条赤须盲蝽形态特征与生物学特性

【目的】明确条赤须盲蝽Trigonotylus coelestialium各虫态的形态特征及其发育历期和成虫繁殖力等生物学特性,为条赤须盲蝽的预测预报及科学防治提供理论依据。【方法】在2021年9-10月郑州室内自然变温(22.0~28.1℃)和25℃恒温条件下,以玉米灌浆期籽粒为食料进行饲养,并观察、记录条赤须盲蝽个体各发育阶段的形态特征,测定其各虫态的发育历期、存活率、成虫寿命及雌成虫产卵量。【结果】条赤须盲蝽卵块产于玉米籽粒基部内颖内侧,卵粒长圆筒形,向一侧略弯。从1龄若虫开始触角呈现红色,随龄期增加红色逐渐明显,至5龄若虫时触角第1节出现3条清晰可见的红色纵纹。翅芽从3龄若虫开始明显可见。雌成虫产卵器长瓣状,平放于生殖节中部的沟槽内。室内自然变温下,条赤须盲蝽卵历期为6.27 d,卵孵化率为89.90%;1-5龄若虫历期分别为2.80, 2.33, 2.70, 2.77和3.90 d,若虫总历期为14.50 d,若虫总存活率为85.97%;雌成虫产卵前期为4.43 d,产卵持续期为13.93 d,单雌产卵19.47块,产卵量为82.55粒。25℃恒温下,条赤须盲蝽卵历期为7.73 d,卵孵化率为81.13%;1-5龄若虫历期分别为2.17, 1.90, 1.77, 1.90和2.93 d;若虫总历期为10.67 d,若虫总存活率为7184%;雌成虫产卵前期为4.17 d,产卵持续期为11.27 d,单雌产卵21.17块,产卵量为72.22粒。【结论】条赤须盲蝽的5龄若虫和成虫的触角第1节的形态特征可用于区分其与该属其他昆虫;其翅芽的发育特征可判别若虫龄期;变温能延长其若虫历期和成虫寿命,同时有利于提高雌成虫产卵量和卵孵化率。     

寄主植物对双斑恩蚜小蜂的发育、存活和繁殖的影响

研究了茄子和扶桑两种不同寄主植物对烟粉虱寄生性天敌双斑恩蚜小蜂Encarsia bimaculata发育、存活和繁殖等特性的影响。在26±0.5℃的条件下,在扶桑上,双斑恩蚜小蜂卵至成虫的发育历期为13.6天,2龄幼虫至成虫的存活率为93.2%;而在茄子上双斑恩蚜小蜂卵至成虫的发育历期和2龄幼虫至成虫的存活率分别为12.1天和91.1％。扶桑上双斑恩蚜小蜂雌性成虫的平均寿命为8.0天,平均单雌产卵量为35.9粒;而在茄子上雌性成虫的平均寿命为6.6天,平均单雌产卵量为27.6粒。双斑恩蚜小蜂在扶桑和茄子植物上的种群内禀增长率分别为0.2081和0.892。两种不同寄主植物对双斑恩蚜小蜂在若虫发育历期和存活率、成虫寿命和平均产卵量以及内禀增长率等方面均存在着显著差异。研究结果表明,寄主植物对双斑恩蚜小蜂的发育、存活和繁殖有较大的影响。     

冷藏温度对日本刀角瓢虫存活及生长发育的影响

【目的】本研究旨在调查不同冷藏温度下日本刀角瓢虫Serangium japanicum成虫生物学特性及F₁代的生长发育,明确日本刀角瓢虫成虫最适冷藏温度。【方法】将日本刀角瓢虫成虫置于不同低温(7,10,13和16℃),贮藏10 d时测定其存活率、单雌产卵量、寿命和对烟粉虱Bemisia tabaci 4龄若虫的日捕食量,以及日本刀角瓢虫F₁代存活率和发育历期;qRT-PCR测定日本刀角瓢虫成虫体内热激蛋白基因Hsp70和Hsp90的相对表达量。【结果】日本刀角瓢虫成虫在16℃低温贮藏10 d时,其存活率、雌雄成虫寿命、单雌产卵量和日捕食量以及F₁代存活率均与贮藏在26℃的对照无显著差异(存活率：99%vs 100%;雌成虫寿命：110.65 d vs 106.87 d;雄成虫寿命：123.12 d vs 108.79 d;单雌产卵量：399.19粒vs 422.63粒;日捕食量：34.70头vs 31.95头;F₁代存活率：80.39%vs 94.12%);但其F₁代发育历期...     

