茶假眼小绿叶蝉发生为害特点调查研究

通过多点系统调查,探讨了茶假眼小绿叶蝉在福建主要茶区发生规律及为害特点。揭示了该虫百叶虫量与百梢虫量及虫梢率的相关性,比较了茶梢不同部位该虫着卵的比率。为茶假眼小绿叶蝉预测预报及防治提供了理论依据。     

永泰县茶假眼小绿叶蝉发生特点与防治对策

茶假眼小绿叶蝉是永泰县茶园的头号害虫,主要以成虫、若虫刺吸茶嫩梢叶片汁液,严重影响茶叶品质。一年发生10代,世代重叠。通过多点茶园系统调查,摸清了茶假眼小绿叶蝉在永泰县茶区的发生为害特点,探索了茶假眼小绿叶蝉的预测预报方法,为茶假眼小绿叶蝉综合防控提供理论依据。     

LED风吸式杀虫灯对有效范围内茶小绿叶蝉虫口动态的影响

为明确LED风吸式杀虫灯对茶小绿叶蝉Empoasca onukii的防治效果,室内测定诱虫光源对茶小绿叶蝉卵和若虫生长的影响,温室内测定不同灯高和不同灯距组合下杀虫灯诱捕的茶小绿叶蝉数量,并计算杀虫灯对茶小绿叶蝉成虫的有效控制范围、诱杀中距离、诱杀黄金距离,并通过2年田间试验比较杀虫灯有效控制范围内不同灯距处、有效控制范围外茶小绿叶蝉成虫数量。结果显示:诱虫光源对茶小绿叶蝉卵和若虫的生长无显著影响,若虫生长历期为18.5 d,存活率为46.85%。随着灯距和灯高的增加杀虫灯对茶小绿叶蝉的诱捕量下降,灯高20～40 cm时,杀虫灯对茶小绿叶蝉的平均有效控制范围、平均诱杀中距离和平均诱杀黄金距离分别为58.17、30.41和23.86 m。茶园内灯距5 m处,茶小绿叶蝉成虫数量率先达到5个灯距中的最大值,不同灯距下茶小绿叶蝉成虫数量随时间推移而呈现出显著差异,虫口峰期时灯距25 m内的茶小绿叶蝉成虫数量为灯距120 m处的49.5%～64.4%。表明LED风吸式杀虫灯可通过诱杀茶小绿叶蝉成虫显著抑制其诱杀黄金距离内茶小绿叶蝉的成虫数量。     

信息素色板诱捕茶小绿叶蝉试验初报

为探讨验证茶小绿叶蝉信息素及色板在茶园茶小绿叶蝉防治上的作用和效果，以获取科学、准确的试验数据，掌握其在规模化标准茶叶园区和茶叶绿色防控技术的使用方法，促进农业部大别山名优茶优质、高产协作项目顺利实施，推进全县高效生态茶园和湖北省茶叶病虫害绿色防控万亩示范区建设，我们承担并实施了茶小绿叶蝉信息素诱捕茶园茶小绿叶蝉试验。     

黄板监测假眼小绿叶蝉田间种群消长试验研究

在重庆永川的自然生态茶园、有机茶园、无公害茶园中,利用黄板诱集和常规方法监测茶假眼小绿叶蝉的田间年发生消长动态。试验结果显示,两种方法监测该虫的发生趋势动态基本一致,相关系数达极显著水平;在越冬期和早春时节,黄板诱集比常规调查方法能更早和更直观地监测叶蝉的越冬虫口和残存虫量;在第1高峰始期预测中,常规方法以假眼小绿叶蝉田间百叶虫量超过10头作为入峰的临界值,对应黄板监测的临界虫口量0.124头/cm2。     

