Host Range ofBrachycaudus rumexicolens(Patch), an Aphid Associated with the Polygonaceae

The aphidBrachycaudus rumexicolensis a recent arrival in Australia where the weedsEmex australis, E. spinosa,andRumexspecies are its recorded hosts. Host range on 114 species representing 42 plant families was assessed in the laboratory to determine the aphid species' potential as a biological control agent againstE. australis.Survival and reproductive success were measured in clip and/or dialysis-tube cages.B. rumexicolensdeveloped most successfully onEmexspp. andRumexspp. and to a lesser extent on other Polygonaceae.Lupinus albus(white lupin) andTriticum aestivum(wheat) were the only non-Polygonaceae plants on whichB. rumexicolensdeveloped to a degree similar to its usual hosts. At a field site in Western Australia,E. australisandPolygonum avicularewere the only Polygonaceae present and the primary host species ofB. rumexicolens.At peak abundance, it was found on other pasture and crop species, but at considerably lower numbers than on its Polygonaceae hosts. It was concluded that this was due to local migration and that populations would not be sustained on non-Polygonaceae plants. It was also concluded that the risk of virus transmission would not be increased by the presence ofB. rumexicolenson nonhosts.B. rumexicolensis considered sufficiently safe to use in programs aimed at augmenting the impact of biological control agents on the weedE. australis.     

Specific PCR-based detection of Phomopsis heveicola the cause of leaf blight of Coffee (Coffea arabica L.) in China

Coffee (Coffea arabica L.) is currently grown in many tropical and subtropical areas countries and is a major traded commodity for the developing world. Coffee leaf blight, caused by Phomopsis heveicola, is one of the most important fungal diseases dangerous to coffee crops in China. This study aimed to develop a PCR-based diagnostic method for detecting P. heveicola in planta. Specific primers (CPHF/CPHR) were designed based on sequence data of region of internal transcribed spacer (ITS1 and ITS4) of P. heveicola. The efficiency and specificity of CPHF/CPHR were established by PCR analysis of DNA from P. heveicola strains isolated from China and fungal isolates of other genera. A single amplification product of 318 bp was detected from DNA P. heveicola isolates. No amplification product was observed with any of the other fungal isolates tested. The specific primers designed and employed in PCR detected P. heveicola up to 3 pg from DNA isolated. This is the first report on the development of a species-specific PCR assay for identification and detection of P. heveicola. Thus, the PCR-based assay developed was very specific, rapid and sensitive tool for the detection of pathogen P. heveicola.     

Influence of fungicides and insecticides on the entomogenous fungus Metarhizium anisopliae a pathogen of the vine weevil,Otiorhynchus sulcatus

In the laboratory, the fungicides chlorothalonil and zineb prevented germination of Metarhizium anisopliae conidia when incorporated into Sabouraud dextrose agar (SDA) at the commercial concentration (based on the manufacturers’ recommended rates for horticultural crops). Twelve other fungicides and six insecticides had no effect on spore germination when applied at the same rate. Mycelial growth of M. anisopliae on SDA plates containing the recommended rate of all the pesticides (except propamocarb) was reduced compared with SDA alone. Two fungicides, benomyl and carbendazim, totally inhibited growth at 0.1 times the recommended rate. Growth was also completely prevented by the fungicides etridiazole, triforine and zineb, and the insecticides dichlorvos and hostathion, at 10 times the recommended rate. In a glasshouse experiment, a prophylactic drench of M. anisopliae conidia reduced vine weevil (Otiorhynchus sulcatus) populations on Impatiens plants by 88%. This level of control was not significantly reduced by subsequent application (7 days after egg infestation) of any of the pesticides at the recommended concentration. Larval control in pots treated with M. anisopliae plus any one of the 12 fungicides and four insecticides examined, ranged from 82% to 98%. The insecticide diazinon applied alone reduced larval numbers by 100%. Two other insecticides, dichlorvos and cypermethrin, and the fungicide pyrazaphos, also reduced weevil populations by over 50%. These experiments demonstrate the limitations of laboratory based in vitro screening programmes for assessing the chemical compatibility of M. anisopliae.     

