Effects of different high constant and alternating temperatures on the development and prey consumption of <Emphasis Type="Italic">Dicyphus tamaninii</Emphasis> Wagner (Heteroptera,Miridae) with <Emphasis Type="Italic">Aphis gossypii</Emphasis> Glover (Homoptera,Aphididae) as prey

The present work aimed to study the effects of high constant and alternating temperatures on the development and prey consumption by Dicyphus tamaninii Wagner (Het., Miridae) with Aphis gossypii Glover (Hom., Aphididae) as prey.Results showed that the predator was able to successfully develop and reach the adult stage, on average, after 20.1 () and 20.6 () days at a temperature of 30 ± 1 °C with A. gossypii as prey. On the other hand, it was not able to develop at 35 ± 1 °C, here all N₁ instars used at the beginning of the experiments had died even before moulting to N₂ instar. At alternating temperatures of 25/15 ± 1 °C, the predator reached the adult stage 23.7 () and 23.5 () days after egg hatching, whereas when the temperatures were increased to 35/22 ± 1 °C, it took a significantly shorter period: 20.6 () and 20.9 () days. In general, the highest mortality occurred during the first two nymphal instars. The total percentage mortality during development from N₁ to adult stage was 30 % and 100 % at the constant temperatures 30 ± 1 °C and 35 ± 1 °C, respectively. At the alternating temperatures of 25/15 ± 1 °C, it was lowest with 16.5 %, while at 35/22 ± 1 °C, it was 20 %.The results of the experiments on prey consumption showed that an individual D. tamaninii consumed during its development to adult stage at 30 ± 1 °C an average of 442.2 (), 433.6 () aphids. At the constant temperature of 35 ± 1 °C, the average daily prey consumption started with 4 aphids and decreased continuously till it approached nil on the 9th day, where all predatory nymphs died. At the alternating temperatures of 25/15 ± 1 °C, the total prey consumption during development was, on average, 359.3 () and 297.0 () aphids, while at 35/22 ± 1 °C it was 348.5 () and 334.0 () aphids. The effect of the four temperatures on the prey consumption by D. tamaninii during the first 10 days after emergence was also studied. At a constant temperature of 30 ± 1 °C, a total of 446.4 () and 372.0 () aphids were consumed, compared to 40.6 () and 39.0 () at 35 ± 1 °C. At alternating temperatures of 25/15 ± 1 °C, the predatory adult consumed, on average, a total of 267.0 () and 207.0 () aphids. Increasing the temperature to 35/22 ± 1 °C resulted in a higher prey consumption by the adult predator, reaching 351.5 () and 267.7 () aphids over the same period.In conclusion, results indicated that D. tamaninii is a promising predator of the melon aphid at a temperature spectrum ranging from 15 ± 1 °C up to 35 ± 1 °C.     

Structure of cellulose microfibrils and the hydration effect in <Emphasis Type="Italic">Cryptomeria japonica</Emphasis>: a small-angle X-ray scattering study

The nanometer scale structure of cell walls in sugi wood (Cryptomeria japonica D. Don) and the hydration dependence were examined by the small angle X-ray scattering technique. Disk-shaped scattering patterns were observed for sugi wood. The radial average of two-dimensional data from the cross section could supply the scattering intensity with statistical accuracy much higher than that obtained from the sector average of the streak-shaped scattering pattern, and both the scattering intensities provided similar structural information. The scattering patterns from the cross section of the wood are characterized by rhombic or cross-shaped isointensity curves for the lower q region and by circularly symmetric isointensity curves for the higher q region. This shows that the disk-shaped scattering has two different kinds of scattering origins. The microfibril radii in the cell wall were determined by fitting the model scattering function of cylindrical fibrils to the scattering data. Values of 12.3 ± 0.3 and 12.2 ± 0.3 were obtained for the fibril radii of the neighboring earlywood and latewood, respectively, in dry specimens. A drastic structural change of the cell walls was detected with increasing water content from 40% to 100%. A low q rise in the scattering intensities below 0.1^–1 became weak and changed into a flat pattern, and the rhombic isointensity curves changed to cross-shaped patterns in the two-dimensional scattering from the cross section. The calculated radii R increased from 12.2 ± 0.3 to 13.3 ± 0.1.Part of this report was presented at the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, Japan, April 2002     

