The host specificity and climatic suitability of the gall fly Cecidochares connexa (Diptera: Tephritidae), a potential biological control agent for Chromolaena odorata (Asteraceae) in Australia

The gall fly Cecidochares connexa (Diptera: Tephritidae) is a potential biological control agent for Chromolaena odorata in Australia. Its host specificity was determined against 18 species in the tribe Eupatorieae (Family Asteraceae) in which C. odorata belongs, in quarantine in Brisbane, Australia. Oviposition occurred and flies developed on only C. odorata and Praxelis clematidea, both of which are in the subtribe Praxelinae. P. clematidea is considered a weed outside tropical America. In both multiple-species-minus-C. odorata choice tests and single-species no-choice tests, the mean number of galls/plant was significantly greater on C. odorata (48 and 41, respectively) than on P. clematidea (2 and 9, respectively). There were also significantly more adults emerging from C. odorata (mean 129 and 169, respectively) in the two types of tests than from P. clematidea (1 and 8, respectively). Paired choice, multiple generation (continuation) and time dependent tests further clarified the extent that C. connexa could develop on P. clematidea. In these tests, the mean number of galls formed and the mean number of emerging adults were consistently less for P. clematidea than C. odorata and populations of C. connexa could not be maintained on P. clematidea. Galls were not seen on any other plant species tested. This study supports the results of host specificity testing conducted in seven other countries and confirms that C. connexa poses little risk to other plant species in Australia. C. connexa has been released in 10 countries and an application seeking approval to release in Australia has been submitted to the Australian Government.     

Influence of laser light on mycelial growth of Hebeloma mesophaeum and ectomycorrhizal development on Scots pine

 The effects of exposure to helium-neon (He-Ne) or Argon (Ar) laser light (λ=632.8 nm and 514 nm, respectively) on the growth of Hebeloma mesophaeum mycelium in pure culture were studied. Growth rates were highest after exposure to the He-Ne laser (1×60 s)+Ar laser (2×60 s) and to the He-Ne laser for 3×30. Container-grown Pinus sylvestris (pine) seedlings were inoculated with a water suspension of H. mesophaeum mycelium previously exposed to different kinds of laser light. After 3 months, the percentage of mycorrhizal associations on pine roots was 34.3% higher after He-Ne laser treatment and 47.1% higher after Ar laser treatment than in the controls with untreated fungus. However, seedlings infected with treated fungus were smaller than the control. Overall, laser light stimulated growth of H. mesophaeum mycelia in pure culture and enhanced mycorrhizal development on Scots pine seedlings.     

Living on the edge: Ecology of an incipient <Emphasis Type="Italic">Betula-</Emphasis>fungal community growing on brick walls

Walls provide extreme habitats where plants are subjected to various environmental hazards, including water deficit, shortage or excess of irradiance, and nutrient unbalance, and soil communities are in initial stages of development. Here we analyzed the soil substrate, mycorrhizal status, leaf structure and chemistry, CO₂ exchange and water relations of birch trees growing on brick walls of a 19th century building. The substrate was characterized by high pH, Ca, S, Zn, Cl, and Na concentrations and low concentrations of P, K, Mg, and Fe. From 45 to 70% of live fine roots were colonized by ectomycorrhizal (ECM) species: Hebeloma mesophaeum, Hebeloma helodes, Lactarius pubescens, Tomentella lilacinogrisea. Birch on the wall had typical leaf N concentrations, but stomatal conductance was extremely low, and as a consequence, so was net CO₂ assimilation rate. This research showed how a rudimentary soil, plant, and microbial community could develop even in a vertical and chemically foreign environment. Birch plants were able to maintain balanced foliar stoichiometry in a highly unbalanced substrate and acquire enough nutrients to drive sufficient C gain to provide energy for themselves and fungal symbionts.     