Estimation of Different Cellular Compounds from the Mycelium of Phomopsis theae, Causal Agent of Phomopsis Canker Disease of Tea

Variations between three isolates (MP, TP and WP) of Phomopsis theae were studied based on the growth pattern, cellular constituents in the mycelium and protein expression profile. The growth initially increased and later decreased. The growth of these isolates in terms of mycelial dry weight exhibited in the order of MP > TP > WP isolates. The quantitative estimation of cellular constituents such as total sugar, reducing sugar, non‐reducing sugar, nitrogen, protein, amino acids, polyphenol, catechin and lipid showed that there was no significant difference in these constituents between the isolates. The detection of amino acids in the mycelium of P. theae isolates showed 16 free forms and 11 bound forms. Amino acids in the bound form were elucidated to be higher in all the isolates than in the free form. All the isolates of P. theae exhibited prominent protein pattern with three common bands, which lies between the molecular weight of 116 and 66.2 kDa.     

Formation of insoluble magnesium phosphates during growth of the archaea Halorubrum distributum and Halobacterium salinarium and the bacterium Brevibacterium antiquum

Stationary phase cells of the halophilic archaea Halobacterium salinarium and Halorubrum distributum, growing at 3-4 M NaCl, and of the halotolerant bacterium Brevibacterium antiquum, growing with and without 2.6 NaCl, took up approximately 90% of the phosphate from the culture media containing 2.3 and 11.5 mM phosphate. The uptake was blocked by the uncoupler FCCP. In B. antiquum, EDTA inhibited the phosphate uptake. The content of polyphosphates in the cells was significantly lower than the content of orthophosphate. At a high phosphate concentration, up to 80% of the phosphate taken up from the culture medium was accumulated as Mg(2)PO(4)OH x 4H(2)O in H. salinarium and H. distributum and as NH(4)MgPO(4) x 6H(2)O in B. antiquum. Consolidation of the cytoplasm and enlargement of the nucleoid zone were observed in the cells during phosphate accumulation. At phosphate surplus, part of the H. salinarium and H. distributum cell population was lysed. The cells of B. antiquum were not lysed and phosphate crystals were observed in the cytoplasm.     

印楝植物内生真菌Phomopsis sp.的代谢产物研究

从印楝植物内生真菌Phomopsis sp．的菌丝体提取物中分离得到4个化合物,通过波谱技术分别鉴定为水苏碱（1）、甲基-β-D-葡萄糖苷（2）、过氧化麦角甾醇（3）、腺嘌呤核苷（4）,这些化合物均为首次从该属真菌中分离得到。     

渐狭蜡蚧菌产生的几丁质酶对芦笋茎枯病菌的抑制作用

目的:研究渐狭蜡蚧菌产生的几丁质酶及其对芦笋茎枯病菌天门冬拟茎点霉的抑制效果。方法:通过乙酰葡萄糖胺法、对硝基苯酚法和活性电泳法测定渐狭蜡蚧菌CGMCC5328的产几丁质酶特性及其粗酶液对芦笋茎枯病菌的抑菌效果。结果:渐狭蜡蚧菌CGMCC5328几丁质酶粗提取液的几丁质降解酶系活性第4 d达到高峰期;几丁质外切酶活性第6 d达到高峰期;活性染色检测到5条几丁质酶谱带,相对分子质量分别为32.9×103、42.1×103、54.1×103、65.6×103和79.6×103。用该几丁质酶粗酶液处理芦笋茎枯病菌,与灭活酶液处理相比较,抑菌效果明显,酶液处理导致菌丝畸形。结论:渐狭蜡蚧菌CGMCC5328产生的几丁质酶对芦笋茎枯病菌有抑制作用。     

