Trap cropping effect on oviposition behaviour of the leek moth Acrolepiopsis assectella and the diamondback moth Plutella xylostella

The potential of trap cropping as a pest control strategy was explored for two specialist moth species, where oviposition behaviour determines larval distribution. Oviposition behaviour was studied at three different scales: Individual plants in the laboratory, small scale field experiments with and without cages, and medium scale field trials. The study insects were the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), a specialist on Brassica species and the leek moth, Acrolepiopsis assectella (Z.) (Lepidoptera: Acrolepiidae), a specialist on Allium species. The diamondback moth preferred Indian mustard, Brassica juncea (L.) over white cabbage, B. oleracea var alba (L.). The leek moth did not show preference when offered leek, Allium porrum (L.) and chives, A. schoenoprasum (L.). However, the leek moth did prefer to oviposit on plants of a larger biomass over smaller plants. In both the small scale and the medium scale field studies the trap crops reduced the number of eggs laid on the primary crop. The total number of eggs laid in the monoculture and the trap crop treatments were the same in the small scale field cage study, but the females distributed their eggs differently. More eggs were laid on trap crops compared with primary crops and this pattern was also validated in the medium scale field trials. In this study only the direct effects of trap cropping were considered. Indirect effects of vegetation diversity such as enhancement of natural enemies could potentially increase the efficacy of trap cropping.     

Trap cropping effect on oviposition behaviour of the leek moth Acrolepiopsis assectella and the diamondback moth Plutella xylostella

The potential of trap cropping as a pest control strategy was explored for two specialist moth species, where oviposition behaviour determines larval distribution. Oviposition behaviour was studied at three different scales: Individual plants in the laboratory, small scale field experiments with and without cages, and medium scale field trials. The study insects were the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), a specialist on Brassica species and the leek moth, Acrolepiopsis assectella (Z.) (Lepidoptera: Acrolepiidae), a specialist on Allium species. The diamondback moth preferred Indian mustard, Brassica juncea (L.) over white cabbage, B. oleracea var alba (L.). The leek moth did not show preference when offered leek, Allium porrum (L.) and chives, A. schoenoprasum (L.). However, the leek moth did prefer to oviposit on plants of a larger biomass over smaller plants. In both the small scale and the medium scale field studies the trap crops reduced the number of eggs laid on the primary crop. The total number of eggs laid in the monoculture and the trap crop treatments were the same in the small scale field cage study, but the females distributed their eggs differently. More eggs were laid on trap crops compared with primary crops and this pattern was also validated in the medium scale field trials. In this study only the direct effects of trap cropping were considered. Indirect effects of vegetation diversity such as enhancement of natural enemies could potentially increase the efficacy of trap cropping.     

Scale surface micro-structures of British freshwater cyprinidae

The scales of the roach (Rutilus rutilus L.), rudd (Scardinus erythropthalmus L.) and Crucian carp (Carassius carassius L.) Cyprinidae, Teleostei, were examined by scanning electron microscopy. The circuli in the overlapped areas of the scales were found to be denticulated. Inter-specific variation of denticular morphology, height and spacing was revealed when circuli of comparable ontogenetic age were investigated. The osseus material forming the circuli is reduced in thickness or absent at the scale radii. On the basis of the results of this study it is considered that the term micro-structure should be used in preference to ‘ornamentation’ to describe scale surface characteristics.     

The Functional Role of the Hollow Region of the Butterfly Pyrameis atalanta （L.） Scale

Questions concerning the functional role of the hollow region of the butterfly Pyrameis atalanta （L.） scale are experimentally investigated. Attention was initially directed to this problem by observation of the complex microstrucmre of the butterfly scale as well as other studies indicating higher lift on butterfly wings covered with scale. The aerodynamic forces were measured for two oscillating scale models. Results indicated that the air cavity of an oscillating model of the Pyrameis atalanta （L.） scale increased the lift by a factor of 1.15 and reduced the damping coefficients by a factor of 1.38. The modification of the aerodynamic effects on the model of butterfly scale was due to an increase of the virtual air mass, which influenced the body. The hollow region of the scale increased the virtual air mass by a factor of 1.2. The virtual mass of the butterfly scale with the hollow region was represented as the sum of air mass of two imaginary geometrical figures： a circular cylinder around the scale and a right-angled parallelepiped within the hollow region. The interaction mechanism of the butterfly Pyrameis atalanta （L.） scale with a flow was described. This novel interaction mechanism explained most geometrical features of the airpermeable butterfly scale （inverted V-profile of the ridges, nozzle of the tip edge, hollow region, and openings of the upper lamina） and their arrangement.     

