跗粗角萤叶甲的生物学特性

跗粗角萤叶甲Diorhabda tarsalis Weise是甘草上的重要食叶害虫,成虫、幼虫危害甘草叶片及幼嫩组织。该虫在河北省保定1年发生3代,以成虫在土缝、洞穴或者枯枝落叶下面的疏松层中越冬。翌年4月下旬越冬成虫开始活动,4月下旬至5月上旬交配产卵,卵产于寄主根部10～15mm的疏松土层。第1代、第2代和第3代幼虫分别于5月中旬、7月上旬和8月上旬孵化,各代幼虫均能对寄主造成严重为害,幼虫3龄。记述该虫的寄主、生活年史、发育历期、生活习性,并提出防治建议。     

外寄生性花绒寄甲的寄生选择及其发育表现

"选择-表现"假说认为,成虫应该选择有利于子代发育的高品质寄主,但在寄主选择中,除了寄主品质外,其他因素也可能影响寄主选择决策。寄主选择研究通常以成虫为对象,而对那些初龄幼虫选择寄主的寄生性昆虫很少关注。以1龄幼虫积极搜寻寄主的寄生性花绒寄甲为模式生物,采用双选试验设计,观察了花绒寄甲初孵幼虫在不同体重青杨天牛幼虫之间、在已被寄生与健康的黄粉虫蛹之间的寄生选择性;然后采用回归设计,观察了花绒寄甲寄生若干不同体重的青杨天牛幼虫后的发育表现。研究结果表明,花绒寄甲1龄幼虫对体型较大的青杨天牛幼虫的选择偏好显著大于对体型较小的寄主幼虫的选择,选择大体型幼虫的比值比是选择小体型幼虫的4.55倍;对已被寄生的寄主黄粉虫蛹的选择偏好显著大于对健康寄主蛹的选择,选择已被寄生寄主的比值比是选择健康寄主的12.57倍。寄生青杨天牛幼虫的花绒寄甲幼虫发育历期平均为11.49 d、蛹历期为26.67 d、幼虫发育至成虫的羽化率50%,这些发育表现与寄生时青杨天牛幼虫的体重没有显著关系。但刚羽化寄甲成虫体重与寄生时寄主的体重存在显著的正直线关系:寄生时的寄主体重每增大0.01 g,羽化出的寄甲成虫体重增大近0.08%;方差分析寄甲成虫体重在不同寄主体重水平之间的差异表明,从体型较大寄主中羽化的寄甲成虫体重显著大于从体型较小寄主中羽化的成虫。研究结果说明,花绒寄甲初孵幼虫在寄主选择决策时,在寄主体型大小与被寄生状态之间可能采取折衷对策,而且对体型大小不同的寄主选择与子代发育适合度表现存在一致性,从而支持"选择-表现"假说。     

沙蒿大粒象的生物学特性

沙蒿大粒象Adosomus sp.,是近几年在我国宁夏、内蒙古、陕西等地沙蒿灌木林中大面积发生的一种钻蛀性害虫。在宁夏盐池,该虫1年1代,以成虫和老熟幼虫在沙蒿根部越冬。越冬成虫始见于4月中下旬,终见于6月中旬;越冬老熟幼虫5月中旬开始化蛹,成虫始见于6月下旬,终见于8月上旬。成虫产卵于沙蒿根茎部至地下2cm之间,外被一层1~2mm厚的沙壳。幼虫主要分布在地下根部12cm以内,主要钻蛀沙蒿根部,在根部作蛹室化蛹;成虫取食沙蒿叶片作为营养补充。     

沙柳木蠹蛾的研究

沙柳木蠹蛾Holcocerus arenicola(Staudinger)是沙柳根部一种钻蛀性害虫.亦为害踏郎、酸刺、毛乌柳、柠条等.国内分布于内蒙、新疆、宁夏、陕西、甘肃等省(区). 该虫四年1代, 以幼虫在寄主蛀道内越冬.老熟幼虫5月上旬入沙化蛹;成虫6月初开始羽化, 中旬达盛期;7月上旬幼虫初孵, 取食、为害至10月下旬越冬.成虫白天静伏于沙柳丛, 傍晚8时半至10时半活动、交配、产卵, 趋光性强.雌蛾对雄蛾性诱力较强.成虫寿命2.9—4.1天, 产卵量平均265.4粒, 性比0.67—0.68:1.     