Effect of environmental factors on disease development caused by the fungal pathogen Plectosporium alismatis on the floating-leaf stage of starfruit (Damasonium minus), a weed of rice

Starfruit, Damasonium minus (R. Br.) Buch, is a herbicide-resistant, aquatic-weed occurring in Australian rice fields. The fungal pathogen Plectosporium alismatis (Oudem) W.M. Pitt, W. Gams & U. Braun is a potential mycoherbicide for the control of this weed. Previous work showed that the fungus can suppress the growth of starfruit juvenile plants. This paper reports the effect of environmental factors on the disease development on starfruit at the floating-leaf stage. Fungal inoculation of plants in advanced phases of floating leaf stage reduced significantly (P<0.05) the green leaf area, but only when the percentages of diseased areas were deducted. However, inoculation when the first floating leaf was emerging reduced significantly (P<0.001) both, plant dry above-ground biomass and leaf area.     

Establishment and dispersal of the biological control weevil Rhinoncomimus latipes on mile-a-minute weed, Persicaria perfoliata

Mile-a-minute weed, Persicaria perfoliata (L.) H. Gross (Polygonaceae), is an annual vine from Asia that has invaded the eastern US where it can form dense monocultures and outcompete other vegetation in a variety of habitats. The host-specific Asian weevil Rhinoncomimus latipes Korotyaev (Coleoptera: Curculionidae) was first released in the US in 2004 as part of a classical biological control program. The weevil was intensively monitored in three release arrays over 4 years, and field cages at each site were used to determine the number of generations produced. The weevil established at all three sites and produced three to four generations before entering a reproductive diapause in late summer. Weevils dispersed at an average rate of 1.5–2.9 m wk⁻¹ through the 50 m diameter arrays, which had fairly contiguous mile-a-minute cover. Weevils dispersing in the broader, more variable landscape located both large monocultures and small isolated patches of mile-a-minute 600–760 m from the release within 14 months. Weevil density ranged from fewer than 10 to nearly 200 weevils m⁻² mile-a-minute weed. Mile-a-minute cover decreased at the site with the highest weevil density. The production of P. perfoliata seed clusters decreased with increasing weevil populations at two sites, and seedling production declined over time at two sites by 75% and 87%. The ability of the weevil to establish, produce multiple generations per season, disperse to new patches, and likelihood of having an impact on plants in the field suggests that R. latipes has the potential to be a successful biological control agent.     

Control of the invasive weed Ambrosia artemisiifolia with Ophraella communa and Epiblema strenuana

Ambrosia artemisiifolia L. is native to North America, and was unintentionally introduced into China in the 1930s, where it has become invasive. The two insect species Epiblema strenuana and Ophraella communa have been considered as biological control agents of A. artemisiifolia in China. The purpose of this study was to examine the control effect of O. communa + E. strenuana on A. artemisiifolia in the field. The mortality of A. artemisiifolia plants increased with time and increasing initial release densities of O. communa and/or E. strenuana in 2008 and 2009. The treatments of 0.53 O. communa + 0.53 E. strenuana per plant and 12 O. communa + 16 E. strenuana per plant at early (60–70 cm tall) and later (90–100 cm tall) growth stages could subsequently kill all plants prior to seed production in both 2008 and 2009. Thus, the two initial densities of the two insect species may be recommended when they are jointly used for biological control of A. artemisiifolia at the two growth stages. However, all or some plants could survive and bear seeds in any other treatment and in the non-treated control plots. This implies that biological control of A. artemisiifolia with the two biological control agents will be recommended in the areas invaded by A. artemisiifolia in China.     

