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1.
树皮是维管形成层以外的所有组织,其功能性状是反映植物生态适应策略的重要研究对象。为了揭示亚热带山地乔、灌木小枝树皮功能性状特征及其关联性,采用独立样本T检验和标准主轴回归方法对武夷山19种常见木本植物小枝树皮的主要功能性状的基本特征及其相关性进行了分析。结果发现:(1)树皮厚度、树皮密度与树皮含水量在乔、灌木之间无显著差异,其均值分别为(0.78±0.06)mm、(0.58±0.03)mg/cm3和(155.07±14.16)%。树皮碳(C)、氮(N)、磷(P)生态化学计量特征在乔、灌木之间差异也不显著,C、N、P平均值分别为(492.43±4.25)mg/g、(8.90±0.74)mg/g和(0.61±0.06)mg/g,树皮C∶N、C∶P与N∶P平均值分别为60.76±4.17、905.53±67.36与15.19±0.84。(2)树皮性状之间存在关联,其中树皮厚度与密度、密度与含水量均呈异速生长关系,而树皮厚度与含水量、氮含量与磷含量均呈等速生长关系。乔木树皮碳含量和磷含量间、灌木树皮密度和氮含量间均呈异速生长关系,乔木与灌木各性状间关系差异不显著。结果表明...  相似文献   

2.
    
Objective: To describe the prevalence of night eating in a community cohort of black and white girls, using different definitions of night eating as described in the literature. Research Methods and Procedures: Three‐day food diaries collected as part of the National Growth and Health Study were examined to identify episodes of night eating, which was defined in five different ways: eating >25% of daily caloric intake after the last evening meal, eating >25% of daily caloric intake after 7 pm, eating >50% of daily caloric intake after the last evening meal, eating >50% of daily caloric intake after 7 pm, or eating between 11 pm and 4:59 am. Results: Frequency of night eating varied tremendously depending on how the behavior was defined. For the least restrictive definition (>25% of total intake after last meal), 50% to 70% of girls reported one night eating event; for the most restrictive (>50% of total intake after last meal), only 1.5% of 11‐year‐old girls' diaries and 3.5% of 19‐year‐old girls' diaries contained a night eating event. The frequency of night eating decreased dramatically (typically by a factor of 10) if the inclusion criteria required multiple night eating events in a given week. Discussion: A standard definition of night eating behavior is needed to advance the field. An agreed‐on operationalized definition that includes time of day, amount of calories consumed, and a frequency criterion would enable cross‐study comparisons and encourage the examination of developmental and clinical considerations of night eating behavior.  相似文献   

3.
In laboratory experiments, isolated eastern tent caterpillars, Malacosoma americanum (Fabricius) (Lepidoptera: Lasiocampidae), grew more slowly than their grouped siblings even though factors previously reported to give grouped caterpillars an advantage were eliminated from our experimental design. Analysis of time-lapse videorecordings of daily foraging bouts showed that, despite their slower growth, isolated individuals fed significantly more often than their grouped siblings. This finding is consistent with previous observations showing that the rate at which tent caterpillars assimilate food is largely independent of foraging frequency and suggests that increased metabolic costs associated with superfluous activity may cause isolated caterpillars to grow slower. More rapid growth of grouped caterpillars also appears attributable to the significantly longer periods of time solitary caterpillars spent inactive during episodes of molting. Our study shows that the distinctive temporal pattern of foraging characteristic of intact colonies of eastern tent caterpillars is a emergent property of the group.  相似文献   

4.
The efficacy of insecticides in controlling Sceliodes cordalis , eggfruit caterpillar, in eggplant was tested in four small plot trials because there has been a very limited range of insecticides available to manage this pest. Weekly applications of bifenthrin, flubendiamide, methoxyfenozide, chlorantraniliprole and spinosad and twice weekly applications of methomyl provided control as measured by a percentage of damaged fruit significantly lower than that in an untreated control. Twice weekly applications of methoxyfenozide, chlorantraniliprole or spinosad were not significantly more effective than weekly applications. Bacillus thuringiensis kurstaki , emamectin benzoate, indoxacarb, methomyl and pyridalyl applied weekly were ineffective, with percentages of damaged fruit not significantly different from the untreated control. These trials have identified a number of insecticides that could be used to manage S. cordalis , including several that would be compatible with integrated pest management programs in eggplant.  相似文献   