野葛的组织培养和植株再生

野葛〔Ｐｕｅｒａｒｉａｌｏｂａｔａ（Ｗｉｌｄ．）Ｏｈｗｉ〕为豆科多年生缠绕藤本植物,分布遍及全国,主产南方［１］,可药食两用,其块根肥厚,富含淀粉、蛋白质、钙、磷、铁及脂肪酸等,还含有多种异黄酮类化合物,对治疗心绞痛、高血压、冠心病,抑制肿瘤等效果显...     

Effect of polyphenols on shoot and root growth and on seed germination

The effect of high concentrations of the simplest polyphenols on extension growth of maize (Zea mays L.) shoot ooleoptile segments, lettuce (Lactuca sativa L.) roots, and on radish (Raphanus sativus L.) seed germination, was studied. Quinone formation in the process of plant incubation in polyphenol solutions was proved. The data obtained are presumably explained by the important part that is played by the quinoid products of phenol oxidation in the ability ofo- andp-biatomic phenols to inhibit growth.     

Trap cropping to manage green vegetable bug Nezara viridula (L.) (Heteroptera: Pentatomidae) in sweet corn in New Zealand

Abstract

• 1 The use of trap crops to reduce green vegetable bug (GVB) Nezara viridula (L.) (Heteroptera: Pentatomidae) damage to process sweet corn Zea mays (L.) was investigated in three field experiments.
• 2 In the first season, small plots (2.7 m by 10 m) of white mustard Sinapis alba (L.) with pea Pisum sativum (L.) were sown along a crop border and compared with sweet corn alone.
• 3 In the second season, black mustard Brassica nigra (L.) was sown at two sowing dates (14 days apart) and compared with a sweet corn control, to examine how the maturity of the trap crop affected numbers of GVB trapped.
• 4 A field scale experiment was also conducted to determine the effectiveness of black mustard as a trap crop to protect larger areas of sweet corn from GVB.
• 5 In all three experiments, GVB populations were much higher on the trap crops compared with the sweet corn.
• 6 In both small plot experiments, GVB were contained largely within the trap crop for 2 weeks until the sweet corn was harvested.
• 7 The field scale experiment demonstrated the efficacy of the trap cropping technique to protect larger areas of crop from GVB.
• 8 Percentages of damaged sweet corn cobs in the outside row of fields protected by a trap crop were 0% and 1%, respectively, compared with 11% and 22% in control fields.
• 9 Trap cropping is recommended as an effective strategy to manage this insect. Options for cultivating or spraying the trap crops to reduce bug survival are discussed.

     

Chloroplast Biogenesis 49 : Differences among Angiosperms in the Biosynthesis and Accumulation of Monovinyl and Divinyl Protochlorophyllide during Photoperiodic Greening

Various angiosperms differed in their monovinyl and divinyl protochlorophyllide biosynthetic capabilities during the dark and light phases of photoperiodic growth. Some plant species such as Cucumis sativus L., Brassica juncea (L.) Coss., Brassica kaber (DC.) Wheeler, and Portulaca oleracea L. accumulated mainly divinyl protochlorophyllide at night. Monocotyledonous species such as Avena sativa L., Hordeum vulgare L., Triticum secale L., Zea mays L., and some dicotyledonous species such as Phaseolus vulgaris L., Glycine max (L.) Merr., Chenopodium album L., and Lycopersicon esculentum L. accumulated mainly monovinyl protochlorophyllide at night.

Under low light intensities meant to simulate the first 60 to 80 minutes following daybreak divinyl protochlorophyllide appeared to contribute much more to chlorophyll formation than monovinyl protochlorophyllide in species such as Cucumis sativus L. Under the same light conditions, species which accumulated mainly monovinyl protochlorophyllide at night appeared to form chlorophyll preferably via monovinyl protochlorophyllide.

These results were interpreted in terms of: (a) a differential contribution of monovinyl and divinyl protochlorophyllide to chlorophyll formation at daybreak in various plant species; and (b) a differential regulation of the monovinyl and divinyl protochlorophyllide biosynthetic routes by light and darkness.