Characteristic Raman bands for <Emphasis Type="Italic">Artocarpus heterophyllus</Emphasis> heartwood

The Raman spectrum of Artocarpus heterophyllus heartwood, which proved to be a rich source of flavonoids, exhibited two characteristic bands, at 1247cm^–1 and 745cm^–1. The bands also appeared in the Raman spectrum of the yellow-brown needles extracted from the heartwood with methanol. Based on the Raman measurements of flavones and related compounds, it was predicted that the Raman band at 1247cm^–1 may be attributed to flavonoid-type compounds. No vibrational band corresponding to the characteristic Raman bands was observed by diffuse reflectance infrared spectroscopy. Thus, it was suggested that observation of the characteristic bands is an advantage of Fourier transform-Raman spectroscopy for nondestructive analysis of wood.     

Effects of stilbenes from bark of <Emphasis Type="Italic">Picea glehnii</Emphasis> (Sieb. et Zucc) and their related compounds against feeding behaviour of <Emphasis Type="Italic">Reticulitermes speratus</Emphasis> (Kolbe)

The effects of stilbene glucosides and related compounds on termite feeding behavior were investigated using paper disc methods against the subterranean termite Reticulitermes speratus. The stilbene-rich fraction and isorhapontin (3-methoxy-3,4, 5-trihydroxystilbene-3--d-glucoside) from bark extracts of Picea glehnii showed avoidance by termites in choice tests. In the no-choice tests using compounds purified from the stilbene-rich fraction, the largest feeding deterrent effect was observed for piceid (3,4,5-trihydroxystilbene-3--d-glucoside), followed by isorhapontin, and astringin (3,3,4,5-tetrahydroxystilbene-3--d-glucoside), at the concentrations from 0.63 to 2.5µmol/disc. No change in activity was observed at retentions of more than 5.0µmol/disc. When the activities of isorhapontin and its aglycone derivative (isorhapontigenin: 3-methoxy-3,4,5-trihydroxystilbene) were compared with that of taxifolin (3,3,4,5,7-pentahydroxyflavanone) in the no-choice test, the stilbenes exhibited a larger antifeedant potential. Methylation of isorhapontigenin increased its termiticidal activity.Part of this study was presented at the 32nd Annual Meeting of the International Research Group on Wood Preservation, 2001     

Nitrogen use by <Emphasis Type="Italic">Pinus densiflora</Emphasis> trees growing on a Mt. Fuji lava flow

To quantify the nitrogen (N) use by Pinus densiflora trees growing on an infertile lava surface, N pools, N requirement and N uptake through fine roots and N deposition from the atmosphere were estimated. The N requirement and the N uptake of fine roots were 55.5kgNha^–1year^–1 and 39.7kgNha^–1, respectively. Thus, the ratio of N uptake to N requirement of the fine roots was 71.5%. Including fine-root contribution, the total N requirement of the P. densiflora trees was 98.6kgNha^–1year^–1, and the total N uptake was 64.2kgNha^–1year^–1. Thus, the N uptake of the P. densiflora trees was 64.1% of the N requirement, indicating that P. densiflora trees growing on an infertile lava surface obtain some of their N from below-ground organic material layers every year and the contribution of N storage in trees for their growth is not any higher than indicated in previous reports that excluded fine-roots contribution. The wet N deposition of our research forest was only 5.8% of the N requirement of the P. densiflora trees and only 8.9% of the N uptake. Movement of the below-ground organic material layer N concentrations in the F- and L-layers coincides with needle development and fine-root growth, suggesting the possibility that P. densiflora trees extract N from the organic N of those layers for growth.     

