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51.
I. W. J. Debyser 《International journal of primatology》1995,16(6):889-907
I review literature on juvenile mortality of captive prosimians in order to evaluate the available information on captive
breeding. Juvenile mortality includes abortion, premature mortality, stillbirth, and death of the unweaned young. Prosimian
juvenile mortality ranges between 25 and 45% in captive populations. It is generally lower in the Lemuroidea, particularly
the Cheirogaleidae, than in the Lorisoidea. Mortality is particularly high in the Lorisinae. Most mortality, including a high
stillbirth rate, occurs on the first day and during the first 10 days thereafter. Stress, maternal neglect and traumatic insults,
not infrequently linked to each other, are the most frequently reported causes of death. The percentage of congenital malformations
tends to be high in some colonies. Sex of the infant and parity seem to be important risk factors for juvenile mortality,
whereas litter size does not appear to be important. Based on few data, wild- caught females appear to have higher breeding
success than those born in captivity. Synchronized births in lemuroids and isolated births in Galagoare more likely to result in successfully weaned infants. 相似文献
52.
Isolates of novel strains of Kashmir bee virus (KBV) were obtained from field-collected dead adults of Apis mellifera from honey bee colonies in Canada and Spain. They differed from other strains of KBV in their tendency to aggregate in dilute buffer solution and in containing only three proteins when analysed by SDS-polyacrylamide gel electrophoresis compared with five proteins resolved in the type strain of KBV from Apis cerana in India and six proteins in KBV strains from South Australia and New Zealand. Immunodiffusion tests and Western blotting studies indicated that the five virus isolates were serologically related and all were related to acute paralysis virus (APV). The world distribution of KBV strains and their apparent relationship with APV are discussed. 相似文献
53.
Naoto Sugiura 《Ecological Research》1995,10(2):171-177
Anthecological observations of an orchidBletilla striata were carried out in Kobe, Japan. The purplish pink flowers were visited by 26 species of insects belonging to Hymenoptera,
Diptera and Lepidoptera, although the flower did not offer food rewards of any kind. Candidates for pollination were seven
species of aculeate Hymenoptera with a body size that well fitted the space in between the column and labellum. The most effective
candidate was the male of the longhorn beeTetralonia nipponensis, judging from its abundance and legitimate intrafloral behavior. The female ofT. nipponensis and the other six species also contributed to promote out-crossing, but to a lesser extent than the maleT. nipponensis, since they occasionally exhibited illegitimate intrafloral behaviors for pollination and also, their flower visitation rate
was lower. 相似文献
54.
Chronological ages of Alouattaon Barro Colorado Island (BCI) were estimated from longitudinal dental wear. Combining these data with visual censuses, we
approximated the study population’s age profile. A stable model was then constructed; from it we derived agespecific mortality
rates. Mortality of immature animals is high, with 88% of the males and 65% of the females dying before 5 years. Adult mortality
is low until 11 years, when it accelerates. The average adult life span is 16.6 years for males and 15.5 for females. The
maximum life span is over 20 years. A pubertal male growth spurt occurs from 3 to 5 years, at which time females are primiparous.
Sexual size differences develop primarily during this time. The 1976 age profile had anomalously few animals aged 7 years
and males aged 8–9 and 15–16 years. With corroborating evidence, we hypothesize that these deficits resulted from excessive
rainfall in 1963 and 1971, which reduced the fall fruit crop and led to a high juvenile mortality. Within half of our study
troops, some adult males have nearly identical ages, suggesting an active process of agemate coalition. We hypothesize a form
of kin selection, wherein peripheral male cohorts from the same natal troop have greater survival and social success than
solitary animals. The stable model suggests an annual growth rate of 1.5% during the 1970s. Estimates of 16.7 and 4% for the
previous two decades, following a yellow-fever epidemic, imply that the BCI population is becoming stationary. A very different
age structure existed on neighboring Orchid Island in 1976, suggesting general food limitation. By contrast, the lowered,
but continuing growth on BCI suggests a less drastic limiting mechanism. We hypothesize that intratroop social competition
limits population growth by regulating subadult survival rates during food scarcity cycles. 相似文献
55.
