice with a strong migratory ability. Previous studies on the migration of C. medinalis were mostly carried out in tropical or subtropical regions, however, and what the pattern of seasonal movements this species exhibits in temperate regions (i.e. Northern China, where they cannot overwinter) remains unknown. Here we present data from an 11-year study of this species made by searchlight trapping on Beihuang Island (BH, 38°24′N; 120°55′E) in the centre of the Bohai Strait, which provides direct evidence that C. medinalis regularly migrates across this sea into northeastern agricultural region of China, and to take advantage of the abundant food resources there during the summer season. There was considerable seasonal variation in number of C. medinalis trapped on BH, and the migration period during 2003–2013 ranged from 72 to 122 days. Some females trapped in June and July showed a relatively higher proportion of mated and a degree of ovarian development suggesting that the migration of this species is not completely bound by the ‘oogenesis-flight syndrome’. These findings revealed a new route for C. medinalis movements to and from Northeastern China, which will help us develop more effective management strategies against this pest.

Sexual maturation of Anastrepha fraterculus is a long process. Methoprene (a mimic of juvenile hormone) considerably reduces the time for sexual maturation in males. However, in other Anastrepha species, this effect depends on protein intake at the adult stage. Here, we evaluated the mating competitiveness of sterile laboratory males and females that were treated with methoprene (either the pupal or adult stage) and were kept under different regimes of adult food, which varied in the protein source and the sugar:protein ratio. Experiments were carried out under semi-natural conditions, where laboratory flies competed over copulations with sexually mature wild flies. Sterile, methoprene-treated males that reached sexual maturity earlier (six days old), displayed the same lekking behaviour, attractiveness to females and mating competitiveness as mature wild males. This effect depended on protein intake. Diets containing sugar and hydrolyzed yeast allowed sterile males to compete with wild males (even at a low concentration of protein), while brewer´s yeast failed to do so even at a higher concentration. Sugar only fed males were unable to achieve significant numbers of copulations. Methoprene did not increase the readiness to mate of six-day-old sterile females. Long pre-copulatory periods create an additional cost to the management of fruit fly pests through the sterile insect technique (SIT). Our findings suggest that methoprene treatment will increase SIT effectiveness against A. fraterculus when coupled with a diet fortified with protein. Additionally, methoprene acts as a physiological sexing method, allowing the release of mature males and immature females and hence increasing SIT efficiency.

The physiological age of adult males of seven mealybug species was measured in relation to the elongation of the male pair of the waxy caudal filaments. These filaments begin to emerge after eclosion and reached their maximum length from 29.4–46.6 h. The studied males were divided into three age groups, expressed as percentages of the total waxy caudal filaments length. Attraction to a sex pheromone source was significantly higher in the oldest male group (maximum filaments growth) compared with youngest one. Only the oldest male group copulated successfully; few of the younger males tested displayed 'courtship' behavior towards conspecific virgin females. The calculated duration of the sexually active phase of the adult male life cycle varied among species ranging from 34.4 to 46.6 h. There were marked variations in the strength of attraction to a pheromone source according to time of day. There was a continuous decrease in sexual activity from morning to evening. Our findings reveal clear maturation periods for adult males of the seven studied species. The long immature phase of the adult male mealybug is probably also related to several physiological processes that are needed to complete male maturation. The most noticeable change is the elongation of the waxy caudal filaments. However, mating may be performed at any time ambient conditions are suitable. Whereas male mealybug flight towards a pheromone source is restricted to a few hours, the male may continue mating activity throughout its sexually active period.

We examined the tooth ultra-structure of harbour porpoises (Phocoena phocoena) from Scottish waters to determine whether the incidence of mineralization anomalies could be related to certain life history events (e.g. the achievement of sexual maturation) as well as other factors that affect the general health of the individual (e.g. persistent organic pollutant (POP) concentrations in blubber). Five distinct types of mineralization anomalies were recorded: accessory lines, marker lines, dentinal resorption, cemental disturbance and pulp stones and the occurrence of these anomalies was scored by sex, age and maturity state. Overall, the incidence of mineralization anomalies was high and tended to increase with age. Marker lines and accessory lines were the most commonly recorded anomalies while pulp stones were least frequent. Duplicate teeth (i.e. from the same individual) always showed the same pattern of anomaly occurrence.