Gamma radiation sensitivity of larvae and adults of the red flour beetle, <Emphasis Type="Italic">Tribolium castaneum</Emphasis> Herbst

In this study, the susceptibility of larvae and adults of Tribolium castaneum (Herbst) to gamma radiation was investigated in the laboratory in Turkey. Gamma radiation was applied at 6 dose levels between 20 and 200Gy to 13–15day-old adults and at 5 dose levels between 20 and 180Gy to 18–20day-old larvae of T. castaneum. All experiments were performed in growth chambers maintained at 27±1°C and 70±5% r.h. The larvae proved to be the more susceptible stage, survival to the adult stage being prevented by exposure of the eggs to 100Gy; the adult stage was less susceptible. LD₅₀ and LD₉₉ values were determined as 19,75 and 42,97Gy for larvae and 33,21 and 64,50Gy for adult stage, respectively. It was concluded that 100Gy is the effective dose for both larval and adult stages.     

In vitro propagation of <Emphasis Type="Italic">Oroxylum indicum</Emphasis> Vent. a medicinally important forest tree

In vitro propagation of Oroxylum indicum Vent. was carried out using cotyledonary node explants. Among the different types of cytokinins used for culture establishment, 6-benzyladenine exhibited the best response with higher concentrations (8.87µM or above) for inducing multiple shoots. Inclusion of indole-3-acetic acid (2.85µM) into 6-benzyladenine-supplemented medium triggered a high frequency of response as well as a proliferation of shoots. The best medium for proliferation was Murashige-Skoog (MS) medium with 6-benzyladenine (8.87µM) and indole-3-acetic acid (2.85µM). However, incorporation of gibberellic acid (1.44µM) was mandatory to enhance shoot elongation. Repeated subculturing of cotyledonary node and in vitro developed nodal segments in MS medium with 6-benzyladenine (4.44µM) at 4-week intervals resulted in continuous mass multiplication of shoots without any evidence of decline. Root induction was best (91.6%) when MS strength was reduced to one-quarter and combined with -naphthalene acetic acid (2.69µM) and indole-3-acetic acid (5.71µM), with a high survival rate (70–72%) of plantlets hardened in either soil rite or soil:sand:soil rite (1:1:2).     

Fogging can control<Emphasis Type="Italic"> Tetranychus urticae</Emphasis> on greenhouse cucumbers

The effect of a fogging system on interactions between Tetranychus urticae and Phytoseiulus persimilis was studied in two cucumber greenhouses in northern Italy. The greenhouses were divided into two compartments, one (referred to as fog area) was humidified using a fogging system and the other was not humidified (no fog area). Four cultivars were investigated: Akito and Frontera during 2000, Dinero and Jazzer during 2001. Tetranychus urticae was released on a number of plants in both compartments. The release of P. persimilis was planned in both compartments at definite T. urticae thresholds. Phytoseiid releases failed, and the colonization by other predators was scarce.Thus, the effect of the fogging system was evaluated only on T. urticae populations. During the first experimental year, spider mite populations reached low densities in the fog area of both cultivars. Higher densities were found in the no fog area, especially in late June and early July. One year later, spider mites were more abundant in the no fog area of the Dinero cultivar. On the Jazzer cultivar, where most plants were infected by powdery mildew, spider mites were less abundant and differences between the two areas were less marked. Since relative humidity values exceeding 90% (considered as effective on T. urticae) were recorded during the night when the fogging system was not active, we suggest that contact with misty water was the main factor responsible for the reduction of T. urticae populations in the fog area.     

