五种杀虫剂对绿鳞象甲的生物活性研究

采用微量点滴法和浸液饲喂法分别测定了5种常用杀虫剂对绿鳞象甲Hypomeces squamosus成虫的生物活性,结果表明:1.8%阿维菌素乳油(EC)的触杀活性较高,致死中浓度LC50为5.71 mg/L;1.8%阿维菌素EC和20%啶虫脒可湿性粉剂(WP)的胃毒作用较强,2种药剂的LC50分别为15.30 mg/L和12.24 mg/L;4.5%高效氯氰菊酯EC和10%联苯菊酯EC对绿鳞象甲的触杀和胃毒活性均较差。田间防治显示,喷药后5 d,1.8%阿维菌素EC 1500和3000倍液对绿鳞象甲的校正死亡率分别为96.46%和87.18%,20%啶虫脒WP 2000和4000倍液分别为91.59%和82.74%。推荐1.8%阿维菌素EC和20%啶虫脒WP用于生产防治。     

不同机理的17种杀虫剂对椰心叶甲的室内毒力测定

选取4类不同作用机理共17种化学药剂对椰心叶甲成虫进行室内毒力测定。通过筛选,敌百虫、吡虫啉、高效氯氰菊酯、灭多威具有优良的毒杀效果,处理24h后,每种药剂3种浓度的校正死亡率均达90%以上;而高效氯氟氰菊酯、氧乐果、丙溴磷.辛硫磷、丁硫.啶虫脒、氯氰菊酯.三唑磷、吡虫啉.三唑磷6种农药药效较差,难以有效防治椰心叶甲。噻嗪酮.异丙威、哒螨灵、杀虫双、三氯杀螨醇、异丙威、三唑磷、乙酰甲胺磷对椰心叶甲没有毒杀作用。     

几种杀虫剂对花椒树上棉蚜的毒力测定

笔者运用浸渍法测定了花椒树上棉蚜对啶虫脒乳油、高渗高效氯氰菊酯乳油、三唑磷乳油和辛硫磷乳油的抗毒力。试验结果表明,啶虫脒乳油对棉蚜的毒力水平最高,LC50值为0.000 178 g/m L;其次为高渗高效氯氰菊酯乳油(LC50为0.001 835 g/m L),辛硫磷乳油(LC50为0.015 003 g/m L),而三唑磷乳油的毒力水平最低,其LC50仅为0.025 260 g/m L.     

刺槐蚜对常用杀虫剂的敏感性研究

采用微量点滴法测定了山西省晋中地区刺槐蚜Aphis robiniae Macchiati种群对常用10种杀虫剂的敏感性.以LD50值为标准进行比较,刺槐蚜对供试杀虫剂的敏感性依次为:甲维盐>氯氟氰菊酯>高效氯氰菊酯>啶虫脒>阿维菌素>联苯菊酯>丁硫克百威>灭多威>辛硫磷>敌敌畏.其中对甲维盐的敏感性最高,LD50值(μg/头)为0.000 029;其次为氯氟氰菊酯、高效氯氰菊酯,其LD50值分别为0.000 401和0.000 544;对有机磷类药剂的敏感性最低,辛硫磷、敌敌畏的LD50值分别为0.004 89和0.010 3.根据试验结果提出治理对策.     

云南云杉长足大蚜毒力测定及田间药效试验

用7种杀虫剂对云南云杉长足大蚜若虫进行室内毒力测定,5种杀虫剂开展田间防治试验,结果表明:供试杀虫剂对云南云杉长足大蚜的毒力大小依次为:0.5%藜芦碱可溶性液剂>1%苦参碱可溶性液剂>4.5%联菊·啶虫脒乳油>4.5%高效氯氰菊酯乳油>10%阿维·毒死蜱乳油>4%甲维.氟铃脲微乳剂>30%吡虫啉·噻嗪酮乳油。在田间防治若蚜时,施药24h后,0.5%藜芦碱可溶性液剂0.025%药液、1%苦参碱可溶性液剂0.033%药液和4.5%联菊·啶虫脒乳油0.017%药液防治效果均达95%以上。     

刺桐姬小蜂药剂防治试验研究初报

用16％虫线清乳油,3％啶虫脒粉剂,雅丹（35％硫丹EC）油剂,20％阿维、三唑磷乳油和25％吡虫啉粉剂等5种药剂对刺桐姬小蜂进行药剂防治试验,试验结果表明,试验药剂对刺桐姬小蜂幼虫和蛹均不起作用,而对成虫有较强杀伤力。几种药剂以16％虫线清乳油、雅丹和20％阿维、三唑磷乳油防治效果比较理想,死亡率较高,最高的死亡率为100％,而各浓度之间的防治效果差异不显著。     

草履蚧幼虫防治药剂筛选试验初报

草履蚧是危害杨树的重要害虫之一。为了筛选出高效低毒的农药,在室内条件下用喷雾法测定了10种杀虫剂对草履蚧1、2龄幼虫的防治效果。结果表明:供试10种药剂对草履蚧均有防治效果,其中40%杀朴磷乳油、2.5%高效氯氟氰菊酯乳油、20%啶虫脒可溶性粉剂、2.3%甲氨基阿维菌素苯甲酸盐乳油防治效果显著,24 h校正死亡率在85%以上,48h校正死亡率在97%以上。结合药剂毒性和防治成本分析,建议将高效氯氟氰菊酯、啶虫脒作为化学防治的首选药剂。     

红棕象甲的初步调查研究

红棕象甲是椰子树主要害虫之一，此虫在海南岛分布于琼山、定安、文昌、琼海、万宁、乐东、儋州等地；成、幼虫为害椰予树叶柄及茎顶，严重为害时可使椰子树致死，据调查此虫对椰子树为害率高达84％，叮通过捡疫、化学防治等措施加以防治。     

几种常用杀虫剂对端尖食植瓢虫幼虫和成虫的室内毒力测定

为筛选出防治端尖食植瓢虫(Epilachna quadricollis Dieke)的高效药剂,采用浸渍法测定了4种常用杀虫剂对端尖食植瓢虫不同龄期幼虫和成虫的毒力。不同龄期的毒力结果表明:高龄期的端尖食植瓢虫对药物具有更强的抵抗能力。不同药剂的毒力结果表明:新烟碱类杀虫剂烯啶虫胺对端尖食植瓢虫的毒理最高,施用后24h后对端尖食植瓢虫的致死中浓度(LC50)最低为0.84mg/L,其次是溴氰菊酯、阿维菌素、氟啶虫酰胺,最低的LC50分别为2.33mg/L、3.74mg/L和7.73mg/L。     

7种药剂对短须突瓣叶蜂室内毒力和田间防效

短须突瓣叶蜂是近年来危害柳树的一种新害虫,选用7种杀虫剂对短须突瓣叶蜂幼虫进行室内毒力测定,筛选出5种杀虫剂开展田间防治试验。结果表明:供试杀虫剂对短须突瓣叶蜂的毒力大小依次为:1.8%阿维菌素乳油>10%阿维·毒死蜱乳油>4.5%高效氯氰菊酯乳油>40%丙溴磷乳油>4.5%联菊·啶虫咪微乳剂>1%苦参碱可溶性液剂>4%甲维·氟铃脲微乳剂。田间药效试验结果显示,施药24h后,1.8%阿维菌素乳油、10%阿维·毒死蜱乳油和4.5%高效氯氰菊酯乳油是防治短须突瓣叶蜂的有效药剂。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.