Fitted binary generalized linear and additive models indicated that the presence of dentinal resorption, cemental disturbance and marker lines in harbour porpoise teeth increased with age, body length and maturity. Males displayed marker lines more frequently than females. Age was the best predictor of the incidence of dentinal resorption and cemental disturbance while age and sex were the best predictors of the incidence of marker lines. The time course of appearance of dentinal resorption and cemental disturbance suggests that their occurrence could be related to physiological stress linked to sexual maturation. Marker lines were found within growth layer groups which coincided with the beginning of weaning and sexual maturation, suggesting an association with these two major life history events. Accessory lines were found in most teeth and may be a normal characteristic of porpoise teeth or reflect regular events. Pulp stones appeared only in mature animals. We found no evidence that the presence of anomalies in teeth was significantly related to POP concentrations in the blubber.

Diet and sexual maturation were examined in the winter–spring cohort of the neon flying squid, Ommastrephes bartramii, during its southward migration through the Kuroshio–Oyashio transition region of the western North Pacific. The main prey items are micronektonic animals and small pelagic fish, which were abundantly distributed throughout the study area. Among the prey species, O. bartramii was dependent on the Japanese anchovy Engraulis japonicus, which also migrate from the northern to southern transition region during the winter, and the micronektonic squid Watasenia scintillans throughout the study period. Other common prey items were Gonatopsis borealis, Diaphus theta, and Ceratoscopelus warmingii from October to November or December, and Tarletonbeania taylori after December. These dietary changes can be explained by the difference in the seasonal north–south migration patterns of the predator and prey species. Male sexual maturation progressed throughout the season, and most individuals were fully mature in January. In contrast, most of the females were immature throughout the study period. The feeding strategy of the squid in relation to their seasonal north to south migration and sexual maturation was discussed.

The purpose of this study was to investigate the association between dietary patterns and sexual maturation among Korean children. A cross-sectional study was conducted in 422 boys and 365 girls aged 9–12 years living in Seoul, Korea. Three-day food records were obtained, and pubertal stages were determined with a questionnaire using Tanner stages. Body fat was measured by bioelectrical impedance analysis, and bone mass content at the right calcaneus was measured by portable dual-emission X-ray absorptiometry. Exploratory factor analysis with a Varimax rotation was applied to identify dietary patterns using twenty-four food groups. Four distinct dietary patterns – ‘rice and Kimchi’, ‘shellfish and processed meat’, ‘pizza and drinks’ and ‘milk and cereal’ – were obtained. Twenty-six per cent (24% stage 2, 2% stage 3) of boys had genital development, and 79% (63% stage 2, 16% stage 3) of girls showed breast development. In boys, genital development was weakly positively associated with ‘shellfish and processed meat’ dietary factor scores (odds ratio 1·65, CI 0·95, 2·89, pfor trend 0·07) after adjusting for confounders. In girls, breast development was significantly positively associated with the factor score of ‘shellfish and processed meat’ (odds ratio 1·88, CI 1·08, 3·26, p for trend 0·05). These results suggest that dietary patterns were related to body composition and sexual maturation among the Korean children. Further investigations are needed to identify components of the foods consumed in high amounts in these patterns and how they are related to sexual maturation.