紫茎泽兰粗提物对草地贪夜蛾生长发育及繁殖的影响

为明确紫茎泽兰粗提物对草地贪夜蛾生长发育及繁殖的影响,在实验室条件下分别利用4个不同稀释浓度（20、15、10、5倍）的紫茎泽兰粗提物处理玉米叶片后喂养草地贪夜蛾初孵幼虫,记录各虫态的发育历期、存活率、重量、成虫寿命以及后代性比、F2代卵孵化率、F2代卵的发育历期。结果表明,随着紫茎泽兰粗提物浓度的升高,草地贪夜蛾各虫态的发育历期延长,5倍稀释液处理下蛹的发育历期最长,达20.27 d,10倍稀释液处理下幼虫的发育历期最长,为21.46 d;随着处理浓度的增加,各虫态的重量逐渐降低,且存活率呈下降趋势,其中粗提物对蛹存活率的影响最大,对1~3龄幼虫存活率的影响较小;随着处理浓度的升高成虫的寿命均缩短,且雌成虫寿命长于雄成虫;随着处理浓度的升高,草地贪夜蛾的产卵前期和F2代卵发育历期延长,产卵期缩短;单雌产卵量、后代性比和卵的孵化率降低。总的来说,紫茎泽兰粗提物对草地贪夜蛾的生长发育及繁殖均造成消极影响。5倍稀释液对草地贪夜蛾的生长发育及繁殖的影响最显著,可作为草地贪夜蛾防治研究中的重要植物源杀虫剂材料。     

寄主植物对B型烟粉虱形态学和生物学特性的影响

为了解B型烟粉虱(Bemisiatabaci)在不同寄主植物上的生物学特性,以制定科学的综合治理措施,作者在271℃的条件下,研究测定了B型烟粉虱在棉花(Gossypiumhirsutum)、一品红(Euphorbiapulcherrima)、甘蓝(Brassicaoleraceavar.capitata)、黄瓜(Cucumissativus)、西葫芦(Cucurbitapepo)、茄子(Solanummelongena)和番茄(Lycopersiconesculentum)上各虫态大小、成活率、发育历期、成虫寿命、平均产卵量等生物学参数。结果表明:取食不同寄主植物的烟粉虱伪蛹在黄瓜和棉花上体型最大,在一品红上最小;烟粉虱从卵到成虫羽化,发育历期以在一品红上最长(22.0d),黄瓜上最短(17.3d);平均单雌产卵量以在番茄上最多(266.5粒/雌),一品红上最少(112.9粒/雌);成虫的寿命在番茄、黄瓜和茄子上显著长于在其他4种寄主植物上。烟粉虱从卵发育到成虫的存活率以在黄瓜上最高(77.8%),西葫芦上最低(55.6%),两者差异显著。综合比较7种寄主植物,黄瓜是烟粉虱种群生长发育和繁殖的最适寄主。     

不同寄主植物对柑橘木虱发育和繁殖的影响

【目的】研究柑橘木虱Diaphorina citri Kuwayama在柚、酸橘、黄皮、九里香、砂糖橘5种代表性芸香科寄主植物上的发育、存活和繁殖情况,为柑橘木虱及黄龙病的可持续防控提供参考。【方法】利用种群生命表的方法,分析了柑橘木虱在5种不同寄主植物上的发育历期、存活率、成虫寿命、性比及产卵量等数据。【结果】柑橘木虱卵、1龄若虫以及整个若虫的发育历期受寄主植物的影响较为明显,在26℃条件下在柚子植物上柑橘木虱若虫的存活率最高(58.10%),在黄皮上最低(46.04%),两者差异显著。寄主植物影响柑橘木虱成虫寿命,在柚子上柑橘木虱成虫的寿命显著长于黄皮上的寿命。黄皮上的柑橘木虱的单雌产卵量(298粒/雌)显著低于其他4种寄主植物。柑橘木虱在九里香上的内禀增长率(rm)最高(0.133 7)、酸橘上最低(0.129 8);而净增值率(R0)在砂糖橘上最高(187.74)、黄皮上最低(145.27)。【结论】在5种寄主植物中,除黄龙病隐症寄主九里香之外,显症寄主中砂糖橘是柑橘木虱的最适寄主。     

