Appresoorium formation of Puccinia hordei on partially resistant barley and two non-host species

One of the components of partial resistance of barley to leaf rust,Puccinia hordei, is a reduced infectibility. It was investigated whether this low infectibility may rest on a hampered appressorium formation of the leaf rust fungus. The appressorium formation on the primary leaves of 11 barley genotypes with an intermediate-to-low infectibility was compared with that on the highly infectible L94. The number of stomata per cm² leaf area occupied by appressoria ofP. hordei was determined per genotype by means of fluorescence microscopy. No cosistent differences could be detected, indicating that the mechanisms causing a low infectibility of partially resistant barley seedlings act at a phase later than the formation of the appressoria. On the non-host wheat not fewer appressoria were formed than on L94, but no appressoria were found on a lettuce genotype. The latter probably lacks the stimuli that enable the fungus to find stomata.Samenvatting Eén van de componenten van partiële resistentie van gerst tegen dwergroest,Puccinia hordei, is een verminderde infectiedichtheid. Het mechanisme, dat hieraan ten grondslag ligt, is onbekend. Een experiment werd uitgevoerd om na te gaan of bij partieel resistente rassen een verminderde appressoriumvorming optreedt. Na inoculatie in een inoculatietoren en een zorgvuldig uitgevoerde incubatie werd het aantal huidmondjes per cm² bladoppervlak bepaald dat bezet was door appressoria vanP. hordei. De elf weinig vatbare gerstlijnen uit deze studie bleken niet reproduceerbaar te verschillen van de zeer vatbare gerstlijn L94 in de mate van appressoriumbezetting. Dit wijst erop dat infectiedichtheidsverschillen t.g.v. partiële resistentie veroorzaakt worden door mechanismen die werken na de appressoriumvorming. In een tweede experiment werd aangetoond dat zelfs op de niet-waardsoort tarwe, waaropP. hordei geen symptomen veroorzaakt, niet minder appressoria worden gevormd dan op L94. Op een sla-genotype trad echter geen appressoriumvorming op. Op deze laatste niet-waardsoort ontbreken waarschijnlijk de stimuli die de schimmel in staat stellen huidmondjes te vinden.     

两种平腹小蜂的研究进展

平腹小蜂是一类优良的卵寄生蜂, 是寄生性天敌昆虫中已具有成熟的规模化繁殖技术和田间释放技术, 并成功应用于害虫防治的天敌昆虫之一, 在防治果树蝽类害虫方面效果显著?平腹小蜂的发育学?行为学?生态学?繁殖技术及田间应用技术的研究已有60多年历史, 近年来, 分子生物学和高通量测序手段的应用促进了对平腹小蜂的生理生化基础研究, 研究领域也开始拓宽?本文从分类学?生物学特性?人工繁殖?共生菌?滞育?寄生机制?毒液蛋白和味觉受体基因等方面, 对目前广泛应用于荔枝蝽和茶翅蝽防治的2种平腹小蜂, 麻纹蝽平腹小蜂Anastatus fulloi Sheng &Wang和日本平腹小蜂 Anastatus japonicus Ashmead近30年的研究进展进行归纳和总结, 并对今后的研究方向进行展望, 旨在为平腹小蜂的深入研究和应用技术研发提供参考?     

Insect-neuroactive substances in two species of the genus Liquidamber

Three insect-neuroactive substances from Liquidamber styraciflua and L formosana were isolated and characterized by spectral analyses as betulonic acid, 1-methoxy-9-caryolanol and eudesm-4(14)-ene-1,6-diol, respectively. ©1999 Society of Chemical Industry     

准噶尔荒漠两种猪毛菜果实扩散特性研究

植物的扩散能力受扩散体数量和形态特征、扩散方式和扩散距离等因素的影响。文中以分布于准噶尔荒漠的紫翅猪毛菜(Salsola affinis)和散枝猪毛菜(Salsola brachiata)为研究材料,对其扩散体形态特征及扩散特性进行了研究。实验结果表明:两种猪毛菜果实数量和株高、果实生物量和植株总生物量呈正相关;果实是该物种的扩散单元,风和水是其主要扩散媒介,风媒扩散属于近距离扩散,水媒扩散属于远距离扩散;果翅的大小对扩散具有显著影响。以上特征是该物种适应荒漠环境的重要因素。     