假眼小绿叶蝉为害致茶梢挥发物变化及其引诱微小裂骨缨小蜂效应

以SDE法提取健康茶梢、假眼小绿叶蝉为害茶梢挥发物,用GC-MS配合标准样品从二者中鉴定了17种共有成分,包括顺-3-己烯-1-醇、反-2-己烯醛、芳樟醇、香叶醇、β-紫罗酮和橙花叔醇等常见茶叶香气成分。从前者另外检出顺-3-己烯基丁酸酯等9种成分,还从后者另外测出了己醛等7种成分。假眼小绿叶蝉为害茶梢挥发物各组分总含量、健康茶梢挥发物各组分总含量相对于内标含量的比例分别是1783.8%和360.3%。从蝉害茶梢测出了丰富的反-2-己烯醛、苯甲醛、α-法呢烯和水杨酸甲酯,4种成分占蝉害茶梢、健康茶梢挥发物总量分别为11.8%和8.3%;室内以蝉害茶梢19种主要挥发物的10-2 g/m L剂量为味源,液体石蜡为CK,以Y管嗅觉仪进行行为测定,结果表明这4种成分皆显著引诱微小裂骨缨小蜂(P0.05)。认为蝉害改变了茶梢挥发性化合物的组成及其相对含量,尤其是产生的反-2-己烯醛、苯甲醛、α-法呢烯和水杨酸甲酯等互利素显著地引诱该叶蝉的卵寄生蜂微小裂骨缨小蜂。     

不同色板对茶假眼小绿叶蝉的诱杀效果

通过性信息素黄板诱杀茶假眼小绿叶蝉的试验结果表明,在诱虫色板上加入专用的小绿叶蝉诱芯后,诱虫量能达到单用诱虫板的6倍以上,而蓝色诱虫板加入诱芯后,诱杀效果是单用黄板的2倍以上。因此,在茶园中安插性信息素诱虫色板,可有效提高诱杀效果,减轻假眼小绿叶蝉的为害。     

黏虫色板诱杀茶小绿叶蝉应用技术研究

本文研究了黏虫色板的颜色、摆放高度、悬挂朝向、有无诱芯色板以及田间设置密度对茶园中茶小绿叶蝉诱杀效果的影响。结果表明,在黄板底部高出20cm,南北朝向时,黄色色板配套诱芯、每667m2悬挂30张时,对茶园中茶小绿叶蝉的防治效果最好。     

假眼小绿叶蝉生物学的观察

笔者先后对江西30多个县(市)低海拔和高海拔(700m以上)茶园的叶蝉作了广泛、大量的调查与采集,已查明,江西各地害茶叶蝉的优势种为假眼小绿叶蝉Empoasca(Empoasca)vitis(Gothe)。鉴于该虫在我省茶园分布广、危害重,省内又尚缺系统研究资料,为此我们对其生物学进行了初步研究,结果如下。1　生活年史在江西婺源,假眼小绿叶蝉除少数年份发生10代外,一般每年可发生11代,以成虫在茶树或茶园内外的杂草、作物上越冬。3月中、下旬产卵,4月初第一代若虫发生,若虫终见期为12月上、中旬(见附图)。2　各虫态发育历期在婺源,假眼小绿叶蝉各虫态历期:卵…     

小绿叶蝉的发生与防治

小绿叶蝉 [Ｅｍｐｏａｓｃａｆｌａｖｅｓｃｅｎｓ (Ｆａｂｒｉｃｉｕｓ) ],是茶树上的主要害虫。以成虫和若虫刺吸茶树嫩梢汁液 ,消耗其养分和水分 ,被害芽梢生长受阻 ,新芽不发 ,为害严重时幼嫩芽叶呈枯焦状 ,无茶可采 ,以后各茶季抽出的芽头瘦小 ,新梢细短 ,叶小而肥厚 ,从而影响茶叶产量和品质。1　发生特点小绿叶蝉在闽北 1ａ发生 1 0～ 1 1代 ,以成虫在茶树上或冬作物 (豆类 )、杂草上越冬。翌年早春当气温超过 1 0℃时成虫开始取食 ,补充营养 ,并开始孕卵 ,3月中、下旬茶树发芽后开始产卵繁殖。秋末冬初茶树芽梢停止生长 ,成虫也停止…     