团角锤天蛾的生物学特性

团角锤天蛾Gurelca hyas(Walker)危害园林植物——银边六月雪(Serissa foetida cv.Aureovaiegata),以幼虫取食寄主叶片和嫩梢。该虫在湖南省衡阳地区1年发生3代,以老熟幼虫在寄主附近土壤中筑土室化蛹并以蛹在土室中越冬。翌年8月上旬越冬代成虫开始羽化。幼虫5龄,多数幼虫在发育过程中会出现体色变化。第1代、第2代和第3代幼虫分别于8月中旬、9月中旬和10月中旬孵化,各代幼虫均能对寄主造成严重为害。     

棉酚对棉铃虫生长及其寄生物齿唇姬蜂发育的影响(英文)

以中国北方棉区的主要害虫棉铃虫Helicoverpaarmigera（Hbner）及其内寄生蜂棉铃虫齿唇姬蜂Campoletischlorideae（Uchida）为试虫,研究了棉花重要抗虫次生性物质棉酚对棉铃虫生长和齿唇姬蜂发育的影响。0．1％的棉酚对棉铃虫幼虫有生长刺激作用,0．5％的棉酚则对棉铃虫幼虫生长有抑制作用。齿唇姬蜂成虫在寄生时对寄主大小有较严格的选择性,92％的被寄生幼虫体重小于18mg。0．1％的棉酚使寄主适合寄生期缩短10．75％;0．5％棉酚使寄主适合寄生期延长28．15％。棉酚对齿唇姬蜂发育有负效应。0．1％棉酚对寄主的生长刺激作用,不能使蜂成虫体重显著增加,但可显著延长蜂卵和幼虫期,缩短蛹期;高浓度的生长抑制作用,导致蜂成虫体重显著减轻,蛹期缩短,蜂卵和幼虫期亦显著延长。据此,对棉花抗虫性与生物防治在害虫综合防治实践中应用的协调性进行了讨论。     

广东地区花绒寄甲替代寄主的研究

将花绒寄甲Dastarcus heloporoides Fairmaire幼虫接于替代寄主黄粉甲Tenebrio molitor、吉丁虫Buprestidaesp和大麦虫Zophobas morio,结果表明,黄粉甲幼虫、蛹和成虫均能繁育出花绒寄甲成虫,平均羽化率能达到20%以上,是较好的替代寄主.用黄粉甲繁育的花绒寄...     

沙蒿尖翅吉丁生物学特性的研究

沙蒿尖翅吉丁Sphenoptera sp.是黑沙蒿上主要的钻蛀性害虫,引起沙蒿长势下降甚至死亡。对其形态特征及生物学特征的观察和研究结果表明:该虫在宁夏1年发生1代,以各龄幼虫在被害沙蒿根部越冬。老熟幼虫于4月中下旬开始化蛹,成虫始见于5月上旬,羽化期有两个高峰,分别是5、6月下旬。成虫羽化后并不马上离开蛹室,2～3d后咬出羽化孔,钻出蛹室。成虫需取食沙蒿叶片补充营养,2～7d后开始交尾,集中在13:00-16:30,雌雄成虫均可多次交尾。幼虫常多头聚集危害同一株沙蒿。大多数老熟幼虫在距坑道端部5mm处的根部化蛹,少数在直径为5～8mm的较粗的枝条内化蛹。沙蒿尖翅吉丁幼虫期有2种寄生性天敌,蛹期和成虫期各有1种寄生性天敌。     

斑痣悬茧蜂寄生、发育和生殖特征与寄主幼虫日龄的关系

【目的】“圆屋顶形”假说认为,对单寄生性姬蜂和茧蜂适合度而言,中间龄期幼虫寄主的品质高于更早和更晚龄期幼虫。该假说得到许多研究支持,但这些研究常以寄主幼虫脱皮划分虫龄,很少观测生殖特征,从而难以确切和全面描述适合度随寄主生长发育变化而变化的关系。本研究旨在检验“圆屋顶形”假说。【方法】本研究以斜纹夜蛾Spodoptera litura不同日龄幼虫为寄主,观测斑痣悬茧蜂Meteorus pulchricornis寄生和发育特征,并测定成蜂生殖力。【结果】线性回归分析表明,雌蜂对中间日龄寄主幼虫的寄生率大于对两端日龄寄主幼虫的寄生率;蜂卵至成虫的存活、成虫体型大小及其生殖力（产卵量）等适合度相关特征均表现出中间日龄寄主幼虫处理大于两端日龄幼虫处理。【结论】研究结果支持“圆屋顶形”假说。     