2种蚜虫在蚕豆上适合度的研究

为了明确豌豆修尾蚜Megoura crassicauda和豆蚜Aphis craccivora在蚕豆上适合度的差异,从中选出适合度较高的蚜虫用于天敌昆虫的大规模繁殖,对两种蚜虫在蚕豆上的发育参数进行了观察并建立了生命表。结果表明：2种蚜虫的成虫历期和世代周期差异虽不显著,但豌豆修尾蚜的若虫历期6.66 d显著低于豆蚜的7.86 d。产蚜量曲线中,豌豆修尾蚜的产蚜量在前期虽迅速增加,但2种蚜虫的生殖力参数差异均不显著。存活率曲线中,豌豆修尾蚜在蚕豆上14～30.5 d时的存活率低于豆蚜,30.5 d后开始高于豆蚜,且其整体存活率曲线比较稳定。生命参数表中,豌豆修尾蚜的周限增长率和内禀增长率分别为1.38和0.32,均高于豆蚜的1.33和0.29。综上,相较豆蚜,豌豆修尾蚜在蚕豆苗上的适合度、存活稳定性更高,更适合在蚕豆上大量扩繁,在蚜虫天敌规模化生产中具有一定的应用潜力。     

两种草地贪夜蛾卵寄生蜂的田间寄生作用调查

草地贪夜蛾Spodoptera frugiperda (J.E.Smith)为新入侵我国的重大害虫,对我国农业生产造成了巨大的威胁.为挖掘、评估及利用广西地区草地贪夜蛾的寄生蜂天敌资源,于2019年8月至10月、2020年8月在南宁市玉米产区进行了草地贪夜蛾寄生蜂的调查.共发现夜蛾黑卵蜂Telenomus remus(...     

Discovery of two northern hemisphere Armillaria species on Proteaceae in South Africa

Armillaria root rot symptoms were observed on native Protea and Leucadendron (Proteaceae) species in Kirstenbosch Botanical Gardens in the Western Cape Province of South Africa. Intergenic spacer (IGS)-1 polymerase chain reaction (PCR) restriction fragment-length polymorphism (RFLP) profiling indicated the presence of at least two Armillaria species. The profiles of two isolates were identical to those of A. mellea s. str., originating in Europe. Phylogenetic analyses incorporating internal transcribed spacer (ITS) and IGS-1 sequence data identified the remaining isolates as closely related to A. calvescens , A. gallica , A. jezoensis and A. sinapina . These isolates displayed mating compatibility with A. gallica. From the RFLP profiles, sequencing results and sexual compatibility studies, it is concluded that the two species on Proteaceae in Kirstenbosch represent A. mellea and A. gallica . These are northern hemisphere fungi that have apparently been accidentally introduced into South Africa. This is the second report of Armillaria being introduced into South Africa. The introduction probably occurred early in the colonization of Cape Town, when potted plants from Europe were used to establish gardens.     

Potential distribution of two Ambrosia species in China under projected climate change

The invasion of Ambrosia artemisiifolia and Ambrosia trifida from their native range to occupy large areas in China has raised considerable concern. Using the maximum entropy (Maxent) method, we developed models for each Ambrosia species, based on occurrence records from both native ranges (North America) and their invaded ranges (e.g. northern and south‐western Europe) to predict the availability and distribution of suitable habitats for these two species in China. For each species, we also assessed potential shifts in habitat suitability for the year 2050, using three general circulation models (GCMs) and two emission scenarios. Elevation and average mean precipitation in October contributed most to model development for both species. Potential distribution projections under future climatic change scenarios suggested an averaged percentage of suitable area (2.21%) and habitat gain (1.49%) in A. artemisiifolia distribution, with further expansion to environmentally favourable locations in south‐east coastal regions, northern Taiwan and the Beijing–Tianjin–Tangshan area in northern China. Future predicted percentage of suitable area for A. trifida was 0.03% with a very limited suitable habitat gain of <1% although this species had the potential to continue to spread in northern China. Our findings suggest that management priorities should be focused on A. artemisiifolia, whilst effective control strategies for A. trifida may be optimised by concentrating efforts on those relatively fewer regions of China where the species is currently abundant.     

