二代棉铃虫为害玉米、大豆严重

1992年棉铃虫在我市大发生,一类棉田一般百株累计卵、虫量1500—2000粒(头),高的达5000粒(头)以上,不仅为害棉花而且为害夏玉米、夏大豆等作物。笔者7月1-3日在丰县、铜山县等县调查,玉米百株平均有虫98.5头,受害株率90.4％。大豆百株平均有虫95.6头,受害株率88.7％。受害严重田     

二化螟枯心丛率及含虫量关系测定简报

二化螟为稻区主要害虫,其枯心率与含虫量是检验螟害程度、防治质量、以及预测预报的重要依据。按常规方法检查枯心率和虫口密度,需逐丛逐株观察和剥查,工作量极大。为简化调查方法,提高工作效率,现将1975年以来调查的有关资料,经过枯心丛率与其枯心株率、枯心株率与其含虫量的相关回归分析,由枯心丛率推算其枯心株率,再由枯心株率推算其含虫量。经过大田试用,效果较好。 一、枯心丛率与枯心株率的关系 经10丘稻田(每丘0.5分,5,308丛枯心丛率与枯心株率的全群查算,测得枯心丛率     

螟害丛率与株率关系及其应用

稻螟危害的枯心或白穗(含死孕穗、虫伤株、下同)率是检验螟害程度和防治质量的依据。螟害率按常规方法需要逐丛、株地调查,工作量即大且烦锁。为了简化调查方法,提高工作效率,现将1975年以来,调查大量资料,经过螟害丛率与株率的相关性测定,然后拟订螟害丛率推算其株率田间应用表,整理于后,供生产实践上参考。一、二、三化螟造成枯心丛率与株率关系经24丘稻田螟害丛、株的全群查算,并列成相关计算表进行检验(表1)。     

甘兰夜蛾暴发为害桑树

甘兰夜蛾在四川垫江县于70年代曾暴发一次。1990年冬气候偏暖有利越冬,加之1991年春季4—5月间降雨偏少,各种作物生长繁茂,食料丰富,至5月下旬,甘兰夜蛾再度暴发。不仅甘兰、四季豆、莴苣、茄子、海椒、玉米、红苕、豌豆、黄豆等作物受害较重,而且严重危害桑树。其中有200余亩桑苗遭受不同程度的危害,平均单株有虫1.7头,受害株率达60—70%;有10余亩桑苗床幼苗受害,重者幼苗被咬断60%以上;有100余亩投产成年桑树亦受害,重者平均每株有虫46.6%,叶片大部     

黑蚱蝉为害苹果树严重

蝉 [黑蚱(Cryptotympana atrata Fabricius)]是果林生产上的害虫,除以成、若虫吸食树液外,主要是成虫以产卵器撬破枝梢产卵,使枝梢开裂枯死,或易被风折断。1988年7月下旬调查,苹果园受害率占95％,受害株率75.8％,1989年7月下旬至8月上旬调查,果园100％受害;受害株率98.5％;受     

棉红蜘蛛为害对棉花生长发育和产量的影响及其防治指标的研究

作者从1978—1983年对棉红蜘蛛的为害进行研究。结果表明,棉花苗期受害后,棉株高度降低,果枝数和青铃数减少。蕾铃期受害后,青铃数明显减少。棉株受害后影响产量。为害指数(x)与减产率(y)的关系式为:苗期y=10.40x±1.21(0≤x≤2.36),蕾铃期y=12.53x±1.5(0≤x≤2.5)。在田间调查时,可根据红斑株率(n)与红斑株平均为害指数(m)的关系式m=0.2165+0.00889n±0.14推算出减产率。利用y=10.40x±1.21,y=12.53x±1.5和m=0.2165+0.00889n±0.14,结合当地棉花的生产水平,可确定以红斑株率表示的防治指标。红斑株率易于调查和推广应用。     

