氮肥对棉田主要害虫种群密度及棉花产量的影响

通过2年的田间研究,分析了3种不同施氮水平对棉花主要害虫棉玲虫、棉蚜种群动态、棉花蕾铃脱落及棉花产量的影响。结果表明,增施氮肥的棉田棉铃虫和棉蚜数量比对照田要高,但它们之间的差异没有达到显著的水平。不同年份对棉铃虫种群密度有显著影响,但对棉蚜种群没有显著影响。蕾花期施肥可减轻棉铃虫为害造成的花蕾脱落和自然脱落,增加有效铃数和产量,但增加量没有达到显著水平。     

浇水与施氮肥对烟粉虱成虫趋性的影响

[目的]探讨土壤浇水与施氮肥对烟粉虱Bemisia tabaci成虫趋性的影响,为通过调节水肥控制烟粉虱种群数量提供理论依据。[方法]设置250、500、750、1 000 mL/盆4个浇水处理和0、0.23、0.46、0.92 g/kg 4个氮肥浓度处理,测定棉花上烟粉虱的成虫数量和叶片含水量。[结果](1)浇水、施氮肥以及两者交互作用对烟粉虱趋性都有显著影响;(2)浇水1 000 mL和施肥0.92 g/kg处理的烟粉虱数量最多(202头/株);(3)经赋值排序后,浇水量对烟粉虱趋性顺序为1 000 mL750 mL500 mL250 mL;施氮肥对烟粉虱趋性顺序为0.23 g/kg0.92 g/kg0.46 g/kg0 g/kg;(4)叶片含水量与浇水量、施氮量呈正相关,烟粉虱数量与浇水、施氮肥呈正相关,与叶片含水量呈正相关。[结论]浇水和施氮肥会加重烟粉虱的发生,要通过合理的水肥管理措施,控制烟粉虱的危害。     

各种天敌对棉蚜种群数量影响程度的研究

通过对１９８３、１９８４、１９８６、１９８８、１９９４和１９９５年６年棉花铃期以前棉蚜种群数量及其天敌种群数量的系统调查,并采用灰色关联分析法,研究各种天敌对棉蚜种群数量影响程度,得出龟纹瓢虫对棉蚜种群数量影响最大,其次是瓢虫类,第三是蜘蛛类．     

棉蚜在棉株上数量动态的初步研究

棉蚜(Aphis gossypii)是棉花苗期至花铃前期的主要害虫之一。长期以来,由于大量使用化学药物,其抗药性不断增加。为了掌握棉蚜种群数量消长的一般规律,给寻找其他有效的防治方法提供依据,本文对棉蚜实验种群的数量动态与其宿主棉株的关系进行了初步探讨。现将结果报道如下。     

不同沟灌方式棉花的水氮耦合效应

研究了交替隔沟灌溉（AFI）、常规沟灌（CFI）、固定隔沟灌溉（FFI)下棉花的水氮耦合效应,施氮量和灌水量采用二次通用旋转组合设计,进行大田小区沟灌试验.结果表明：在施氮量56.2～95.2 kg N·hm^-2范围内,棉花产量与施氮量呈显著正相关,在施氮量95.2～134.2 kg N·hm^-2范围内变化不明显;在灌水量37.52～160.00 mm范围内,棉花产量与灌水量呈显著正相关,在灌水量160.00～218.48 mm范围内变化不明显;不同施氮量和灌水量情况下,AFI与CFI的产量差异不显著,CFI平均比FFI高9.15%.在56.2～122.8 kg N·hm^-2范围内,棉花水分利用效率(WUE)与施氮量呈显著正相关,在122.8～134.2 kg N·hm^-2范围内变化不明显;在灌水量37.52～160.00 mm范围内,棉花WUE与灌水量呈显著负相关,在灌水量160.00～218.48 mm范围内,棉花WUE无明显变化;不同施氮量和灌水量情况下,CFI与AFI的WUE差异不显著,CFI平均比FFI高9.01%.施氮量56.2～134.2 kg N·hm^-2范围内,棉花氮素利用效率(NUE)与施氮量呈显著负相关;在灌水量37.52～160.00 mm范围内,棉花NUE与灌水量呈显著正相关,在160.00～218.48 mm范围内变化明显;不同施氮量和灌水量情况下,AFI与CFI的NUE差异不显著,FFI则平均比CFI低6.34%.根据大田沟灌棉花的水氮耦合效应,以棉花产量、WUE、NUE的优化管理为目标,提出了不同沟灌方式水氮高效利用策略.     

