Effect of tool angles on the chips generated during milling of wood by straight router-bits

 The effect of tool angles on the shapes of chips generated by parallel-to-grain and end-grain milling was explored for China fir and maple under fixed spindle and feed speeds and cutting depth. The milling path was up-milling by straight router-bits with a diameter of 12 mm. The chip shapes could be distinguished as five types: spiral, splinter, flow, thin, and granules or powder. The flow and thin chips were generated most often (on a weight percentage basis) for all tool angles investigated for parallel-to-grain and end-grain milling of China fir and maple. More granule chips were produced with parallel-to-grain milling than with end-grain milling for both woods. The measured chip thickness (t′) was thicker than the calculated thickness (t _max). Thicker and longer maple chips were produced by end-grain milling than by parallel-to-grain milling. The tool geometries of 40°/15° (sharpness of the angle–rake angle), 50°/15°, and 60°/15° for China fir and 40°/25°, 50°/5°, and 60°/5° for maple produced relatively more flow chips with parallel-to-grain milling. Furthermore, the tool geometries of 40°/5°, 50°/15° and 60°/25° produced more flow chips (weight percentage) by end-grain milling of China fir and maple. Received: May 23, 2001 / Accepted: June 28, 2002 Acknowledgment This study was supported by a grant from the National Council of Science, Taiwan (NSC89-2313-B-415-011).     

Effects of slash chips placed around trees planted after whole-tree logging: movement and nutrient supply

 Whole-tree harvesting at clearcutting sites using cable yarding systems and processors disrupts the process of nutrient return via leafy and woody slash otherwise left on the forest floor. This study examined the effect of placing slash chips around trees planted in a clearcut area. Chips made from branches with needles (branch chips) and three types of wood scrap chips (wood chips) were prepared for the study. Changes in the thickness of slash chip layers and in the concentration and weight of decomposing chips were measured. The nutrient effect of applying chips to the soil was analyzed, and the effects of chip coverage on weed control were measured. The branch and 18-mm-thick wood chips were stable on slopes; 9- and 4-mm-thick wood chips readily shifted to the lower and outer positions in the plots. On branch chips and wood chips, the annual rate of decomposition (k) calculated by exponential model was 0.69–0.7 and 0.04–0.17/year, respectively. Branch chips provided more nutrients for decomposers, and were rapidly decomposed during the first month. Nevertheless, the nutrient effect on the soil could not be confirmed. Placing branch or wood chips around planted trees effectively eliminated the need for weeding for 1 year, but these light materials did not suppress shrub sprouting. Received: November 14, 2001 / Accepted: September 26, 2002 Acknowledgments The authors thank the graduates of Kochi University, especially Ms. Y. Shinnobu, Ms. A. Fujita, Ms. A. Sugiyama, and Ms. Y. Suzuki for their help with the field work and chemical analyses. This study was supported by a Grant-in-Aid for Scientific Research (No. 09660164) from the Ministry of Education, Culture, Sports, Science and Technology of Japan. Correspondence to:J. Gotou     

Microscopic structure and properties of wood-based foaming composites

In order to reduce the density of wood-based composites without causing a deterioration of their mechanical properties, we studied the process of manufacturing wood-based composites. A combination of polymer foaming technology and flat hot-pressing technology was used. The microscopic structure of the various wood-based composites was analyzed with a scanning electron microscope (SEM). Modulus of rupture (MOR), modulus of elasticity (MOE), impact strength, and thickness expansion rate of water sorption (TS) were all measured. The results showed that fibers loosely interweave, and fibers had been connected by micropore. They also showed that spaces between fibers had big micropore structure. MOR, MOE and impact strength were the highest among three levels of ratio. When the total content of resin and foaming agent were 20% by weight, TS was higher. A hot-pressing temperature of 120°C was optimal. At the low temperatures of 80°C, the foaming process was uncompleted. At a higher temperature, micropores burst at a certain pressure. Based on the variance analysis and maximum difference analysis, a significance test shows that the optimum conditions for the total content of resin and foaming agent is 20% by weight, with a hot pressing temperature of 120°C for 15 min. Under these conditions, the properties of wood-based foaming composites all achieved the industry standard. __________ Translated from Journal of Beijing Forestry University, 2007, 29(3): 154–158 [译自: 北京林业大学学报]     