5.
Binge eating disorder (BED) and night eating syndrome (NES) are putative eating disorders frequently seen in obese individuals. Data suggest that BED fulfills criteria for a mental disorder. Criteria for NES are evolving but at present do not require distress or functional impairment. It remains unclear whether BED and NES, as they are currently defined, are optimally useful for characterizing distinct patient subgroups. We propose that a distinction be made between “eating disorders” and “non‐normative” eating patterns without associated distress or impairment. Although non‐normative eating patterns may not be considered mental disorders, they may be very important in terms of their impact on body weight and health. More precise behavioral and metabolic characterization of subgroups with eating disorders and non‐normative eating behaviors has important implications for understanding the etiology, pathophysiology, and treatment of obesity. Ultimately, better understanding of the many pathways to increased energy intake may lead to targeted strategies for prevention of overweight and obesity in at‐risk individuals and populations.  相似文献   

6.
树皮由维管形成层以外的所有组织组成;其功能特性反映植物重要的生态适应策略。为揭示弄岗喀斯特季节性雨林常见树种树皮厚度在不同类群和功能群间的差异以及生物因子和环境因子对树皮厚度的影响;以弄岗15 hm2永久森林监测样地内多度大于20的128种常见树种为研究对象;分析不同类群和功能群之间树皮厚度的差异;以及生物因子和环境因子对树皮厚度的影响。结果发现:弄岗128种常见树种的树皮总厚度、外树皮厚度、内树皮厚度均值分别为2.95、0.70、2.26 mm;亚麻科(Linaceae)、紫葳科(Bignoniaceae)、茶茱萸科(Icacinaceae)的树皮相对较厚;树皮厚度在不同类群和功能群间均呈显著差异;且内树皮厚度>外树皮厚度;不同功能群中;落叶种>常绿种(外树皮厚度除外);乔木种>小乔木种>灌木种;树皮厚度的系统发育信号较弱;因此树皮厚度主要受生境因素影响;在影响树皮厚度的多种生物因子中;物种因子的解释率最高;此外;树皮厚度变异受地形因子和土壤因子驱动;不同群丛位置存在相似性;树皮总厚度与林分因子和环境因子均存在相关性。综上;弄岗喀斯特季节性雨林群落内树种的树皮厚度较薄;不同树种间和功能群间的树皮厚度存在较大差异;表明这些树种对当地湿润气候的适应性;环境因子对树皮厚度的解释揭示了树种通过调整树皮厚度来适应不同环境条件和生态位的策略。  相似文献   

7.
    
  • Frost events occur with a significant frequency in savannas of the Southern Hemisphere, especially in the Cerrados of Brazil. One of the main strategies to deal with such events is to invest in thick and dense bark, which can insulate internal branch tissues and protect buds, essential to ensure resprouting if frost damage causes plant canopy die‐back. Such strategies may be fundamental to determine the persistence of savanna species in regions where low temperatures and frost events are recurrent.
  • Here we describe bud protection and bark strategies of 53 woody species growing in typical savanna vegetation of central Brazil. In addition, we used an experimental approach exposing branches to 0 °C to measure temperature variation in internal branch tissue and test its relationship to bud protection and bark properties.
  • We found that the majority of species (69%) showed medium to high bud protection against extreme temperatures; however, the degree of bud protection was not clearly related to bark properties, such as bark thickness and density. Bark density is a fundamental trait in determining protection against low temperatures (0 °C), since species with low bark density showed lower temperature variation in their internal branch tissues, independently of the bud protection degree.
  • Bark properties and bud protection are two different (albeit related) strategies for the protection and persistence of savanna trees under extreme environmental temperatures and can explain ecological observations related to savanna tree responses after frost events.
  相似文献   

