桑天牛幼虫空间分布型及抽样技术

桑天牛AprionagermariHope是桑树的重要害虫,成虫咬食桑枝和产卵为害;幼虫蛀茎为害,造成桑枝衰老、干枯、折断、甚至整株枯死,严重影响桑树生长和桑叶产量。为摸清此虫发生规律,1992年作者进行了幼虫田间分布型调查,并依此确定了适合的抽样技术。现将结果整理如下。l空间分布型l．l调查方法选择杂交桑田5块,面积7O3．sin‘,随机取点130个,每点20株,共查2600株,调查结果见表1。1．2空间分布型指数检验将以上调查结果,用扩散系数、k值、聚集指标、扩散型指数及南一7回归检验［’I。1．2．l扩散系数检验C的95％置信区间的检验如…     

陕北烟田多异瓢虫空间分布型与抽样技术研究

根据1995年烟田多异瓢虫Hippodamiavariegats（Goeze）调查,计算了6种分布型指数,以及频次拟合优度检验,结果表明：该虫幼虫、蛹在陕北烟田里聚集分布,其聚集强度随种群密度增加而降低,聚集原因是环境差异;卵块分布同时具有聚集和随机的趋势,成虫为随机分布。同时建立了各虫态的理论抽样量公式,估测种群密度公式。     

桃蛀螟幼虫在板栗上的空间分布型研究

通过对不同板栗园桃蛀螟Dichocrocis punctiferalis Guenee幼虫的调查,用昆虫分布型的4种常用理论公式分别进行配合适度的Х^2检验,再用6种空间分布型聚集度指标、Taylor幂法则及Iwao回归法对桃蛀螟幼虫的空间分布型进行测定。结果表明：桃蛀螟幼虫种群在板栗园中全部呈聚集分布,而且均符合负二项分布,其聚集原因是由该虫习性与环境因素共同造成的。此外,还利用了分布型参数确定了桃蛀螟幼虫的理论抽样数。     

豚草条纹萤叶甲各虫态的空间分布型

豚草条纹萤叶甲Ophraella communa LeSage是恶性入侵豚草(Ambrosia artemisiifolia L.)的天敌,用频次分布拟合和多种聚集指数测度等方法对该叶甲的成虫、幼虫和蛹、卵的空间分布型进行研究。结果表明,豚草条纹萤叶甲卵、幼虫+蛹、成虫的空间分布符合负二项分布,种群个体的空间分布为聚集分布。用几种衡量聚集度的指标,对上述各虫态分布的聚集程度进行测定;然后计算出各虫态田间最适理论抽样数。     

玉米田斜纹夜蛾空间分布型及抽样技术

对秋甜玉米田的斜纹夜蛾不同发生密度田块调查 ,取得了 7组样本资料 ,运用聚集度指标法、Iwao法和Taylor法等对其空间分布型进行测定检验 ,结果表明斜纹夜蛾幼虫呈聚集分布 ,其聚集原因经Blackith种群聚集均数测定 ,当m <3 .2 60 4时 ,其聚集是由于某些环境如气侯、土壤湿度、植株生长状况等所致 ;当m >3 .2 60 4时 ,其聚集是由于害虫本身的群集行为与环境条件综合影响所致。在此基础上 ,通过几种抽样方式比较以五点式为最佳 ,并提出了最佳理论抽样数和最佳序贯抽样模型 :N =1 D2 (3 .8981 m +0 .75 0 3 ) ,To(n) =0 .5n± 2 .865n。     

竹小蜂幼虫空间分布型及抽样技术研究

竹小蜂幼虫空间分布型属于负二项分布;聚集度各指标测定结果表明,幼虫是聚集分布;经测定M^*=6．2836 0．3028^ˉx,屑于聚集分布。并用刀切法和F偏离度检验法对M^*进行了估计和检验测定为聚集分布。中分析并计算了林间调查的理论抽样数和序贯抽样决策,为今后该虫林间调查与防治提供了科学的依据。     

苜蓿籽蜂幼虫空间分布型及抽样技术的研究

应用多个聚集度指标和Iwao、Taylor回归分析方法,对苜蓿籽蜂Bruchophagus roddi幼虫的空间分布型进行研究。结果表明其空间分布型为负二项分布,个体间相互排斥,其基本成分的空间分布格局为聚集分布,其聚集是由昆虫行为或环境条件引起的,聚集强度随着种群密度的升高而增加。应用 Iwao抽样模型建立了籽蜂幼虫的田间理论抽样数公式：N=(0.5833/m+2.3370)/D∧2。      