Effect of rhizobial inoculation methods and host plant provenances on nodulation and growth of <Emphasis Type="Italic">Acacia senegal</Emphasis> and <Emphasis Type="Italic">Acacia nilotica</Emphasis>

The purpose of this work was to determine the most efficient methods of inoculation to significantly improve nodulation and growth of Acacia senegal and Acacia nilotica, grown under greenhouse conditions. Our results showed that inoculation using dissolved alginate beads containing rhizobia significantly improved the growth of both acacia species better than the growth of plants in other treatments. The experiment with A. nilotica was conducted in two unsterilised soils from different areas. Plants grown in soil from Bel Air were well-nodulated and showed better growth than plants grown in soil from Sangalkam. However, no difference between these soils was shown between the several methods of inoculation and their effect on the nodulation and growth of plants. An interaction between A. senegal and A. nilotica provenances and the effect of inoculation with rhizobia was also demonstrated. Bel Air provenance of A. senegal, Dahra and RIM provenances of A. nilotica grew best of several provenances tested. These results suggest that (1) it may be possible to improve growth and yield of A. senegal and A. nilotica by careful selection of each symbiotic partner; and (2) nursery-grown seedlings of A. senegal and A. nilotica should be inoculated, just after sowing, with dissolved alginate beads containing a mixture of selected rhizobia. Résumé. Lobject de notre travail était de déterminer la méthodologie dinoculation la plus efficace pour améliorer significativement la nodulation et la croissance dAcacia senegal et dAcacia nilotica poussant dans des conditions de serre. Nos résultats ont montré que linoculation utilisant des billes dalginate dissoutes améliorait significativement la croissance des deux espèces dAcacia par rapport à celle des plantes des autres traitements. Lexpérience avec A. nilotica a été faite dans deux types de sol non stériles. Nous avons observé que les plants poussant dans le sol de Bel Air étaient plus nodulés et mieux développés que ceux poussant dans le sol de Sangalkam. Cependant, aucune différence significative entre les deux sols na été mise en évidence en termes deffet des différentes méthodologies dinoculation sur la nodulation et la croissance des plantes. Il a aussi été démontré lexistence dune interaction entre les provenances dA. senegal et dA. nilotica et leffet de linoculation avec rhizobium. Cest ainsi que les provenances Bel Air dA. senegal, Dahra et RIM dA. nilotica ont le mieux poussé parmi les différentes provenances testées. Lensemble de ces résultats suggèrent: ⁽¹⁾ il devrait être possible daméliorer la croissance et la production dA. senegal et dA. nilotica par une sélection des deux partenaires symbiotiques; ⁽²⁾ Les jeunes plantules dA. senegal et dA. nilotica produites en pépinière devraient être inoculées juste après le semis avec des billes dalginate dissoutes contenant un cocktail de souches sélectionnées.     

Gas chromatographic and mass spectrometric (GC-MS) analysis of lignin-derived products from <Emphasis Type="Italic">Cryptomeria japonica</Emphasis> treated in supercritical water

Sugi (Cryptomeria japonica D. Don) wood was treated with supercritical water (374°C, 22.1MPa), and fractionated into the water-soluble portion, the methanol-soluble portion, and the methanol-insoluble residue. The methanol-soluble portion mainly consisted of the lignin-derived products. To characterize the compounds in the methanol-soluble portion, gel permeation chromatographic (GPC) and gas chromatographic-mass spectrometric (GC-MS) analyses were performed. The GPC analysis indicated that the methanol-soluble portion contained lignin-derived monomeric and dimeric products. GC-MS analysis detected 31 products which were expected to be monomeric compounds, and 18 of these were identified to be guaiacol, methylguaiacol, ethylguaiacol, vinylguaiacol, eugenol, propylguaiacol, vanillin, cis-isoeugenol, homovanillin, trans-isoeugenol, acetoguaiacone, propioguaiacone, guaiacylacetone, 2-methoxy-4-(1-hydroxypropyl)phenol, homovanillic acid, 2-methoxy-4-(prop-1-en-3-one)phenol, coniferyl aldehyde, and ferulic acid. In addition, 22 dimeric products were detected, and 4 of these were believed to be compounds with biphenyl type (5-5), diphenylethane type (-1), stilbene type (-1), and phenylcoumaran type (-5) structures. These results clearly indicated that the methanol-soluble portion included various monomeric and dimeric compounds produced as a result of the cleavage of ether linkages and propyl chains of lignin.     