亚洲玉米螟在玉米和甘蔗不同种植模式下的产卵行为

为明确玉米和甘蔗间作对亚洲玉米螟产卵行为的影响,在尼龙网室研究了亚洲玉米螟在玉米和甘蔗不同种植模式下的产卵时间、产卵部位及产卵量的差异。结果表明,不同种植模式下亚洲玉米螟均于23∶00开始产卵,02∶00~03∶00达产卵高峰。单作甘蔗、单作玉米和间作甘蔗叶背的玉米螟卵块和卵粒数均高于叶面,而间作玉米叶背与叶面的玉米螟卵块数无显著差异,叶背的卵粒数高于叶面。单作玉米叶脉的玉米螟卵块和卵粒数均显著高于叶缘;间作玉米和单作甘蔗叶脉与叶缘卵块数间无差异,但叶脉处卵粒数高于叶缘,间作甘蔗叶脉的卵块数高于叶缘,叶缘卵粒数高于叶脉。单作甘蔗叶背的亚洲玉米螟卵块主要分布在距叶鞘69.14 cm处,而叶面的卵块主要分布在距叶鞘21.09 cm处;间作甘蔗叶背和叶面卵块分布于距叶鞘35.17 cm和12.34 cm处,二者差异显著。单作玉米上亚洲玉米螟卵块仅分布于叶背沿叶脉远离叶鞘处,而间作玉米叶背和叶面卵块分布于近叶鞘。表明玉米和甘蔗间作对亚洲玉米螟雌蛾产卵选择性具有明显的影响。     

甘蔗间作玉米对亚洲玉米螟发生为害的控制作用

为明确甘蔗间作玉米对亚洲玉米螟Ostrinia furnacalis(Guenée)发生和为害的控制作用,于2012—2013年在云南省元江县甘蔗种植区设置甘蔗间作玉米小区,采用目测法和马氏网法系统调查了该生境下亚洲玉米螟卵块密度与卵粒密度、蛀孔密度与百秆虫量、寄生性天敌昆虫种类及其种群动态。结果表明:与甘蔗间作种植的玉米上亚洲玉米螟落卵量、蛀孔密度、百秆虫量均明显低于单作玉米田,2012和2013年,间作玉米上百株卵块数比单作玉米分别减少了29.32%和35.73%,每卵块所含的卵粒数分别减少了34.22%和51.02%,百秆玉米蛀孔数分别减少了42.53%和31.25%,百秆虫量分别降低了58.18%和52.73%。间作田中亚洲玉米螟的3种主要寄生蜂螟蛉绒茧蜂Apanteles ruficrus、黄眶离缘姬蜂Trathala flavoorbitalis和大螟钝唇姬蜂Eriborus terebrans的种群密度显著高于单作玉米田,而数量较少的广大腿小蜂Brachymeria lasus及广黑点瘤姬蜂Xanthopimpla punctata种群密度在间作与单作田间无显著差异。表明甘蔗间作玉米对亚洲玉米螟的发生为害具有明显的控制作用,可用于亚洲玉米螟的生态控制。     

Promotion of first internode elongation in perennial paddy weeds Sagittaria trifolia and Sagittaria pygmaea tubers by oxygen depletion and carbon dioxide

The semiaquatic plants, S agittaria trifolia and S agittaria pygmaea, are perennial and troublesome weeds of rice paddy fields. These species mainly reproduce vegetatively via tubers, which sprout after the rice paddy fields are irrigated. Sprouting finally leads to the emergence of the shoots from the water in the paddy fields. In both species, the first internode elongates around the time of emergence and this lifts the shoot meristems in the soil, aiding in the establishment of the young plants. Therefore, elongation of the internode is a factor that determines the weed damage to rice caused by these species. In this study, the first internode elongation of both species was characterized. During emergence, S . trifolia and S . pygmaea showed distinct growth patterns. In S . trifolia, the internodes elongated before the emergence of the shoots from the water; whereas, in S . pygmaea, the internodes started to elongate only after emergence. We examined environmental prerequisites for internode elongation, and found that the internode elongation of S . trifolia was induced by submergence and was independent of the soil cover, while that of S . pygmaea required both submergence and covering. Next, we determined which gaseous factors were responsible for internode elongation. Treatment with ethylene, which enhances growth of several other aquatic and semiaquatic plants, did not stimulate internode elongation in either species under an anaerobic condition. Our results suggested that the gaseous factor stimulating internode elongation in S . trifolia and S . pygmaea may be oxygen depletion and carbon dioxide, respectively.     

