拟异尾华枝的取食量研究

拟异尾华枝ＳｉｎｏｐｈａｓｍａｐｓｅｕｄｏｍｉｒａｂｉｌｅＣｈｅｎ雌、雄性的个体取食量：雌性一生总食叶量为１７．８８ｌｇ，其中１～４龄低龄若虫期的占５．４８％，５～７龄老龄若虫期的占２２．７１％，成虫期的占７１．８１％；雄性为７．２１５ｇ，其中１～４龄低龄若虫期的占６．２０％，５～６龄老龄若虫期的占３１．１０％，成虫期的占６２．７０％，老龄若虫期和成虫期是主要的危害期；并分别建立了雌、雄性个体食叶量、个体日均食量指数增长模型，胸径为８～１２ｃｍ的寄主，其防治指标为１５８．４头。     

松褐天牛成虫补充营养特性研究

１９９７－１９９８年浙江省杭州市和岱县进行的松褐天牛成虫补充营养特性研究表明：松褐天牛成虫主要取食１年生树枝，室内测定雌成虫取食１年生树枝面积占总面积的３６．５８％，雄成虫占３８．９９％，林间测定点２６．３４％，成虫羽化后２０天以内的取食量最大。伐倒松材线虫病致枯萎的松树，统计天牛取食痕和取食面积在树冠上的分布显示，松褐天牛更多选择树冠下部１年生的树枝取食、取食痕和取食面积分别占５０．４２％和５１．０６％。     

金斑蝶成虫行为学特征

[目的]为摸清金斑蝶成虫的行为特征,[方法]在田间的网室内跟踪观察其飞行、取食、求偶、交配和产卵行为。[结果]表明:金斑蝶成虫羽化主要集中在8:00—10:00,成虫羽化当天基本处于停歇状态;羽化第2天起至交配前,雌雄成虫的日平均飞行次数及日平均飞行时间均逐渐增加,雄成虫的日飞行高峰在13:00—15:00,雌成虫的日飞行高峰期在9:00—11:00和15:00—17:00,雌雄成虫的日平均飞行次数、平均飞行时间和日飞行规律的差异均不显著(p0.05);飞行次数与飞行时间均呈显著正相关(雌蝶:r=0.978,p0.05;雄蝶:r=0.957,p0.05)。金斑蝶雌雄成虫羽化次日开始取食,自羽化第2天起,雌雄成虫的日平均取食次数及日平均取食时间均逐渐增加,雄虫的日取食活动高峰期在9:00—11:00,雌虫日访花高峰期在11:00—13:00和15:00—17:00,雌雄成虫的日平均取食次数、平均取食时间和日取食规律的差异均不显著(p0.05);取食次数与取食时间均呈不显著正相关(雌蝶:r=0.949,p0.05;雄蝶:r=0.853,p0.05)。最早交配时间发生在羽化第4天,雌雄成虫均可多次交配,交配主要发生在14:00—16:00。产卵时间主要在11:00—13:00,雌成虫的产卵方式为散产,主要产卵于寄主植物叶片背面。[结论]金斑蝶成虫期可分为运动器官成熟阶段、补充营养和促进生殖器官发育阶段、求偶和交配阶段、产卵等4个阶段,各阶段内行为有交叉。     

拟异尾华枝Xiu的取食量研究

拟异尾华枝Ｘｉｕ Ｓｉｎｏｐｈａｓｍａ ｐｓｔｕｄｏｍｉｒａｂｉｌｅ Ｃｈｅｎ雌、雄性的个体取食量：雌性一生总食叶量为１７．８８ｌｇ，其中１－４龄低龄若虫期的占５．４８％，５－７龄老龄若虫期的占２２．７１％，成虫期的占７１．８１％；雄性为７．２１５ｇ，其中１－４龄低龄若虫期的占６．２０％，５－６龄老龄若虫期的占３１．１０％，成虫期的占６２．７０％，老龄若虫期和成虫期是主要的危害期；并分别建立了雌、     