飞机草对热带珊瑚岛的生理生态适应性

入侵植物对环境的适应性是探究其入侵性的基础.西沙群岛为热带珊瑚岛,具有高盐、强碱、高温、强光、干旱等恶劣环境特点.近年来,西沙群岛的一些原生植物群落中出现了飞机草(Chromolaena odorata)入侵现象,可能会对当地脆弱的生态系统造成严重的危害.该文研究了西沙群岛原生植物群落林窗中和文昌市郊飞机草的叶片形态解...     

香辣蓼,中国春蓼属(蓼科)一新归化植物

报道了中国春蓼属一新归化植物：香辣蓼[Persicaria odorata（Lour.） Soják],并对其形态学特征进行了详细描述,提供了形态照片,同时分析了其用途。该种原产于中南半岛,被作为香料植物在云南、广西、广东及江西等地的傣族或客家人聚居区广泛栽培,现在云南西双版纳傣族自治州及德宏傣族景颇族自治州发现大量归化居群。香辣蓼与特产于中国江西的武功山春蓼（P.wugongshanensis B.Li）最为近似,二者叶片均具有强烈的气味,叶片及花被片具腺点,二型花柱,花序基部间断,花梗长于苞片,区别在于本种为多年生草本植物,具发达的根状茎,叶片披针形至狭披针形,果实表面光滑有光泽。     

Infection of maize leaves with Ustilago maydis prevents establishment of C4 photosynthesis

The Basidiomycete fungus Ustilago maydis is the common agent of corn smut and is capable of inducing gall growth on infected tissue of the C₄ plant maize (Zea mays). While U. maydis is very well characterized on the genetic level, the physiological changes in the host plant in response to U. maydis infection have not been studied in detail, yet.Therefore, we examined the influence of U. maydis infection on photosynthetic performance and carbon metabolism in maize leaf galls.At all stages of development, U. maydis-induced leaf galls exhibited carbon dioxide response curves, CO₂ compensation points and enzymatic activities that are characteristic of C₃ photosynthesis, demonstrating that the establishment of C₄ metabolism is prevented in infected tissue. Hexose contents and hexose/sucrose ratio of leaf galls remained high at 6 days post infection, while a shift in free sugar metabolism was observed in the uninfected controls at that time point. Concomitantly, transitory starch production and sucrose accumulation during the light period remained low in leaf galls. Given that U. maydis is infectious on young developing tissue, the observed changes in carbohydrate metabolism suggest that the pathogen manipulates the developing leaf tissue to arrest sink-to-source transition in favor of maintaining sink metabolism in the host cells.Furthermore, evidence is presented that carbohydrate supply during the biotrophic phase of the pathogen is assured by a fungal invertase.     

Management of nursery practices for efficient ectomycorrhizal fungi application in the production of Quercus ilex

The application of ectomycorrhizal (ECM) fungi on forest nursery production is regarded as part of good management practice. However, before employing large scale inoculations in a nursery the interaction between ECM symbionts, growth substrate and fertilisation input should be studied to select the most suitable nursery practices for promoting plant growth and ECM colonisation. In this study, seedlings of Quercus ilex were inoculated with Paxillus involutus, Hebeloma mesophaeum or Cenococcum geophilum and grown in three different substrates commonly used in forest nurseries: peat-based compost, forest soil or composted pine bark. The effect of various fertilisation regimes was also studied. The choice of substrate had a significant effect on plant growth and ECM colonisation. The most appropriate combination of substrate and ECM fungus for Q. ilex growth and nutrition was peat and H. mesophaeum. Plants grown on a peat-based compost and inoculated with H. mesophaeum had a significantly greater biomass and leaf phosphorus concentration without fertilisation. Composted pine bark was found not to be suitable for growth or for mycorrhization. If the appropriate growth substrate is selected, it is possible to replace the use of chemical fertilisers by inoculation with selected ECM fungi. This results in a significant increase in plant development, and thus ECM fungi can be recommended as a more environmental friendly biotechnological approach to plant management in the nursery.     

