抗梅岭霉素和阿维菌素二斑叶螨种群生命力和繁殖力的研究   总被引：3，自引：0，他引：3  

李瑞娟  王开运  姜兴印  仪美芹 《农药学学报》2004,6(1):81-84

采用营养液培养的棉苗饲养二斑叶螨Tetranychus urticae Koch,用梅岭霉素、阿维菌素对其逐代进行抗性选育,至第9代,测定了两个抗性种群的抗性水平、生命力和繁殖力。结果表明:梅岭霉素抗性种群的抗性达7.9倍,其雌成螨寿命、产卵量、卵的孵化率和后代若螨成活率分别比对照增加54.08%、39.93%、6.57%和-15.44%。阿维菌素抗性种群的抗性达5.8倍,其雌成螨寿命、产卵量、卵的孵化率和后代若螨成活率分别比对照增加15.88%、10.87%、5.86%和-9.32%。由此发现梅岭霉素和阿维菌素对二斑叶螨的生长发育和繁殖有一定有利作用,抗性风险性较大,应引起重视。  相似文献   

中国美利奴多胎肉用细毛羊羊毛品质分析     

何其宏  魏荣安  马春萍  库木斯汗  刘正山 《中国草食动物》2004,24(5):52-53

对正在培育的中国美利奴多胎肉用细毛羊的羊毛品质做了综合分析.在毛丛自然长度方面，断奶公羔为4.37cm，母羔为4.43cm，周岁公羊为12.60cm，周岁母羊为11.47cm；羊毛的伸直长度周岁公羊为15.01cm.周岁母羊为14.86cm；羊毛纤维直径周岁公羊为21.67μm.周岁母羊为20.36μm；羊毛密度周岁公羊为5212根/cm^2.周岁母羊为5430根/cm^2.比2002年中国美利奴羊周岁羊相比还有较大差距；羊毛净毛率周岁公羊为64.60％.周岁母羊为65.64％。由上可知.除羊毛密度外.中国美利奴多胎肉用细毛羊总体上符合品种培育的要求.在今后的选育中要注意羊毛密度的提高。  相似文献   

Assessing variability in fecundity of Amaranthus powellii using a simulation model     

D C Brainard  & R R Bellinder† 《Weed Research》2004,44(3):203-217

Estimates of weed fecundity and its variability are critical for the development of population dynamic models and for evaluating the long‐term consequences of weed management practices. The purpose of this research was to estimate Amaranthus powellii fecundity across years, seasons and competitive environments using a mechanistic model. Existing models were modified to account for weed responses to shade, and to dynamically simulate seed production among subthreshold densities of A. powellii. The model was parameterized and tested using five sets of field data in which A. powellii was grown either alone or with transplanted broccoli. The model overestimated A. powellii height, but predicted both dry weight and fecundity well. Mean simulated fecundity for A. powellii ranged from 0 to 268 000 seeds per plant depending on year, crop maturity date, relative time of emergence and location. Year‐to‐year variability in simulated fecundity was large with coefficients of variation ranging from 77 to 128 under low and high competitive environments respectively. Our results suggest that estimates of weed fecundity based on 1 or 2 years of empirical data may result in significant errors in population dynamic models, and that the use of economic optimum thresholds based on weed density alone entails considerable risks.  相似文献   

An investigation on the influence of feline flea allergy on the fecundity of the cat flea     

B.J. McDonald  C.S. Foil  L.D. Foil 《Veterinary dermatology》1998,9(2):75-79

Survival, egg production and egg viability of fleas allowed to feed on eight flea-allergic and six flea-naive cats were compared. Fifty fleas, in feeding cages or free roaming, were allowed to feed on the cats. Flea-allergic cats removed significantly more free-roaming fleas than did flea-naive cats. Female fleas produced fewer eggs on flea-allergic cats than on flea-naive cats regardless of feeding method. There was no significant difference in egg viability between the two groups. The data suggest that flea-allergic cats efficiently removed fleas by grooming and that they also produce unknown factor(s) that affect the fecundity of fleas.  相似文献   

湖羊产羔性状的微卫星标记与其产羔数的关联性分析   总被引：1，自引：0，他引：1  

孙伟  常洪  张明  梁荣旺  金银  钱建共  吴文忠  陈玲 《中国畜牧杂志》2008,44(15)

选用位于绵羊第6号染色体上与多胎基因(FecB)紧密连锁的微卫星O arAE101、BM 1329、BM 143和O arH H 55以及位于第4号染色体上的O arH H 35标记对湖羊的产羔性状进行研究。结果发现湖羊的5个微卫星位点都达到了高度多态水平(PIC>0.5),这5个微卫星位点可以用于湖羊产羔性状的遗传多样性的评估。方差分析结果表明:5个位点中O arAE101、BM 143各基因型产羔数之间存在极显著差异(P<0.01),BM 1329、O arH H 35各基因型产羔数之间存在显著差异(P<0.05),O arH H 55、BM 1329各基因型产羔数之间差异不显著(P>0.05),本研究对今后湖羊品种的标记辅助选择和分子育种具有重要的应用价值。  相似文献   

Demography of Lolium rigidum in winter barley crops: analysis of recruitment,survival and reproduction     

Fernandez‐Quintanilla  Barroso  Recasens  Sans  Torner  Sanchez Del Arco 《Weed Research》2000,40(3):281-291