蕾铃期繁殖器官的损失对棉花产量的影响——人工模拟为害试验

1994、1995连续两年在华北棉区第3代棉铃虫发生期间,通过一系列人工摘蕾模拟为害和人工接虫为害试验,研究了棉花对蕾铃期繁殖器官损失的补偿效应。试验结果表明：蕾、铃被害会诱导棉株产生补偿效应,即提高结铃数,增加生物产量。但棉花的补偿效应是有限的,蕾铃期单株被害蕾超过12个,被害铃超过4个,或被害超过2蕾2铃,都会导致皮棉显著减产。通过数学模型分析,1994年,单株被害0-11．80个蕾或0—2．26个铃都不会造成减产;1995年．单株损失0—10．58个蕾或0—3．8个铃,同样不会降低棉花产量。模型中各决策变量的边际产量表明,棉花蕾铃期铃的损失对皮棉产量的影响最大。     

氮、钾营养对烤烟产量、产值和优质烟叶比例的影响

通过田间小区试验,研究氮素和钾素对烤烟产量、产值及优质烟叶(中上等烟叶)比例的影响,结果表明：(1)烤烟产量与施钾肥量具有显著正相关,并与施氮肥量有关;(2)产值与施氮肥量呈显著二次曲线相关性;(3)中上等烟比例与施肥比例(N／K)呈显著负相关,与施钾量、烟叶含钾量、土壤供钾能力有关。试验区烤烟优质、适产,要求施氮量(N)105一l12．8kg／hm2,施钾量(K)217．95—261．45kg／hm2,施肥比例(N／K比)0．40—0．48(N：K＝1：2．1—2．50或N：K2O＝1：2．5—3．0)。     

棉田绿盲蝽种群密度的调查方法

本文比较研究了棉田绿盲蝽Apolygus lucorum(Meyer-Dür)种群的调查方法。全株调查法中,目测法调查到的绿盲蝽种群密度最高,显著高于扫网法和盆拍法。局部调查法发现,蕾上的绿盲蝽种群数量显著高于叶片和花上;蕾上种群数量与整株密度之间呈显著正相关关系(y=1.18 x+3.69)。间接调查法表明:在苗期和蕾期,叶片受害等级和绿盲蝽种群密度之间呈显著正相关关系(苗期:y=25.28 x+8.20;蕾期:y=43.99 x+27.58)。     

Sampling techniques for estimating the population density of Apolygus lucorum in cotton fields

本文比较研究了棉田绿盲蝽Apolygus lucorum(Meyer-Dür)种群的调查方法.全株调查法中,目测法调查到的绿盲蝽种群密度最高,显著高于扫网法和盆拍法.局部调查法发现,蕾上的绿盲蝽种群数量显著高于叶片和花上;蕾上种群数量与整株密度之间呈显著正相关关系(y=1.18x+3.69).间接调查法表明:在苗期和蕾期,叶片受害等级和绿盲蝽种群密度之间呈显著正相关关系(苗期:y=25.28x+8.20;蕾期:y=43.99x+27.58).     

棉花蕾花铃生物量、氮累积特征及临界氮浓度稀释模型

在大田栽培条件下，于河南安阳（黄河流域黄淮棉区）和江苏南京（长江流域下游棉区）设置了棉花氮素水平试验，对不同氮素水平条件下棉花蕾花铃的生物量、氮素累积及氮浓度的动态变化进行分析，并依据Justes的临界氮浓度稀释模型确定方法，研究棉花蕾花铃临界氮浓度稀释模型。结果表明：棉花蕾花铃的生物量增长和氮吸收累积均受氮素水平的影响，其动态变化符合S型曲线，氮累积的快速起始时间较生物量早1～5d；氮浓度过高或过低均不利于产量形成，蕾花铃等器官存在氮奢侈消费现象；氮浓度随施氮量的增加而升高、随生育进程的推移而降低，其生物量累积量与氮浓度间符合幂函数关系，两试点蕾花铃氮稀释曲线模型形式相同，但模型参数a不同，不同生态区存在独立的临界氮稀释曲线模型。由于临界稀释模型具有明确的生物学意义，可以作为定量诊断蕾花铃氮营养动态变化的指标之一。     