速生材制生物机械浆研究Ⅱ、泡桐(Paulownia elongata)酶液预处理机械浆

研究了兰考泡桐（Ｐａｕｌｏｗｎｉａｅｌｏｎｇａｔａ）木片用４种酶液（纤维素酶液ＥＳ２８、半纤维素酶ＥＡｎ７６、木质素酶Ｅ０２５及Ｅ０１４）预处理制生物机械浆。测定了预处理对木片主要化学组成、磨浆能耗、纸浆强度的影响。结果表明：（１）Ｅ０１４、Ｅ０２５、ＥＳ２８、ＥＡｎ７６预处理后，木片失重３．１８％～３．７２％，其中３．９％～１８．６％为木质素损失，纤维素损失则高达３８．２％～４６．２％；（２）磨浆度为５５ＳＲ时，４种酶液可节省能耗２．０％～７．０％，裂断长变化为－１８．１％～７．９％，耐破度变化为－１３％～７．３％，撕裂度为－１２．９％～８．４％，光学性质（如白度、光散射系数）变化不大，不透明度几乎不变。综合能耗节省与强度性质的提高，Ｅ０１４及ＥＡｎ７６效果较好，ＥＳ２８则由于纤维素酶对纤维的损伤效果不佳，Ｅ０２５效果则一般。     

Effect of thermo-mechanical refining on properties of MDF made from black spruce bark

The effects of thermo-mechanical refining conditions on the properties of medium density fiberboard (MDF) made from black spruce (Picea mariana) bark were evaluated. The bark chips were refined in the MDF pilot plant of Forintek Canada Corporation under nine different refining conditions in which preheating retention time was adjusted from 3 to 5 to 7 min and steam pressure was set at either 0.6, 0.9 or 1.2 MPa. The resulting bark fibers were blended with 12% UF resin (based on oven-dry fiber weight) using a mechanical blender. The resinated fibers were manually formed into fiber mats and hot-pressed into MDF panels using consistent parameters. Two panels for each refining condition were produced, resulting in a total of 18 panels. Analysis of variance (ANOVA) was used to analyze the significance of factors. Regression coefficients and 3D contour plots were used to quantify the relationship between panel properties and the two test factors. The results from this study indicated that the preheating retention time was a significant factor for both modulus of rupture (MOR) and modulus of elasticity (MOE), the steam pressure was a significant factor for internal bond strength (IB), MOR and MOE, whereas both factors were insignificant for thickness swelling, water absorption and linear expansion. The properties of MDF panels were quadratic functions of retention time and steam pressure. Compared to the ANSI standard for 120-grade MDF, most panels with a nominal density of 950 kg/m³ had very high IB (>1 MPa) and acceptable MOR, MOE and dimension stabilities. These results suggest that black spruce bark residues can be considered as a potentially suitable raw material for manufacturing MDF products.     

Structural mechanism and effect of hole compressibility on mechanical strength of MFLB