We tested the hypothesis that along with gill Na+K+ATPase activity reduction, branchial energetic metabolism of brook charr (Salvelinus fontinalis) is altered during sexual maturation. Maturing and sterile fish were transferred from freshwater (FW) to seawater (SW). The activity of gill pyruvate kinase (PK), cytochrome C oxidase (COX), citrate synthase (CS) and lactate dehydrogenase (LDH) was measured at different intervals. Following 1 month in SW, twofold increases in Na+K+ATPase activity were recorded in all groups, while mean metabolic enzyme activities were sharply reduced (COX: 0.051 ± 0.029 to 0.036 ± 0.018; PK: 1.670 ± 0565 to 1.210 ± 0.340 LDH: 2.245 ± 0.690 to 1.642 ± 0.381 μmol mg–1 protein min–1). Interestingly, during this period, no mortality occurred. After 5 months, comparison of Na+K+ATPase:CS and Na+K+ATPase:LDH ratios of mature and sterile fish held either in FW or SW, indicated that the response of Na+K+ATPase largely exceeds the response of the metabolic enzyme apparatus in hyperosmotic conditions. Hence, the reduced iono-osmoregulatory capacity and higher mortality observed in SW-maturing fish during the reproductive season appears to be mainly attributable to Na+K+ATPase activity reduction rather than the alteration of gill metabolic capacity, since no concurrent increase of metabolic enzyme activity with Na+K+ATPase activity occurred.

The aim of the present study is to test the extent to which different intensities of continuous additional light affect somatic growth and sexual maturation in Atlantic salmon postsmolts in sea cages. Postsmolts (9 200 individuals) were randomly distributed among four commercial sized sea cages and exposed to either natural light or natural light + continuous additional light of low, medium or high intensity from January to June. In May the high light intensity group had a signiticantly higher mean live body weight than the other groups, and at the end of the experiment in June, all groups differed in mean gutted weight. There was apositive logarithmic regression between level of light intensity exposure during night and mean gutted weight. A small proportion of fish matured sexually (after 1.5 years in seawater) in the natural light group, whereas no maturation was detected in the light groups. These results suggests that to affect growth and proportion or maturation in Atlantic salmon by additional light, there might be different threshold values of light intensity.

Le présent travail est consacré à l'étude de la maturation sexuelle d'une cohorte née en 1977 d'Eledone cirrosa dans le golfe du Lion en Méditerranée. Plusieurs indices de maturation tel que le rapport gonado-somatique, l'indice de Guerra pour les deux sexes, l'indice du pénis pour les mâles ainsi que l'indice de la glande de l'oviducte sont examinés en vue de choisir le meilleur moyen d'exprimer numériquement les différents stades de maturation de l'espèce pour des études de populations. Dans ce but, l'on suggère d'utiliser l'indice de Guerra pour les mâles et l'indice de la glande de l'oviducte pour les femelles pour lesquels trois phases de maturation (immature, intermédiaire et mature) peuvent être différenciées. Les clefs numériques correspondant à trois phases de maturation avec les indications des observations du développement de la gonade sont établies.

The mating behaviour, with emphasis on the sexual maturation, of male tsetse, Glossina morsitans centralis (Machado, 1970) reared at the Uganda Trypanosomiasis Research Organization (UTRO) was investigated. Mating behaviour of 2–15 day-old males and 3-day-old females was observed. Three mating phases were recognized as courtship, mounting and genital interlocking (coupling), and jerking in most male flies tested.

The efficiency in coupling increased with age. Most males mounted the female mates after one attempt. The mating period in most males tested was between 1 and 3 hr, while the jerking period was on average 2.5 min. Most of the matings resulting in insemination lasted longer than 1 hr in all the age groups tested. The ability to inseminate and the degree of insemination produced by the older male flies were better than those by the younger ones. These results are discussed in relation to laboratory rearing of Glossina.

Proteins of male accessory reproductive gland secretions and the spermatophore of the tsetse, Glossina morsitans morsitans, have been characterised by electrophoresis. The spermatophore contains all the major proteins of accessory gland secretions and no new proteins were detected.

Influence of blood meals and neurosecretions on synthesis of accessory gland secretions and insemination are discussed. It is concluded that synthesis of accessory gland secretions commences prior to adult emergence and continues uninterrupted in the adult, independent of the corpus allatum.