菜粉蝶幼虫田间分布型及其序贯抽样技术的研究

应用不同测算方法测得菜粉蝶4～5代卵、低龄幼虫(1～3龄)和高龄幼虫(4～5龄)的田间分布型属于聚集分布,主要适合于负二项分布。运用分布型的有关参数和中、晚熟甘蓝莲座期高龄幼虫的经济阈值(ET),设计了序贯抽样方案,以提高对该虫的测报水平和综合治理水平。     

萧氏松茎象幼虫的空间分布型和抽样技术

萧氏松茎象Hylobitelus xiaoi Zhang是我国近年来发现的危害松林的新害虫。该文利用1wao等7种方法对萧氏松茎象幼虫的空间分布型进行了测定。结果表明,萧氏松茎象幼虫在林间呈聚集分布,且符合负二项分布,由此得出了林间理论抽样数公式,其抽样方式以对角线最佳;其有虫株率与平均虫口密度之间的关系可用冥函数曲线方程：Y=2．916X^0.887来进行描述。     

棉田玉米螟卵的空间分布及抽样技术

本通过采用平均拥挤度的概念和聚集性指标。运用随机分布的偏离度假设测验。对玉米螟Ostrlnia funacalis(Guenee)在棉田的空间格局进行了系统的研究．以聚集度和格局纹理描述了卵的不同密度在棉田的分布变化过程及分布特征．得出江苏沿江．沿海棉区二代玉米螟在棉田内为聚集分布。服从Neyman A概型的核心分布;三代卵在百株25块以下的密度为随机分布。服从Poisson分布。而在高于百株25块的密度下则为聚集分布。并根据分布型计算出理论抽样和抽样单位大小．从获得的资料中建立了预测模式：二代：m↑^=1．2167[-ln(1-P)]^1.0173r=0．9966三代：m↑^=1.1263[-ln(1-P)]^1.2423r=0．9871用有卵样点率(P)简单估计田间卵的平均密度(m^)为研究测定棉花受害损失、决定防治策略和指标提供了依据。     

Estimating Relative Error in Nematode Numbers from Single Soil Samples Composed of Multiple Cores

Spatial distributions of several species of plant-parasitic nematodes were determined in each of three fallow vegetable fields and in smaller subunits of those fields. Goodness of fit to each of several theoretical distributions was tested hy means of a X² test. Distributions for most species showed good agreement with a negative binomial model. An exception occurred with Crictmemella sp., which showed a better fit to the Neyman Type A distribution. For nematodes distributed according to the negative binomial model, the number of cores per composite sample needed to achieve specified relative errors was calculated. For a given nematode species, such as Quinisulcius actus (Allen) Siddiqi or Meloidogyne incognita (Kofoid &White) Chitwood, the k values for the negative binomial distribution increased as field size decreased, with the result that fewer cores were needed to achieve the same level of precision in a smaller field. Best results were achieved when the single sample was used to estimate populations in fields of 0.25-0.45 ha in size. When using only a single composite sample to estimate mixed populations of the nematodes studied here in a field of that size, approximately 22 cores per composite sample would be needed to estimate all population means within a standard error to mean ratio of 25%. Considerably, more cores were needed to maintain a given level of precision in fields of 1.0 ha or greater, and it may be necessary to subdivide larger unils (ca. 1.5 ha and up) for accurate sampling.     

粘虫种群空间结构的探讨

研究昆虫种群的空间结构可分为下列三个层次,即田间集团分布,地理分布和猖獗区的分布。伊藤正春(1959)曾提出这三种空间结构层次与时间上的联系,即(1)世代内构成种群的个体在其栖息场所内的分布,称为Intra-generation range。(2)世代间种群的季节性生境转移所造成的水平分布及垂直分布,称为Generation range。(3)年代间种群猖獗的常发区或偶发区的地理分布,称为Inter-generation range。     

湘西油茶树群落中蛇足石杉种群的水平分布格局

采用方差,均值法、负二项参数K、Cassie指数、丛生指数、平均拥挤度、聚块性指数、Green指数、泊松分布、负二项分布及奈曼分布的X2理论拟合,研究了湘西油茶树群落中蛇足石杉种群的分布格局,结果表明湘西油茶树群落中蛇足石衫种群的分布格局类型呈集群分布,且符合n=1的奈曼分布,此格局的形成主要与其繁殖的生物学特性、特定的环境条件及共生真菌等因素密切相关．     