油茶叶肿病子房瘿体和叶片瘿体的形态结构特征观察

采用光学显微镜观察了油茶叶肿病子房瘿体和叶片瘿体的形态特征和组织结构特点。结果表明:(1)油茶叶肿病瘿体是油茶的幼嫩子房和幼叶被细丽外担菌感染后所导致的组织增生而成的,细丽外担菌分布于成熟子房瘿体的外表面和叶片瘿体的表面。(2)子房瘿体由受感染的雌蕊子房增殖而来,成熟后表皮层脱落。(3)子房壁分两层,外层子房壁肉质肥厚,主要由大型薄壁细胞构成,是食用的主要部分,内层子房壁为较薄的心皮层,内外两层子房壁之间具有较大的空隙;心皮内有胚珠,胚珠着生在中轴胎座上,胚珠内部中空而没有育性。(4)叶片瘿体为受感染的幼嫩叶片增殖所致,由大型薄壁细胞构成,瘿体表面具表皮层,成熟后表皮脱落。(5)在正常叶片与叶片瘿体的过渡区内有维管束相通,瘿体侧的厚度比正常叶片厚度增加3～4倍,细胞体积增大5～10倍,但瘿体细胞内无叶绿体。     

不同入侵程度下飞机草对喀斯特地区土壤理化性质的影响

外来生物入侵威胁着全球的生物多样性和生态系统的功能,研究外来入侵植物对土壤理化性质的影响有助于理解外来入侵植物的入侵机制。以广西喀斯特地区飞机草（Chromolaena odorata）入侵生境为研究对象,比较分析了不同飞机草入侵程度下（对照、轻度入侵、中度入侵、重度入侵）土壤物理和化学指标变化特征。结果表明：随着飞机草的入侵程度加重,土壤容重显著增加,轻度入侵、中度入侵和重度入侵生境下土壤容重分别比对照增加了10.3%、16.7%、22.3%,土壤非毛管孔隙度、总孔隙度和土壤含水量显著降低,土壤毛管孔隙度无显著变化;飞机草入侵对土壤pH值无显著影响,随着入侵程度加重,土壤速效磷和速效钾的含量显著升高,在重度入侵生境下土壤速效磷和速效钾含量分别比对照增加了4.3倍、3.8倍,土壤全氮和有机质含量显著降低。飞机草入侵显著改变了土壤理化性状,导致喀斯特地区土壤物理结构退化,生态系统水土保持能力下降,同时飞机草通过改变土壤养分循环提高了土壤可直接利用养分的水平,创造对自身有利的土壤环境,进而促进其生长和扩散。     

Laboratory studies on the biology and host range of Dichrorampha odorata (Lepidoptera: Tortricidae), a biological control agent for Chromolaena odorata (Asteraceae)

Dichrorampha odorata (Lepidoptera: Tortricidae) is a moth from Jamaica whose larvae bore into, and kill, the shoot tips of the invasive alien plant, Chromolaena odorata (L.) King and Robinson (Asteraceae). This study reports aspects of the biology of D. odorata, and also determined the host specificity (larval and adult no-choice trials) of the moth. Adults were short lived (ranging from 2 to 7 days), with females laying a mean of 15.4 eggs. Eggs took 9 days to hatch, larvae 20–23 days to develop and the pupal stage lasted 11–12 days, giving an overall lifecycle period of 41–45 days. Larval no-choice tests using 34 asteraceous test species indicated that only C. odorata could sustain complete development of D. odorata to adulthood, although there was slight initial boring 14 test species (plus chromolaena). Results from the adult nochoice trials, in which seven test-plant species were exposed to D. odorata, were consistent with those from larval trials, with larval damage, pupae and adults of D. odorata recorded from only C. odorata. This confirmed that only C. odorata is a suitable host for D. odorata in South Africa. Permission has subsequently been granted for the release of D. odorata in South Africa, thus making it the first shoot-tip attacking agent to be released against C. odorata. It is hoped that in the field, high levels of damage by the moth will reduce the height and therefore competitiveness of C. odorata, thereby contributing to the success of biological control of this plant.     