Differential Growth Inhibition of Diaporthe and Phomopsis Isolates by the Metabolic Activity of Five Actinomycetes

Fifty-five cultures derived from Diaporthe perithecia and Phomopsis pycnidia found on diverse host plant species collected at different times and sites in Vojvodina, Yugoslavia, showed distinguishing quantitative reactions to the fungistatic activity of five actinomycetes obtained as fortuitous laboratory contaminants coming from field material. Streptomyces albidoflavus , S. albus , S. diastaticus , Streptomyces sp., and Streptoverticillium sp. could be ranked by their growth-inhibitory potential, with S. albus showing the strongest, and Streptomyces sp. the lowest. The responses of the fungi varied depending on the tested actinomycetes, but two major groups could be distinguished: A, which encompased the isolates that were less affected by the proximity of the actinomycetes; and B, with those which exhibited high sensitivity in all the experiments. Group A was typically represented by Diaporthe arctii , Phomopsis longicolla, and the Phomopsis type-1 cultures from Xanthium italicum; group B was typically represented by Diaporthe/Phomopsis helianthi, Phomopsis type-2 cultures from X. italicum , and isolates from Lactuca serriola . The results obtained underscore the dissimilarities between D. arctii and D. helianthi , and corroborate the value of the physiological aspects of congeneric isolates in considering taxonomic problems in the coelomicete genus Phomopsis.     

Evaluation ofMicrothrix inconspicuella, [Lepidoptera: Pyralidae], a potential biological control agent forEmex australis in Australia,carried out in apple orchards in South Africa

Host specificity tests carried out in the laboratory in Australia during 1977, showed thatMicrothrix inconspicuella Ragonot could develop on young apple leaves (Harley et al., 1979). Field studies in unsprayed apple orchards in South Africa showed that some feeding occurred, but fewer than 40% of late instar larvae developed to adults when confined in sleeves on apple tree branches. No feeding or survival occurred in large field cages or in the open. Adults which developed from apple fed larvae were smaller, deformed, occasionally mated and laid fertile eggs but their progeny did not feed or develop on apple fruit or leaves. In conclusion,M. inconspicuella larvae did not develop on apple fruit or leaves in the field, damage was mainly limited to apples already injured and feeding on leaves was minimal. Under normal pest control practicesM. inconspicuella populations did not survive on any part of the apple tree or onE. australis growing under the trees.      

Impact of mowing and weed control on broadleaf weed population dynamics in turf

Abstract

Various turf management activities may influence weed population dynamics and interfere with weed control. The effects of a biocontrol agent, Sclerotinia minor, a chemical herbicide, Killex?, and mowing height on broadleaf weed dynamics were examined in two turfgrass stands for two consecutive years. Mowing did not reduce the population densities of dandelion or the ground cover of broadleaf weeds. In the second year, mowing significantly reduced white clover density, but significantly increased broadleaf plantain density, particularly at the closest mowing height (3–5 cm). Apart from the close height, the S. minor and Killex? treatments were equally effective in suppression of dandelion, white clover, broadleaf plantain, and prostrate knotweed in the second year. Common mallow increased in the herbicide treated plots and other species including yellow woodsorrel, yellow toadflax and lambsquarters increased in abundance in plots mowed at the 3–5 cm height and in plots treated with Killex?. Significant differences between the Killex? and S. minor treatments on dandelion population dynamics were rarely present and did not favour either treatment. S. minor did not damage the turfgrass, but Killex? reduced turf quality in 25% of the plots. The application of S. minor with a regular, medium height (～7 cm) mowing regime was highly effective in controlling broadleaf weeds in temperate Kentucky bluegrass turf.     