花生、大豆田蛴螬土内分布型与抽样调查

本项研究通过1981-1982两年的调查,查明暗黑、铜绿、黑绒、华北大黑四种蛴螬土内分布型除低密度情况以外,在各类型田内,均属负二项分布。调查蛴螬的抽样单位以0.2222米²为宜;在允许误差为0.2时,根据20块田的公共k值,算得在不同虫口密度下的适宜的样本容量。     

杨扇舟蛾卵和幼虫的空间分布型及抽样技术

研究了杨扇舟蛾Clostera anachoreta(Fabricius)卵和幼虫的空间分布型及抽样技术,结果表明杨扇舟蛾卵和幼虫在杨树林的分布型均为聚集型中的负二项分布。几种抽样方法中,卵以棋盘式最好,幼虫以平行线法最好。同时建立了杨扇舟蛾卵的下层抽样模型为y=2.4481x 0.4243;幼虫的中、下层抽样模型为y=2.4605x 3.9126。     

中华通草蛉卵、幼虫和成虫在麦田分布型的研究

研究了中华通草蛉卵、幼虫和成虫在麦田的分布型,均属聚集分布,分析提出适宜的取样调查方法,即双对象线或棋盘式10点,每点调查1m^2麦株。     

负二项分布与昆虫种群空间格局分析的研究现状

对农业有害生物及其天敌种群密度的正确估计是实施IPM(有害生物综合治理)方案的先决条件,因此,抽样方法一直被列为昆虫学,生态学和植物保护科学中最重要的基本     

Use of compound-probability distributions in the study of induced post-implantation dominant lethals

The nature of the probability distribution of post-implantation dominant lethality was investigated in terms of the distribution of dead implants per female. It has been postulated that this distribution would be poisson in a control series of females but may follow a compound or a contagious distribution such as the beta binomial, negative binomial or Neyman type A in the treated series of females. The nature of these compound distributions for fitting mammalian mutagenicity has been examined. The implications of the results on the estimation of induced mutation rates are discussed.     

Sampling for the sugarcane borer (Lepidoptera: Crambidae) on sugarcane in Louisiana.

A 3-yr study was conducted in 0.6- to 2.0-ha sugarcane fields throughout south Louisiana under varying sugarcane borer, Diatraea saccharalis (F.), density levels to determine the spatial dispersion of infestations and to develop a sequential sampling plan. Infestations of D. saccharalis were randomly dispersed. Infestation levels (percentage of stalks infested) ranged from 0.6 to 33.3%. Frequency distributions of the number of infested stalks indicated that the Poisson distribution best fit the data Tests of other distributions (negative binomial [aggregated], binomial [uniform], geometric, and hypergeometric) resulted in poorer fits. The sequential sampling plan devised, with lower and upper D. saccharalis infestation limits of 2 and 5% and 5 and 10%, required maximum average sample numbers of 7.1 and 5.5 (20-stalk samples), respectively, to make terminating management decisions. It is our assessment that implementation of these plans would decrease sampling effort by 50-60% when compared with sampling programs currently in use for D. saccharalis management decisions in Louisiana.     

Distribution of Polymorphus minutus among its intermediate hosts

Hirsch R. P. 1979. Distribution of Polymorphus minutus among its intermediate hosts. International journal for Parasitology10: 243–248. In 1971, Crofton investigated patterns of distribution of Polymorphus minutus in the intermediate host, Gammarus pulex. Among his conclusions were: (1) P. minutus populations occur in patterns similar to negative binomial distributions, and (2) parasite-induced host mortality results in patterns similar to truncated (high end) negative binomial distributions. Those conclusions, however, were not tested by statistical analyses. To test Crofton's observations, Chi-square goodness of fit tests were applied to data used by Crofton and an additional two stations sampled by Hynes & Nicholas in 1963. Analyses were expanded to include five theoretical distributions, four patterns of host mortality and various rates of host mortality. Truncated forms of negative binomial, positive binomial and Poisson distributions were also investigated where nontruncated distributions failed to fit observed distributions. It was found that negative binomial distributions most frequently describe patterns of P. minutus distribution with the exception of one population described by Poisson and another by positive binomial distributions. Crofton's assumption that truncated distributions result from parasite-induced host mortality seems unlikely in light of those analyses.