We have studied the structural mechanism of micron flaky wood fiber light density board (MFLB), of which voids are an important structural characteristic. A new parameter called hole compressibility (η) was added to study the characteristics of MFLB further, in order to produce various levels of hole compressibility. A set of hot pressures was applied, and uniform parts at cross-sections of MFLB were selected to study the effects of hole compressibility on the modulus of elasticity (MOE) and modulus of rupture (MOR) of MFLB by microscopic analyses. The results showed that MFLB (0.3 g/cm³ in density) processed at various hot pressures (from 1.6 to 2.2 MPa) all meet the norms of the Japan Light Particleboard Industrial Standard JISA 5908, where η ⩽ 0 ranging from −0.0487 to −0.068. The critical value of hole compressibility at which the strength began to decrease was also obtained. We compared the void distribution, size and shape at different void contents and hole compressibility and discussed the effects of hole compressibility on MOE and MOR of MFLB as well. To a certain density of raw material and micro-fiber of a certain thickness, the strength of MFLB can be decreased with an increase in hole compressibility. When the hole compressibility of MLFB exceeds a certain critical value, loading at a lower level will decrease MOR and MOE of MFLB considerably. __________ Translated from Scientia Silvae Sinicae, 2007, 43(6): 123–127 [译自: 林业科学]     

Development of binderless fiberboard from kenaf core

Binderless fiberboards with densities of 0.3 and 0.5 g/cm³ were developed from kenaf core material using the conventional dry-manufacturing process. The effects of steam pressure (0.4–0.8 MPa) and cooking time (10–30 min) in the refining process, fiber moisture content (MC) (10%, 30%), and hot-pressing time (3–10 min) on the board properties were investigated. The results showed that kenaf core binderless fiberboards manufactured with high steam pressure and long cooking time during the refining process had high internal bond (IB) strength, low thickness swelling (TS), but low bending strength values. The binderless fiberboards made from 30% MC fibers showed better mechanical and dimensional properties than those from air-dried fibers. Hot-pressing time was found to have little effect on the IB value of the binderless board at the refining conditions of 0.8 MPa/20 min, but longer pressing time resulted in lower TS. At a density of 0.5 g/cm³, binderless fiberboard with the refining conditions of 0.8 MPa/20 min recorded a modulus of rupture (MOR) of 12 MPa, modulus of elasticity (MOE) of 1.7 GPa, IB of 0.43 MPa, and 12% TS under the optimum board manufacturing conditions. Part of this article was presented at the 54th Annual Meeting of the Japan Wood Research Society, Hokkaido, August 3–5, 2004     

Field investigation on Salix psammophila plant morphology and airflow structure

The field investigation was undertaken to determin the characteristics of Salix psammophila plant morphdogy and airflow structure of single-line S. psammophila on the southern edge of the Mu Su sandland. The results showed that artificially cultivated single-line S. psammophila could accumulate sand because the plant decreased the windward and leeward wind velocity. There was a significant correlation (R = 0.696) between accumulated sand volume (V ₂) and plant volume (V ₁). The wind velocity was 6 m/s at a 4 m height of single-line S. psammophilahedge row. The wind velocity decreased at 3 H windward and increased at 2 H to windward. The wind velocity then steeply decreased to leeward and reached its lowest value at 1 H to leeward and gradually recovered to the open field velocity. The protection distance of the single-line S. psammophila was about 17 H′ and the effective protection distance was about 13 H′. Single-line S. psammophila had few effects on the wind velocity when the wind was above the plant height. __________ Translated from Chinese of Applied Ecology, 2005, 16(11) [译自: 应用生态学报, 2005, 16(11)]     

Long‐term survival and non‐vector spread of the pinewood nematode,Bursaphelenchus xylophilus,via wood chips

