湖南稻田蜘蛛群落生态特点及控虫作用研究

总结近年来对湖南省境内不同地理、生态类型的稻田蜘蛛群落结构的研究结果;报道湖南稻田蜘蛛198种,隶属25科87属,及其常见类群和主要优势种:拟水狼蛛、食虫沟瘤蛛、八斑鞘腹蛛。并应用测定群落结构特征的多种指数公式比较分析不同地理、生态类型的稻田蜘蛛群落的时空格局特点、物种多样性差异、主要优势种差异以及农药对稻田蜘蛛群落结构的影响和蜘蛛群落对目标害虫的控制效应的定性定量分析结果。     

沈阳地区稻田节肢动物群落结构及群落生态研究

通过对沈阳地区稻田生态系统节肢动物群落结构及群落生态研究。共查得。属昆虫纲的有10个目的29科66种,其中天敌昆虫种类有7目20科51种,属蜘蛛纲的有蜘蛛目10科20种。用空间及时间生态位分析了害虫与天敌两个营养阶层间的关系。稻田生态系统节肢动物的多样性指数、均匀度与优势度分析表明,各类群落受外界干扰都很敏感,且表现一致性。依据节肢动物群落的结构及规律,结合沈阳地区水稻生长、栽培条件,用最优分割方法将稻田群落分为4个阶段,并提出了不同阶段害虫群落特点及害虫防治对策。     

抗虫转基因水稻和化学杀虫剂对稻田节肢动物群落的影响

从功能团优势度、功能团内科组成及其优势度、功能团个体数量、群落主要参数及群落结构相异性等方面,就含crylAb／crylAc融合基因的Bt水稻和化学杀虫剂对稻田节肢动物群落影响进行比较研究．结果表明,与对照田相比,Bt稻田的节肢动物功能团组成及其优势度、各功能团内科组成及其优势度分布、功能团内个体数量的时间动态、群落参数(物种丰富度、Shannon-Wiener多样性指数、均匀性指数、优势集中性指数)及时间动态在大多情况下均无显著差异,两者间群落结构相似性较高．Bt水稻对稻田节肢动物群落基本无明显的负效应、而化防田的功能团优势度等群落特征指标与对照田相比,有时具有明显甚至显著的差异;群落结构相似性也较低．综合分析表明,Bt水稻对稻田节肢动物群落的影响明显弱于化学杀虫剂。     

广东亚热带森林群落的生态优势度

本文应用simpson优势度指标,测定广东亚热带14个森林群落的生态优势度。对测定结果深入分析,说明了生态优势度指标在森林群落分析上有较大的意义,可以衡量不同的群落类型,作为群落分类的辅助指标;能反映群落生境变化对群落结构的影响,以及说明森林群落演替过程群落结构的变化;广东亚热带森林在自然状况下向气候顶极群落的演替过程中,生态优势度指标逐渐下降。 本文还进一步探讨生态优势度的生态学涵义。说明生态优势度指标的群落生态学意义,指出与物种多样性指数、群落均匀度在概念上的联系与差别,以及三者在应用上的异同。     

青海湖湖盆南岸植物群落的生态优势度与海拔梯度

利用Ｓｉｍｐｓｏｎ优势度指标对青海湖湖贫南岸的植物群落优势度进行了测定,并讨论了群落生态优势与海拔梯度之间的相互关系。结果表明,海拔梯度是通过影响群落内和中群组成影响群落的生态优势度,群落生态优势度与群落内植物种群数呈相关,群落内种群越丰富,群落生态优势度就越小,反之越大。     