Harmonious interaction of kaolin and two insect predator species in plant protection

Lacewings and lady beetles represent two important groups of natural enemies for pest control. Kaolin is used in various crop ecosystems to reduce abiotic plant stressors and pest colonization. Compatible methods aimed at reducing abiotic and biotic plant stressors are desired in crop management systems. Therefore, this work evaluated the development and survival of Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) and Eriopis connexa (Germar) (Coleoptera: Coccinellidae) larvae of different ages treated with kaolin at three different concentrations (ca. 60, 80, and 100 g/L) and prey consumption when treated with kaolin at a field rate of 60 g/L. The prey used were the whitefly Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae) and the aphid Lipaphis erysimi (Kalt.) (Hemiptera: Aphididae). Survival rates and development durations for E. connexa larvae topically treated with kaolin at different ages were similar to those for untreated larvae. However, larvae of C. externa reduced survival and delayed development when treated with kaolin concentrations greater than the recommended field rate. Otherwise, kaolin treatments did not affect prey consumption by larvae and adults of both predator species.     

Induced tolerance of Sclerotinia sclerotiorum to isothiocyanates and toxic volatiles from Brassica species

The response of Sclerotinia sclerotiorum , the causal agent of stem rot of oilseed rape ( Brassica napus ), to toxic volatiles produced by the glucosinolate-myrosinase system was studied. Mycelium plugs were exposed to inoculated leaf discs of oilseed rape cultivars and two related species, black mustard ( Brassica nigra ) and white mustard ( Sinapis alba ). Growth of exposed colonies was inhibited by more than 87% compared with controls. Despite inhibition of exposed fungal colonies, the fungus continued to grow in infected tissue. Repeated exposure of the fungus to hydrated mustard powder (which contains both glucosinolates and myrosinase) or synthetic isothiocyanates (ITCs) resulted in growth inhibition decreasing from initial levels of up to 80% to insignificant levels after 2–3 days, suggesting that S. sclerotiorum has the ability to adapt to volatiles during the infection progress. This adaptation was studied by investigating induction of glutathione S-transferase-like genes identified from the S. sclerotiorum genome. Three genes, with locus numbers SS1G_07195.1, SS1G_01918.1 and SS1G_10295.1, appeared to be up-regulated following exposure of S. sclerotiorum to mustard powder or allyl ITC. A fourth gene, SS1G_07319.1, appeared to be down-regulated. In addition, glutathione S-transferase catalytic activity in crude mycelium extracts was doubled following 48 h of exposure to mustard powder volatiles. This adaptation could allow S. sclerotiorum to parasitize tissues of Brassica species despite the production of toxic metabolites.     

两种油菜露尾甲外生殖器结构的观察

对春油菜上的两种露尾甲害虫 ,油菜叶露尾甲和油菜花露尾甲的雌雄外生殖器的形态结构进行了比较研究 ,发现两种露尾甲的产卵器结构差异较大 ,是其产卵时对油菜造成危害不同的基本原因。通过对两种露尾甲的雄性外生殖器结构比较 ,表明其雄性外生殖器结构不同 ,特别是阳茎基差异明显 ,可用于两者的区别     

极旱环境中两种梭梭蒸腾的生理生态学特点

白梭梭(Haloxylon persicum)和梭梭(H.ammodendron)是我国干旱荒漠区的优良固沙植物,列入我国第一批保护植物,白梭梭主要分布在新疆北部的古尔班通古特沙漠,梭梭除了分布在新疆外,还分布在青海、甘肃、内蒙古等地,对于它们的生物生态学特性的研究,国内已先后做过不少工作,关于生理方面的研究也有报导。本项工作是从水分生理观点着手,结合     