The pinewood nematode, Bursaphelenchus xylophilus, is the causal agent of pine wilt disease and is transmitted to new host trees by beetles of the genus Monochamus. The increasing interest in imported wood chips from North America for paper production and energy purposes and the corresponding phytosanitary risk of non‐vector transmission of B. xylophilus has been discussed since 1984, the year of the first interception of B. xylophilus in wood chips in the European Union. The long‐term survival of B. xylophilus in wood chips and its non‐vector spread from infested wood chips to non‐infested trees were studied. Pinus sylvestris logs were inoculated with a suspension of B. xylophilus to produce infested wood chips. During the long‐term storage test, B. xylophilus in P. sylvestris wood chips were examined. Four variants, including sealed and openly stored wood chips at both 15°C and 25°C, were studied. For the test of non‐vector spread, B. xylophilus ‐infested wood chips were placed on three‐ to four‐year‐old P. sylvestris saplings under different conditions. Bursaphelenchus xylophilus survived for more than 1 year at both temperatures in the sealed wood chips, which was significantly longer than for the openly stored variant at 25°C. Temperature, tree condition and wood chip location all influenced non‐vector spread through wood chips. Of the 480 trees that were in contact with infested wood chips and showed clear symptoms of pine wilt disease, B. xylophilus were extracted from 42 pines at 25°C and one pine at 15°C. The highest B. xylophilus infestation rates resulting in clear pine wilt disease symptoms (75%) were found in infested wood chips directly attached to stem‐wounded trees at 25°C. However, more variants exhibited B. xylophilus infestation at this temperature; trees with stem or root injuries plus direct contact with infested wood chips to the wounded part were primarily affected. Moreover, non‐vector spread was also detected in stem‐ and root‐injured pines without any direct contact with infested wood chips. Our results confirmed that B. xylophilus can survive for long periods in wood chips and can be transmitted from infested wood chips to damaged trees, but the likelihood of such PWN establishment should be low compared to spread through vectors. These findings must be considered in the pest risk analysis of B. xylophilus, and studies using outdoor trials should be carried out to complete this pest risk analysis.     

Characterization of wood-based molding bonded with citric acid

The wood-based moldings were fabricated by using only citric acid as an adhesive. The mechanical properties, water resistances, thermal properties and chemical structure were investigated. Wood powder obtained from Acacia mangium was mixed with citric acid under certain weight ratios (0–40 wt%), and each powder mixture was molded using two types of metal molds at 200°C and 4 MPa for 10 min. The modulus of rupture and the modulus of elasticity values of the wood-based molding containing 20 wt% citric acid were 35.8 MPa and 5.4 GPa, respectively. The maximum impact strength was 0.94 kJ/m² with the same citric acid content. The water resistance increased with increasing citric acid content, and the good resistance to boiling water was also recognized. However, some elution of substances derived from citric acid was observed at high levels of citric acid, causing a decrease in the thermal properties. The ester linkages were detected by Fourier transform infrared spectroscopy, indicating that the citric acid reacted with the wood. Our results demonstrated that citric acid brought about good adhesiveness for fabricating the wood-based molding.     

Dynamic simulation of disintegration of wood chips caused by impact and collisions during the steam explosion pretreatment

Steam explosion (SE) pretreatment produces damaged and disintegrated biomass with a large surface area which facilitates enzymatic hydrolysis for the production of biofuels and other value-added chemicals. It was observed during experiments that wood chips disintegrate into smaller pieces because of collisions and impact with each other and the walls of the SE equipment. In this study, these events were simulated using the finite element method. Wood chips were simulated in this model as a linear elastic material until failure. The damage initiation was identified using Hashin’s damage initiation criteria. Once the damage was initiated, additional loading caused the evolution of damage, i.e. degradation and breakage of the material, which was modelled using the material property degradation model and deletion of the failed elements. Elastic and strength properties of spruce wood were estimated at ambient conditions (12 % moisture content at 20 °C) and at SE conditions (30 % moisture content at 160 °C). Comparison of simulations performed using material properties at ambient and SE conditions revealed that the damage in wood chips significantly increased because of the steam treatment. The effects of wood chip velocity and orientation at the time of impact were studied as well. It was found that wood chips moving at high velocity and impacting with the steel wall in the radial direction acquire the most damage.     