白蜡吉丁柄腹茧蜂的羽化和产卵与寄主之间的关系

白蜡窄吉丁是危害白蜡属树木的一种重要蛀干害虫,因其幼虫期高度的隐蔽性生活而极难检测和防治.白蜡吉丁柄腹茧蜂是新发现外寄生于白蜡窄吉丁幼虫的优势天敌种,对寄主害虫的控制作用较强,具有良好的生物防治利用前景.研究调查了白蜡吉丁柄腹茧蜂及其寄主白蜡窄吉丁越冬代成虫羽化的时序差异、不同时期林间的寄生率、寄主密度与寄生率的关系以及寄主幼虫大小与茧蜂产卵量的关系.结果表明,越冬后白蜡吉丁柄腹茧蜂的羽化时间比其寄主害虫白蜡窄吉丁的羽化要晚1个多月.2003年白蜡吉丁柄腹茧蜂越冬代成虫的羽化从6月中旬持续到8月中旬,羽化高峰期在7月份;寄主白蜡窄吉丁的羽化期在5月中下旬.2004年白蜡吉丁柄腹茧蜂越冬代成虫的羽化从5月下旬持续到7月下旬,羽化高峰期在6月下旬至7月上旬;寄主羽化期在4月中旬至5月中旬（室内）.越冬后天敌的羽化时间刚好适应最早寄主发育到可供寄生的龄期,这是二者长期协同进化的结果,也表明白蜡吉丁柄腹茧蜂很可能是一种专性寄生蜂.林间白蜡吉丁柄腹茧蜂对白蜡窄吉丁幼虫的自然寄生率随着时间的推移总体上是逐步上升的.自然条件下茧蜂决定是否产卵与寄主幼虫的大小即龄期有关,它仅在前胸宽和体宽1.5 mm、体长12 mm以上,即3～4龄的寄主幼虫体表产卵,但只要接受寄主并产卵,不同龄期寄主幼虫上的产卵量无显著的差异.     

Forage radish and cereal rye cover crop effects on mycorrhizal fungus colonization of maize roots

Forage radish (Raphanus sativus L. var. longipinnatus) is being used by increasing numbers of farmers as a winter cover crop in the Mid-Atlantic USA. It is a non-host to arbuscular mycorrhizal fungi (AMF) and releases anti-fungal isothiocyanates (ITCs) upon decomposition in the winter. Field experiments were conducted to determine the effect of forage radish and cereal rye (Secale cereale L.) cover crops on arbuscular mycorrhizal fungus colonization of and P acquisition by a subsequent maize (Zea mays L.) silage crop. Cover crop treatments included forage radish, rye, a mix of forage radish and rye, and no cover crop. Mycorrhizal fungus colonization of maize roots at the V4 stage following forage radish cover crops was not significantly different from that in the no cover crop treatment. In 3 out of 6 site-years, a rye cover crop increased AMF colonization of V4 stage maize roots compared to no cover crop. These findings suggest that forage radish cover crops do not have a negative effect on AMF colonization of subsequent crops.     

Penetration of cover crop roots through compacted soils

Tap-rooted species may penetrate compacted soils better than fibrous-rooted species and therefore be better adapted for use in “biological tillage”. We evaluated penetration of compacted soils by roots of three cover crops: FR (forage radish: Raphanus sativus var. longipinnatus, cv. ‘Daikon’), rapeseed (Brassica napus, cv. ‘Essex’), two tap-rooted species in the Brassica family, and rye (cereal rye: Secale cereale L., cv. ‘Wheeler’), a fibrous-rooted species. Three compaction levels (high, medium and no compaction) were created by wheel trafficking. Cover crop roots were counted by the core-break method. At 15–50 cm depth under high compaction, FR had more than twice and rapeseed had about twice as many roots as rye in experiment 1; FR had 1.5 times as many roots as rye in experiment 2. Under no compaction, little difference in root vertical penetration among three cover crops existed. Rapeseed and rye root counts were negatively related to soil strength by linear and power functions respectively, while FR roots showed either no (Exp.1) or positive (Exp. 2) relationship with soil strength. We conclude that soil penetration capabilities of three cover crops were in the order of FR > rapeseed > rye.     