星天牛行为及控制技术研究Ⅰ.天牛行为及危害木麻黄规律的研究

通过野外调查和室内外人工饲养,结果表明星天牛[Anoplophorachinensis(Forster)]成虫大多在白天活动,在自然条件下有趋向木麻黄防护林带飞翔的行为。雌、雄成虫一生可多次交尾,每天8时和16时为交尾高峰。成虫补充营养最喜欢取食苦楝树(MeliaazedarachL.)。苦楝树饲养雌虫每头产卵156～198粒,平均176 4粒,是木麻黄饲养的3 10倍;取食苦楝树的雌虫寿命72～110d,平均91 8d;雄虫寿命88～125d,平均103d,雌、雄成虫分别比取食木麻黄(Casuarinaequi setifolia)的多存活30 2d、40d。幼虫主要集中在离地面40cm高度内的树干根际附近,占总虫数的94 8%。1年生林分受害株至第2年5月成虫羽化期死亡率最高,达66 7%,3～7年生林分有虫株率最高;7年生以下林分应重点防治。在生境条件相似的同龄林中,星天牛则喜欢危害基径较大的木麻黄,6cm以下的树则较少受害。     

冷杉芽小卷蛾研究初报

冷杉芽小卷蛾,在长春市一年发生一代。以幼虫在针叶内越冬。蛹期18～20天。平均每雌产卵12粒,雌成虫寿命9～12天,雄成虫寿命7～9天。卵期10～12天,孵化率约86％。该虫发生与林木组成、林龄、郁闭度有关。在幼虫取食盛期,喷雾防治,药效显著。     

磷化铝毒丸防治油松大小蠹药效试验

１９９９ 年，油松大小蠹（学名待定）在山西省许多地区的油松林内暴发成灾，对３０年生或胸径１２ ｃｍ 以上的油松危害极大，造成了严重损失。该虫为害油松系首次发现。其成虫大多在距根基部１ ｍ 以内的树干部位侵入蛀食韧皮部，雌虫产卵量一般为１００ 多粒。幼虫继续取食韧皮部，常造成油松死亡。该虫营隐蔽生活，一般的化学防治方法效果很差。采用钻孔塞入磷化铝毒丸薰杀法，成虫死亡率可达９６．４％ ，幼虫死亡率可达９７．７％ 。     

朴平刺巢沫蝉生物学特性的研究

朴平刺巢沫蝉ＨｉｎｄｏｌｏｉｄｅｓｓｐａｒｓｕｔａＪａｃｏｂｉ模式标本采自福建邵武，寄主不详。生物学尚无详细报道。作者在山西太谷小叶朴树ＣｅｌｔｉｓｓｉｎｅｎｓｉｓＰｅｒｓ．上发现其密度很大。１９９０—１９９２年研究结果表明：该虫寄主专一为小叶朴。一年发生一代，以老龄若虫在当年生枝上结钙质巢越冬。４月上旬，小叶朴发芽开花期，越冬若虫出蛰。成虫羽化期从４月中旬到５月。成虫雌雄比为１：１．０８。每雌虫平均产卵量为８０粒。卵产在小叶朴果实表面，成单列横排，一块有２－１４粒，以８—１０粒者为多，一果有１—４块；单粒卵为靴形。卵期约３０天，孵化率８２．８％。若虫共５龄，各龄历期分别为１８天、２０天、３０天、３０天、２３０天。６月和７月，幼龄若虫以排泄物在果柄上结夏巢，隐蔽巢内取食；８月份第３龄若虫退出夏巢，迁移到当年生枝上结冬巢。并在其中取食发育，越冬，直到翌年春末羽化为成虫。夏巢和冬巢均为螺旋形，蜗牛壳状，灰白色，质硬，化学成份主要为碳酸钙ＣａＣＯ３。但夏巢远小于冬巢。对各虫期形态特征作了描绘。     

棉蝗的生物学特性观察及其发生环境因子的调查

棉蝗在广东湛江地区，１年发生１代，以卵在沙土中越冬，至翌年４月中旬卵孵化为幼蝻，脱皮６次（或７次）后，子６月中旬至７月中旬陆续羽化为成虫，７月中旬起，成虫支尾产卵，并于９月上、中旬陆续死亡。卵平均孵化率为８８％，６龄或７龄跳蝻数量各占５０％左右，５龄后期至成虫交尾产卵前取食量最大，成上平均产卵量达９３．６粒。棉蝗适宜生长于滨海沙土、ｐＨ值为５．８６～７．８７、表土全盐量为０．２３～１．６７ｇｋｇ－１的海洋性气候环境。木麻黄无性系林较普通木麻黄林抗虫。     