Cell growth and nutrient uptake by cell suspensions of <Emphasis Type="Italic">Cupressus lusitanica</Emphasis>

 Conditions for cell growth of suspension cultures of Cupressus lusitanica, which has high β-thujaplicin productivity, were studied. The medium that provided the highest growth rate was IS-1 medium (pH 5.5), modified from Gamborg B5 medium containing 32 mM of total nitrogen. Its NO₃-N/NH₄-N ratio was 30 : 2. The maximum growth represented a 25-fold increase over the initial biomass on a fresh weight basis after 30 days of culture in this medium. The highest cell growth was obtained with an initial pH of 3.5–5.5, but the pH of the medium settled to about pH 4.0 from any of the initial pH values in this report. The cells cultured under this condition were able to produce a high level of β-thujaplicin. Received: September 7, 2001 / Accepted: May 7, 2002 Present address: Teijin Ltd., Ehime 791-8530, Japan Present address: Q'SAI Co. Ltd., Fukuoka 811-3422, Japan Part of this report was presented at the 10th international symposium on wood and pulp chemistry, Yokohama, Japan, June 1999 Correspondence to:K. Fujita     

Volatile composition analysis by solid-phase microextraction applied to oak wood used in cooperage (Quercus pyrenaica and Quercus petraea): effect of botanical species and toasting process

The purpose of this study was to investigate the sorption of selected volatile substances from oak wood-chip samples (Quercus pyrenaica Willd. and Quercus petraea L.) subjected to different toasting levels, namely, without toasting, with medium toasting, and with strong toasting, through the use of solid-phase microextraction (SPME). The main volatile compounds identified as a function of the toasting level and botanical species were furfural, hexanal, α-pinene, d-limonene, decanal, vitispirane, ethyl hexanoate, cis-3-methyl-γ-octalactone (“oak lactone” or “whisky lactone”), α-terpineol, p-xylene, and nonanal. Considering the data obtained from the toasted woods (medium and strong intensity) in comparison with those of nontoasted woods, it can be pointed out that the average peak area and the number of compounds identified in the gas chromatogram decreased during the toasting process. In general, regarding the compounds analyzed, quantitative differences were found between the two oak wood species under study. High values of volatile compounds were found in Quercus pyrenaica oak wood chips. In addition, for the number of compounds identified in oak wood extracts and directly extracted from solid oak wood chips by SPME, it is concluded that the best extraction process for volatile compounds from oak wood is the use of oak wood-chip liquid extracts.     

外力作用下4种植物根系易损部位的研究

[目的]为探讨根系在轴向拉力和径向折力下的易损部位。[方法]以3 4 a的柠条、沙柳、沙棘和白沙蒿为研究对象,采用TY8000伺服控制材料试验机测定4种植物侧根分支处和相邻直根的抗拉力与抗折力。[结果]表明:在1 4 mm根径范围内,4种植物侧根分支处和相邻直根的抗拉力、抗折力均与直径呈幂函数正相关,抗拉强度、抗折强度均与直径呈幂函数负相关;同径级时,每种植物单根的抗拉强度和抗折强度均表现为侧根分支处小于相邻直根,4种植物侧根分支处和相邻直根的抗拉强度为柠条((23.70±3.97)、(28.02±4.40)MPa)沙柳((14.86±1.28)、(20.33±1.76)MPa)沙棘((10.60±2.40)、(15.86±3.90)MPa)白沙蒿((5.07±1.25)、(8.80±1.74)MPa),侧根分支处和相邻直根的抗折强度为:柠条((33.66±7.74)、(47.06±4.41)MPa)沙柳((17.31±1.91)、(27.54±3.82)MPa)沙棘((3.97±1.23)、(8.75±1.70)MPa)白沙蒿((2.18±0.39)、(6.15±1.01)MPa)。[结论]无论受轴向拉力还是径向折力,4种植物根系易损部位均为侧根分支处。造成垂直根模型(WWM)和纤维束模型(FBM)预测根系固土能力偏高的补充原因为:(1)模型根系全部计入直根的抗拉力,忽略了侧根分支处,而侧根分支处是根系固土的薄弱点。(2)模型假设所有根系为轴向受拉的杆件。实际根土复合体发生剪切时,根可能承受轴向拉力,也可能承受径向折力。对于抗折强度小于抗拉强度的植物,模型必然高估根的实际固土能力。     