Seasonal occurrence of Laodelphax striatellus (Hemiptera: Delphacidae) in a rice-forage crops mixed cropping area in central Kyushu,Japan

The small brown planthopper, Laodelphax striatellus (Fallén) is an important pest of rice in East Asia because it is a vector of rice stripe virus. In this study, we examined the seasonal occurrence of L. striatellus in an agricultural area in central Kyushu in which cropping systems have been changing since the 1970s. The first generation of L. striatellus emerged in the spring, not only on barley, oats, and Italian ryegrass but also on spring crops of forage maize. The second generation of L. striatellus adults emerged in forage maize fields in July, after harvesting of winter crops of barley, oats, and Italian ryegrass. These results suggest that spring crops of forage maize are important hosts of L. striatellus from spring to early summer. The overwintering generation of L. striatellus was collected from rice ratoon, suggesting this is a favorable host for L. striatellus during winter. The appearance of these novel hosts may be a factor in the recent re-emergence of L. striatellus in central Kyushu.     

豆科牧草基因工程研究进展

豆科牧草既是重要的饲料作物,又在土壤改良、水土保持,以及生态环境保护方面发挥着积极作用。随着分子生物学和植物转化技术的发展和改进,通过基因工程技术对豆科牧草进行改良和培育已成为可能。本文就近几年来基因工程技术在各种豆科牧草的高产、抗病虫害、抗逆及品质改良等方面的研究进展进行了较全面的综述。 Progress in the Biotechnology of Legume Forage Plants ZHANG Zhen-xia1,2,FU Yi-kun1,CHU Cheng-cai2 1.College of Tasture,Gansu Agricultural University,Lanzhou 730070,China; 2.Institute of Genetics and Developmental Biology,Chinese Academy of Sciences,Beijing 100101,China Abstract:As important forage crops,legume forage plants can play an important role in improving natural environment,maintenins water and soil.With development of molecular biology and improvement of plant transformation techniques,molecular breeding of legume forage plants by biotechnology is possible.This review summarized recent progress on improvement of several forage crops,including improvement of nutrient quality,increase of biomass,enhancement of the assimilation and efficient absorb of nutrient element,and enhancement of abiotic and biotic stress resistance. Key words：legume forage plants; transgene; progress     

Root Growth Effects on Soluble C and P in Manured and Non-manured Soils

There is limited research on relationships between root characteristics and soil chemical properties and processes. Because previous studies have shown specific C compounds may release previously sorbed P and make P more plant-available, crops which contribute to high soil C levels could play an important role in soil P cycling. The objectives of this study were to determine (1) whether rotation crops had different amounts of root growth, (2) whether different amounts of root growth among the crop species could be related to different levels of soluble soil C and (3) whether there were differences in P concentration among the soils under different crops that could be related to soluble C soil concentration. Roots and soil from potato (Solanum tuberosum L.), barley (Hordeum vulgare L.), soybean (Glycine max (L.) Merr.), and a forage consisting of alfalfa (Medicago sativa L.) and timothy (Phleum pretense L.) were sampled from the Aroostook Research Farm in Presque Isle, Maine, during the summers of 2003 and 2004 to determine root length density (RLD) and soluble C and P concentrations. Half of the sampled plots were amended with beef manure and half were not amended. Barley and forage consistently had higher RLD than potato or soybean crops. Barley and forage typically had higher concentrations of soluble soil C than potato or soybean, but the differences were significant at only three of the five sampling dates. RLD was significantly correlated to soluble C (r=0.56) only for amended soils on the August 2003 sampling date. For other dates r values were non-significant and ranged from 0.32 to 0.49. As with soil C, soluble soil P levels were typically higher in barley and forage than in potato or soybean crops. Significant differences were detected at four of the five sampling dates. Correlations between soluble C and soluble P were significant at two of the five sampling dates (r = 0.58 and 0.62) in amended soils and one of five sampling dates (r = 0.80) in unamended soils. Although the correlations between RLD and soluble C were not significant at every sampling date, the August 2003 data do suggest a possible effect of roots on soluble C. In addition, significant correlations between soluble C and soluble P at several sampling dates suggest a relationship between these parameters. Therefore cropping systems that include crops with higher amounts of root growth may promote increased soluble soil C levels and enhance P bioavailability.     