广西生态茶园和普通茶园的节肢动物群落结构和稳定性分析

为了解广西生态茶园与普通茶园节肢动物群落结构特点及其稳定性,本文采用Shannon-Wiener多样性指数（H′）、群落物种优势度指数（D）、丰富度指数（J）、物种均匀度指数（E）等分析了茶园节肢动物群落的多样性结构,应用群落相似度指数对生态茶园和普通茶园节肢动物的群落相似性进行了分析,用灰色关联度方法综合分析多样性指数与优势度、均匀度等6个特征参数间关系的密切程度。结果表明,在广西茶园节肢动物共34种,其中害虫（螨）17种,优势种群是：小贯小绿叶蝉Empoasca onukii Matsuda、茶蓟马Scirtothrips dorsalis Hood、蚜虫、白粉虱Trialeurodes vaporariorum Westwood;天敌8种,优势种群是：棕管巢蛛Clubiona japonicola Boeset Str.、八斑球腹蛛Theridion octomaculatum Boes. et Str.、异色瓢虫Harmonia axyridis(Pallas);中性昆虫9种,优势种群是：蚊虫、蚁类。多样性指数、群落均匀度指数与物种优势度在生态茶园比普通茶园高。生态茶园的群落稳定性比普通茶园的强。不同茶园间的群落相似性指数q在0.444~0.9355之间,群落间相似性关系在中等不相似与极度相似之间。与多样性指数密切相关的前3位群落特征参数依次是群落物种优势度、益害物种的个体数比、丰富度,其中关系最密切的特征参数是群落物种优势度。研究结果为茶园害虫的综合防控提供了理论依据。     

粤北天然林优势种群生态位研究

基于粤北始兴县罗坝保护区内2个2500m^2样地的群落分层频度调查数据,以不同林层作为一维资源位状态,以个体多度为生态位计测的资源状态指标,对天然常绿林群落中的12个优势树种（栲树、马尾松、茶木、枫香、罗浮柿、杨梅、鹿角栲、黄瑞木、甜锥、山杜英、牛耳枫及鸭公树）进行了生态位的计测和分析。结果表明,大部分的耐荫树种具有较大的生态位宽度值;而阳性树种（如马尾松等）同表现为较小的生态位宽度值。其中马尾松和枫香的生态位宽度值为0,与这两个种在群落演替中的衰退地位相一致,各优势树种,无论是耐荫种类抑或是阳性种类,均表现出一定程度的对现有环境适应的相似性。群落1中相似性比例在0.5以上的占54.5%;也表现出一定程度的生态位重叠,群落1中重叠值大于0.2的占51.5%。结合经典的森林群落分层频度分析,则可以更准确地判定种群在群落中的地位和更新发展潜力;另一方面,把群落分层作为资源位,考虑不同的个体多度的分层中的分布情况,这些分析结果也从一个侧面反映树种对生境的要求情况,不同的群落由于其中树种组成结构不同,使树种生态位宽度值产生变化,从而影响树种之间的生态位相似比例和生态位重叠值。     

不同种植方式下转Bt基因水稻对稻田节肢动物群落的影响

如何设置庇护所使其在转基因作物靶标害虫抗性治理中达到更高的效率,就此,本文 研究了Bt水稻与非Bt水稻不同种植方式对Bt稻田节肢动物群落的影响。结果表明,整体上,块块种植和列列混栽方式对Bt稻田节肢动物群落多样性、均匀度和优势集中性无显著影响;但混栽方式下的Bt稻田节肢动物群落个体密度和物种丰富度显著偏低。在水稻发育中期,混栽方式下Bt稻田节肢动物群落季节动态与块块种植方式下的明显不同,其多样性、均匀度、优势集中性指数均类似于同种植方式下非Bt稻上各参数的季节动态。混栽方式下的庇护所效应更明显。     

长苞铁杉群落优势种群高度生态位研究

基于天宝岩国家级自然保护区内长苞铁杉群落的调查数据 ,以不同高度作为一维资源位状态 ,以个体多度为生态位计测的资源状态指标 ,对群落中的 1 2个优势树种进行了生态位的计测和分析。结果表明 ,长苞铁杉具有较大的生态位宽度值 ,具有一定的稳定性 ;各优势树种 ,均表现出一定程度的对环境适应的相似性和生态位重叠。长苞铁杉与阳性树种柳杉、耐荫树种中偏阳性树种木荷之间的生态位相似性和生态位重叠值比与耐荫性树种深山含笑、细叶青冈之间的都要大。这些分析结果为珍稀濒危植物长苞铁杉的保护提供了科学依据     

