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141.
This paper explores the problem of China's ‘missing’ girls—estimated to run into many millions. It considers the impact of the underpinning Confucian value system in China that has produced a culture of son preference and which, together with China's compulsory family planning program and ‘one child policy’, has effectively established a ‘one son policy’. Discussion of the various means by which the birth or survival of daughters have traditionally been prevented provides the context for identifying the contribution of new sex selection procedures to the maintenance of son preference in contemporary Chinese society. The paper concludes that China's son preference is not simply a personal problem for the millions of ‘missing girls’ who were destined to live a shorter life and for the surviving girls who continue to face considerable discrimination simply because they are of the ‘wrong’ sex; it heralds a social and demographic disaster of major proportions for which neither the government nor the people of China appear to have the will or the means to forestall. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
142.
Caroline Schluth Bérénice Doray Françoise Girard-Lemaire Monique Kohler Bruno Langer Bernard Gasser Véronique Lindner Elisabeth Flori 《黑龙江环境通报》2002,22(13):1177-1180
The 49,XXXXY syndrome is a rare sex chromosome anomaly with an approximate incidence of 1 in 85 000 male live births. The diagnosis is usually ascertained postnatally by the association of mental retardation, variable growth deficiency, Down syndrome-like facial dysmorphy, hypogenitalism and other malformations, especially involving the heart and skeleton. Prenatal diagnosis of the pentasomy 49,XXXXY is generally fortuitous and sonographic features have rarely been described in the literature. We report here on two cases of 49,XXXXY syndrome diagnosed prenatally because of sonographic abnormalities. In the first, amniocentesis was performed at 26 weeks' gestation for polyhydramnios, unilateral clubfoot and micropenis. In the second, a karyotype was carried out on chorionic villi at 13 weeks' gestation for cystic hygroma. These observations and the six previously reported cases demonstrate that cystic hygroma in first or second trimester of pregnancy may be associated with sex chromosome aneuploidy other than Turner syndrome. Moreover, they emphasize the importance of detailed sonographic examination in the second trimester, as small penis and abnormal posturing of the lower extremities are very suggestive of the 49,XXXXY syndrome. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
143.
Abstract: Pheromone‐based monitoring is a promising new method for assessing the conservation status of many threatened insect species. We examined the versatility and usefulness of pheromone‐based monitoring by integrating a pheromone–kairomone trapping system and pitfall trapping system in the monitoring of two saproxylic beetles, the hermit beetle Osmoderma eremita (Coleoptera: Scarabaeidae) and its predator Elater ferrugineus (Coleoptera: Elateridae), which live inside hollow trees. We performed mark–recapture studies of both species with unbaited pitfall traps in oak hollows combined with pheromone‐baited funnel traps suspended from oak branches to intercept dispersing individuals. For O. eremita, the integrated trapping system showed that the population in the study sites may be considerably higher than estimates based on extrapolation from pitfall trapping alone (approximately 3400 vs. 1100 or 1800 individuals, respectively). Recaptures between odor‐baited funnel traps showed that males and females had similar dispersal rates, but estimating the number of dispersing individuals was problematic due to declining recapture probability between subsequent capture events. Our conservative estimate, assuming a linear decrease in capture probability, suggested that around 1900 individuals, or at least half of the O. eremita population, may perform flights from their natal host trees, representing higher dispersal rates than previous estimates. E. ferrugineus was rarely caught in pitfall traps. One hundred thirty‐nine individuals, likely almost exclusively females, were caught in odor‐baited funnel traps with approximately 4% recapture probability. If recapture probability over consecutive capture events follows that of O. eremita, this would correspond to a total population size of 2500–3000 individuals of the predator; similar to its supposed prey O. eremita. Our results demonstrate that pheromone‐based monitoring is a valuable tool in the study of species or life‐history stages that would otherwise be inaccessible. 相似文献
144.