Fiber- and fine fractions-derived effects on pulp quality as a result of mechanical pulp refining consistency

High-yield pulping of wood chips using low-consistency (LC) refining in combination with primary-stage high-consistency (HC) refining has previously been shown to produce paper with quality parameters (tensile strength and light-scattering coefficient) commonly targeted for newsprint with significantly less refining energy input than using only HC refining. However, questions remain on the differences in the refining action between the two refiner types and for high-yield pulping, the refiner energy demand is a crucial process parameter. Therefore, fines- and fiber-fraction development in HC and LC refining has been studied in detail using Bauer-McNett fractionation, and the respective tensile strengths of the different fractions have been compared. Quantitative and qualitative (morphological) characteristics of the isolated fine fractions have also been analyzed in detail using a newly developed automated fluorescence microscopy method and scanning electron microscopy. The results suggest the difference in LC/HC pulp properties (strength and optical) is partly derived from deviating fiber and fines morphologies and mass balances. The quality of the fines generated during HC and LC refining also differs. LC-refined pulps contain thinner fibrillar fines (thread-like) and HC-refined pulps broader fibrils such as lamellae-type fines. Flake-like fines from the outer fiber wall decreased in relative amount with energy input.     

Distribution of Frankia, ectomycorrhizal fungi, and bacteria in soil after the eruption of Miyake-Jima (Izu Islands, Japan) in 2000

Miyake-Jima, a round island of about 8 km in diameter, is located about 200 km south of Tokyo, Japan (34°08′ N, 139°53′ E). In July 2000, the central cone of this island collapsed and a new eruption started with the falling of volcanic ash and SO₂ emission. In October 2001, we measured the distribution of bacteria, and Frankia, a symbiotic nitrogen-fixing actinomycete that forms root nodules, and ectomycorrhizal fungi associated with alder in newly deposited ash and its underlying soil by cultivation of Alnus sieboldiana seedlings in these soils. There were fewer bacteria growing on the nutrient broth agar and fewer bacteria growing on 100-fold diluted nutrient broth agar in newly deposited volcanic ash than there were growing in the buried old soil. In four out of five sites, little or no nodulation was observed in newly deposited ash; abundant root nodules were formed in the underlying soil. Ectomycorrhizae formed in the seedlings cultivated in the underlying soil. In May 2003, the distribution of Frankia and ectomycorrhizal fungi in soil at different depths (up to 160 cm) was also investigated. Frankia and ectomycorrhizal fungi were relatively abundant in surface soil layers.     

Initial shapes of stress-strain curve of wood specimen subjected to repeated combined compression and vibration stresses and the piezoelectric behavior

This study investigated the relationship between the initial shape of the stress (σ)-strain (ε) curve of a Chamaecyparis obtusa wood specimen subjected to repeated combined compression and vibration stresses at various angles between the fiber direction and load direction and the piezoelectric behavior. The main findings of the study are: (1) the σ-ε curve became convex initially, and then the stress was proportional to the strain. The σ-ε curve had almost the same shape during both loading and unloading. (2) The σ-piezoelectric voltage (P) curve was nonlinear, with a maximal point or cusp on the curve, which had almost the same shape during both loading and unloading, as was also observed for the σ-ε curve. (3) The plot of the first derivative of the stress [dσ/dε (= σ′)] against ε was nonlinear. The σ′-ε and P-ε curves at various angles were fairly similar. (4) The stress at the maximal point (or cusp) of the σ-P curve decreased with an increase in the angle between the fiber direction and load direction. The tendency of the stresses was very similar to that of Young’s modulus and compression strength calculated from Hook’s law and Hankinson’s law, respectively.     