不同夏玉米品种穗部主要害虫发生现状调查

在夏玉米穗期,对16个不同品种雌穗上棉铃虫、玉米螟、桃蛀螟发生情况进行了调查。结果显示,河北馆陶夏玉米穗部害虫棉铃虫、玉米螟、桃蛀螟混合发生,不同品种间虫量水平差异显著。各品种平均百株虫量,以桃蛀螟最高,达38.7头/百株;玉米螟次之,为16.0头/百株;棉铃虫最低,为5.6头/百株。各品种平均百株总虫量60.3头/百株。其中,总虫量最高的品种为北承190,高达195.6头/百株;同时,万盛69、郑单958、登海710品种的平均百株总虫量低于13.3头/百株,存在某种程度的抗虫性。不同品种受害穗率和粒腐穗率不同,平均受害穗率83.3%,最高100%,,平均粒腐穗率33.7%,最高74.4%;受害穗率与粒腐穗率变化趋势一致,较高的受害穗率引起玉米粒腐、穗腐的发生。     

新疆额敏县山杨楔天牛发生与为害调查

山杨楔天牛(Saperda carcharias)在新疆额敏县主要为害杨树,2年发生1代。对山杨楔天牛在额敏县的生活史及为害情况进行了调查,研究了山杨楔天牛的为害程度与受害树冠幅的关系,以及山杨楔天牛在树干上的垂直分布与水平分布规律。结果表明,山杨楔天牛在额敏县主要为害山杨、北京杨和苦杨,树木受害率达85%以上。生长季节可见山杨楔天牛的不同虫态,世代交替现象明显。山杨楔天牛在受害树上的株虫孔数量与树冠的垂直投影面积呈二次曲线关系。在寄主树上主要分布于树干下部0～3m的范围内,在树干不同水平方向上的分布差异不明显。初步提出了山杨楔天牛的防治策略。     

油桐尺蠖为害园林树木严重

油桐尺蠖是湖南油桐林一大食叶害虫。1991年以来,在株洲、长沙等地的园林内逐渐蔓延成灾。据调查,1991年株洲市石峰公园发生油桐尺蠖450亩,其中严重受害150亩;1992年发展到2350亩,其中严重受害1300亩,死亡树木150亩。受害的树木种类有樟树、檫木、白玉兰、法国梧桐等35种,仅洋玉兰、水竹、紫竹没有受害。被害树木叶片残缺不齐,严重影响环境美观。 1992年7月上旬,在石峰公园随机取样300株树木,在树菊1.5米范围内挖蛹调查。有蛹株率为95.8％,蛹密度平均每株79.6     

美国白蛾在西安市南郊发生为害

美国白蛾1984年传入陕西武功县后,经过几年的防治,取得不少成效。但1989年8月上旬,美国白蛾又在两安市南郊的陕西师范大学校园内发现,树木受害率达19.7%,受害树种有法桐、泡桐、白腊、杨树和椿树等,其中以白腊树受害最普遍,受害株率达66.7%,法桐次之,为31.8%。与该校仅一墙之隔的西安外国语学院和西安化工学校也发     

Characterization of brown planthopper damage on rice crops through hyperspectral remote sensing under field conditions

Field experiments were conducted to characterize the brown planthopper (BPH) (Nilaparvata lugens (Stål.) damage stress on rice crops through hyperspectral remote sensing. The BPH-damaged rice crop had higher reflectance in visible (VIS) and lower reflectance in near-infrared regions (NIR) of the electromagnetic spectrum compared with uninfested plants. Mean reflectance of the rice crop varied among different BPH damage levels in various wavebands, with the greatest variation in NIR (740–925 nm). Correlations between plant reflectance and BPH damage depicted four sensitive wavelengths, at 764, 961, 1201 and 1664 nm in relation to BPH stress on the rice crop. Three new brown planthopper spectral indices (BPHI) were formulated by combining two or more of these sensitive wavelengths. Some of the hyperspectral indices reported in the literature were also tested for their suitability to detect BPH stress on rice crops. Based on crop reflectance corresponding to the sensitive wavelengths, a multiple-linear regression model was developed (R²=0.71, RMSE=1.74, P<0.0001) and validated (R²=0.73, RMSE?=?0.71, P<0.0001) that would help to monitor BPH stress on a rice crop and to issue forewarnings to growers.     