杨树橙斑白条天牛的生物学特性

橙斑白条天牛(Batocera davidia Deyrolle)是福建省杨树的新害虫,该虫在福建省2a发生1代,以幼虫和成虫越冬,一般成虫于秋季羽化,停留于蛹室越冬,次年春夏陆续自蛹室向外作椭圆形的羽化孔而飞出。成虫5月上旬开始产卵,5月下旬初孵幼虫开始取食危害,次年7月下旬开始化蛹,8月中下旬成虫羽化。少部分成虫在8月下旬爬出羽化孔,补充营养后交配产卵,大部分成虫在蛹室内越冬。在幼龄林,雌虫主要产卵于树干基部,随着树龄的增加和树皮的增厚,多产卵于2m以下的树干上。每雌产卵38-52粒,平均46.2粒。林间卵的孵化率为53%-76%。     

Improving the evaluation of multiple-dowel-type connection strength

Our study focuses on predicting the ultimate short-term load carrying capacity of timber-to-timber connections with dowel-type fasteners. The wide range of possible configurations in practice makes the resolution of these values by tests unrealistic. Moreover, different current regulations do not consider some specific failure mechanisms. In many countries, the reduction of resistance involved by this phenomenon is taken into account by considering an effective number of dowels (n_ef) smaller than the actual number of dowels (n) in the connection. However, these different regulations disagree on the values of n_ef and on other points (spacing, partial coefficient of security, formulas). These discrepancies in design rules invite the fundamental research on this topic and, therefore, new methods are sought in order to estimate the load carrying capacities of the connections. In the light of these, our approach consists of predicting the load carrying capacity with the neural network numerical tool. The results obtained by this analysis tool are satisfactory, although the model remains complex. Subsequently, we focus on the simplification of this numerical model with classical regression techniques in order to implement it in a design code.     

Effects of the lignan, pinoresinol on the moulting cycle of the bloodsucking bug Rhodnius prolixus and of the milkweed bug Oncopeltus fasciatus

The furano-lignan pinoresinol was toxic to fourth-instar larvae of the milkweed bug Oncopeltus fasciatus and of the haematophagous insect Rhodnius prolixus, a vector of Chagas disease. At lower doses, it also exerted antifeedant activity and dose-dependent antimoulting activity on both insects.     

Traditional fallow systems of the Americas

Six neotropical traditional fallow systems are described: 1) enriched fallows of the Amazon, 2) Babassu palm (Orbignya phalerata Mart.) forests of central and northern Brazil, 3) bracatinga (Mimosa scabrella Benth) improved fallow of southeastern Brazil, 4) carbon negro (Mimosa tenuiflora Willd.) fallow of the wet-dry zone of Mesoamerica, 5) frijolillo (Senna guatemalensis Donn. Smith) of high-elevation zones in southern Honduras, and 6) caragra (Lippia torresii) fallow of humid zones of Costa Rica.These systems include both biologically and economically enriched fallows. Some (e.g., the enriched fallows of the Amazon) require a considerable degree of human intervention, while others (e.g., the bracatinga and carbon negro fallows) seem to form with little human encouragement, following the burn in shifting cultivation systems. Some of the systems (e.g., frijolillo and caragra) are quite site-specific and have a limited distribution; others (e.g., babassu, bracatinga, and carbon negro) occur over large areas and could be adapted to considerable areas in the Americas. As economic analyses are generally lacking, it is unclear what benefits would be achieved from a wider use of these systems. Most of the biologically enriched fallows seem able to maintain low yields of food crops at low input levels. Some of the economically enriched fallows seem able to produce higher economic returns.     

