玉米螟赤眼蜂的寄生卵块在玉米上的田间分布型

玉米螟赤眼蜂是松辽平原玉米带寄生亚洲玉米螟卵的优势种。通过几年来的田间释放结果,取得优异的成效。通过对它在玉米田间的分布型研究,揭示了它在玉米田间第一代螟卵发生期间的分布规律,为以疏松的寄生卵块集团形式呈聚集分布;集团内寄生卵块的分布是随机的,无论在高密度时,还是在一般密度条件下,均为聚集分布型;它不受风向的影响。这一研究结果为它的田间释放和应用技术提供重要的科学依据。     

玉米田截形叶螨种群动态的研究

1999～2001年于内蒙古巴彦卓尔盟杭锦后旗研究了玉米田截形叶螨田间种群动态。结果表明．截形叶螨在玉米田的空间格局为聚集格局,随着叶螨种群密度的上升,其聚集强度下降应用最优分割法将玉米截形叶螨田间种群动态划分为5个阶段：①7月上旬前为种群初建期,叶螨在玉米田刚开始发生,种群数量很低,只分布在极少数植株上;②7月中旬为种群缓慢增长期,种群数量低,增长缓慢,聚集强度高;③从7月下旬至8月中旬为种群快速增长期,种群数量高,增长迅速,叶螨分布至全田,聚集强度下降;④8月下旬为种群高峰期,种群数量最高,聚集强度较低;⑤9月以后为玉米截形叶螨种群的衰落期,由于玉米受害严重及玉米进入生长后期,中下部叶片大部分均已枯死,上部叶片也已老化营养水平下降,加之气温下降,叶螨种群数量迅速下降。     

大螟在玉米田的空间格局及其抽样研究

<正> 大螟Sesamia inferens Walker是我区玉米生产上的主要害虫。春玉米常年受害在1—9.4％,最重达39.1％。第三代在秋玉米上的为害率达44.7—53.4％。为进一步了解其种群内部的行为习性与环境适应的程度和有效地控制其危害对大螟的卵,幼虫在玉米田的空间格局,个体群的大小,抽样等问题进行了研究。 一、方法 1979—1981年在青义选择麦冬间作,苕园     

玉米田蚜虫种群的空间动态

【目的】明确我国黄淮海地区玉米蚜虫种类及其空间分布,掌握玉米蚜虫田间发生规律。【方法】采用系统调查法于2009—2010年在河北廊坊对春玉米、夏玉米上玉米蚜虫种群的发生动态进行了研究。【结果】结果表明,该地区取食为害玉米的蚜虫有5种;玉米蚜Rhopalosiphum maidis(Fitch)和禾谷缢管蚜R.padi(L.)混合发生,为玉米田蚜虫的优势种群。【结论】几种蚜虫的混合种群在玉米田间的动态分布始终呈聚集分布;二项分布k和聚集型指标m~*/x判断表明,随着玉米的生长发育,玉米蚜虫表现扩散-聚集-再扩散-再聚集的趋势。     

黄淮海玉米田蓟马种群动态及其空间分布研究

为研究和分析黄淮海玉米区玉米蓟马种群动态,掌握其发生规律,同时为玉米田蓟马发生的预测预报及防治提供一定依据。在玉米田间蓟马发生时期采用5点取样,调查记录蓟马发生种类及数量,分析玉米田蓟马种群动态及空间分布型。结果表明玉米田间蓟马种类主要为黄呆蓟马Anaphothrips obscurus Müller、禾花蓟马Franklinielle tenuicornis Uzel和稻单管蓟马Haplothrips aculeatus Fabriecius;不同时期优势种不同,春玉米上禾花蓟马在苗期所占比例为67.8%,是玉米苗期蓟马优势种,为主要防治对象;6月下旬至7月上旬,黄呆蓟马和稻管单蓟马占总蓟马数比例为47.7%和42.7%,二者为优势种;7月中旬,稻单管蓟马所占为61.1%,为优势种,在夏玉米上有相似趋势。种群消长动态呈随时间上升到达高峰期然后下降的斜坡形,在春玉米上蓟马发生高峰在6月下旬,在夏玉米上发生高峰期在8月中旬。通过多种聚集度指标分析判定了玉米蓟马各时期田间分布型均属于一般负二项型聚集分布,其聚集原因是由蓟马生物学特性所致。     