Agrobacterium-mediated transformation of cork oak (<Emphasis Type="Italic">Quercus suber</Emphasis> L.) somatic embryos

A simple method is presented for the unreported genetic transformation of cork oak (Quercus suber L.). Pro-embryo masses (PEMs) were induced on immature zygotic embryos applied to medium supplemented with 2.3 M 2,4-dichlorophenoxyacetic acid. The established PEMs were inoculated with Agrobacterium tumefaciens LBA4404/p35S GUS INT/pCAMBIA 1301 strain. Transformants were selected on hygromycin (HYG) 94 M-supplemented medium. Viable embryos constituted 13% of those selected on HYG during 4 months. Expression of -glucuronidase at 4 months following co-cultivation confirmed transformation in 5.8% embryos selected on HYG. This method forms a basis for genetic transformation of cork oak somatic embryos.     

Crystallinity of wood and the size of cellulose crystallites in Norway spruce (<Emphasis Type="Italic">Picea abies</Emphasis>)

X-ray diffraction was used to study variations in the crystallinity of wood and the average thickness and length of the crystallites of cellulose as a function of the number of the year ring in Norway spruce [Picea abies (L.) Karst.]. The crystallinity increased from ring 4 to ring 10 from the pith and was constant after ring 10. The crystallinity of mature wood was about 30% ± 5%. The average thickness and average length of the crystallites were 3.2 ± 0.1nm and 28 ± 2nm, respectively; and no systematic variation of these values with the number of the year ring was observed. The mean microfibril angle decreased near the pith but was constant in the mature wood.     

Interactions between the striped stem borer <Emphasis Type="Italic">Chilo suppressalis</Emphasis> (Walk.) (Lep., Pyralidae) larvae and rice plants in response to nitrogen fertilization

A screenhouse experiment was conducted to examine the damage and compensation in rice plants when injured by the striped stem borer, Chilo suppressalis (Walker), larvae at tillering stage, as well as larval survival and development of the insect at different nitrogen (N) fertilization levels. Potted plants were fertilized at late seedling stage at the rates 0, 200, 400, 600 and 800mgN/pot, respectively. More deadheads were caused as fertilization increased. Plants compensated well for injury at the fertilization concentrations of 200 and 400mgN/pot by producing new tillers, but such compensation did not take place at 600 and 800mgN/pot. Two weeks after infestation, the highest number of remaining healthy tillers was found in plants fertilized at 400mgN/pot. Larval survival varied little among the treatments 200 to 800mgN/pot. Larval weight attainment and/or developmental rate increased with increasing fertilization level from 200 to 600mgN/pot, but both declined rapidly as fertilization reached 800mgN/pot, indicating the great dependence of plant suitability on N fertilization levels. Conclusively, both the compensation response of rice plants and their suitability for C. suppressalis larvae could be significantly affected by N fertilization levels.     

Minimum distance boundary method: maximum size-density lines for unthinned <Emphasis Type="Italic">Acacia mangium</Emphasis> plantations in South Sumatra,Indonesia

A minimum-distance boundary method that will minimize the sum of distances between measured points and a fitted self-thinning lines on log–log coordinates of stand density and quadratic mean diameter was proposed in order to estimate the maximum size density line: an upper boundary of self-thinning line. The lines for A. mangium were inferred with this method using data in two areas of unthinned plantations in South Sumatra, Indonesia. Slopes of the lines were deduced as –1.63 and –1.67 within the range of 10–21cm of quadratic mean dbh. The intensity of self-thinning was examined as a rate of reduction of density in relation to dbh increment. The rates were found to be higher than the slopes in the range close to the maximum line; hence the lines inferred in this study were likely existent. Maximum basal area deduced from the size-density line was 28–30m²/ha at 12cm of dbh and then it increased up to 34–37m²/ha at 20cm of dbh.     