Within‐plant distributions of heliothis armigera eggs on cotton in Thailand

Abstract

Heliothis armigera (Hbn.) eggs on cotton tended to be placed on flat parts such as leaf laminas and bracts at the expense of linear parts such as stems, petioles and peduncles, which accounted for less than 3% of eggs in samples of 100–216 eggs. Numbers of eggs on bracts and leaves respectively rose and fell from 0% and 97% at 34 days after planting to 81% and 18% at 104 days; the levels were equal at 49% on day 83. Categorisation of leaves by stage of development showed that 80–90% of all leaf‐laid eggs were found on leaves at the ‘young’ to ‘soft‐expanded’ stages of development while categorisation by position showed that the first three leaves from the top of the stem received 90% of all leaf‐laid eggs. There was no consistent trend for egg laying on main‐stem or lateral stem leaves and over 97% were located on the upper (adaxial) leaf surface. Bracts of larger buds (more than 50% developed) were most favoured as sites for egg laying, but oviposition on bracts of bolls had overtaken that on buds by day 97. These preliminary, small‐scale investigations should be extended so that possibilities for the use of an integrated sample unit for eggs and small larvae can be assessed.     

间作对甜玉米田主要害虫与天敌动态的影响

为明确甜玉米间作不同作物对害虫的控制作用,采用目测法系统调查了甜玉米单作、甜玉米与绿豆、菜豆、甘薯或花生间作生境玉米主要害虫和天敌种群发生动态,并比较了不同生境亚洲玉米螟的为害情况。间作生境中捕食性天敌蜘蛛和瓢虫类群的个体数量均明显增加,其中甜玉米间作绿豆或甘薯生境蜘蛛类群增长21%以上,瓢虫类群增长83%以上,显著高于甜玉米单作生境;不同生境间玉米螟赤眼蜂发生量差异不显著,对亚洲玉米螟卵的寄生率均达到86%以上。间作生境玉米生育期内亚洲玉米螟落卵量、斜纹夜蛾及玉米蚜发生量均与甜玉米单作无显著差异,但收获期甜玉米间作生境玉米螟为害率低于单作生境,其中以甜玉米间作绿豆生境最低,总蛀孔数和活虫数分别比单作生境下降55.72%和76.70%。表明间作不同作物对甜玉米田具有一定的控害增益作用。     

Mechanisms of resistance in cotton to whitefly (<Emphasis Type="Italic">Bemisia tabaci</Emphasis>): antixenosis

Screenhouse experiments were conducted under free-choice conditions to determine the mechanism of resistance operating in cotton against whitefly, Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae). Twelve cotton genotypes belonging to Gossypium hirsutum and G. arboreum were assessed for oviposition preference by whitefly. The trichome density and length, distance from lower leaf surface to nearest vascular bundles, leaf lamina thickness and compactness of vascular bundles were estimated for each genotype and correlations with number of eggs laid were determined. The genotypes RS2098, CNH911, and PA183 were non-preferred for oviposition and exhibited an antixenosis mechanism of resistance. NHH44, LK861, Supriya, RS2013 and LD694 were categorized as moderately resistant while IS-376/4/1/20/72 and F846 were categorized as susceptible. Greater leaf lamina thickness and more compact vascular bundles were correlated with egg laying by whitefly.     

Influence of common carp on apple snail in a rice field evaluated by a predator - prey logistic model

The hypothesis that common carp can be used for the control of apple snails in rice fields was tested experimentally. In a rice field, 12 plots of 4 2 5 m were set and enclosed by plastic walls to prevent snail emigration and immigration. The experiment continued from June to September. Three replicated treatments were used for the plots: zero, four and 12 carp were released, giving carp densities of 0.0, 0.2 and 0.6 m^?2, respectively. Snail densities were estimated by the Jolly-Seber mark-recapture method. Newly laid egg masses were counted and measured for size, and hatching was monitored. The numbers of eggs per egg mass (y) were estimated using a regression equation obtained from the product of the maximum length and width of the egg mass (x): y =0.10x^1.24. Using these measures and the monthly mean hatching rate obtained from eggs laid in two outdoor aquaria from April to September, the number of hatched eggs was used to estimate the birth rate over a given time. A logistic model incorporating these estimates revealed that the snail population proliferated only in the zero-carp plot throughout the experiment. The study, together with other reports on snail longevity, predicts that a snail population would be eliminated in 2 years at a stocking density of 2000 carp hectare^?1, if no immigration of the snail occurred.     