黄土丘陵区草地主要种群生态位及其环境解释

以黄土丘陵区不同生长年限撂荒草地群落为对象,研究种群生态位特征及其影响因素.结果表明: 铁杆蒿、茭蒿、猪毛蒿、达乌里胡枝子和硬质早熟禾等为优势物种,且不同生长年限优势种不同.草地生长从5年到10年,种群生态位宽度随年限的增加逐渐拓宽,对环境适应性增强;草地生长从10年到25年,种群生态位宽度随年限的增加先变窄(20年)再拓宽;草地生长超过25年,种群生态位宽度逐渐变窄,对环境适应性减弱.多数种群分别在10、25年生态位宽度达到峰值,对环境适应性最强.种群优势度与生态位宽度受种群动态影响而无线性关系.种群间生态位重叠均值先增大后减小,且在15年时达到最大值,表明种间竞争先增强后减弱,且在15年时种间竞争最为激烈.海拔、土壤含水量、土壤有机质含量为草地群落种群生态位宽度的主要影响因素;土壤全氮含量、海拔、土壤含水量为种群生态位重叠的主要影响因素.种群生态位宽度与生态位重叠主要影响因素不同,受资源空间异质性以及生长阶段影响而无线性关系.随着草地生长年限增加,种群适应性普遍增强,种群间对资源竞争先增强再减弱.海拔、土壤含水量、土壤全氮含量是影响种群适应性、种间关系的主要环境因子.     

棉田蜘蛛群落的组成及生态位分析

1997年对山西太谷棉田的蜘蛛群落进行了调查研究,共发现蜘蛛7科、17种、群落主要成分是星豹蛛和草间小黑蛛;对7种棉田主要蜘蛛的时间、空间及时空二维生态位进行了分析,结果表明星豹蛛和草间小黑蛛的时空二维生态位宽度值和重叠值均较大,说明这2种蜘蛛不但发生时间长,而且分布范围广,是棉田蜘蛛的优势种;根据生态位重叠值,利用模糊聚类法将7种棉田主要蜘蛛划分为4个类群。     

Effects of chlorpyrifos and sulfur on spider mites (Acari: Tetranychidae) and their natural enemies

In many agricultural systems spider mites are believed to be induced pests, only reaching damaging densities after pesticides decimate predator populations. Wine grapes typically receive two types of pesticides, insecticides and fungicides. Chemicals in either class could impact spider mite densities both directly through spider mite mortality, and indirectly by negatively affecting natural enemies. The impact of a broad-spectrum insecticide (chlorpyrifos) and an inorganic fungicide (sulfur) on mites and their natural enemies was monitored in replicate open-field experiments conducted in an abandoned vineyard in Washington State. In both experiments, chemicals were applied within a 2 × 2 factorial design, allowing assessment of both main and interactive effects of the two chemicals. Following typical management practices on wine grapes in Washington State, we made a single insecticide application early in the season, but repeatedly applied sulfur throughout the season. In the absence of sulfur, chlorpyrifos application led to higher spider mite densities. The main effect of chlorpyrifos appeared to be indirect, perhaps mediated through mortality of generalist phytoseiid mites; generalists appeared to be unable to recover following even a single insecticide application, while there was no evidence for harmful effects of chlorpyrifos on specialist phytoseiid mites. Sulfur had direct suppressive effects on both pest and predatory mites, although in the second experiment the suppressive effect of sulfur on spider mites was weaker when chlorpyrifos was also applied. These field experiments suggest that a complex mix of direct and indirect effects of the two chemicals impacted spider mite population dynamics in our system.     