向日葵螟幼虫的空间分布型及抽样技术

欧洲向日葵螟Homoeosoma nebulellum Denis et Schiffermüller是向日葵上的主要害虫,本文利用6种聚集指标对向日葵螟幼虫的空间分布型进行了测定,结果表明其呈现聚集分布。样本平均数(m)与方差(S2)的对数值的关系式为:lgS2=lg0.2130+0.5639lgm,显示向日葵螟幼虫的空间分布随密度的升高而趋向均匀分布。Iwao的m*-m回归方程为:m*=8.1177+0.1447m,显示该虫在田间分布的基本成分是个体群,个体间相互吸引,个体群的空间分布型为均匀分布。对聚集原因进行分析,得出λ<2,表明向日葵螟幼虫的聚集是由于环境作用所引起的。用Iwao的理论抽样数模型计算出向日葵螟幼虫的理论抽样数模型为:D=0.1时,n=911.77/m-85.53,D=0.2时,n=227.94/m-21.38。采用m*-m关系的序贯抽样模型制定出食葵田间的序贯抽样模型为:T1(n),T0(n)=7.40n±4.54n,油葵田间的序贯抽样模型为:T1(n),T0(n)=10.05n±2.29n。     

玉米心叶期玉米螟卵块的分布型及其在实践上的应用

根据1961—1964年对两个品种、19块春玉米地心叶期着卵量及着卵株率的调查资料,分析了:1)卵块在田间的分布型式,2)着卵株率与百株累计卵量的关系,3)百株高峰卵量与累计卵量的关系。 分析表明:心叶期卵块在田间的分布型式符合于随机分布,因此着卵株百分率与百株累计卵块数之间存在着正相关的关系。 着卵株率(p)与百株累计卵块数(x)间有 P=1-e^{-0.00985_x0.9984}的曲线函数关系。作者利用此式制成了一个由著卵株百分率来推算百株累计卵块数的检索表(表3)。 心叶期百株高峰卵块数(x)与百株累计卵块数(Y)之间则有直线回归的关系,以百株高峰卵块数估计百株累计卯块数的回归式为:Y=11.47+2.64x。 利用上述两种调查方法来估计心叶期的累计卵块数可以大大节省时间和人力。这两个方法在实用上各有其优缺点,可以根据具体情况任用一法。     

一种估算草地贪夜蛾卵块中卵粒数量的简易方法

草地贪夜蛾Spodoptera frugiperda (Smith)是2019年发现入侵我国的一种重要的外来害虫,对我国粮食种植业造成严重威胁。明确虫情是做好草地贪夜蛾预测预报和制定科学防控策略基础。在田间调查中需要一种简便、快速估计落卵量的方法,以明确田间虫口数量。本研究在实验室条件下收集草地贪夜蛾雌虫产于玉米叶片上的卵块,记录了每个卵块的长、宽、层数和卵粒数量,获得了卵块面积,建立了卵粒数量与卵块面积的指数函数模型：Y=e(2.1596×0.00832X),并依据该模型提出了根据卵块面积测算卵粒数量的分级表。该方法为田间调查中卵块卵粒数量量的快速估计提供了参考。     

两类不同玉米田蚜虫发生动态数学模型与空间分布型测定

蚜虫是我国各地玉米植株上的重要刺吸类害虫。为了进一步阐述该虫的发生与环境之间的关系,以及其在转基因抗性玉米上的空间分布,本文在田间系统调查蚜虫种群动态的基础上,使用多元回归分析法、Iwao回归分析法和5种常用指标参数法,探明了玉米田蚜虫发生与环境因素之间相关的数学模型,以及在常规玉米和抗性玉米植株上的空间分布。结果表明:江苏扬州地区两类不同玉米植株上发生的蚜虫以玉米蚜为主,玉米蚜虫的发生与当日最低气温关系最密切;玉米蚜虫在玉米植株上部的分布数量可达70%～80%,其全株玉米上的蚜量(y)与玉米植株上部1/3上的蚜量(x)关系为y=1.33x;玉米蚜虫在植株上的分布为聚集分布,其聚集由自身特性和环境因素共同确定。本研究为开展转基因玉米田蚜虫的测报防控提供了重要依据。     

三化螟卵块在本田分布规律的考察

在栽培治螟中,如何确定秧苗的安全移栽日期,适当调节水稻的发育速度;在药剂治螟中,如何正确期分防治对象田,做到重点挑治,集中消灭;其主要关键在于彻底摸清螟卵的田间分布规律。1963年,我们在本院农场选择了涂家(包括试验站)和北岗二个生产大队,对三化螟卵块田间分布情况进行系统调查(第一代     