Crop management and agronomic context of the Farm Scale Evaluations of genetically modified herbicide-tolerant crops

The Farm Scale Evaluations of genetically modified herbicide-tolerant crops (GMHT) were conducted in the UK from 2000 to 2002 on beet (sugar and fodder), spring oilseed rape and forage maize. The management of the crops studied is described and compared with current conventional commercial practice. The distribution of field sites adequately represented the areas currently growing these crops, and the sample contained sites operated at a range of management intensities, including low intensity. Herbicide inputs were audited, and the active ingredients used and the rates and the timings of applications compared well with current practice for both GMHT and conventional crops. Inputs on sugar beet were lower than, and inputs on spring oilseed rape and forage maize were consistent with, national averages. Regression analysis of herbicide-application strategies and weed emergence showed that inputs applied by farmers increased with weed densities in beet and forage maize. GMHT crops generally received only one herbicide active ingredient per crop, later and fewer herbicide sprays and less active ingredient (for beet and maize) than the conventional treatments. The audit of inputs found no evidence of bias.     

Evaluation of sewage sludge, septic waste and sludge compost applications to corn and forage: Ca, Mg, S, Fe, Mn, Cu, Zn and B content of crops and soils

This is the second of two papers presenting the data from an experiment on the application of aerobically-digested sewage sludge (AES), anaerobic lagoon septic wastes (ANS), sewage sludge compost and fertilizer to soils for grass forage and feed corn production at two different sites in Nova Scotia. Crop yields, plant tissue and Mehlich-1 extractable soil nutrients were evaluated; 15 elements were analyzed in the plant tissue and 9 elements in the soil extracts. This paper describes the Ca, Mg, S, Fe, Mn, Cu, Zn and B content of the crops and the Mehlich-1 extractable content of the soils. The response to the amendments was not consistent at the two sites with the two different crops. We found that the septic sludge (ANS) produced the highest forage Fe, Cu and Zn levels and was equal to compost in elevating corn stover and forage S and the forage B content. The compost produced the highest forage Ca and corn Zn, the AES produced the highest corn Mn, and fertilizer produced the highest forage Mn. None of the amendments produced excessive levels of the above nutrients; rather, the amendments improved the feed quality of the forage and corn stover. Lastly, it was noted that the Mehlich-1 extract only had a significantly positive correlation with forage Cu content.     

Harvesting forage of the perennial grain crop kernza (Thinopyrum intermedium) increases root biomass and soil nitrogen cycling

Plant and Soil - Emerging perennial grain crops yield less grain than annual crops, but the economic viability of these perennial systems could be improved if both forage and grain are harvested....     

Resistance to the rice leaf bug, Trigonotylus caelestialium, is conferred by Neotyphodium endophyte infection of perennial ryegrass, Lolium perenne

Neotyphodium fungal endophytes form mutualistic symbiotic associations with many grasses of the subfamily Pooideae, including important forage and turfgrass species. This relationship provides a competitive advantage to the host plant by increasing abiotic/biotic stress tolerance, such as its resistance to drought, diseases, and insect pests. The insect deterrent effects of endophytes are now receiving attention in Japan, as insect pests growing in meadows are causing problems in adjacent rice paddies. One of the most serious problems is the kernel spotting of rice grains caused by the rice leaf bug, Trigonotylus caelestialium Kirkaldy (Heteroptera: Miridae), which reproduces on Lolium species grown as forage. To determine the potential of Neotyphodium endophytes to reduce the invasion of rice crops by T. caelestialium from adjacent Lolium crops, we carried out choice and no‐choice feeding tests using endophyte‐infected and endophyte‐free clonal perennial ryegrass (Lolium perenne L.) (Poaceae). Our experiments revealed that the presence of the Neotyphodium endophyte strongly deterred the feeding of both first‐instar larvae and adults of T. caelestialium. These results show the potential of Neotyphodium endophytes to reduce the number of T. caelestialium in forage fields and grasslands, and thus to reduce the damage to rice grains caused by this insect pest.     

Efficiency of different methods of extracting the rice root nematode Hirschmanniella oryzae from rice and wheat soil and root samples

The nematode extraction method of centrifugal-floatation proved to be more efficient and significant (p ≤ 0.01) in extracting the rice root nematode, Hirschmanniella oryzae adults and larvae from soil or roots of rice and wheat crops than those extracted by sieving and tissue paper filtration technique. The extracted nematode from rice roots using incubation method is time-dependent and the peak of nematodes occurred four days after incubation. The number of extracted nematode varied according to crop, nematode mobility in soil particles, the number of nematodes present and tissue paper permeability.