     

Synthesis and plant growth inhibitory activity of N-trans-cinnamoyltyramine: its possible inhibition mechanisms and biosynthesis pathway

The search for potent, selective bioherbicides has been the focus of numerous studies for several decades. Developing an economically viable total chemical synthesis procedure has been the challenge for commercial-scale application of these nature-derived chemicals. An efficient and low-cost total synthesis of an allelopathic and antitumor N-trans-cinnamoyltyramine (NTCT) first reported in rice (Oryza sativa L.) was successfully achieved by one-step amidation from trans-cinnamic acid and tyramine. The synthesized NTCT inhibited root and hypocotyl growth of cress (Lepidium sativum L.) and barnyardgrass (Echinochloa crus-galli L.) at concentrations as low as 0.24?μM. The means of ED₅₀ (the effective dose required for 50% plant growth inhibition) levels of the compound on cress and barnyardgrass hypocotyl and root elongations were 0.96 and 0.73?μM, respectively. Potential mechanisms underlying NTCT growth inhibition and its biosynthesis pathway were also suggested. The developed synthesis strategy could permit production of this synthesized allelochemical at a commercial scale as a bioherbicide.     

The influence of explant orientation and contact with the medium on the pathway of shoot regeneration in vitro in epicotyl cuttings of Troyer citrange

The effect of orientation as regards to gravity, and that of contact with the medium of culture, on shoot regeneration at the cut edges of epicotyl explants of Troyer citrange (Citrus sinensis (L.) Osbeck×Poncirus trifoliata (L.) Raf.) have been separated. The shoot regeneration pathway was not affected by the orientation of the explants as regards to gravity, and was determined by explant polarity and the contact with the culture medium. At the apical edge of the explants, the contact with the medium shifted the pathway of shoot regeneration from a direct one to an indirect one, with formation of a callus. This callus formation was cytokinin-dependent, but the change in the pathway of organogenesis was not caused by the increase in cytokinin availability resulting from the contact with the medium. In contact with the media, regeneration at the basal edge of the explants occurred through an indirect pathway after callus formation. No regeneration occurred, at the basal edge, if the contact with the media was prevented. The orientation of the explants as regards to gravity affected shoot formation through the direct pathway of organogenesis. The number of buds differentiated, and that of growing shoots increased when the orientation of the explants departed from the vertical upright position.     

Viability of Plants and Isolated Organs under Salinity Conditions

The viability and root formation of whole seedlings and isolated organs were compared in kidney bean (Phaseolus vulgaris L.) and sunflower (Helianthus annuus L.) plants grown in the presence of various concentrations of sodium chloride. The response of plant structures depended on the level of their organization. Organ tolerance to NaCl and its ability to root formation increased with the complexity level of the system comprising this organ. We suppose that plant integrity represents a special functionally labile system, which determines plant resistance to adverse environmental conditions. It is noted that the response of individual structures does not necessarily reflect characteristics of the intact plant tolerance.     

Deoxyribonucleic Acid, Ribonucleic Acid, Protein and Uncombined Amino Acid Content of Legume Seeds During Embryogeny

The nucleic acid, protein and uncombined amino acid contentof seeds of soya-bean (Glycine max L. Merr.), garden pea (Pisumsativum L.), kidney bean (Phaseolus vulgaris L.) and peanut(Arachis hypogaea L.) were measured at various times duringseed formation in an effort to understand why the soya-beanhas nearly twice as much protein as the other legume seeds.In all these species the concentration of deoxyribonucleic acid,ribonucleic acid and uncombined amino acids decreased duringseed formation. The protein level of kidney bean was relativelyconstant during development whereas the protein levels of pea,peanut and soya-bean increased during development. The proteincontent of the soya-bean increased throughout development whereasthe protein increase in peanut took place early and that inpea took place later in development. The ratio of protein toribonucleic acid was highest in peanut, less in soya-bean, andlowest in pea and kidney bean. Similarly, the ratio of proteinto deoxyribonucleic acid was higher in kidney bean than in soya-bean.Soya-beans had a lower amino acid content than any of the otherseeds at all stages of development. These results indicate thatneither total deoxyribonucleic acid, ribonucleic acid nor uncombinedamino acid content is responsible for the higher protein contentof soya-beans.     