Demographic studies were conducted with Lolium rigidum Gaud. growing in winter barley crops at five sites in central and eastern Spain, over a period of 2 or 3 years. Although threefold differences (34–97%) in annual recruitment were recorded in the various experiments, most of the values were close to the overall average (67%). Seedling emergence took place in a very short period of time after sowing, with 90% emergence generally being reached after a thermal time of 242 d°C (provided soil moisture was adequate at sowing). Seedling survival was very high (78–95%) in most experiments, with no clear relationship between this parameter and any of the environmental variables studied. Survival curves were relatively linear, with plant mortality increasing gradually throughout the life cycle of the plant. There were 34‐fold differences (from 7 to 237 seeds per plant) in the fecundities recorded in the various experiments. Variation in fecundity resulted partly from differences in crop and weed densities and total precipitation received during the growth cycle. The annual rate of population growth was estimated based on the above‐mentioned parameters. The potential for population growth was high (average λ=6.21), but large differences were obtained for the different sites and years.  相似文献   

Egg production in the salmon louse [Lepeophtheirus salmonis (Krøyer)] in relation to origin and water temperature   总被引：2，自引：0，他引：2  

P A Heuch  J R Nordhagen  ; T A Schram 《Aquaculture Research》2000,31(11):805-814

Egg strings of salmon lice, Lepeophtheirus salmonis (Krøyer 1837), collected from farmed and wild Atlantic salmon had similar length and number of eggs string^?1. Egg production was investigated at water temperatures from 7.1 °C to 12.2 °C. A regression model indicated that at low temperatures egg strings were longer and had more eggs. Mean length of single eggs was significantly smaller and the percentage of non‐viable eggs in the strings was higher at 7.1 °C than at 12.2 °C. Adult females survived for up to 191 days at 7.2 °C, and during this period 11 pairs of egg strings were produced.  相似文献   

东海带鱼繁殖力及其资源的合理利用   总被引：9，自引：0，他引：9       下载免费PDF全文

凌建忠  严利平  林龙山  李建生  程家骅 《中国水产科学》2005,12(6):726-730

根据2003年东海区渔业资源监测网的调查数据，利用单位补充量繁殖力和单位补充量亲鱼资源生物量估算模型，对东海带鱼（Trichiurus japonicus Temminck et Schlegel，1844）渔业资源现状进行分析，结果表明：（1）根据单位补充量繁殖力的估算，当tc=0．5龄、F≥1．15时和当tc=1龄、F≥2．30时，带鱼渔业处在高危险区；而当tc≥1．5龄时，可以承受较大的捕捞压力。（2）根据单位补充量亲鱼资源生物量的估算，当tc=0．5龄、F≥1．22时和当t。=1龄、F≥2．40时，带鱼渔业处在高危险区；而当tc≥1．5龄以上时，可以承受较大的捕捞压力。（3）目前（2003年为例）东海带鱼现行渔业资源状况为：tc=0．5龄、F=2．60，处于高危险区的较高危险点上。因此，在降低现有捕捞强度较难的情况下，建议提高带鱼开捕规格，以便更好地养护东海带鱼，使其资源能得到可持续利用。  相似文献   

Comparing Immature Development and Life History Traits in Two Coexisting Host-Feeding Parasitoids,Diglyphus isaea and Neochrysocharis formosa （Hymenoptera：Eulophidae）     

ZHANG Yi-bo LU Shu-long LIU Wan-xue WANG Wen-xia WANG Wei WAN Fang-hao 《中国农业科学(英文版)》2014,(12):2690-2700

Coexisting natural enemies that share a common host resource in the same guild usually exhibit variation in their life history traits, due to their need to share a similar ecological niche. In this study, we compared the immature development times and adult life history traits of two coexisting, host-feeding parasitoids, Diglyphus isaea Walker and Neochrysocharis formosa Westwood （Hymenoptera：Eulophidae）, of which both attack larvae of the same agromyzid leafminers. These two species are both synovigenic, idiobiont parasitoids, whose adults consume host lfuids （“host feeding”） and lay anhydropic eggs. Of the two, D. isaea has a larger body but little or no initial egg load, and engages in similar lifetime host-feeding events. However, it achieves higher fecundity, longer adult longevity, and higher host suppression ability than N. formosa, which has a smaller body and higher initial egg load. Although D. isaea engages in similar lifetime host-feeding events with N. formosa, all of its gains in life history traits per host-feeding event of D. isaea were larger than those of N. formosa. The age-speciifc fecundity and host mortality curves of N. formosa were more skewed in early life than those of D. isaea. In addition, the ovigeny index of N. formosa was negatively correlated to body size. Our results conifrmed that two coexisting parasitoids, which share the same host resource, show different immature development patterns and life history traits, suggesting that different resource allocation mode could be a general rule of coexisting species sharing the same habitat or host.  相似文献   

针毛鼠种群年龄组的划分标准及其繁殖力     

杨再学  雷邦海  郑元利  杨通武  炳智 《贵州农业科学》2014,(10)

为丰富国内针毛鼠的种群生态学研究资料并为其预测预报提供科学依据,利用1984-2013年贵州省余庆县、岑巩县、凯里市和雷山县的稻田与旱地耕作区鼠情监测中捕获的针毛鼠数据,对其种群年龄组的划分标准及繁殖力进行研究。结果表明：针毛鼠平均体重为（70．12±23．60）g,根据体重的频次分布特征,参照其繁殖状况,将针毛鼠种群年龄划分为5个年龄组,制定了各年龄组的体重划分标准：幼年组（Ⅰ）体重≤35．0 g,亚成年组（Ⅱ）35．1～55．0 g,成年Ⅰ组（Ⅲ）55．1～75．0 g,成年Ⅱ组（Ⅳ）75．1～95．0 g,老年组（Ⅴ）＞95．0 g。不同年龄组形态特征具有一定变化,随着种群年龄的增长而不断增加。雌鼠怀孕率和胎仔数、雄鼠睾丸下降率和繁殖指数随着种群年龄的增长而增加。成年Ⅰ组、成年Ⅱ组和老年组为该鼠的主要繁殖群体。不同季节种群年龄组成变化明显。  相似文献