Litterfall,litter decomposition and the use of mulch of four indigenous tree species in the Atlantic lowlands of Costa Rica

Litterfall, forest-floor litter biomass and nutrients, short-term litter decomposition and the effects of leaf mulches on initial growth of maize were studied for four indigenous tree species with agroforestry potential:Stryphnodendron microstachyum Poepp. et Endl.(S. excelsum), Vochysia ferruginea Mart,Vochysia guatemalensis Donn. Sm. (V. hondurensis) andHyeronima alchorneoides (O), growing in a young experimental plantation in the Atlantic humid lowlands of Costa Rica. Total annual leaf litterfall was higher inV. ferruginea plots, followed byS. microstachyum, V. guatemalensis andH. alchorneoides; all with values comparable to those reported for other tree species grown in agroforestry combinations in humid tropical regions. Forest-floor litter accumulation was highest underV. ferruginea andV. guatemalensis. Both litterfall and forest-floor litter material had similar patterns in nutrient concentrations: N was higher inS. microstachyum, Ca was higher inV. guatemalensis, K was higher inH. alchorneoides; Mg was higher inV. guatemalensis andH. alchorneoides; H. alchorneoides andV. guatemalensis had the highest P.V. ferruginea litter decomposed more slowly, whileS. microstachyum apparently decomposed faster than the other species. The twoVochysia species showed increases in N and P concentration in decomposing litter after seven weeks in the field,H. alchorneoides showed an increase in litter N and a decrease in litter P, andS. microstachyum showed a net decrease in both N and P over the same time period. The patterns found in the litter bag study were confirmed by results obtained in a tethered-leaves experiment.S. microstachyum andV. ferruginea litters lost more weight when mixed in a 11 proportion than either of them alone. Maize seedlings growing in plots mulched withS. microstachyum andH. alchorneoides leaves showed greatest initial growth, confirming patterns found in decomposition and nutrient release studies. The results show that these species could be used in agroforestry combinations with different advantages according to the specific objectives desired, whether these are soil protection, nutrient recycling, or enhancement of the growth of associated crops.     

Influence of leaf portion and plant species on the egg-laying behaviour of the predatory ladybird Serangium parcesetosum Sicard (Col., Coccinellidae) in the presence of a natural enemy

The effectiveness of natural enemies against arthropod herbivores can depend on the characteristics of the plant on which they are found. The influence of the plant on the egg-laying behaviour of the promising whitefly predator, Serangium parcesetosum Sicard (Col., Coccinellidae) was examined in order to be able to use it effectively in biological control programs. The present work investigated the possible influence of the portion of the leaf on the number of eggs laid as well as the effect of plant species on the way in which eggs are deposited by S. parcesetosum. The experiments were conducted on cucumber and cotton leaves with Bemisia tabaci (Genn .) (Hom., Aleyrodidae) as prey in the absence and presence of a natural enemy, the lacewing, Chrysoperla carnea (Stephens) (Neur., Chrysopidae) at two different temperatures. The results showed that at 18°C, S. parcesetosum females significantly preferred to lay their eggs between the veins and close to the veins of cucumber leaves, mean of 10.1 and 7.5 eggs, in the absence of C. carnea, respectively, while in its presence significantly more eggs were deposited close to the veins and close to the petiole. On cotton leaves, close to the petiole, a mean of 8.4 eggs in the absence of the lacewing, as well as close to the veins, mean of 6.3 eggs in the presence of the lacewing, were found to be the most suitable leaf portions for egg-laying. At 30° C, the females laid their eggs preferentially close to the veins of cucumber leaves in the absence and presence of C. carnea. On cotton leaves, S. parcesetosum females significantly preferred to lay their eggs close to the petiole, mean of 7.6 and 6.1 eggs, as well as close to the veins, mean of 6.2 and 8.7 eggs, in the absence and presence of the lacewing, respectively. At both temperatures, the ladybird females laid their eggs singly on cucumber leaves in the absence and presence of C. carnea. While on cotton leaves, the females had a tendency to deposit their eggs together in the absence and presence of the lacewing, except at 30°C in its absence. Within the same plant species, significant differences were found in the total number of eggs laid by S. parcesetosum females on cotton leaves at 18°C as well as on cucumber leaves at 30°C in the absence and presence of the natural enemy. In addition to the effects of presence and absence of C. carnea, and where eggs were laid, some significant differences due to plant species was found at both temperatures.This article is dedicated to Prof. Dr Wolfgang Schwenke on his 84th birthday.     