Some effects of single and split applications of carbofuran on the incidence of and damage by Locris Maculata,Busseola Fusca and Sesamia Calamistis on maize

Abstract

Studies have been carried out on the efficacy of carbofuran (Furadan 5G) in reducing the incidence of the major insect pests of maize in Nigeria. A single dose of 1.5 kg a.i./ha applied in the planting hole was found to reduce the incidence of spittle bug (Locris Maculata F.) and stem borers (Busseola fusca (Fuller) and Sesamia calamistis (Hmps.)) when compared with split applications of the same dose applied at planting and 40 days after planting. The number of damaged plants was reduced from 40% in the control to 11.7% in the treated plots. Yields of fresh maize cobs were also increased significantly in treated plots. A significant positive correlation was established between the mean number of stem borer larvae and mean percentage damage, and significant negative correlations between the mean yield and mean percentage damage and between the mean yield and mean number of stem borer larvae.     

稻田中华稻蝗发生动态、危害损失及防治指标

系统地研究了中华稻蝗发生动态与危害损失。结果表明,中华稻蝗在浙江年发生1代,主要危害早稻和早播单季晚稻。水稻分蘖期接入虫量10～50头/m2,叶被害率为52.61%～78.81%,叶被害指数为14.51～25.00,产量损失率为2.31%～27.42%,孕穗至破口期接入虫量1～17头/m2,叶被害率为56.63%～88.00%,叶被害指数为14.69～31.32,产量损失率为1.28%～32.74%,随着虫口密度增加,危害程度上升,产量损失率加大,两者具有密切相关性,建立了危害损失关系式。水稻叶片受害、光合能力减弱、幼穗分化不良、实粒减少、秕谷增加和粒重下降是导致水稻减产的主要原因。模拟测试表明,随着水稻受害生育期推迟损失增大,且分蘖期危害具有一定的补偿能力。在现有生产条件下,经济允许损失水平为2.5%～3.0%;2～3龄蝗蝻为防治适期,氟虫腈、三唑磷等有较好防治效果。提出水稻分蘖期和孕穗至破口期防治指标分别为10头/m2和5头/m2。     

Bt籼稻对褐飞虱取食、产卵行为的影响

比较了褐飞虱在2个Bt籼稻纯合品系，即TT9-3、TT9-4，及亲本对照IR72上的取食和产卵行为。结果表明，在选择性条件下，褐飞虱于稻株上的着虫比率在Bt籼稻与对照间无显著差异，而稻株中部和整个叶鞘的取食刺探痕数、产卵选择比率和产卵量则均以Bt籼稻显著为低。在非选择性条件下，稻株叶鞘上的取食刺探痕数在Bt籼稻与对照间无显著差异，而排泄的蜜露量则多以Bt籼稻尤其是TTP9-4显著为少。可见，供试的2个Bt籼稻品系不利于褐飞虱的取食或产卵，表现有抗褐飞虱的能力。     

水稻矮缩病毒对3种内源激素含量及代谢相关基因转录水平的影响

本文以抗病品种宜香2292(Oryzas ativa L. ssp. indica cv. Yixiang 2292)为材料,采用高效液相色谱技术(HPLC)和Real-time PCR技术研究了水稻矮缩病毒(Rice dwarfvirus,RDV)胁迫下水稻内源赤霉素(GA3)、生长素(IAA)和脱落酸(ABA)的动态变化。结果表明,受RDV侵染后,病株体内GA3含量显著低于健株,在显症后的第1d和第10d最为明显,分别较健株低6.28和5.92倍;IAA含量呈现波动变化,但病株体内的IAA含量始终较健株低,在显症后的10d最为明显,比健株低3.58倍;与GA3和IAA相反,病株体内ABA的含量始终高于健株,显症后的第1d和第13d最为明显,分别较健株高2.29和2.84倍。Real-time PCR定量检测了植物内源激素相关基因mRNA的表达,结果显示,GA3代谢相关的氧化还原酶基因表现为下调,而IAA和ABA代谢相关的Cullin-1和P-glycoprotein1基因表现出不同程度的上调。以上结果表明:水稻矮缩病的症状表现可能与病株体内的植物内源激素失调有关。     

Competitive interactions between weedy rice and cultivated rice as a function of added nitrogen and the level of competition