寄主作物对B型烟粉虱生长发育和种群增殖的影响

在恒温28℃、湿度80％的条件下研究了5种寄主植物对B型烟粉虱(Bemisia tubaci)生长、发育和繁殖的影响。结果表明：取食棉花、烟草、花生、大豆和玉米的烟粉虱。其形态、发育历期、存活率、成虫繁殖力和寿命等生命参数均有明显差异。棉花、大豆和玉米不利于烟粉虱卵和若虫的生长发育。表现为虫体较小、卵期和生命周期延长、存活率降低。烟粉虱在棉花、大豆、花生、烟草和玉米上的生命周期分别为32．03d、32．11d、25．69d、24．43d和20．68d。其存活率分别为49．86％、54．41％、86．86％、69．93％和29．38％。与烟草和玉米相比。棉花、大豆和花生明显有利于烟粉虱的种群繁殖．在棉花、大豆、花生、烟草和玉米上生长发育的成虫寿命和单雌产卵量分别是27．8d和235．O粒、23．2d和191．1粒、22．Od和131．1粒、6．25d和28．O粒、2．42d和5．1粒。在花生、大豆、棉花、烟草和玉米上的内禀增长率(rm)分别为O．1590、O．1364、O．1236、O．0841和-O．0285．其种群趋势指数(I)分别为113．85、117．38、103．98、19．58和O．4274。     

取食不同夏季寄主对牧草盲蝽若虫生长发育和成虫寿命的影响

【目的】牧草盲蝽Lygus pratensis Linnaeus再次演替为新疆棉花主要害虫。为明确取食不同夏季寄主对棉田牧草盲蝽若虫生长发育和成虫寿命的影响。【方法】在人工气候条件下,对牧草盲蝽初孵若虫在14种主要夏季寄主植物上的发育历期、羽化率和成虫寿命进行观察,并结合其在田间不同夏季寄主上的发生情况进行了相关性分析。【结果】在14种寄主植物中,牧草盲蝽若虫无法在猪毛菜、灰藜和龙葵上完成生长发育。不同夏季寄主饲养的牧草盲蝽若虫发育历期与成虫寿命存在较大差异。其中,取食向日葵的若虫总发育历期最长,为（23.20±0.66）d,取食灰绿藜的最短,为（12.15±0.25）d;取食向日葵的雌成虫寿命最长为（13.42±0.28）d,取食猪毛菜的最短,为（5.33±0.47）d;取食油菜的雄成虫寿命最长,为（11.40±0.95）d,取食猪毛菜的最短,为（5.13±0.38）d。牧草盲蝽若虫取食不同夏季寄主其发育历期与田间寄主上若虫发生情况基本一致,与羽化成虫的数量呈正相关;取食不同夏季寄主的牧草盲蝽成虫寿命与田间成虫发生情况基本一致。【结论】夏季牧草盲蝽成虫在取食和产卵寄主选择中存在一定差别,明确了牧草盲蝽对夏季寄主的利用模式,为筛选牧草盲蝽夏季诱集寄主和季节性治理对策提供依据。     