Summary. We describe the use of pieces of silicone tubing
to analyse the mandibular gland components of queen and
worker honeybees and show that these compounds can be
efficiently trapped on bis(trimethylsilyl)trifluoroacetamide
(BSTFA) treated pieces of tubing. The use of this technique
rather than that of solid phase microextraction (SPME) techniques
with commercially available fibres that have been
shown to be efficient at sampling secretions from the cuticle
of insects, is necessitated by a requirement for collection of
large sample numbers in a short space of time or for
sampling in the field. The technique may be generalised for
use with semiochemicals of low volatility in other insect
communciation systems. 相似文献
145.
Sierra Leone suffered from 11 years of civil war (1991-2002) resulting in tens of thousands of deaths and mutilations together with massive population displacement. In 2001, ARC International, Sierra Leone conducted a baseline survey of 201 commercial sex workers (CSWs) and 202 military respondents on the knowledge, attitudes and practices surrounding HIV/AIDS and STIs in Port Loko, Sierra Leone. In 2003, a comparable post-intervention survey of 202 CSWs and 205 military respondents was performed. Comparison of baseline and post-intervention results showed that HIV/AIDS knowledge increased among both groups, with those able to name three effective means of avoiding AIDS increasing from 5 per cent to 70 per cent among CSWs, and 11 to 75 per cent among the military. Reported condom use during last sex increased among CSWs from 38 to 68 per cent and among military from 39 to 68 per cent. These results demonstrate that, despite the challenges inherent in a post-conflict country, good-quality AIDS-prevention programmes can be effective. 相似文献
146.
Heike Pröhl 《Behavioral ecology and sociobiology》2005,58(3):310-315
Both modelling and field data from three breeding seasons show that an environmental factor, clutch loss (CL), affects the operational sex ratio (OSR) and therefore male mating frequency in strawberry poison frogs. Clutch loss affects the length of reproductive cycles of both sexes: with increasing clutch losses, males spend proportionately more time than females in parental investment activities. Because of this, males spend relatively less time in the mating pool, i.e. exhibit proportionately more time-out than females in comparison to a situation with low or no clutch loss. Hence, clutch loss leads to a less male-biased OSR, coupled with a decrease in the opportunity for sexual selection. Furthermore, this study resolves an apparent paradox, the negative correlation between mating frequency and reproductive success (=number of produced tadpoles) of individual males in one breeding season. Clutch loss decouples the correlation between mating frequency and reproductive success because females re-enter the mating pool when they lose their offspring. However, clutch loss diminishes the reproductive output. Similar consequences of clutch loss on the OSR may be true for many species where both sexes reproduce frequently in one breeding season.Communicated by J. Christensen-Dalsgaard 相似文献
147.
Hassane Mahamat Ahmed Hassanali Hezekiel Odongo Baldwyn Torto El-Sayeed El-Bashir 《Chemoecology》1993,4(3-4):159-164
Summary The accelerating effect of mature males of the desert locust,Schistocerca gregaria, on the maturation of immature male and female conspecifics was confirmed. The onset of sexual activity was found to correlate with yellowing of the male insects. Using the colour as an indicator of maturation, the maturation-hastening effect of an hexane extract from mature males was also confirmed. Likewise, volatiles from mature males placed in the upper storey of a two-chamber bioassay system (no visual or tactile contact possible) and charcoal-trapped volatiles from the mature males also induced accelerated maturation in recipient males placed in the lower storey. GC and GC-MS analysis of volatiles collected from 4-week-old mature males showed the presence of anisole, benzaldehyde, veratrole, phenylacetonitrile and 4-vinylveratrole, roughly at the ratio 4.8:7.0:3.3:79.8:5.0. In addition, guaiacol, phenol, benzoylnitrile, benzyl alcohol and 2-benzoyloxyphenylacetonitrile were present in smaller amounts. These compounds were either absent or found only in trace amounts in the female volatiles. Earlier, we had shown that essentially the same blend collected from younger males (10–20 d old, not yet demonstrating signs of maturation) induced strong aggregation of both sexes of adult desert locusts, suggesting a parsimonious role for the pheromone system: as an adult aggregation signal and as a maturation accelerant in young adults. 相似文献
148.
Gérard?CoureaudEmail author Dominique?Langlois Guy?Perrier Benoist?Schaal 《Chemoecology》2003,13(4):187-192
Summary. In the rabbit, lactating females emit a volatile
compound in milk, the mammary pheromone (MP), that
triggers rooting for the nipple and its grasping in pups.