Nuclear changes induced by the nematodesXiphinema diversicaudatum andLongidorus elongatus in root-tips of perennial ryegrass,Lolium perenne

Summary The DNA content and size of individual nuclei from galls of perennial ryegrass root-tips induced byX. diversicaudatum andL. elongatus were measured. Feeding byX.diversicaudatum increased the DNA content of the nuclei by varying amounts. No regular doubling pattern of the DNA content was discernible. The DNA values varied up to between 32–64C. Generally the size of the nuclei was not increased, although some were larger than control nuclei. The modified nuclei probably have an altered metabolic function, which increases the food value of the gall to the nematode. Some bi-nucleate cells were also observed, which probably result from mitosis without cytokinesis. A preliminary examination of nuclei from galls induced byL. elongatus revealed similar nuclear changes, but no bi-nucleate cells were found. Editor's note: Awarded the Viviane Maggi prize for the best paper presented by a beginner at the Annual Meeting of the Histochemistry and Cytochemistry Section of the Royal Microscopical Society in April 1981. This paper is a full report of that presentation.     

Response of Three Hymenopteran Parasitoids Introduced for Fruit Fly Control to a Gall-Forming Tephritid,Procecidochares alani(Diptera: Tephritidae)

The response of three larval–pupal parasitoids,Diachasmimorpha longicaudata(Ashmead),Diachasmimorpha tryoni(Cameron), andTetrastichus giffardianusSilvestri, to the Hamakua pamakani gall fly,Procecidochares alaniL., was determined in the laboratory. We also observed responses of these parasitoids to their normal rearing hosts,Bactrocera dorsalis(Hendel) andCeratitis capitata(Weidemann).D. tryonilanded on pamakani galls or on dishes containingP. alanilarvae as frequently as on dishes containingC. capitata.In contrast,D. longicaudataonly rarely landed on the galls.D. tryoniandD. longicaudataoviposited in galls in fewer than 1% of our observations.D. longicaudataprobedP. alanilarvae as frequently asB. dorsalislarvae, but no parasitoid offspring were observed.D. tryonioviposited more frequently inC. capitatathanP. alani.NoD. tryonideveloped inP. alanilarvae.T. giffardianuslanded on pamakani galls andP. alanilarvae more frequently than any other host substrate. In contrast,T. giffardianusentered galls with artificially opened windows one time in 10 observations. We observed 12% parasitism ofP. alanilarvae dissected from the galls and 20% of parasitismP. alaniin the windowed galls. We discuss the implications of our results for future augmentative or classical biological control studies.     

梭梭叶苞状虫瘿结构特征和生长发育研究

该研究采用形态和显微结构观察方法,并结合基于转录组测序和差异表达基因富集分析,研究梭梭叶苞状虫瘿的生长发育特点以及梭梭叶苞状虫瘿与梭梭之间的相互关系,为昆虫与植物协同进化和梭梭虫害防治提供理论依据。结果表明:(1)叶苞状虫瘿的生长发育阶段可以分为3个时期,生长期、形成期和衰亡期。(2)在生长期和形成期的叶苞状虫瘿与梭梭同化枝、鳞叶部位的解剖结构有明显的差别:生长期叶苞状虫瘿的表皮细胞外的角质层损伤,但表皮细胞完整、形态差异不大、排列紧密,没有栅栏细胞组织和花环结构,只有含水量较高的海绵组织,且细胞比同化枝和鳞片小而密,细胞数量是鳞片中的2倍左右,维管柱直径比同化枝和鳞片小;形成期叶苞状虫瘿的表皮细胞外的角质层受到严重损伤,表皮细胞不完整、形态差异大、排列疏松,海绵组织含水量严重减少,维管组织不明显。(3)梭梭叶苞状虫瘿中与植物细胞正常发育相关、光合作用相关的基因富集下调表达,与胁迫相关基因富集上调表达。研究认为,梭梭的叶苞状虫瘿只为促进木虱的生长发育,在提高梭梭光合作用方面没有作用。     