栎黄枯叶蛾生长发育与几种寄主内含物的关系

【目的】探讨饲喂不同寄主植物对栎黄枯叶蛾Trabala vishnou gigantina Yang生长发育及繁殖的影响,分析寄主植物内含物与其生长发育及繁殖的关系,为研究不同寄主植物对栎黄枯叶蛾种群动态的影响提供理论依据。【方法】在室内条件下,利用沙棘Hippophae rhamnoides、山杏Armeniaca sibirica、山杨Populus davidiana、旱柳Salix matsudana饲养该虫,观察幼虫发育历期、蛹历期、蛹重及产卵量等指标,同时测定寄主叶片中可溶性糖、可溶性蛋白质、水分、单宁及黄酮的含量,并进行线性回归分析。【结果】不同寄主植物饲喂栎黄枯叶蛾幼虫的发育历期、蛹历期、蛹重及产卵量均存在显著差异。取食沙棘的幼虫历期最短,仅为(74.50?1.76)d,而取食旱柳历期最长,达(106.00?1.51)d。取食山杨的蛹历期最长,为(44.00?1.41)d,最短的是取食旱柳的,仅为(32.70?3.13)d。饲喂沙棘和山杏的雌、雄蛹重和成虫产卵量显著高于饲喂山杨和旱柳的。对不同寄主的营养物质、次生物质和水分含量测定结果表明:不同寄主间营养物质、次生物质与水分的含量差异显著。回归相关分析表明:幼虫发育历期与寄主植物可溶性蛋白质含量呈显著负相关;雌蛹重和产卵量与寄主植物可溶性糖含量呈显著负相关;雌、雄蛹重与寄主植物含水量呈显著正相关;蛹历期与单宁含量呈显著正相关,但黄酮含量的高低与栎黄枯叶蛾生长发育等指标无相关性。【结论】沙棘是栎黄枯叶蛾生长发育及繁殖的最适寄主植物;并且寄主植物中可溶性糖、单宁的含量低、含水量和可溶性蛋白质含量高有利于栎黄枯叶蛾的生长发育和繁殖。     

茶翅蝽生长发育、繁殖及若虫各龄期形态特征研究

【目的】为掌握茶翅蝽Halyomorphahalys(St?l)的发生及为害特性,进一步采取有效的防治措施,本文测定了茶翅蝽卵到成虫的发育历期、成虫的寿命及其繁殖能力,并研究了茶翅蝽若虫各龄期的形态特征。【方法】本文在温度(25±1)℃,湿度RH 70%±5%,光照周期16 L∶8 D的实验条件下,采用单头饲养法,测定了茶翅蝽从卵到成虫的生长发育历期、1-5龄若虫的形态特征,并通过新羽化成虫配对饲养测定成虫的寿命及雌虫的繁殖能力。【结果】茶翅蝽卵到成虫的发育历期为(44.98±2.54)d,其中卵的发育历期为(6.90±0.05)d,孵化率为96.06%;若虫总发育历期为(38.08±2.49)d,1-5龄历期分别为(5.41±0.17)、(9.17±0.15)、(6.73±0.16)、(7.46±0.49)和(9.28±0.32)d,若虫总存活率为59.97%;雌、雄成虫寿命分别为(30.80±2.41)d和(36.56±2.82)d;雌成虫产卵前期为11.80 d,持续产卵期为14.08 d,单雌一生平均产卵量为83.80粒。茶翅蝽1龄若虫色彩鲜艳,黄色、褐色或橘红色,体长为(1.93±0.03)mm,宽为(1.43±0.02)mm,足胫节黑色无白斑;2-5龄若虫主体均为黑色,2龄胸部背板黑色、无黄斑,足胫节黑色无白斑,体长为(2.52±0.05)mm,宽为(1.73±0.03)mm;3龄胸部背板黑色且有黄斑、无翅芽,足胫节黑色并带有白斑或白环,体长为(4.29±0.05)mm,宽为(2.93±0.06)mm;4龄翅芽开始显现延伸至后胸后缘,足胫节有白环,体长为(6.46±0.10)mm,宽为(4.46±0.08)mm;5龄翅芽末端近达腹部第2节后缘,足胫节有白环,体长为(9.25±0.19)mm,宽为(6.18±0.16)mm。【结论】在25℃下,茶翅蝽卵到成虫的发育历期为44.98 d,卵到成虫的存活率为57.60%,平均每雌产卵量为83.80粒。翅芽的发育特征及足胫节上是否有白色环纹是辨别若虫各龄期的重要依据。     

中国禾谷类作物野生近缘植物在育种中的利用

中国主要禾谷类作物有水稻、小麦、大麦、燕麦、玉米、高粱、粟、黍稷,它们的野生近缘植物在中国禾谷类作物育种中得到了较好的利用,不仅拓宽了作物的遗传基础,而且培育出优良品种在生产上大面积推广,在提高粮食产量中起到了重要作用.     