8.
马尾松林天敌昆虫群落对马尾松毛虫控制作用的研究   总被引:3,自引:0,他引:3  
本文通过对马尾松林松毛虫天敌昆虫群落优势种的选择及功能表述、用典型相关分析选择关键林分因子进行林地分类,研究了表示天敌昆虫群落对松毛虫控制作用的途径。结果表明,用天敌昆虫群落功能指标选择的重要林分因子为郁闭度、灌木层高度及盖度、草木层高度及总盖度。用这些林分因子可以把常灾区林地划分为4种类型,且这4类林地在天敌昆虫群落多样性、种数、个体数及松毛虫密度上都存在明显差异。最后分别建立了4类林地松毛虫密度变化率与多样性等功能指标及郁闭度等林分因子间的回归模型,回归相关性进一步表明用林分因子代替天敌昆虫的作用是合适的,这样代替的结果克服了生产应用时数据调查的困难,增加了实用性。  相似文献   

9.
    
Oral administration of root extracts of a medicinal plant, Ashwagandha (Withania somnifera) to last instar larvae of a polyphagous pest, Spodoptera litura resulted into abnormal morphogenesis and the effects comprised mortality, delay in larval-pupal and pupal-adult ecdysis, ecdysial stasis, formation of larval-pupal and pupal-adult intermediates, reduced pupation and formation of abnormal pupae, complete suppression of normal adult emergence and formation of adultoids. These effects are similar to those produced by the administration of JHAs and may be due to interference with the normal hormonal mechanism of moulting and metamorphosis.  相似文献   

10.
分别在2005年和2006年的5、6月份,在Kamalpur和Hunterpara茶园、孟加拉西部以及印度地区对一种昆虫致病真菌球孢白僵菌对油桐尺蛾Buzura (=Biston) suppressaria Guen.的生物效力进行了评估。以农场主常用的化学杀虫剂40% SP灭多虫和25% EC氯氰菊酯作为标准检测物。试验中球孢白僵菌浓度为1.50 g,2.00 g和2.5 g/lit. of water;灭多虫和氯氰菊酯浓度分别为0.75 mL,1.00 mL和1.50 mL,和0.50 mL,1.00 mL和1.50 mL/lit. of water。在喷洒2.5 g/lit. of water 球孢白僵菌3天后,Kamalpur和Hunterpara茶园中油桐尺蛾种群个体数分别降低了88.00%和84.00%。死的毛虫变成黑色,垂悬在叶片上。并且发现球孢白僵菌的杀虫活性与高剂量的灭多虫和氯氰菊酯的相当。  相似文献   

11.
Abstract  Natural enemies play an important role in inhibiting population growth of pine caterpillar, but they are difficult to be used in systematic management models. This paper attempts to use some forest stand factors to substitute the effect of natural enemies, which could be used in management models. Through the studies from more than 200 stand plots with different stand conditions in Qu County, Changshan County, and Longyou County of Zhejiang Province, 16 predominant species groups from insect community were selected, and the canonical correlation coefficient between the diversity index, species number, individual number of predominant species and the stand factors was analyzed. The results indicated that the canopy density and ground vegetation were the key stand factors for characterizing the function of insect community. The forest area was divided into four types according to the variation of canopy and vegetation conditions by using cluster analysis. The regression models between the rate of variation of pine caterpillar density and the forest factors including canopy density and vegetation covers were developed in each type of forests. There were significant differences in diversity index, species number, individual number of insect community and population density of pine caterpillar among four types of forests, and correlation coefficients of the four regression models were rather high ( r =0. 924 — 0. 964). This means that the classification of the forest stands is reasonable and the stand factors can characterize the effect of natural enemies in practice.  相似文献   

12.
    
Ophiocordyceps sinensis, an entomopathogenic fungus of the Tibetan Plateau is one of the most valuable traditional Chinese medicines. A fungal pathogen of O. sinensis, Polycephalomyces sp. GIMCC 3.570 (isolate 2010A-0818) was characterized by morphology, related to sequences of six genes (SSU, ITS, LSU, TEF1-α, RPB1 and ATP6) found in a BLAST search and five genes (SSU, LSU, TEF1, RPB1 and RPB2) by phylogenetic analysis using maximum parsimony, maximum likelihood and Bayesian methods. The results strongly support placement of P. sp. GIMCC 3.570 in the genus Polycephalomyces. To determine the influence of P. sp. GIMCC 3.570 on the reproduction of its host, 30 artificially infected O. sinensis samples were compared with 30 uninfected controls. In the infected fungus, the life span of the stroma was significantly shorter and significantly fewer ascospores were produced compared with uninfected O. sinensis (p < 0.01).  相似文献   