Measurement of the refining degree of bamboo charcoal by an alternating current method

We investigated a method for measuring the refining degree of bamboo charcoal using an alternating current. The bamboo charcoal was made under heating conditions of 400°–900°C (set temperature) and 0—3 h (holding time at each set temperature). The qualities of the bamboo charcoal could not be estimated from the yield, and electric tests were required. The effect of the variation in sample thickness on the impedance could be ignored. Attaching two plate electrodes to the same surface of a specimen enabled high accuracy and practical use. The impedance was found to be a suitable index for estimating the refining degree of the bamboo charcoal, such as the specific electric resistance. We believe that bamboo changes from an insulator to a conductor suddenly when processed at 600°–750°C for 0–2 h. It is possible that the integral of temperature with time in a specimen during heating is useful for approximately estimating impedance.     

Assessment of the effect of a fully closed hillside afforestation mode on the natural Pinus tabulaeformis forest

The Huanglong Mountain forest zone is one of the major natural secondary forest zones in the southern Loess Plateau in Shaanxi Province, China. Since 1950, a mode of fully closed hillside afforestation (FHA) has been applied in the forest. On some special sites, the forest age exceeds 80 years. Pinus tabulaeformis forests form the most important vegetation cover in the warm temperate regions of China. Similarly, populations of P. tabulaeformis are dominant in existing forest ecosystems. Quercus liaotungensis, Syringa oblata, Populus davidiana, Prunus davidiana, Betula platyphylla and Toxicodendron vernicifluum can be occasionally found in the tree layer and shrub species are abundant. Based on the data collected from 31 plots and 93 soil samples, the state of health of the forest ecosystem is discussed and the appropriate FHA age has been determined. Twelve indices representing vegetation and soil properties in natural, secondary P. tabulaeformis forest ecosystems were generated by sensitivity analysis and an assessment index system for the FHA mode was established. According to the equal distance method, a clustering technique and five grades of an integrated index for evaluating the FHA mode were compartmentalized. The effect of the FHA mode on natural secondary P. tabulaeformis forests was evaluated by an integrated index method with the aid of an analytical hierarchy process (AHP). The results are as follows: values of the integrated index in the FHA mode of 16, 25, 30, 45, 60 and 75 year old stands were 7.25, 6.88, 7.82, 5.51, 4.78 and 2.79 respectively. With an increase over age of the FHA stands, the effect of the FHA mode deteriorated. We conclude that natural forests should not be protected in the FHA way after 45 years. At that stage, mixing suitable tree species, selection cutting and other silvicultural and management measures should be adopted. __________ Translated from Acta Ecologica Sinica, 2007, 27(1): 288–295 [译自: 生态学报]     

Inhibitory effects of alkaloids from Sophora alopecuroids on feeding, development and reproduction of Clostera anastomosis

Alkaloids from Sophora alopecuroids were bioassayed with Clostera anastomosis for their antifeedant and growth inhibitory effects. The antifeedant rate in choice test reached 62%–86% at the dose 2.5 mg/mL, while in non-choice bioassay the rate was only 20%–29%. In choice bioassay, the antifeedant rate increased with larval instars of C. anastomosis and did not in non-choice experiment. The alkaloids also imposed a strong influence on the growth of C. anastomosis larvae, i.e., after feeding on the leaves treated with alkaloid, the larvae lost their weight, weight gain, and relative growth rate (RGR) significantly when compared with the controls. In the second day after treatment with the dose at 10 mg/mL of the alkaloid, the RGR reduced by 39.8%, and the food intake and the feces weight were respectively 57.7% and 57.4% of the controls. The approximate digestibility (AD) increased significantly, and the efficiency in converting digested food (ECD), and the efficiency in converting ingested food (ECI) decreased greatly after feeding the treated leaves. Moreover, the eggs laid per female were also inhibited by this alkaloid. The significance and prospect of the alkaloids in controlling forest insect pests were also discussed. __________ Translated from Scientia Silvae Sinicae, 2005, 41(4) [译自: 林业科学, 2005, 41(4)]