Effects of root applications of gibberellic acid on photosynthesis and growth in C3 and C4 plants

The effects of root applications of gibberellic acid (GA₃) on growth and photosynthesis of 12 species of plants including C₃ monocots (Triticum aestivum L., wheat, Hordeum vulgare L., barley and Avena sativa L., oat), C₃ dicots (Vigna radiata L., mung bean, Cucurbita moschata L., squash and Capsicum annuum L., pepper), C₄ monocots (Zea mays L., corn, Sorghum vulgare L., sorghum and Panicum ramosum L., millet) and C₄ dicots (Amaranthus retroflexus L., pigweed, Kochia scoparis L., kochia and Gomphrena celosoides L., gomphrena) were evaluated. Relative growth rates (RGR) of barley, oat, squash, pepper, corn, sorghum, millet, pigweed and kochia were increased above the control by 12.7%, 9.9%, 11.3%, 10.7%, 19.2% 10.1%, 11.5%, 16.4% and 32.7% respectively, four days following optimum GA₃ treatments. There was no effect of GA₃ on RGR in wheat, mung bean, and gomphrena. Gibberellic acid decreased the chlorophyll content expressed on an area basis by 20.0%, 13.9%, 20.9%, 17.1%, 11.9% and 28.0% in barley, squash, pepper, sorghum, pigweed and kochia, respectively, while that of oat, wheat, mung bean, corn, millet and gomphrena remained unchanged. When photosynthetic rates were expressed per mg of chlorophyll, it showed that GA₃ could stimulate photosynthesis in barley, squash, pepper, sorghum, millet, pigweed and kochia by 20.4%, 20.6%, 16.5%, 17.4%, 10.4%, 24.2%, and 29.4%; while there was no effect in oat, wheat, mung bean, corn and gomphrena. An increase in leaf blade area and/or length of sheath were observed in GA₃ treated plants of oat, barley, mung bean, squash, pepper, corn, sorghum, millet and kochia. The transpiration rate remained unchanged following GA₃ treatment in all 12 species.This work was supported in part by the Fair Funds administered by the Pennsylvania Department of Agriculture. Contribution No. 39, Department of Horticulture, The Pennsylvania State University. Authorized for publications as paper no. 6886 in the journal series of the Pennsylvania Agricultual Experiment Station.Research assistant and assistant professor respectively.     

Host status of wheat and corn for Chilo suppressalis (Lepidoptera: Crambidae)

Host plant specificity depends on recognition of the host and the ability to discriminate it from nonhost plants. Chilo suppressalis (Walker) (Lepidoptera: Crambidae), an important insect pest of rice, is considered to be polyphagous, although few papers have ever reported infestation of C. suppressalis on most of the recorded hosts. The present investigation was designed to test whether two important gramineous crops, wheat and corn, are host plants of C. suppressalis based on the host-plant finding process in cage and Y-tube olfactometer tests, oviposition and egg hatching, and larval feeding and survival. In the cage tests, gravid C. suppressalis females did not differentiate rice plants from wheat or corn plants when only visual cues were involved, but were more attracted to rice plants when only olfactory cues or both vision and olfaction were present. The Y-tube olfactometer tests further confirmed that the females did not prefer wheat or corn plants, and revealed that they responded equally to clean air and odors from wheat or corn plants. Under no-choice and choice condition alike, the females laid eggs on a lower proportion of wheat and corn plants and egg number and hatching rate were significantly reduced on wheat and/or corn plants than on rice plants. Larval feeding was not observed in wheat and lower in corn than in rice plants, and no pupae or surviving larvae were collected from wheat and corn plants. The results suggest that wheat and corn are not host plants of C. suppressalis. These findings are discussed in context of host-finding process in C. suppressalis and management of resistance to transgenic Bt rice.     

A certain but non-exclusive association between Polymyxa graminis special forms and cereals