The competitive outcomes between weedy rice from Malaysia (MWR), the Philippines (PWR), and Vietnam (VWR) and cultivated rice (IR64) grown in pots were evaluated in a replacement series experiment with added N (0, 50, 100, and 150 kg N ha^?1) and competition with IR64 plants (no competition, eight weedy rice plants : 0 IR64 plants; low competition, six weedy rice plants : two IR64 plants; and high competition, two weedy rice plants : six IR64 plants). The growth observations were taken at 10 weeks after sowing. When grown in a monoculture (no competition with IR64 plants), the PWR plants had a lower shoot biomass across N rates than did the MWR and VWR plants. The leaf area and shoot biomass of weedy rice across populations significantly increased with an increase in the N application rate. Each weedy rice population and the IR64 population showed linear responses of the leaf area and shoot biomass to the N rate at all levels of competition. The weedy rice and IR64 plants, when grown without competition, had a similar rate of response in the shoot biomass to the N rate. However, when grown in competition, the response to the added N varied among the weedy rice populations. The MWR plants under competition produced a similar amount of shoot biomass to the IR64 plants per unit addition of N. In contrast, the PWR and VWR populations under competition produced a greater amount of shoot biomass with each additional unit of N, compared to the IR64 population. The results illustrate that N fertilizer management might affect the outcome of weedy rice competition. This information could be incorporated into weedy rice management strategies.     

Estimation of rice yield losses due to the African rice gall midge,Orseolia oryzivora Harris and Gagne

Abstract

The African rice gall midge, Orseolia oryzivora Harris and Gagne (Diptera: Cecidomyiidae), is an important pest of rice, Oryza sativa, in Burkina Faso as well as other countries in West and East Africa. In spite of its importance, little is known regarding the relationship between gall midge populations and grain yield losses. To determine yield losses the gall midge was reared in cages and adult midges were placed on caged plants of the rice variety ITA 123 at different population levels. The seven treatments consisted of different numbers of insects infested on the plants; 0 insect pairs (non‐infested check), and 1, 5, 10, 15, 20 or 25 midge pairs/cage. The loss in yield in relation to the non‐infested control was highly positively correlated (R² = 0.81) with the percentage of gall midge damaged tillers. The infestation by the insect on the plants resulted in the compensatory production of tillers which developed in response to the gall midge damage but the compensation was not sufficient to make up for the loss of yield due to the damaged tillers. Yield loss ranged from 0% in the control to 65.3% in the treatment with 25 pairs of adults. One per cent of tillers damaged resulted in 2% grain yield loss.     

稻纵卷叶螟危害损失的通径分析及经济阈值的数学模型

根据稻纵卷叶螟Cnaphalocrocis medinalis Guenee对水稻危害的特点,作者对不同虫量的危害程度与水稻产量损失的关系,进行了测定和分析。结果表明:危害平均严重度或危害指数与产量损失呈平衡动态关系,空壳率的上升是产量损失的直接原因,其防治费用与产量损失金额相等时的经济阈值为:X_1=(1/(0.243))ln((1.7102CN+C_1)/(4.9034CN)(卷叶率)一般田块,防治指标的虫口密度为百株3.19—4.92头二、三龄幼虫。     

抗除草剂转基因水稻对稻纵卷叶螟田间自然种群的影响

［目的］明确抗除草剂转基因水稻对非目标生物的影响。［方法］以稻纵卷叶螟为指示物种,调查其在抗除草剂转基因籼稻‘Bar68 1’稻田与非转基因亲本对照‘D68’稻田的种群密度、发育进度以及水稻的受害程度。［结果］在转基因和非转基因稻田中,除2007年水稻乳熟期外,稻纵卷叶螟幼虫的发生密度无显著差异;稻纵卷叶螟不同龄期幼虫比例（%）在转基因稻田与非转基因稻田之间表现出较高的一致性;除2007年分蘖末期外,处理与对照间的单株受害叶片数和卷叶率（%）差异均不显著;转基因水稻与对照植株的卷叶指数（%）表现基本一致。［结论］转基因抗除草剂水稻‘Bar68 1’对非目标物种稻纵卷叶螟不造成影响。     

稻曲病损失率测定初报

通州、如皋两市的田间调查和室内考种结果表明,稻曲病对水稻的为害主要表现为:增加单穗病粒率,降低结实率,同时对病粒附近健粒,尤其是对靠近主轴的稻粒的千粒重有影响。通径分析结果显示,其为害损失率,主要决定于病粒率,其次是结实率。