13.
In addition to damaging trees, the eastern tent caterpillar is implicated in early fetal loss and late‐term abortion in horses. In a field study, we evaluated the potential biological control of the caterpillar using eastern tent caterpillar nuclear polyhedrosis virus (ETNPV), a naturally occurring virus that is nearly species‐specific. Egg masses were hatched and second instar larvae were fed virus‐inoculated foliage to propagate the virus in vivo. Then, a viral pesticide was formulated at concentrations of 104, 106 and 108 polyhedral inclusion bodies per ml. The pesticide was applied to foliage on which second, third and fourth instar caterpillars were feeding. When the majority of surviving larvae reached the sixth instar, colonies were collected and the surviving caterpillars counted. Mean numbers of surviving caterpillars per treatment were compared via 95% bootstrap confidence intervals. The data indicate second instar caterpillars were highly susceptible to the virus, but only at the highest concentration tested. Third instar caterpillars were also somewhat susceptible to high virus concentrations, while fourth instar caterpillars were fairly resistant. Our data provide the strongest evidence to date that ETNPV can be propagated, harvested and refined for formulation as a biological control agent for eastern tent caterpillar. Its use on this insect may be merited in circumstances where landowners and managers need to protect trees and horses.  相似文献   

14.
    
This study investigated the morphological and biochemical characteristics of the CB1, CB3, CB5, CB8 and CB12 cotton varieties and evaluated their effects on third instar larval movement, and body weight of the cotton armyworm Spodoptera litura at different developmental stages. The cotton varieties differed in their plant architecture, branching, stem color and hairiness, leaf color and hairiness, leaf trichome density, flower color, numbers of leaves and bolls per plant, concentrations of protein and starch, and boll length, width and weight. The CB1 and CB3 varieties possessed significantly higher trichome densities, while CB8 produced larger and heavier bolls. Boll bearing was found to be highest in CB1 and lowest in CB8. Biochemical analyses indicated the highest percentage of protein in CB5, and of starch in CB8; concentrations of both were lowest in CB12. Cotton varieties did not affect larval foraging, but their abundance on leaflet, mature and square differed significantly. Analysis of the growth response parameters of S. litura as a result of feeding on the tested varieties revealed that larval instars, pupae and adult moths attained the highest body weight on CB8, followed by CB5, and the lowest weight on CB12. Collectively, the results of this study show that the CB5 and CB8 varieties are favorable host‐plants for cotton armyworms; therefore, these varieties are the least suitable for cultivation.  相似文献   

15.
Two new diterpenes were isolated from the fraction exhibiting anti-allergic activity obtained from the bark of Cinnamomum cassia. They have been given the trivial names cinncassiol D4 and cinncassiol D4 glucoside and their structures determined on the basis of chemical and spectral evidence.  相似文献   

16.
    
Objective: The objective was to test the hypothesis that, in women, the association between obesity and impairment in psychosocial functioning is mediated by levels of weight and shape concerns and/or binge‐eating frequency. Research Methods and Procedures: Self‐report measures of eating disorder psychopathology, mental health functioning, subjective quality of life in the psychological and social domains, and days “out‐of‐role” associated with any (physical or mental) health problem, were completed by a community sample of women classified as obese (BMI ≥30 kg/m2, n = 639) or non‐obese (BMI <30 kg/m2, n = 4253). For each of the dependent measures, regression models were used to test the hypothesis of mediation by comparing the strength of the relationship between independent and dependent variables with and without inclusion of the putative mediator in the regression model. Results: On each measure, the conditions for perfect mediation were satisfied when weight or shape concerns acted as the putative mediator, indicating that there was no association between obesity and functional impairment after controlling for weight or shape concerns. In contrast, associations between obesity and impairment in psychosocial functioning remained highly significant when binge‐eating frequency was the putative mediator. Discussion: The findings suggest that in women, weight and shape concerns are an important mediator of the relationship between obesity and impairment in psychosocial functioning, whereas binge eating may not be of primary importance. A greater focus on body acceptance in obesity treatment may be indicated.  相似文献   