棉蚜种群动态预报模型

对1980-1989年河南棉区棉蚜种群动态分析表明,棉蚜为害可分为苗蚜和伏蚜两个时期,根据环境因子(气温、相对湿度、降雨量)和不同危害期,建立了2个模糊预报模型,并取得了较满意的预测效果。     

棉蚜种群动态预报模型

对１９８０—１９８９年河南棉区棉蚜种群动态分析表明,棉蚜为害可分为苗蚜和伏蚜两个时期,根据环境因子（气温、相对湿度、降雨量）和不同危害期,建立了２个模糊预报模型,并取得了较满意的预测效果．     

棉田烟粉虱种群的空间格局

在转Bt基因棉花（国抗22号）和对应的常规亲本棉（泗棉3号）棉田中对烟粉虱的垂直分布和水平分布格局进行了调查.结果表明,7月份烟粉虱成虫在棉株垂直方向上分层不明显;8月份以后,棉株上层虫口密度显著高于中层和下层.在水平分布上,烟粉虱成虫和若虫的空间格局基本相同,种群密度较低时呈均匀分布,较高时呈聚集分布,且种群密度越高,聚集强度越大.从整个发生期间看,烟粉虱成虫和若虫都处于扩散和聚集交替进行的动态过程中.国抗22号和泗棉3号棉田烟粉虱的空间格局基本一致.     

不同类型品种棉花上棉蚜适生性及种群动态

通过田间调查、室内网罩盆栽苗测定选择性等方法,考察了常规棉（泗棉3号,石远321）、杂交抗虫棉（辽棉19号,鲁棉研18号）、转单价基因抗虫棉（国抗12号,中棉所32）和转双价抗虫棉（SGK321,中棉所41）4种类型8个品种棉花上棉蚜的适生性及种群动态。结果表明： 棉蚜在各棉花品种上的种群动态有明显差异（P<0.05）,单株蚜量以转单价基因抗虫棉中棉32上最高,常规棉泗棉3号上最低,分别为297.81头/株和76.88头/株。棉蚜对4种类型棉花品种的选择性有明显差异（P<0.05）,其中对转单价基因抗虫棉有很强的选择性。根据棉蚜实验种群的参数判断,其在不同品种棉花上的生长发育、存活及繁殖存在显著差异： 若虫发育历期常规棉石远321上最长（6.46天）,双价棉中棉所41上最短（5.75天）; 存活率转单价基因抗虫棉中棉32上最高（88.21%）,双价棉SGK321上最低（76.46%）; 单雌产蚜量杂交抗虫棉辽棉19上最大（44.48头）,双价棉SGK321上最小（33.51头）; 内禀增长率转单价基因抗虫棉中棉32上最高（0.3695）,双价棉中棉所41上最低（0.3389）。综合评价,棉蚜的生存和繁殖适合性在转单价基因抗虫棉上最高,在双价棉上最低。     

Species composition and population dynamics of some arthropod pests in cotton fields of irrigated and semi-arid regions of Punjab,Pakistan

The present study aimed to record seasonal dynamics and diversity of different insect pests in cotton agroecosystems. Two well-known cotton growing districts i.e. district Layyah and Vehari were selected for the study from the cotton belt of Punjab, Pakistan. Sampling was done bi-weekly for two consecutive years from July to October during 2018 and 2019. Sweep netting, visual counting, hand picking, wet finger method, beat sheets, aspirator and pitfall trapping methods were used for collection. Shannon-Wiener and Simpson indices were used to compute diversity while Menhinick and Margalef indices were used for the estimation of species richness. A total of 94,343 individuals representing 43 species, 40 genera, 28 families and 6 orders were recorded. Family Aleyrodidae dominated over other pest families. Bemisia tabaci (Gennadius, 1889) of family Aleyrodidae was the dominant species with 39.68% share among all pest species. Estimated species richness of all arthropod pest species belonging to both districts were about 94%. The densities of pests fluctuated with time. The peaks of sucking pest densities were observed in July and August while densities of chewing pests peaked in late September or early October each year. Population densities of jassids Amrasca biguttula (Ishida), armyworm Spodoptera litura (Fabricius), and pink bollworm Pectinophora gossypiella (Saunders), showed strong negative correlation with temperature, humidity and rainfall while thrips population density showed positive correlation with these parameters. Minor loss due to pests are acceptable everywhere, but it is only possible when their populations remain below their economic threshold levels. Present study will aid to design pest management strategies in cotton growing areas round the globe.     