Plastic deformation in small clear pieces of Scots pine (<Emphasis Type="Italic">Pinus sylvestris</Emphasis>) during densification with the CaLignum process

Specimens made of clear wood from Scots pine (Pinus sylvestris L.) were compressed semi-isostatically at 25°C in a Quintus press. Pressure ranged from 0 to 140MPa and the maximum decrease in the crosscut area was about 60%. Quarter-sawn and plain-sawn specimens were densified with the inside face (pith side) up or down. A laser-made dot grid on the crosscut area of the uncompressed specimen was used to calculate plastic strains by image analysis of the displacement of dots after compression. Multivariate models were developed to determine the causes of deformation. The lower face was restrained by the press table and remained flat whereas sides attached to the rubber diaphragm became more irregularly shaped when compressed. Most of the total compression occurred below 50MPa and was determined exclusively by pressure. Above 50MPa, wood density was more important and compression was lower in the interior of specimens and in heartwood. Plastic compressive strain occurred predominately in the radial direction and toward the rigid press table. Strains were dependent on the sawing pattern and orientation. The growth rings of quarter-sawn specimens oriented with the outer face (bark side) down tended to buckle.     

Influences of host age,sex ratio,population density,and photoperiod on parasitism by <Emphasis Type="Italic">Trichogramma evanescens</Emphasis> Westw. (Hym., Trichogrammatidae)

Moth species Ephestia kuehniella and Sitotroga cerealella are serious pests in cereal-based food processing facilities and stores in Turkey. Control of these pests is undertaken by regular space treatment of infested areas with pesticides. An alternative control method could be the release of parasitic wasps of the genus Trichogramma. In laboratory tests, we use T. evanescens as a parasitic wasp reared on the eggs of Ephestia kuehniella. Adult wasps emerging from the host were maintained in glass tubes at 27±1° C, 60–70±5% r.h and L14:D10 and fed on honey solution. Adults of T. evanescens in vials without food enclosed from host eggs and all died within 1.8days; in comparison, in vials with honey, live adults were evident for 15.2days. Fresh (6–48h) and old (72–96h) host eggs were offered to T. evanescens and fresh eggs were more accepted than old. Host acceptance of females with males in vials was better than without males. The number of females in the vials also influenced the parasitization rate and single female parasitized more eggs. Adults living in light regime (L14:D10 and L6:D18) parasitized more eggs than in total darkness. Results are discussed with relation to enhancing parasitoid effectiveness in biological control in processing facilities and mills.     

Antioxidant activity of extracts from <Emphasis Type="Italic">Calocedrus formosana</Emphasis> leaf,bark, and heartwood

Calocedrus formosana Florin (Cupressaceae) is an endemic tree to Taiwan. To evaluate the antioxidant activity of the plant extracts from heartwood, bark, and leaf of C. formosana, assays for 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and superoxide anion scavenging activities, as well as prevention of DNA strand cleavage were performed in this study. Similar IC₅₀ values against the DPPH radical were found for the heartwood and bark extracts at approximately 23µg/ml. Moreover, the heartwood extract exhibited the highest inhibitory activity against superoxide radicals among the test samples; a 2.3-fold lower value of IC₅₀ for superoxide radical inhibition was found in the heartwood extract relative to that of (+)-catechin. Much less effect on inhibition of DPPH and superoxide radicals was found from the leaf extract of C. formosana. More than 70% of superoxide radicals were inhibited in the presence of 10µg/ml heartwood extract, whereas only 15% inhibition was obtained from the leaf extract. The heartwood extract, at a dose of approximately 0.5mg/ml, apparently completely prevented the X174 supercoiled DNA cleavage induced by ultraviolet photolysis of H₂O₂, as judged by agarose gel electrophoresis. This report also suggests that the antioxidant activities of the plant extracts of C. formosana are in good correlation with their phenolic contents.     