17.
测定10个树种树木上的三年生枝条树皮内绿色组织的叶绿素含量、光合速率和枝干的呼吸速率的结果表明:10个树种树皮内叶绿素含量为0.0649~0.3460mg·g^-1(FW),叶绿素a/b为1.05~1.91,均低于叶片或针叶;树皮内绿色组织的光合速率为0.21(红松)~2.06(水曲柳)μmol(O2)·m^-2·s^-1,枝干呼吸速率1.76(红松)~3.21(落叶松)μmol(O2)·min^-1·g^-1(FW)。树皮内绿色组织的光补偿点(LCP)、光饱和点(LSP)低于叶片,而表观量子效率(AQY)高于叶片或针叶。据此认为,树皮内绿色组织适应于阴生环境,所以有较强的耐阴能力。  相似文献   

18.
杨树皮类脂萃取试验   总被引:1,自引:0,他引:1  
毛白杨(Populus tomentosa Carr)树皮类脂萃取小试和扩大试验证明,用石油醚作萃取剂,工艺可行,类脂产品得率为干树皮重量的4—8%. 杨树皮类脂是一种新的树皮化学加工产品.经分析,产品中含有不饱和脂肪酸(60—70%)、胡萝卜素(不低于100毫克/公斤)、维生素E(不低于1000毫克/公斤)、磷脂(0.6—1.0%)、不饱和甾醇(2.0—2.5%)等生物活性物质,该产品可作为医药与日化产品的药用添加剂。  相似文献   

19.
    
Objective: To examine the prevalence and correlates of night eating, the core behavioral symptom of night eating syndrome among adolescents and adults, using two public access survey databases of nationally representative samples. Research Methods and Procedures: Data were extracted for individuals age 13 years or older who completed food diary data for the National Health and Nutrition Examination Survey III (N = 18, 407) or the Continuing Survey of Food Intakes by Individuals (N = 10, 741). Prevalence estimates were calculated for three commonly used definitions of night eating. Logistic regression was used to examine correlates of night eating: type of day, season, gender, age, race/ethnicity, and BMI or obesity. Results: With few exceptions, findings were similar in the two surveys. Night eating is most common during the weekend; prevalence is greatest among young adults (18 to 30 years of age) and least common among individuals age 65 years or older; and is not associated with BMI or obesity. Gender or ethnicity effects were not found to be stable across surveys. Discussion: Experts need to consider type of day, age group, and possibly gender and race/ethnicity when examining population differences in night eating. Longitudinal studies are needed to further examine the link between night eating and obesity.  相似文献   

20.
Objective: To investigate the relationships between alexithymia and emotional eating in obese women with or without Binge Eating Disorder (BED). Research Methods and Procedures: One hundred sixty‐nine obese women completed self‐report questionnaires, including the Beck Depression Inventory, the State Trait Anxiety Inventory, the Stress Perceived Scale, the Dutch Eating Behaviour Questionnaire, and the Toronto Alexithymia Scale. The presence of BED, screened using the Questionnaire of Eating and Weight Patterns, was confirmed by interview. Results: Forty obese women were identified as having BED. BED subjects and non‐BED subjects were comparable in age, body mass index, educational level, and socioeconomic class. According to the Dutch Eating Behaviour Questionnaire, BED subjects exhibited higher depression, anxiety, perceived stress, alexithymia scores, and emotional and external eating scores than non‐BED subjects. Emotional eating and perceived stress emerged as significant predictors of BED. The relationships between alexithymia and emotional eating in obese subjects differed between the two groups according to the presence of BED. Alexithymia was the predictor of emotional eating in BED subjects, whereas perceived stress and depression were the predictors in non‐BED subjects. Discussion: This study pointed out different relationships among mood, alexithymia, and emotional eating in obese subjects with or without BED. Alexithymia was linked to emotional eating in BED. These data suggest the involvement of alexithymia in eating disorders among obese women.  相似文献   

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