Polymyxo graminis, a ubiquitous plasmodiophorid obligate root endoparasite, is recognized as the vector of about 15 viruses on cereals and groundnut in temperate and tropical areas. Within the species, five special forms have been distinguished on the basis of specific ribotypes. Three of them occur in tropical areas: P. graminis f.sp. colombiana on rice, P. graminis f.sp. subtropicalis on cereals cropped in the tropics such as maize, pearl millet and sorghum but also on barley and/or wheat, and P. graminis f.sp. tropicalis mainly on maize, pearl millet and sorghum. Their particular host ranges distinguish them significantly from P. graminis f.sp. temperata and P. graminis f.sp. tepida found in temperate areas on barley and wheat. In order to assess whether these special forms commonly infect these cereals, barley and wheat plants were grown under controlled conditions on two soils from Belgium and France and both infested by P. graminis f.sp. temperata and P. graminis f.sp. tepida. The infection of each cereal species by each form was quantified by real-time quantitative PCR with specific primers and Taqman probes. The infection of P. graminis f.sp. temperata was significantly higher on barley than on wheat, whereas the quantities of P. graminis f.sp. tepida on wheat were higher than on barley. These results show that the distinction between these special forms, based on the ribotype, reflects differences in ecological features.     

Cereal prolamin evolution and homology revealed by sequence analysis

Prolamin mixtures were isolated from oats, rice, normal and high-lysine sorghum, two varieties of pearl millet, two strains of teosinte, and gamma grass and subjected to NH₂-terminal amino acid sequence determinations. In each case (except for rice, whose prolamins apparently have blocked or unavailable NH₂-terminal residues), primarily a single sequence was observed despite significant heterogeneity, suggesting that prolamin homology in each cereal arose through duplication and mutation of a single ancestral gene. Comparisons were then made to prolamin sequences previously determined for wheat, corn, barley, and rye. Within genera, different varieties or subspecies exhibited few differences, but more distantly related genera, subtribes, and tribes showed increasingly large differences. Within the subfamily Festucoideae, no homology was apparent between prolamins of oats and those of the subtribe Triticinae (including wheat, rye, and barley, for which prolamin homology was previously demonstrated). Within the subfamily Panicoideae, corn was shown to be closely related to teosinte but more distantly to Tripsacum. Sorghum was shown to have diverged less from corn than had millet. These comparisons demonstrate that prolamin sequence analyses can successfully predict and clarify evolutionary relationships of cereals.     

Effects of intergenerational host plant alterations on developmental parameters of Spodoptera frugiperda (Lepidoptera: Noctuidae)

The fall armyworm (FAW), Spodoptera frugiperda (Smith), is known as a destructive moth pest of agricultural crops such as corn, rice, and sorghum. Recently, its damage threatens crops in Asian temperate regions due to its high migration ability. Two genetic types of FAW, a corn strain mostly found on corn and a rice strain associated with rice, have been reported. The objective of this study was to evaluate whether migrated corn-collected population of FAW could maintain its population on various seasonal plants including non-preferred Poaceae plants, with special emphasis on Jeju, Korea. Development-related parameters were compared after switching host plants including corn (C), Sudan grass (S), proso millet (M), and rye (R) when rearing FAW. Most developmental parameters showed dynamic changes according to sequential alternation of host plants with the progress of generations. When all R₀ (net reproductive rate) values were scaled by the R₀ in C to C alteration, the scaled values of other alterations were less than “1.0”, indicating less fitness than C to C alteration (R₀ value: 0.57 for C to S, 0.49 for C to M in F3 generation; 0.82 for S to S, 0.65 for S to M, and 0.58 for S to C in F4 generation, 0.50 for M to M, 0.59 for M to R, and 0.83 for M to C in F5 generation). Although our results did not show that S. frugiperda adapted perfectively on new host plants, this pest was able to successfully reproduce up to five generations with non-preferred host plants. Results indicate that winter crops such as rye might be hosts for migrated corn-preferred populations of S. frugiperda during winter after breeding three to four cycles on other host plants before winter if weather condition is allowed for its survival.     

Bright Greenish-Yellow Fluorescence and Aflatoxin in Agricultural Commodities

The corn milling industry has widely accepted the presence of bright greenish-yellow fluorescence under a black light as a presumptive indicator of aflatoxin (a poison produced by the mold Aspergillus flavus). This test was applied to wheat, oats, barley, rice, coconut, white corn, yellow corn, peanuts, sorghum, and soybeans, and evaluated in the laboratory. Our study supported the use of bright greenish-yellow fluorescence as a presumptive test for aflatoxin in wheat, oats, barley, corn, and sorghum.     