Niche partitioning and niche filtering jointly mediate the coexistence of three closely related spider species (Araneae,Philodromidae)

1. Several mechanisms can mediate the coexistence of species, such as the neutral dynamic, niche filtering and niche partitioning. The present study investigated which of these mechanisms mediate the coexistence of closely related spider species at the scale of one locality. 2. The coexistence of three spider species of the genus Philodromus (Philodromidae) (Philodromus albidus, Philodromus aureolus and Philodromus cespitum) was studied. The study area comprised three habitat types, including a deciduous forest, a scrub and a plum tree stand. The spatial niche properties of the Philodromus species were explored by comparing their micro/macrohabitat preferences. The natural diet of these species was analysed. Laboratory experiments involving prey acceptance were conducted to investigate the trophic niche properties. The species' phenologies were studied to compare their temporal niches. 3. The philodromids had differentiated their trophic and habitat niches. The coexistence mechanisms were therefore assessed by studying the relationships between niche overlaps and the pairwise product of relative abundances. A negative relationship was observed between functional niche overlaps and the product of relative abundances, whereas a positive relationship was observed between spatial niche overlaps and the product of relative abundances. 4. The present results suggest that different mechanisms influence different niche dimensions. Niche partitioning influenced functional niches, whereas niche filtering influenced spatial niches. The results also suggest that the filtering process in one dimension was facilitated by niche differentiation in another dimension.     

宁虫素对蔬菜、水稻害虫的毒力及药效特性研究

本研究了复方生物农药宁虫素对蔬菜、水稻害虫的毒力及药效特性,结果表明,该药集速效性、特效性于一体,对蚜虫、褐飞虱的毒力分别为：0.63ppm和2.00ppm。田间试验表明,宁虫素可有效地控制蔬菜蚜虫、小菜蛾、菜青虫、稻飞虱等的危害,防效显。田间使用宁虫素后,平均蛛虱比明显优于噻嗪酮和吡虫啉,生态安全性好。     

麦蚜及其天敌生态位的初步研究

本研究分析了麦蚜及其天敌生态位的概貌．结果表明两种麦蚜以黍缢管蚜生态位宽度较广（B=0．7284）;麦长管蚜生态位宽度较窄(B=0．6264);麦长管蚜与黍缢管蚜存在生态位重叠（L=0．6497）．在天敌群落中生态位宽度依次为食蚜蝇>飘虫>蚜茧蜂>蜘蛛>食虫蝽。天敌之间亦存在生态位重叠．五类天敌与麦长管蚜的生态位重叠均值高于与黍缢管蚜的均值．即天敌对麦长管蚜的空间跟随,控制作用越大．     

Trophic overlap between fish and riparian spiders: potential impacts of an invasive fish on terrestrial consumers

Studies on resource sharing and partitioning generally consider species that occur in the same habitat. However, subsidies between linked habitats, such as streams and riparian zones, create potential for competition between populations which never directly interact. Evidence suggests that the abundance of riparian consumers declines after fish invasion and a subsequent increase in resource sharing of emerging insects. However, diet overlap has not been investigated. Here, we examine the trophic niche of native fish, invasive fish, and native spiders in South Africa using stable isotope analysis. We compared spider abundance and diet at upstream fishless and downstream fish sites and quantified niche overlap with invasive and native fish. Spider abundance was consistently higher at upstream fishless sites compared with paired downstream fish sites, suggesting that the fish reduced aquatic resource availability to riparian consumers. Spiders incorporated more aquatic than terrestrial insects in their diet, with aquatic insects accounting for 45–90% of spider mass. In three of four invaded trout rivers, we found that the average proportion of aquatic resources in web‐building spider diet was higher at fishless sites compared to fish sites. The probability of web‐building and ground spiders overlapping into the trophic niche of invasive brown and rainbow trout was as high as 26 and 51%, respectively. In contrast, the probability of spiders overlapping into the trophic niche of native fish was always less than 5%. Our results suggest that spiders share resources with invasive fish. In contrast, spiders had a low probability of trophic overlap with native fish indicating that the traits of invaders may be important in determining their influence on ecosystem subsidies. We have added to the growing body of evidence that invaders can have cross‐ecosystem impacts and demonstrated that this can be due to niche overlap.     