吉林省二代区亚洲玉米螟危害趋势研究

【目的】明确吉林省二代区亚洲玉米螟Ostriniafurnacalis(Guenee)发生趋势,为亚洲玉米螟的早期防治提供理论依据。【方法】2002—2013年采用田间调查的方法对吉林省二代区亚洲玉米螟的田间落卵量及为害趋势进行研究,同时分析田间落卵和为害情况的关系。【结果】亚洲玉米螟1代卵始见期在6月14日左右,高峰期在6月25日左右,末期在7月15日左右;2代卵始见期在7月25日左右,高峰期在8月15日左右,末期在9月1日左右。1代落卵量呈整体下降趋势,2代落卵量呈整体增加趋势,两代之间微弱相关(r=-0.058,P=0.857)。百株虫孔数呈整体下降趋势,虫量和被害株率在年度间呈不规则波动,整体发生趋势12年间未发生明显变化。通过对亚洲玉米螟卵量和玉米受害情况进行相关分析和通径分析,表明亚洲玉米螟为害是两代共同作用的结果,1代落卵量对越冬虫量影响很小,秋季剖杆时玉米螟的越冬虫量主要由2代落卵量决定,但1代落卵量对秋季剖杆百株虫孔数和被害株率的贡献大于2代。【结论】1代玉米螟发生重,秋季收获时虫孔数较多;2代玉米螟发生重,秋季收获时虫量较大;玉米螟秋季剖杆百株虫孔数整体下降,但被害株率没有发生显著变化,说明2代玉米螟为害呈逐年加重趋势。     

Distribution of second generation European corn borer,Ostrinia nubilalis, egg masses in field corn and relationship to subsequent tunneling damage

The relationship between second generation European corn borer (Ostrinia nubilalis Hübner) egg mass numbers and subsequent field corn damage, as measured by stalk cavity numbers, was studied in 79 fields in northeastern North Carolina over three years. A mean of 0.028 egg masses per plant (645 egg masses/23400 plants) was found over the course of the study. Significant differences in oviposition rate were detected between fields and years. Ca. 85% of egg masses were deposited in a five leaf zone surrounding the primary ear; of these, 89% were found on the lower four leaves in this zone. Egg masses appeared to be distributed randomly within fields but at low rates of incidence, and oviposition was relatively uniform between sampling areas within individual fields. Under moderate to high oviposition pressure (mean number of egg masses per plant over the duration of the oviposition period >ca. 0.02), eggs laid during the early phases of the oviposition period account for more subsequent stalk damage than eggs laid during the later phases of the oviposition period. Variations in second generation egg mass numbers accounted for ca. 70% of variation in stalk cavity numbers.     

Importance of plant size, distribution of egg masses, and weather conditions on egg parasitism of the European corn borer, Ostrinia nubilalis by Trichogramma ostriniae in sweet corn

Trichogramma ostriniae (Hym: Trichogrammatidae), an egg parasitoid of the European corn borer, Ostrinia nubilalis (Lep: Pyralidae), were released into sweet corn (Zea mays L.) fields to study the effects of weather, plant size and distribution of egg masses on egg parasitism by the wasp. Sentinel European corn borer eggs were stapled onto leaves located in the upper, middle and lower third of sweet corn plants 5 to 35 meters away from the wasp release point in either a radial or grid manner. Weather conditions and plant architecture were monitored during the experiments. Logistic regression was used to analyze the data. The results indicated that percentage of eggs parasitized was negatively related to an increase in leaf area as well as an increase in distance eggs were located from the point of release of wasps. Eggs distributed on plants at different directions from the release point received different levels of parasitism. Eggs that were stapled onto leaves in the upper third of a corn plant received much less parasitism than those on the middle and lower third of the plant. Higher mean temperature adversely affected the level of parasitism during hotter times of the season and conversely, lower temperatures (<17 °C ) reduced the egg parasitism during cooler times of the season. The longer the exposure of eggs to wasps, the higher the level of egg parasitism. However, the levels of egg parasitism for 2 day's exposure were almost the same as that for 3 day's exposure due to the limited longevity and egg-laying behavior of the wasp. These results suggest that inundative releases of T. ostriniae should be made every two to three days, with multiple release points per hectare. In addition, weather conditions and plant architecture, especially temperature, plant height and leaf area must be taken into consideration to optimize levels of parasitism.     

苜蓿叶象甲卵块在苜蓿植株上垂直分布的研究

苜蓿叶象甲卵块分布在苜蓿植株层次之间,差异显著;在不同田块之间,差异不显著。分布区间随着生育期的变化而变化,在分枝期,主要集中在0～20cm,区间估计为[0．6524,0．7876];在开花期,主要在0～60cm,区间估计为[0．8427,1．000]。苜蓿叶象甲每个卵块的卵粒平均数为8．4粒,卵块与卵粒数存在着显著的线性关系：y＝0．0069＋8．6594xr＝0．8422**     

Distribution and mortality of corn earworm (<Emphasis Type="Italic">Helicoverpa armigera</Emphasis>, Lepidoptera,Noctuidae) on maize plants in Krasnodar Territory

The three-year periodic surveys of maize fields in Krasnodar Territory showed the upper side of the leaf blades to be the most attractive place for Helicoverpa armigera Hbn. oviposition during the vegetative phase. After flowering, the downy part of leaf sheaths and stalks became more preferable for egg laying (43–50%). Egg mortality varied from 23 to 55%, both its level and the factors responsible for it depending on the insect generation. The probability of egg death also depended on its location on the host plants. An express examination of maize plants (omitting the leaves) may result in biased estimates of the density and mortality of corn earworm eggs.     