56.
Ahmed Youssef Moussa 《Journal of invertebrate pathology》1978,31(2):204-216
Reovirus particles were isolated from adults in laboratory colonies of the housefly, Musca domestica. These particles were spherical in outline, 57–76 nm in diameter, and were found only in hemocyte cytoplasm, where virions have been disclosed by a new technique. Virions were present in large numbers, and viral inclusion bodies were identified. The virus particles had pentagonal and hexagonal shapes resembling a simple icosahedral structure. The virus was shown to be infectious and pathogenic to adult flies through injection or by feeding them suspensions from flies that had died of the virus. Electron micrographs of midgut sections from infected flies showed that the midgut cells were packed with dark undulating threads which were not present in uninfected flies. However, no virus particles or inclusion bodies could be seen in these cells. On the basis of their association with infected flies, and the similarity to results from other studies on reoviruses and insect viruses, it is suggested that these threads are an alternative replicative form of the reovirus. When the virus suspensions from heavily infected flies were dialyzed against weak alkaline solutions, the threads showed an inner component of coiled material, 12 nm in diameter, inside an envelope with a diameter of 50–83 nm, mean 60.3 ± 7.5, composed of subunits 7–8 nm long and 7–8 nm across. 相似文献
57.
ABSTRACT.
- 1 The population biology of Anthocharis cardamines (L.) is described and shown to vary with locality. Southern and Western populations emerge earlier than Northern ones, but Western and Northern populations occupy similar, wetter habitats and are associated primarily with Cardamine pratensis (L.). Southern populations are recorded mostly from Alliaria petiolata (Bieb.).
- 2 Studies on egg and larval survival indicate that host plant-induced death and parasitization by a tachinid are important mortality factors. However, a key-factor analysis on one population indicates that the major determinant of population size may be the number of eggs laid by ovipositing females, itself dependent upon weather during the oviposition period. Populations in different localities do show similar trends in abundance, corroborating the effect of weather.
- 3 Human effects on distribution and abundance are discussed, and some conservation strategies suggested.
58.
急性病毒性肝炎的发病率慢性肝炎患病率和肝病死亡率的研究 总被引:15,自引:0,他引:15
1984~1987年,在黑龙江、河北、河南、湖南、上海五个省市城乡10.08855人口中进行急性肝炎发病率、慢性肝炎患病率、与病毒性肝炎有关的肝病死亡率的研究。急性肝炎标化发病率为152.19/10万,主要发生在20~50岁组人群;因无甲肝暴发流行,除上海外各点季节发病率分布均衡。慢性肝炎标化患病率为158.25/10万(诊断标准为6个月前有明确急性肝炎病史,现有明显的临床症状或体征,肝功能异常,故实际慢肝患病率要高于此数字);与病毒性肝炎有关的肝病死亡(包括肝癌)标化率为22.65/10万,其中肝病为 13.14/10万。男性死亡率显著高于女性。 相似文献
59.
本文着重分析了广西城市和农村脑血管病发病情况的差异。我们发现城市CVD发病率、患病率明显高于农村,但是农村CVD的死亡率高于城市,其中我们对其原因作了初步的探讨。 相似文献
60.
J. Sivinski 《BioControl》1991,36(3):447-454
Among the host fruits of the Caribbean fruit fly there are a variety of sizes and shapes. These morphological differences
may influence the vulnerability of the larvae to parasites. In the laboratory, Caribbean fruit fly larvae placed in the smaller
of 2 different sizes of artificial ‘fruit’ (cloth spheres filled with a diet material) were parasitized at a higher rate by
the braconid,Diachasmimorpha longicaudata (Ashmead) when spheres were presented separately. However, when parasites were simultaneously presented with 6 different
sizes of ‘fruit’ there was no significant relationship between size and parasitization rate. This may be due to the parasites
preference to search for larvae in larger ‘fruit’. In field collections of different species of host fruit, a significant
inverse correlation exists between fruit radius and rate of parasitization. However, host fruit size accounts for only about
5% of the variance in yearly parasitization rates.
相似文献