Shoot apical meristem: A sustainable explant for genetic transformation of cereal crops

Summary Immature zygotic embryo has been the widely used explant source to develop embryogenic callus lines, cell suspensions and protoplasts for transformation of cereal crops including maize, wheat, rice, oat, barley, sorghum, and millet. However, the lack of competence of immature embryos in certain elite lines is still a barrier to rontine production of transgenic cereal crops in certain commercial cultivars. In addition, a great deal of effort is required to produce immature embryos, manipulate cultures, of immature embryos or their cell suspensions, and cryoperserve cultures for further use. In addition, undifferentiated cells may have reduced regenerability after a few months, of in vitro culture. Alternative explants and regeneration systems for efficient transformation of cereal crops are needed to avoid or reduce the above limitations. During the past decade, scientists have successfully manipulated the shoot apical meristerms from seedlings of maize oat, sorghum, millet, wheat, and barley in an effort to develop a less genetype-dependent and efficient cereal regneration system that can be maintained in vitro for long pertiods of time without the need for cryopreservation. Furthermore, apical mesistem regeneration systems were used to stably transform maize, wheat, rice, oat, barley, sorghum, and millet.     

Biology,host preferences and fitness of <Emphasis Type="Italic">Oulema melanopus</Emphasis> (Coleoptera: Chrysomelidae), a recent invasive pest in Western Canada

The developmental parameters and fitness of a recent invasive insect pest of cereals in western Canada, the cereal leaf beetle, Oulema melanopus (L.) (Coleoptera: Chrysomelidae), were compared on live plants and excised leaves of commercial cultivars of potential cereal hosts including wheat (winter and spring), oats, barley, corn, rye and triticale. Host preference and utilization within the fundamental host range of O. melanopus differed. The biological parameters differed significantly when the larvae were reared on excised tissues versus on live host plants. In both studies, wheat (winter and spring), oat (cv. Morgan) and barley were the most preferred hosts in terms of development, survivorship, adult weights and fecundity. Prolonged development with low fitness gains was noted on corn. Although the development on hosts such as rye and triticale was prolonged and adult fitness was low, the survivorship was high on these hosts. Hence, these crops can act as secondary hosts for the beetle in its new eco-region. Larvae fed foliage of Waldern, a local oat cultivar, had increased developmental time and lower survivorship compared with other cereal hosts. Despite differences in fitness gains among hosts, similar numbers of eggs were laid on all hosts. Hence, the oviposition choice of O. melanopus may not be driven by fitness gains alone and it may indicate adaptive strategy to hosts in newer environments.     

寄主转换对稻纵卷叶螟寄主种群适合度及生命表参数的影响

【目的】稻纵卷叶螟Cnaphalocrocis medinalis是水稻的迁飞性害虫之一,同时也能在玉米上完成世代。本研究旨在探究寄主转换对稻纵卷叶螟寄主种群适合度的影响。【方法】稻纵卷叶螟玉米种群和水稻种群分别取食原寄主和转换寄主,形成取食玉米的稻纵卷叶螟玉米种群、取食水稻的稻纵卷叶螟玉米种群、取食玉米的稻纵卷叶螟水稻种群和取食水稻的稻纵卷叶螟水稻种群4个处理组合,构建这些处理组合的稻纵卷叶螟寄主种群年龄 龄期两性生命表,测定其适合度和生命表参数。【结果】稻纵卷叶螟幼期发育历期以取食水稻的稻纵卷叶螟水稻种群最长(29.2 d),以取食水稻的稻纵卷叶螟玉米种群最短(24.8 d);适合度指标(蛹重、化蛹率、羽化率、产卵量)、生命表参数(存活率、最大繁殖力、最高繁殖值、幼期寿命期望值)、种群参数(内禀增长率、周限增长率、净增殖率)均在两种群取食玉米时最大,在取食水稻的稻纵卷叶螟玉米种群中最小(除蛹重外),而且取食玉米的稻纵卷叶螟水稻种群又往往优于取食水稻的稻纵卷叶螟水稻种群。【结论】稻纵卷叶螟玉米种群在寄主转换后适合度和种群增长显著下降,而稻纵卷叶螟水稻种群在寄主转换后适合度和种群增长有所上升,表明玉米比水稻更有利于提高稻纵卷叶螟的适合度和种群增长,这一与自然条件下稻纵卷叶螟极少在玉米上发生为害相悖的现象值得深入研究。