播种时间对棉田害虫和天敌种群的影响

通过对3种不同时间播种的棉田内害虫、天敌系统调查,分析和比较了播种时间对棉田害虫、天敌种群和群落的影响。结果表明,播种期推后,可减轻或避免第二代棉铃虫的为害,加重第三代和第四代棉铃虫的为害;但不同播种日期对不同时期的棉蚜影响不同,苗蚜以迟播棉田内种群数量最高,伏蚜则以夏播棉田内种群数量最高。播种期的推后,不利于棉田捕食性瓢虫、蝽类、蜘蛛和寄生性天敌种群增长。棉田害虫和天敌群落多样性指数也随播种期的推后而下降．因此．应针对不同时间播种的棉田开展相应的害虫生态管理。     

Characteristics of three cotton varieties and their impact on feeding and growth of cotton armyworm

This study investigated morphological and biochemical characteristics of CB9, CB10 and SR05 cotton varieties and observed their effect on feeding and growth of cotton armyworm Spodoptera litura. Morphological characters of plant architecture, branching, color, hairiness, trichome density and boll size indicated that CB9 is a bushy, well developed, branched, light bronze colored and hairy variety with number of trichomes 193/cm² and boll weight 5.5–6.0 g/boll. Both CB9 and CB10 bear normal leaves and spherical bolls whereas SR05 has well‐ventilated branching, okra shaped and ventrally arranged light bronze colored leaves and oval bolls ranging 4.0–4.5 g/boll. Biochemical analysis indicated significant differences in starch and protein contents, which range 11.4–21.3 and 17.5–30.6%, respectively. The lowest percentages of starch and protein were found in SR05 and CB9, respectively. Cotton varieties showed significant effects on second, third, fourth and fifth instar larval weight and they attained the highest weights (22.7, 133.8, 168.2 and 1190.2 mg, respectively) when fed SR05. Larvae and moths fed SR05 also showed the significantly highest cocoon, exuviae, and adult male and female weights (434.5, 19.2, 161.3 and 232.4 mg, respectively). The cotton armyworm showed the significantly highest growth index (1.5) as well as lowest feeding index (0.05) on SR05. Results of this study indicated that SR05 is suitable for larval feeding and development, and suggest that this variety is least suitable for cotton growers in areas where S. litura is a major pest.     

胚轴切断法诱导棉株对棉铃虫生长发育的影响

通过室内饲喂棉铃虫的方法,测定了诱导棉株对棉铃虫幼虫发育历期、幼虫体重和肾重的影响。结果表明,不加菌处理和加菌处理的诱导抗性棉株可分别使棉铃虫幼虫发育历期延长０．５和３ｄ,幼虫体重（５龄）降低１１．４５％和１９．６０％,蛹重降低６．５４％和１０．８１％。用诱导棉株叶片饲养８日龄棉铃虫幼虫３天后,菌诱导和无菌诱导分别使棉铃虫的相对生长率降低２２．９％和１７．２％,相对取食量降低２６．１％和２１．４％     

Species composition,seasonal abundance and population dynamics of predatory spiders from cotton field plots of irrigated and semi-arid regions of Punjab,Pakistan

The purpose of the current study was to document the variety of predatory spider species present in the cotton fields of two major cotton-producing districts in Punjab, Pakistan, as well as the population dynamics of those spiders. The research was carried out between May and October 2018 and 2019. Manual picking, visual counting, pitfall traps, and sweep netting were the procedures used to collect samples on a biweekly basis. A total of 10,684 spiders comprising 39 species, 28 genera, and 12 families were documented. Araneidae and Lycosidae families contributed a major share to the overall catch of spiders, accounting for 58.55 percent of the total. The Araneidae family's Neoscona theisi ) was the most dominating species, accounting for 12.80% of the total catch and being the dominant species. The estimated spider species diversity was 95%. Their densities were changed over time in the study, but they were highest in the second half of September and the first half of October of both years. The cluster analysis distinguished the two districts and the sites chosen. There was a relationship between humidity and rainfall and the active density of spiders; however, this association was not statistically significant. It is possible to increase the population of spiders in an area by reducing the number of activities detrimental to spiders and other useful arachnids. Spiders are considered effective agents of biological control throughout the world. The findings of the current study will help in the formulation of pest management techniques that can be implemented in cotton growing regions all over the world.