ENSO and NAO affect long‐term leaf litter dynamics and stoichiometry of Scots pine and European beech mixedwoods

Litterfall dynamics (production, seasonality and nutrient composition) are key factors influencing nutrient cycling. Leaf litter characteristics are modified by species composition, site conditions and water availability. However, significant evidence on how large‐scale, global circulation patterns affect ecophysiological processes at tree and ecosystem level remains scarce due to the difficulty in separating the combined influence of different factors on local climate and tree phenology. To fill this gap, we studied links between leaf litter dynamics with climate and other forest processes, such as tree‐ring width (TRW) and intrinsic water‐use efficiency (iWUE) in two mixtures of Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.) in the south‐western Pyrenees. Temporal series (18 years) of litterfall production and elemental chemical composition were decomposed following the ensemble empirical mode decomposition method and relationships with local climate, large‐scale climatic indices, TRW and Scots pine's iWUE were assessed. Temporal trends in N:P ratios indicated increasing P limitation of soil microbes, thus affecting nutrient availability, as the ecological succession from a pine‐dominated to a beech‐dominated forest took place. A significant influence of large‐scale patterns on tree‐level ecophysiology was explained through the impact of the North Atlantic Oscillation (NAO) and El Niño–Southern Oscillation (ENSO) on water availability. Positive NAO and negative ENSO were related to dry conditions and, consequently, to early needle shedding and increased N:P ratio of both species. Autumn storm activity appears to be related to premature leaf abscission of European beech. Significant cascading effects from large‐scale patterns on local weather influenced pine TRW and iWUE. These variables also responded to leaf stoichiometry fallen 3 years prior to tree‐ring formation. Our results provide evidence of the cascading effect that variability in global climate circulation patterns can have on ecophysiological processes and stand dynamics in mixed forests.     

Acetylcholine and Red-light Influence on Ethylene Evolution from Soyabean Leaf Tissues

Acetylcholine (Ach) and red light inhibited ethylene evolutionfrom excised green soyabean (Glycine max (L.) Merr.) leaf discs.Neostigmine, an Ach-esterase inhibitor, mimicked this effectwhile atropine, an Ach antagonist, increased ethylene evolution.Acetylcholine and red light partially overcame the atropine-inducedresponse. The results were interpreted as an influence of acetylcholineupon the ethylene formation process. Glycine max, ethylene inhibition, leaf discs     

Increased 8-hydroxyguanine content of chloroplast DNA from ozone-treated plants

The mechanism of ozone-mediated plant injury is not known but has been postulated to involve oxygen free radicals. Hydroxyl free radicals react with DNA causing formation of many products, one of which is 8-hydroxyguanine. By using high performance liquid chromatography with electrochemical detection, the 8-hydroxy-2′-deoxyguanosine (8-OHdG) content of a DNA enzymatic digest can be sensitively quantitated. Beans (Phaseolus vulgaris L.) and peas (Pisum sativum L.) were treated with an ozone regime that caused acute injury. Chloroplast DNA was obtained from plants harvested either immediately after ozone treatment or 24 hours later. Ozone-exposed plants in general had nearly two-fold higher levels of 8-OHdG as compared to control plants. In vitro treatment of DNA in buffer solution with ozone did not cause formation of 8-OHdG in DNA, even though ozone did react directly with the macromolecule per se. Exposure of isolated, illuminated chloroplasts to ozone caused nearly a seven-fold increase in the amount of 8-OHdG in the chloroplast DNA as compared to none-ozone-exposed chloroplasts. These results suggest that ozone exposure to plants causes formation of enhanced levels of oxygen free radicals, thus mediating formation of 8-OHdG in chloroplast DNA. The reaction of ozone with DNA per se did not cause formation of 8-OHdG. Therefore, it is the interaction of ozone with plant cells and isolated chloroplasts which mediates oxygen free radical formation.     

Analysis of meiosis and non-random bivalent formation in desynaptic mutants of Pennisetum americanum (L.) Leeke

Meiotic behaviour of induced desynaptic mutants of Pennisetum americanum (L.) Leeke in general was described.The frequency distribution of bivalents in induced desynaptic mutants was compared with that expected on the basis of the binomial series. The deviation from the binomial distribution was tested as to its conformity with models based on intra-and intercellular differences in bivalent formation. It is suggested that in these desynaptic mutants of Pennisetum americanum bivalent formation is non-random, which is largely due to the result of intracellular differences in chromosome behaviour regarding their requirements for chiasma formation.     

Dendrometer and intra-annual tree growth: What kind of information can be inferred?