Trioza hopeae sp. nov. (Hemiptera: Triozidae): A pest on Hopea odorata (Malvales: Dipterocarpaceae) in Vietnam

Trioza hopeae sp. nov. is described and illustrated from Vietnam. Trioza hopeae develops on Hopea odorata, a valuable timber tree on which it causes serious damage by inducing leaf galls. The new species is closely related to Trioza minuta (Mathur) comb. nov. (from Ceropsylla Riley), an Indian species associated with Shorea robusta. Differences between the two species are discussed. Another five Indian species are transferred here from Ceropsylla to Trioza Foerster as T. ferruginea ( Mathur, 1975 ) comb. nov., T. fulvida ( Mathur, 1975 ) comb. nov., T. indica ( Kandasamy, 1986 ) comb. nov., T. longivenata ( Kandasamy, 1986 ) comb. nov., and T. parvus ( Kandasamy, 1986 ) comb. nov.     

永州广聚萤叶甲和豚草卷蛾的种群动态及对豚草的控制效果

【目的】豚草是一种重要的入侵杂草,严重危害农业生产和人类健康。广聚萤叶甲和豚草卷蛾是豚草的专一性天敌。研究这2种天敌在永州的种群动态及其对豚草的控制效果,可以为永州豚草的防控及这2种天敌的有效利用提供依据。【方法】在湖南省永州市江永县豚草大面积发生区域,人工释放广聚萤叶甲和豚草卷蛾,调查这2种天敌在释放区和扩散区的种群动态和对豚草的防治效果,以及这2种天敌在扩散区的越冬情况。【结果】广聚萤叶甲和豚草卷蛾的扩散能力强。释放1个月后,在释放区,广聚萤叶甲各虫态及豚草卷蛾虫瘿均被发现。整体上,随时间延长,广聚萤叶甲各虫态虫口密度先增后减,而豚草卷蛾虫瘿密度呈逐渐降低趋势。释放2个月后,在距释放区边缘10 km的豚草发生区,发现了广聚萤叶甲和豚草卷蛾,且成功建立了种群并顺利越冬。释放区豚草株高几乎没有增加,且叶片最终被取食精光,几乎全部死亡;扩散区豚草株高略有增加,最终近75%叶片被取食。【结论】广聚萤叶甲和豚草卷蛾可在永州成功建立种群并安全越冬,还能自行扩散,可持续控制野外豚草的发生。     

Impact of the shoot-boring moth Dichrorampha odorata (Lepidoptera: Tortricidae) on growth and reproductive potential of Chromolaena odorata (Asteraceae) in the laboratory

A 9-month laboratory study was carried out to determine the impact of herbivory by a moth with shoot-boring larvae, Dichrorampha odorata Brown and Zachariades (Lepidoptera: Tortricidae) on growth and reproductive ability of its host plant, Chromolaena odorata (L.) King and Robinson (Asteraceae), a major invasive alien plant species in southern Africa. Newly hatched D. odorata larvae were inoculated onto 0 (control), 50 and 100% of the shoot tips of C. odorata in the laboratory. At all treatment levels, the basal stem diameter of C. odorata was not affected by D. odorata larval feeding. Larval feeding by D. odorata significantly reduced the height of the main shoot and flower production in C. odorata relative to the control treatment but promoted branching by increasing the number of shoot tips. However, the differences in plant height and number of flowers between the 50 and 100% inoculation levels were not statistically significant. Dichrorampha odorata is the first shoot-tip attacking agent that is being released as a biological control agent against C. odorata in South Africa. In general, the impacts of D. odorata on the weed were relatively small even though statistically significant. The findings of this study suggest that high levels of damage by the moth will modestly reduce the height, flower production, and the competitiveness of C. odorata, thereby contributing to the biological control of the weed in South Africa.     