Dispersal of Trichogramma ostriniae in field corn

Trichogramma ostriniae has shown success as a biological control agent for European corn borer (Ostrinia nubilalis) in sweet corn and the species offers potential for suppression of lepidopteran pests of field corn. Field corn is typically planted at higher densities, is taller, and has greater leaf area than sweet corn, presenting a possible restriction on T. ostriniae dispersal and efficacy. Therefore, parasitoid dispersal in field corn from the centre of a 6.25 ha square grid was determined using sticky cards to capture adult T. ostriniae and sentinel eggs of O. nubilalis to monitor parasitism after releases of ~1 million of T. ostriniae each into four fields of corn. Dispersal was rapid and extensive, achieving distances of ~175 m within 4–7 days after release. The pattern of movement fit well with a diffusion model of dispersal, with the greatest level of dispersal occurring from 7 to 10 days post-release. Parasitism of O. nubilalis sentinel egg masses declined linearly with distance from the release foci, and was also greatest 7–10 days post-release. However, measurement of association showed no significant differences between the spatial distributions of sticky trap captures and percentage parasitism of O. nubilalis egg masses. The distances from the release point that encompassed 98% of re-captured T. ostriniae increased over time and were estimated to range from a low of 100 m at 4 days post-release to 365 m at 14 days post-release. The results of this research suggest that T. ostriniae relies initially on random movement to locate host patches, and that a single release locus per hectare would be sufficient in field corn.     

烟草潜叶蛾幼虫空间分布型及其应用研究

本文就烟草潜叶蛾幼虫空间分布型及其垂直分布规律进行了探讨,结果表明：烟草潜叶蛾幼虫在田间呈聚集分布,聚集强度不因种群密度的改变而改变,幼虫主要聚集分布在烟草下部第一段（4片叶）上;降集或随机分布在第二段上;随机分布在第三段上,此外,应用虫株率进行田间种群密度的估计,其中Wilson模型和Gerrard模型所配理论曲线的预测值与实测值显著适合,但Gerrard模型的抽样估计误差较Wilson模型的小,最后本文用Taylor式中的参数a,b确定理论抽样数及序贯抽样,其模型分别为。     

Quantification of diapausing fourth generation and suicidal fifth generation cotton bollworm, Helicoverpa armigera, in cotton and corn in northern China

Cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), is a major pest of cotton and corn crops in northern China. A phenological differentiation between fourth generation cotton bollworms from cotton and those from corn fields was observed in northern China during 1999–2000. The proportion of pupation in late fall was marginally higher in cotton fields compared to that in corn fields; however, the proportions of fall emergence of moths from cotton fields were significantly higher than those from corn fields. The proportion of spring emergence of moths was also significantly higher for larvae collected from cotton (28.0%) than from corn (14.5%). The overwintering duration of females was significantly shorter than that of males in both crops. Moreover, the overwintering duration of bollworm populations from cotton was significantly longer than that from corn. The early spring population of H. armigera came from both cotton and corn fields, but the spring emergence of moths from larvae collected from cotton took about 5 days longer to reach 100% emergence compared to that from corn.     

Influence of the egg parasitoidPlatytelenomus busseolae [Hym.: Scelionidae] on the population ofSesamia nonagrioides [Lep.: Noctuidae] in central greece

The egg parasitoid,Platytelenomus busseolae (Gahan) (Hymenoptera: Scelionidae) was recorded from egg masses of the corn stalk borer,Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae) on maize in the area of Istiaea, Central Greece. Natural parasitism was studied during the years 1986, 1987. A total of 3,382 egg masses, containing 205,227 eggs, was collected from corn fields. Parasitized eggs were found from end July to mid-October. In 1986. 76.2% of the egg masses and 42.8% of all eggs were parasitized, while in 1987, respective values were 27.6% and 12.9%. The inferior performance of the parasitoid in 1987 may be due to the unfavorable winter and summer conditions. Parasitism decreased when the host population was at its peak, but it increased again within 1 to 3 weeks. A small percentage of egg masses was completely parasitized (9.5% and 4.7% for the 2 years respectively). In 1987, the sex ratio, ♀♀/♂♂ was 1.5: 1 and 26.2% of the egg masses produced only ♂♂. Mated ♀♀ produced 3 times more ♀♀ than ♂♂. It seems that the parasitoid, under favorable weather conditions, can play a significant role in the control of the corn stalk borer.