Web-Construction Behavior of Linyphiid Spiders (Araneae,Linyphiidae): Competition and Co-Existence Within a Generalist Predator Guild

The web-construction behavior of three species of linyphiid spider (Erigone autumnalis, Meioneta unimaculata and Bathyphantes pallida) was studied in the laboratory to examine competition and co-existence within predator guilds. Competitive interactions between spiders potentially reduce their role in biological control. We tested the hypothesis that at high densities, intraguild competition for web-sites would occur but spatial separation of microhabitat would reduce interguild competition, thus allowing co-existence. High mortality and reduced web-size were observed at high B. pallida densities but Linyphiinae co-existed with Erigoninae which constructed webs at different strata. Competitive exclusion by larger individuals occurred between species whose microhabitat niche overlapped. The biocontrol potential of spider or arthropod predator guilds could ultimately be enhanced by maximizing the diversity of species whose niche axes vary.     

Direct and indirect effects of imidacloprid on fecundity and abundance of Eurytetranychus buxi (Acari: Tetranychidae) on boxwoods

Populations of spider mites often reach high levels on urban plants. In many cases, insecticide applications targeting other herbivores trigger outbreaks of spider mites. Recently, elevated populations of spider mites on a diversity of plants in urban landscapes have been associated with applications of imidacloprid, a neonicotinoid insecticide. Imidacloprid has also been linked to increased fecundity in two species of spider mites. In this study, we evaluated the indirect (plant-mediated) and direct impact of imidacloprid on fecundity and longevity of Eurytetranychus buxi Garman (Acari: Tetranychidae), feeding on boxwoods, Buxus sempervirens L. Moreover, we compared the abundance of E. buxi on imidacloprid-treated and untreated boxwoods in the landscape and a greenhouse to determine if changes in the fecundity of mites exposed to imidacloprid were linked to outbreaks of E. buxi. We found that females consuming imidacloprid-treated plants laid more eggs than females feeding on untreated boxwoods, while their longevity remained unchanged. Fecundity was not affected, however, when spider mites were directly sprayed with imidacloprid and consumed foliage of untreated boxwoods. Furthermore, populations of E. buxi were greater on boxwoods treated with imidacloprid in the landscape and greenhouse. On landscape boxwoods, elevated populations of E. buxi persisted into a second year. We also observed general lack of predators of spider mites on treated and untreated boxwoods in the field suggesting that imidacloprid’s eruptive effect on E. buxi stems more from indirect changes in plant quality than from a loss of top-down regulation from E. buxi’s natural enemies.     

Capture efficiency and trophic adaptations of a specialist and generalist predator: A comparison

Specialist true predators are expected to exhibit higher capture efficiencies for the capture of larger and dangerous prey than generalist predators due to their possession of specialized morphological and behavioral adaptations. We used an araneophagous spider (Lampona murina) and a generalist spider (Drassodes lapidosus) as phylogenetically related model species and investigated their realized and fundamental trophic niches and their efficacy with respect to prey capture and prey handling. The trophic niche of both species confirmed that Lampona had a narrow trophic niche with a predominance of spider prey (including conspecifics), while the niche of Drassodes was wide, without any preference. DNA analysis of the gut contents of Lampona spiders collected in the field revealed that spiders form a significant part of its natural diet. Lampona captured significantly larger prey than itself and the prey captured by Drassodes. As concerns hunting strategy, Lampona grasped the prey with two pairs of legs possessing scopulae, whereas Drassodes immobilized prey with silk. Lampona possess forelegs equipped with scopulae and a thicker cuticle similar to other nonrelated araneophagous spiders. Lampona fed for a longer time and extracted more nutrients than Drassodes. We show that specialized behavioral and morphological adaptations altogether increase the hunting efficiency of specialists when compared to generalists.