Variation in host plant has no effect on the performance and fitness‐related traits of the specialist herbivore Pareuchaetes insulata

The effect of host plant dissimilarity on insect preference and performance was tested using two morphological forms of Chromolaena odorata (L.) King & Robinson (Asteraceae) (one from Florida, USA, another from South Africa), and a specialist herbivore, Pareuchaetes insulata (Walker) (Lepidoptera: Erebidae: Arctiinae) from Florida, USA, that was introduced as a biological control agent in South Africa. Although this insect did establish at one site, of some 21 sites at which over 800 000 individuals were released, its population level in the field has remained low after an initial outbreak in 2006. To explain the poor performance of P. insulata, we hypothesised that P. insulata larvae prefer Floridian C. odorata to the southern African C. odorata, which is morphologically and probably genetically distinct, and that larvae reared on Floridian C. odorata should have higher fitness and performance. We tested this by comparing insect performance metrics on each of the two plant forms in laboratory experiments. Apart from pupal mass, which was significantly greater on southern African C. odorata, P. insulata performance metrics were similar on both plant forms; there were no significant differences in total leaf area consumed, egg and larval development, immature survival rates, feeding index, host suitability index, growth index, and fecundity between the Floridian and southern African C. odorata plants. In sum, we could not demonstrate that differences in plant forms in C. odorata are responsible for the poor performance of P. insulata in South Africa.     

Influence of the introduced parasitoid Torymus sinensis (Hymenoptera: Torymidae) on T. koreanus and T. beneficus as indigenous parasitoids of the chestnut gall wasp Dryocosmuskuriphilus (Hymenoptera: Cynipidae) on chestnut trees in Nagano Prefecture, Japan

We describe here the parasitoid wasps Torymus sinensis Kamijo and T. beneficus Yasumatsu & Kamijo (early-spring and late-spring strains), which are introduced and indigenous natural enemies of the chestnut gall wasp Dryocosmus kuriphilus Yasumatsu, an invasive chestnut pest in Japan. We recently discovered specimens of T. koreanus Kamijo, endemic in Korea, among Torymus parasitoids collected from D. kuriphilus galls in a Japanese chestnut orchard. In this study we compare the composition of Torymus parasitoids emerging from D. kuriphilus galls before and after the release of T. sinensis. Before the release of T. sinensis, early-spring and late-spring strains of T. beneficus predominated (58.3 and 20.8% of specimens collected). However, a few years after the release, both T. beneficus strains had been almost completely displaced by T. sinensis. In contrast to the rapid decrease in T. beneficus, T. koreanus did not decrease drastically before and even after the release of T. sinensis (approximately 10–20% of specimens collected). These results suggest that not a few T. koreanus were present in the Japanese chestnut orchard investigated at least several years after the release of T. sinensis, although both the T. beneficus strains were rapidly displaced by T. sinensis during this period.     

Life history,damage assessment and control of Trioza hopeae (Hemiptera: Psylloidea), a serious pest on Hopea odorata (Malvales: Dipterocarpaceae) in Vietnam

Young plants of the commercially important timber species Hopea odorata Roxb. are seriously damaged by the psyllid Trioza hopeae Burckhardt & Vu in nurseries in South Central and Southern Vietnam. Farmers routinely use Class 1 toxic insecticides to control the psyllids but these pose serious health risks in the urban environment. As a precursor to developing a pest management strategy, we studied the life cycle of T. hopeae and trialed several control measures. Trioza hopeae is polyvoltine with overlapping generations peaking in mid wet season. Females laid approximately 135 eggs; however, there was a natural attrition rate of about 80% in first‐instar nymphs due to the nymph's inability to find a suitable feeding site. Feeding nymphs induced pit galls on young H. odorata leaves and were present on all trees examined during the study. The pre‐adult life cycle lasted approximately 13 days and adult life span approximately seven days. Several toxic insecticides were found to be effective for controlling T. hopeae, but a novel non‐toxic alternative was equally as effective. We discuss these methods and potential biological control measures.