Previous studies have shown that the MP seems to act selectively,
in terms both of intensity and quality. Here, we aimed
to add new evidence to these properties of the MP. Newborn
rabbits (n=825) were submitted to an oral activation test
allowing to measure their searching/grasping responses
towards different stimuli. In Experiment 1 we assessed
whether pups respond to the MP in an intensity-dependent
manner. In Experiment 2 we assessed the activity of 20
volatiles previously identified in rabbit milk, other than the
MP, which were never systematically tested for intensitydependence.
The assays showed that a) neonatal responses
are released by the MP only for a limited range of concentrations;
b) the 20 other odorants from milk are inactive at
any concentration. Thus, the MP appears to be the single
volatile from rabbit milk that releases searching/grasping
behaviour in pups. 相似文献
149.
Thomas Hartmann Claudine Theuring Till Beuerle Elizabeth A. Bernays 《Chemoecology》2004,14(3-4):207-216
Summary. The alkaloid profiles of the life history stages
of the highly polyphagous arctiid Estigmene acrea were
established. As larvae individuals had free choice between
a plain diet (alkaloid-free) and a diet that was supplemented
with Crotalaria-pumila powder with a known content and
composition of pyrrolizidine alkaloids (PAs). Idiosyncratic
retronecine esters (insect PAs) accounted for approximately
half of the PAs recovered from the larvae. These alkaloids
were synthesized by the larvae through esterification of dietary
supinidine yielding the estigmines, and esterification of
retronecine yielding the creatonotines. The retronecine is
derived from insect-mediated degradation of the sequestered
pumilines (macrocyclic PAs of the monocrotaline type).
With one exception, the PA profiles established for larvae
were found almost unaltered in all life-stages as well as
larval exuviae and pupal cocoons. The exception is the
males, which in comparison to pupae and adult females,
showed a significantly decreased quantity of the creatonotines
and pumilines. These data support the idea that
the creatonotines are direct precursors of the PA-derived male
courtship pheromone, hydroxydanaidal. Crosses of PA-free
males with PA-containing females and vice versa confirmed
an efficient trans-mission of PAs from males to females and
then from females to eggs. In single cases a male bestowed
almost his total PA load to the female, and a female her total load
to the eggs. The results are discussed with respect to pheromone
formation, PA transmission between life-stages, and the
defensive role of PAs against predators and parasitoids 相似文献
150.
Foraging behavior and the mechanisms that regulate foraging activity are important components of social organization. Here
we test the hypothesis that brood pheromone modulates the sucrose response threshold of bees. Recently the honeybee proboscis
extension response to sucrose has been identified as a ”window” into a bee’s perception of sugar. The sucrose response threshold
measured in the first week of adult life, prior to foraging age, predicts forage choice. Bees with low response thresholds
are more likely to be pollen foragers and bees with high response thresholds are more likely to forage for nectar. There is
an associated genetic component to sucrose response thresholds and forage choice such that bees selected to hoard high quantities
of pollen have low response thresholds and bees selected to hoard low quantities of pollen have higher response thresholds.
The number of larvae in colonies affects the number of bees foraging for pollen. Hexane-extractable compounds from the surface
of larvae (brood pheromone) significantly increase the number of pollen foragers. We tested the hypothesis that brood pheromone
decreases the sucrose response threshold of bees, to suggest a pheromone- modulated sensory-physiological mechanism for regulating
foraging division of labor. Brood pheromone significantly decreased response thresholds as measured in the proboscis extension
response assay, a response associated with pollen foraging. A synthetic blend of honeybee brood pheromone stimulated and released
pollen foraging in foraging bioassays. Synthetic brood pheromone had dose-dependent effects on the modulation of sucrose response
thresholds. We discuss how brood pheromone may act as a releaser of pollen foraging in older bees and a primer pheromone on
the development of response thresholds and foraging ontogeny of young bees.
Received: 24 May 2000 / Revised: 26 September 2000 / Accepted: 15 October 2000 相似文献