Nutrient composition of the leaf biomass of three selected woody leguminous species

In order to assess the value of leaf biomass the foliar nutrient content of Leucaena leucocephala, Gliricidia sepium and Flemingia macrophylla was studied under field conditions. In total 5 series of leaf samples were collected and analysed for nitrogen, phosphorus, potassium, calcium and magnesium content over a period of 42 months of growth observation. Results are compared with mean values derived from a literature study. Factors contributing to the variation observed are discussed and suggestions towards variation control are made.     

The importance of seedling competition in the segregation of spruce and fir in the southern Appalachians

Fraser fir (Abies fraseri [Pursh] Poir.) and red spruce (Picea rubens Sarg.) are codominants of southern Appalachian spruce-fir forests. Fraser fir generally dominates above 1740 m, while red spruce usually dominates below this elevation. This study was designed to determine whether the present segregation of the two species along elevational gradients is associated with seedling competition or contrasting physiological responses to environmental factors. Seedlings were grown for two years in a replacement series experiment along two elevational transects extending from 1300 m to 1900 m, and harvested for growth analysis.Competition increased with decreasing elevation and Fraser fir was apparently the stronger competitor. Mortality was inversely correlated with elevation and was most evident in red spruce in May, and in fir in late summer. Fir growth increased with elevation and red spruce grew most at the middle elevation (1600 m). Neither competitive interactions nor growth responses completely explained the elevational segregation of red spruce and Fraser fir. We hypothesize that the early-successional Fraser fir quickly dominates at higher elevations following disturbance and that continued disturbance will favor its dominance at higher elevations. However, the late-successional noncompetitive red spruce slowly establishes itself and, while consistently present, may only dominate in the absence of disturbance and where other species are at the margins of their distribution.     

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.     

松材线虫(Bursaphelenchus xylophilus)耐久型幼虫(LIV)携带的香茅醇假单胞杆菌(Pseudomonas citronellolis)分离与鉴定

[目的]目前有关松材线虫与伴生细菌的关系及伴生细菌的病原作用是松树枯萎病研究的重点。为了揭示松材线虫与伴生细菌之间存在的密切关系,作者对松材线虫L_IV幼虫携带的细菌进行了分离鉴定。[方法]根据培养性状和16S rDNA序列同源性以及系统发育学等方面进行分析鉴定。[结果]确定L_IV幼虫携带的是香茅醇假单胞杆菌（Pseudomonas citronellolis）,携带率为100%;每条L_IV幼虫携带量在1.4×10⁵~4.5×10⁵。L_IV幼虫生活在松褐天牛体内,是引起松材线虫病侵染流行的唯一虫态;新发现的香茅醇假单胞杆菌能分解纤维素及降解或合成萜烯和酚类化合物。[结论]L_IV幼虫携带香茅醇假单胞杆菌的发现,揭示了松树、松褐天牛、松材线虫、细菌同为一体的紧密关系,并为揭示松树枯萎病机制提供了一种新病原和重要的研究思路。     

A Comparison of the Utility and Agronomic Traits of Indigenous and Exotic Trees in the Mount Kenya Region

On-farm indigenous (Cordia africana) and exotic (Grevillea robusta) tree species were compared in terms of the quality of their utility and their agronomic traits in the Meru Central district of Kenya. These two species are the most common indigenous and exotic trees, respectively, among the recorded 117 trees on farms. Interviews with farmers and collected documents on tree felling and planting showed that farmers considered C. africana to be more useful than G. robusta. However, farmers wanted to plant more G. robusta than C. africana because the easily established and fast growing G. robusta has a higher short-term contribution to the household economy. The advantages of C. africana, however, should be redefined in terms of its long-term contribution to farmers; C. africana contributes to farming more effectively than does G. robusta. The lower growth performance and relative difficulty in the establishment of C. africana can be compensated for by its higher timber quality and coppicing ability.