三种盐胁迫对互花米草和芦苇光合作用的影响北大核心CSCD

互花米草(Spartina alterniflora)的入侵给海岸带盐沼生态系统的结构和功能带来了显著影响。互花米草盐沼中的硫含量高于附近的土著芦苇(Phragmites australis)盐沼。为探讨硫元素对互花米草和芦苇竞争过程的可能影响及其作用机制,以50mmol·L–1的Na2SO4和Na2S对互花米草和芦苇进行处理,分析处理前后5天内两种植物光合气体交换和叶绿素荧光指标变化的差异,实验另设等Na+浓度的Na Cl处理作为比较。研究发现:Na2S对互花米草和芦苇光合作用影响的差异最大,Na Cl次之,Na2SO4最小。Na2S处理后,互花米草净光合速率(Pn)出现显著上升,芦苇Pn值大幅度下降。互花米草的光饱和点(Isat)上升而芦苇的Isat值无变化。表明Na2S处理对互花米草的光合能力有促进作用,但对芦苇的光合能力有抑制作用。Na Cl处理后互花米草Pn值也出现小幅上升,而芦苇Pn值略有下降。Na2SO4处理对互花米草和芦苇的Pn值均无显著影响。除Na2SO4处理的互花米草外,不同盐处理后的互花米草和芦苇非光化学淬灭(NPQ)均出现上升趋势。研究结果表明互花米草对环境硫胁迫的适应能力显著高于芦苇,暗示盐沼高硫环境尤其是硫化物有助于互花米草相对于芦苇的竞争,也很可能是其形成单一植被的重要原因之一。     

Identification of potential natural enemies of the pea leaf weevil,Sitona lineatus L. in western Canada

Sitona lineatus L., the pea leaf weevil, is an invasive pest of Pisum sativum L. (field pea) that has recently become established in Alberta, Canada. Adults consume seedling foliage and larvae feed on Rhizobium root nodules thereby reducing nitrogen fixation; both life stages can reduce yield. Eggs and adults are vulnerable to predators and parasitoids. In 2009, a series of experiments was undertaken to identify potential indigenous natural enemies of S. lineatus in southern Alberta. In three test arenas, eggs were exposed to starved ground beetles in no‐choice tests for 48 h. Egg debris was observed when eggs were exposed to Bembidion quadrimaculatum L., Microlestes linearis (LeConte), Bembidion rupicola (Kirby), Bembidion timidum (LeConte), Poecilus scitulus LeConte, and staphylinid beetles. Of the two most abundant carabid species, the smaller B. quadrimaculatum consistently removed significantly more eggs (94.6%) than the larger Pterostichus melanarius (17.4%). Similar results were observed in Petri dish and egg card tests. No egg debris was observed in tests with Pt. melanarius. Presence of the larger beetle, Pt. melanarius, resulted in a lower rate of egg removal by the smaller B. quadrimaculatum relative to the rates observed for B. quadrimaculatum alone. Intraguild predation of B. quadrimaculatum by Pt. melanarius was observed in 47% of tests. These results suggest that B. quadrimaculatum is a potential predator of S. lineatus eggs in field pea agroecosystems and should be considered for use in conservation biological control and integrated pest management programs.     

Efficacy ofTrichoderma chitinases againstRhizoctonia solani, the rice sheath blight pathogen

Thirty-five strains ofTrichoderma viride andT. harzianum were screened for their antagonistic ability against the rice sheath blight pathogen,Rhizoctonia solani. The strains that inhibited/overgrew the phytopathogenic fungus were considered effective. Light microscopic studies showed the antagonism of the hyphae of effectiveTrichoderma strains towards their host hyphae. Chitinase activity ofTrichoderma culture filtrates was enhanced, when colloidal chitin was used as the sole carbon source, instead of glucose. Chitinase pattern differed among the four select strains. The chitinase isoforms are induced differentially by carbon sources. The chitin affinity column fraction ofTrichoderma culture filtrate inhibited,in vitro, the growth ofR. solani.     

Sunflower stem weevil and its larval parasitoids in the Central and Northern Plains of the USA