Identification of tea foliar diseases and pest damage under practical field conditions using a convolutional neural network

Lesions of tea (Camellia sinensis) leaves are detrimental to the growth of tea crops. Their adverse effects include further disease of tea leaves and a direct reduction in yield and profit. Therefore, early detection and on-site monitoring of tea leaf lesions are necessary for effective management to control infections and prevent further yield loss. In this study, 1,822 images of tea leaves with lesions caused by three diseases (brown blight, Colletotrichum camelliae; blister blight, Exobasidium vexans; and algal leaf spot, Cephaleuros virescens) and four pests (leaf miner, Tropicomyia theae; tea thrip, Scirtothrips dorsalis; tea leaf roller, Homona magnanima; and tea mosquito bug, Helopeltis fasciaticollis) were collected from northern and central Taiwan. A faster region-based convolutional neural network (Faster R-CNN) was then trained to detect the locations of the lesions on the leaves and to identify the causes of the lesions. The trained Faster R-CNN detector achieved a precision of 77.5%, recall of 70.6%, an F1 score of 73.91%, and a mean average precision of 66.02%. An overall accuracy of 89.4% was obtained for identification of the seven classes of tea diseases and pests. The developed detector could assist tea farmers in identifying the causes of lesions in real time.     

新疆杨树/紫花苜蓿林草复合系统中根系分布特征及生产力

为了解杨树（Populus L.）/紫花苜蓿（Medicago sativa L.）林草复合系统中两种植物根系的分布及相互关系，利用WinRHIZOTM对3 a生紫花苜蓿和7 a生杨树在单作和间作条件下0~60 cm土层中的根长密度（RLD）、平均根直径（ARD）和比根长（SRL）的分布进行测定分析。结果表明：间作紫花苜蓿RLD降低了10.01%~54.29%，20~60 cm土壤中紫花苜蓿ARD降低了11.15%~37.30%, 间作苜蓿的SRL比单作苜蓿高10.52%~28.78%；间作增加了 0~40 cm土层中杨树ARD的20.36%~28.08%，增加了苜蓿种植区域0~20 cm土层中杨树RLD的15.51%~34.23%。杨树SRL受到的影响较小，仅在8月5日的0~20 cm 土层中测得单作和间作SRL存在差异，单作杨树SRL比间作杨树高14.46%。单作和间作苜蓿的最高产量均在第一次收获时期，间作降低了苜蓿的产量，在第一次、第二次和第三次收获中产量分别降低了24.7%、30.9% 和 43.7%，与单作苜蓿相比，杨树/紫花苜蓿林草复合系统中苜蓿的总产量减少了31.2%。通过计算土地当量比，发现杨树与紫花苜蓿复合经营为杨树林带增加了额外来自紫花苜蓿的收入，能够提高系统41%的生产力。综上所述，林草复合系统中紫花苜蓿根系分布及生长受到了不利影响，而杨树根系受到了有利的影响。相比单作种植，林草复合系统有较高的生产力和资源利用效率，具有提高新疆地区防护林带生态和经济回报率的潜能。     

春小麦品种对麦秆蝇抗性机制的研究

本文系1957—1979年间,根据多次田间调查春小麦品种对麦秆蝇抗性机制研究的结果。麦秆蝇有趋向遮荫较差麦田的习性,卵散产,主要产在叶片正面近基部处。研究结果表明,春小麦品种对麦秆蝇的抗性,主要是由此虫产卵对不同品种的选择性决定的。影响产卵选择性的特性已证明有生育期、叶面茸毛性、叶片宽度及叶片与茎秆间交角。抽穗愈早、叶面茸毛密而长、叶片狭或叶片与茎秆间交角大,则着卵较少。统计分析这些差异都是显著的。此外,有一年的田间调查表明叶色深的品种着卵较少,叶色深浅与着卵量有显著的负相关。但这需要进一步验证。还有,品种生育期的长短与幼虫入茎成活率,已证明有显著的正相关,因此品种生育期也起一定的抗生作用。