Delignification of cell walls of <Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis> during alkaline nitrobenzene oxidation

To clarify the behavior of whole lignins in wood cell walls during alkaline nitrobenzene oxidation, the delignification process from cell walls in normal and compression woods of Chamaecyparis obtusa Endl. (Cupressaceae) was observed using ultraviolet and transmission electron microscopies. The lignin content conspicuously decreased to around 10% after 35min in normal wood. The lignin content in compression wood finally leveled off at aroumd 10% after 50min. In gel filtration of oxidation products in ethyl acetate, a high molecular weight fraction was prominent in extracts from the early stage of the reaction. As the oxidation progressed, the high molecular weight fraction became less prominent in both normal and compression wood. Changes in the weights of cell wall residues during reaction indicated that approximately half of the components other than lignin were also removed from the cell walls. This shows that the majority of lignin with relatively high molecular weight is removed from the cell walls together with polysaccharides in the early stage of the reaction and that further oxidative degradation occurs in solution in later stages. Only a small amount of the lignin with low molecular weight could be analyzed by gas chromatography.Parts of this report were presented at the 47th (Kochi, April 1997) and 48th (Shizuoka, April 1998) Annual Meetings of the Japan Wood Research Society, and at the Lignin Symposium, Sapporo, October 1997     

A study on some anatomical parameters of the piercing-sucking process in leaves and branches of<Emphasis Type="Italic"> Pittosporum tobira</Emphasis> L. (Pittosporaceae) infested by the cottony cushion scale,<Emphasis Type="Italic"> Icerya purchasi</Emphasis> Maskell (Homoptera: Coccina,Margarodidae)

Pittosporum tobira L. (Family Pittosporaceae) is an important plant species grown in parks and gardens in Turkey. The cottony cushion scale, Icerya purchasi Maskell (Homoptera: Coccina, Margarodidae), is an important pest of P. tobira, and causes damage mainly to the leaves, branches and stems of the host plant. In spite of the great economic importance of I. purchasi to its host plant P. tobira, information has been limited on some basic anatomical parameters of the nature of the damage to leaves and branches. The present study was, therefore, initiated to investigate the insertion and penetration of stylets into the leaves and branches of P. tobira, the length of stylets and depth of penetration in both of these tissues, and penetration of stylets into the cortex, xylem and phloem tissues and into the secretory and non-secretory canals of the leaves and branches. The results showed great variations between the leaves and branches in all the criteria observed in I. purchasi infesting P. tobira. The study found 20 whole and 23 broken mouthparts in the leaves as compared to 3 whole mouthparts and 1 broken in the branches. Length of the stylets inserted into the leaves ranged from 33.83 m to 540.93 m and into the branches from 202.85 m to 340.8 m. The stylets reached greater depths in the leaves, at 540.93 m, as compared to 498.67 m in the branches. The stylets in the leaves were associated with 12 secretory canals, but with none in the branches. It was found that three stylets reached xylem in the leaves as compared to one in the branches. Similarly, 17 stylets in the leaves reached to the phloem, but only 2 in the branches. No stylets were found in the cortex of the leaves, but one was found in the branches. In the leaves, 11 stylets reached and remained in the non-secretory canals, but none in the case of the branches.     

Light availability and understory vegetation four years after thinning in a <Emphasis Type="Italic">Larix leptolepis</Emphasis> plantation of central Korea

We measured photosynthetically active radiation (PAR) beneath the forest canopy, understory species richness and diversity, and biomass in a Larix leptolepis plantation in central Korea 4 years after thinning. Four different thinning intensities (control, 10%, 20%, and 40% stocking reduction) were applied in 1997. Mean annual intercepted PAR at 30cm and 1m above ground level was significantly different among the thinning intensities and strongly correlated with the number of stems remaining after thinning. Understory species richness and diversity were lowest in the unthinned stands and increased with thinning intensity, and there were significant correlations between the total number of understory species or diversity index (Shannons diversity index, H) and the number of stems per hectare after thinning. Also understory above-ground biomass was significantly increased with thinning intensity in both sampling months (June and August 2001). Thinning increased light inputs to the ground and resulted in higher species richness and diversity and above-ground biomass. These results suggested that light availability and understory responses to thinning at a comparable intensity are likely to last well beyond the 4 years of this study.