The sunflower stem weevil, Cylindrocopturus adspersus (LeConte) (Coleoptera:Curculionidae), is apest of cultivated sunflower (Helianthusannuus L) from the southern to the northernGreat Plains. The incidence of weevilinfestation in fields from the six differentstates sampled during 1996 and 1997 ranged from33% (Minnesota) to 100% (Kansas, Colorado,Nebraska). Weevil populations in the fieldssampled were statistically greater in thecentral Plains (Colorado, Kansas, Nebraska)with a mean of 12.3 and 19.5 larvae per stalkcompared with the northern Plains (North andSouth Dakota, Minnesota) of 0.7 and 1.3 larvaeper stalk in 1996 and 1997, respectively.Parasitization of weevils varied from field tofield ranging from 1 to 100%, but was usuallyless than 20%. The nine species oflarval parasitoids recovered were allHymenoptera and included: Nealioluscurculionis (Fitch), N. collaris(Brues), Bracon sp. (Braconidae); Neocatolaccus tylodermae (Ashmead), Chlorocytus sp., Pteromalus sp.(Pteromalidae); Quadrastichus ainslieiGahan (Eulophidae), Eurytoma tylodermatisAshmead (Eurytomidae); and Eupelmus sp.(Eupelmidae). Nealiolus curculionis wasthe most prevalent parasitoid reared from C. adspersus, and it was recovered from allstates sampled. Parasitoid species richness wasgreatest in the central Plains. Thereduced number of parasitoid species foundattacking C. adspersus in the northernPlains may be caused by low host populationlevels, slow migration by parasitoids into theregion, or lack of adaptation to climaticconditions. Additional work to understandthe population dynamics of the parasitoidcomplex associated with C. adspersus mayresult in improved biological control of thesunflower stem weevil in cultivatedsunflower.     

三种盐胁迫对互花米草和芦苇光合作用的影响

互花米草(Spartina alterniflora)的入侵给海岸带盐沼生态系统的结构和功能带来了显著影响。互花米草盐沼中的硫含量高于附近的土著芦苇(Phragmites australis)盐沼。为探讨硫元素对互花米草和芦苇竞争过程的可能影响及其作用机制, 以50 mmol·L^-1的Na₂SO₄和Na₂S对互花米草和芦苇进行处理, 分析处理前后5天内两种植物光合气体交换和叶绿素荧光指标变化的差异, 实验另设等Na⁺浓度的NaCl处理作为比较。研究发现: Na₂S对互花米草和芦苇光合作用影响的差异最大, NaCl次之, Na₂SO₄最小。Na₂S处理后, 互花米草净光合速率(P_n)出现显著上升, 芦苇P_n值大幅度下降。互花米草的光饱和点(I_sat)上升而芦苇的I_sat值无变化。表明Na₂S处理对互花米草的光合能力有促进作用, 但对芦苇的光合能力有抑制作用。NaCl处理后互花米草P_n值也出现小幅上升, 而芦苇P_n值略有下降。Na₂SO₄处理对互花米草和芦苇的P_n值均无显著影响。除Na₂SO₄处理的互花米草外, 不同盐处理后的互花米草和芦苇非光化学淬灭(NPQ)均出现上升趋势。研究结果表明互花米草对环境硫胁迫的适应能力显著高于芦苇, 暗示盐沼高硫环境尤其是硫化物有助于互花米草相对于芦苇的竞争, 也很可能是其形成单一植被的重要原因之一。     

In vitro screening of systemic fungicides against Phomopsis azadirachtae,the incitant of die-back of neem

Abstract

Phomopsis azadirachtae Sateesh, Bhat & Devaki is the causal organism of die-back of neem (Azadirachta indica A.Juss.) which is, presently, a major crippling disease of neem in India. Six systemic fungicides such as Bavistin (carbendazim), Contaf (hexaconazole), Beam (tricyclazole), Fuji-one (isoprothiolane) Roko (thiophanate methyl) and Downymil (metalaxyl) were evaluated against P. azadirachtae under in vitro conditions. Colony diameter, mycelial dry weight, pycnidial formation and the germ tube length of the pathogen were the parameters studied. The results indicated that carbendazim was the most effective in inhibiting the growth followed by thiophanate methyl. Among the different concentrations tested, carbendazim at 0.25 ppm and thiophanate methyl at 0.75 ppm were optimum for controlling the growth of the pathogen. Both these fungicides can be utilized for the control of die-back of neem.