引诱剂对两种外来白蚁的引诱作用

利用白蚁喜食的植物和添加剂等配制了4种白蚁诱饵并在进口木材上进行了诱捕试验，筛选出了效果较好的2种配方。并对其在木材白蚁检疫中的应用进行了探讨。     

梨树两种害虫的测报

梨树是江西中、北部的一种重要果树,随着果树种类结构的调整,形成了"南桔北梨"的布局,梨树种植的面积也得到相应的扩展。由于梨树害虫种类繁多,不少害虫为害甚重,往往由于防治失时,     

Response of two lacewing species to biorational and broad-spectrum insecticides

Green lacewings, includingChrysoperla rufilabris (Burmeister) andCeraeochrysa cubana (Hagen), are predators of small, soft-bodied insects including whiteflies. The silverleaf whitefly,Bemisia argentifolii Bellows & Perring [formerlyB. tabaci (Gennadius) strain B], is an important pest of agronomic, vegetable and ornamental crops. Practical use of these lacewings as biological control agents would be facilitated by better understanding of their responses to both biorational (selective) and broad-spectrum insecticides. The topical and residual toxicity of azadirachtin (Azatin-EC^TM), insecticidal soap (M-Pede^TM), paraffinic oil (Sunspray Ultra-Fine Spray Oil^TM) and the pyrethroid bifenthrin (Brigade^TM) to eggs, larvae and adults of the lacewings were studied in the laboratory. Larvae ofC. cubana were much more tolerant to residues of bifenthrin than wasC. rufilabris and were somewhat more tolerant to topically applied soap. At normal field concentrations, azadirachtin (0.005%, by wt a.i.), paraffinic oil (1.0% by volume) and soap (1.0% by volume) were not toxic to larvae or adults of either species either topically or residually. Oil was toxic topically to eggs but azadirachtin and soap were not. Bifenthrin was toxic topically and residually to larvae and adults but was not so toxic to eggs as was oil. Thus, selectivity of all materials tested was relative to lacewing species and lifestage. The relative tolerance to insecticide residues exhibited byC. cubana larvae may be related to its trash-carrying habit, suggesting that use of trash-carrying chrysopids in place of non-trash carriers for augmentative biological control would increase options for non-disruptive chemical intervention when necessary.     

美国甜豆中2种壳二孢综合症病菌的检疫鉴定

从进境邮件截获的美国甜豆中分离到两株可疑菌株,通过菌落特征、分生孢子形态比较、ITS和G3PD基因扩增、核酸序列比对、系统发育分析及致病性测定,确定截获的两株菌分别为豌豆脚腐病菌(Phoma pinodella)和豌豆球腔病菌(Ascochyta pinodes),这是我国首次从同一样品中同时检出两种壳二孢属真菌。     

The occurrence of two phytoplasmas associated with stunted Rubus species in the UK

Polymerase chain reaction using universal primers to sequences in the 16S rRNA gene, and group-specific primers to sequences in the 16S/23S spacer region, revealed two distinct phytoplasmas occurring in Rubus plants showing symptoms of rubus stunt. One phytoplasma appeared similar to phytoplasmas in the elm yellows group; the other appeared to fall into the X disease group. This finding was confirmed by RFLP analysis of PCR products. This is the first identification of phytoplasmas from either of these groups occurring in the UK, and the first report of a phytoplasma belonging to the X disease group in Rubus .     

Some factors affecting the susceptibility of two nematode species to phorate

The uptake and metabolism of phorate has been compared in two species of free-living, soil nematodes, Aphelenchus avenae and Panagrellus redivivus, which differ greatly in their sensitivity to this pesticide. The dynamics of uptake and metabolism are analyzed using a simple catenary model. Estimated rate constants indicated a much greater rate of phorate metabolism in P. redivivus than in A. avenae, and qualitative differences in the toxic metabolites of phorate produced by the two species were also found. The toxicological importance of these factors is discussed.