Dendrometer measurements provide time series composed of the rhythm of water storage fluctuations over the year and seasonal tree growth. For slow-growing trees, however, difficulties have been found in the identification of crucial events such as growth onset, stem growth period and cessation, rendering it necessary to define what can be measured and at which time scale. Time scale means the time interval (from one day to one month) at which stem radius variation is extracted. In this study, two conifer species were monitored by an automatic band dendrometer to assess several time scales and analysis approaches. Data were collected from 8 trees of Picea abies (L.) Karst and Larix decidua L., growing at 1020 and 2080 m a.s.l. in the eastern Italian Alps, from 2000 to 2003. Time series of stem radius variation were extracted with different approaches, such as the stem cycle, daily mean and daily maximum. Several approaches can be used, as very similar time series of stem radius variations were produced with high coefficients of correlation among the series. At lower altitude, the approximate onset was identified at the beginning of May with a 10-day time scale, when the distribution of stem radius variation differed from zero. The main growth period, from May to June–July, corresponded mainly with earlywood cell formation. At higher altitude, a time scale of at least 15 days facilitated identification of the main period of stem growth only, corresponding with earlywood cell formation. Even if latewood cells were produced in August at both altitudes, the variability in stem radius changes was higher than the amount of growth in terms of cell-wood production. For a slow-growing species in a cold environment, an understanding of the growth period, assessed with several time scales, is necessary when using time series of stem radius variation to assess growth and climate relationships. The period used for growth and climate analysis should correspond only with the main period of stem growth.     

Enzymes of the glyoxylate cycle in rhizobia and nodules of legumes

The relatively high level of fatty acids in soybean nodules and rhizobia from soybean nodules suggested that the glyoxylate cycle might have a role in nodule metabolism. Several species of rhizobia in pure culture were found to have malate synthetase activity when grown on a number of different carbon sources. Significant isocitrate lyase activity was induced when oleate, which presumably may act as an acetyl CoA precursor, was utilized as the principle carbon source. Malate synthetase was active in extracts of rhizobia from nodules of bush bean (Phaseolus vulgaris L.), cowpea (Vigna sinensis L.), lupine (Lupinus angustifolius L.) and soybean (Glycine max L. Merr.). Activity of malate synthetase was, however, barely detectable in rhizobia from alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.) and pea (Pisum sativum L.) nodules. Appreciable isocitrate lyase activity was not detected in rhizobia from nodules nor was it induced by depletion of endogenous substrates by incubation of excised bush bean nodules. Although rhizobia has the potential for the formation of the key enzymes of the glyoxylate cycle, the absence of isocitrate lyase activity in bacteria isolated from nodules indicated that the glyoxylate cycle does not operate in the symbiotic growth of rhizobia and that the observed high content of fatty acids in nodules and nodule bacteria probably is related to a structural role.     

A taxonomic revision of Labiostrongylus (Labiostrongylus) (Yorke & Maplestone, 1926) and Labiostrongylus (Labiomultiplex) n. subg. (Nematoda: Cloacinidae) from macropodid and potoroid marsupials

The morphological characters used to differentiate species in the genus Labiostrongylus Yorke & Maplestone, 1926, parasitic in macropodid and potoroid marsupials, are discussed. The genus is divided into three subgenera Labiostrongylus (Labiostrongylus), L. (Labiomultiplex) n. subg. and L. (Labiosimplex) n. subg. on the basis of the presence or absence of interlabia and the morphology of the oesophagus. A key to the subgenera is given and a detailed revision of two of the subgenera is presented. Keys to each of the subgenera are given, the species discussed being: L. (L.) labiostrongylus) (type-species) (syn. L. (L.) insularis, L. (L.) grandis, L. (L.) macropodis sp. inq. and L. (L.) nabarlekensis n. sp., in the subgenus Labiostrongylus, and L. (Lm.) eugenii, L. (Lm.) novaeguineae, L. (Lm.) onychogale, L. (Lm.) uncinatus, L. (Lm.) billardierii n. sp., L. (Lm.) constrictis n. sp., L. (Lm.) kimberleyensis n. sp., L. (Lm.) thylogale n. sp., and L. (Lm.) potoroi, n. sp., in the subgenus Labiomultiplex.     

Role of Ethylene in Abscisic Acid-induced Callus Formation in Citrus Bud Cultures

The induction of callus formation in cultured buds of Shamouti orange (Citrus sinensis [L.] Osbeck) by abscisic acid (ABA) is a multiphasic process. (Altman, and Goren 1974 Physiol Plant 32: 55.) A study of the mediation by ethylene on this effect of ABA was undertaken. It was found that: (a) ethylene and (2-chloroethyl) phosphonic acid, as well as ABA, induced callus formation; (b) callus induction is best attained when explants are exposed to ethylene during the 1st day after excision; and (c) ABA-induced callus formation is inhibited by rhizobitoxine analog, an inhibitor of ethylene biosynthesis. It is concluded that the effect of ABA on callus formation is mediated via ethylene.