宁夏新垦区昆虫群落生态演替及有害种预警系统研究

以宁夏中宁县长山头、大战场（荒漠半荒漠）、灵武市狼皮子梁（沙漠）、青铜峡市渠口农场（草原化荒漠）３类垦前环境及其垦后不同耕作年限（１－１５ａ）农田昆虫群落演替进行了系统调查与研究，事理鉴定出昆虫１１目７９科２０４种，按其分布和种群动态变化划分为原生性种类、共生性种类、继生性种类和迁入性种类４个生态型类群。在此基础上研究了不同目、不同营养型类群和不同生态型类群昆虫多样性变化及时间系列演替，发现随着荒     

黔南喀斯特土壤螨类对火烧和垦殖的响应

为了解不同干扰对黔南喀斯特土壤螨类的影响,按季节于2016年10月至2017年4月选取了火烧+垦殖、火烧和农业耕作(农田)3种干扰形式,以自然林为对照研究土壤螨类多样性变化.调查共获得土壤螨类5 254只,隶属81科,优势类群奥甲螨科(Oppiidae)和杆棱甲螨科(Mochlozetidae).主成分分析(PCA)结果表明不同干扰方式下土壤螨类群落结构与自然林均存在明显差异.火烧+垦殖土壤螨类类群数、个体密度和Shannon-Wiener指数(H’)显著低于自然林(P 0.05),农业耕作土壤螨类类群数显著低于自然林(P 0.05),其余无显著不同;季节变化对土壤螨类类群数、个体密度和Shannon-Wiener指数(H’)无显著影响.有效磷与土壤螨类类群数和个体密度显著负相关(P 0.05).本研究结果说明干扰频率是影响土壤螨类分布的重要因素,高频度干扰较低频度干扰对土壤螨类的负面影响强,而高频度的干扰中,双重干扰较单一干扰对土壤螨类的负面影响大.(图2表4参49)     

SO2和酸雨对大豆的单一及复合效应

应用开顶式熏气装置研究了SO2和模拟酸雨对大豆的单一与复合作用效应．结果表明：经SO2和酸雨处理后，大豆叶绿素含量减少、膜透性增加，叶液pH值降低，但SO2和酸雨对叶片含糖量的影响不明显；SO2＋酸雨对大豆的复合作用效应明显大于SO2或酸雨单因子作用效应；SO2＋酸雨对大豆的复合作用效应与SO2熏气浓度，酸雨pH和暴露时间有密切关系.     

松嫩平原西部不同土地覆被水盐动态对比研究

通过对6种土地覆被2003年6～10月水盐时空动态进行分析，对比不同土地覆被水盐动态变化差异，结果发现：采样期内，不同土地覆被(碱斑地除外)0-120cm剖面含水量均出现明显峰值，大豆地和羊草草地在7月底出现峰值，玉米地和向日葵地在8月初，退化草地则在8月底才达到，比羊草草地滞后了一个月。除羊草草地外，其他土地覆被剖面含水量变化呈W型，只是波动幅度各不相同。采样期内，羊草草地剖面含水量的相对变率最大，为74％，其他依次为退化草地、大豆地、向日葵地、玉米地，碱斑地最低，仅为6．4％。相对于农田土地覆被，在0～40cm，羊草草地、退化草地和碱斑地随盐渍化程度的加重，含盐量剖面变异逐渐减小，而农田的三种土地覆被之间变异比较接近。整个采样期，向日葵地储盐量随时间的变化呈下降趋势，其他土地覆被波动变化一致，都经历了下降-上升-下降过程，但波动幅度不同，且羊草草地在7月7日出现上升，其他4种土地覆被在9月8日开始出现滞后于含水量的变化。相对于采样初期，不同土地覆被含盐量的相对变率均为负值，农田的下降幅度大，草地次之，碱斑地最小。协方差分析表明：95％置信度下，土地覆被、土壤剖面和两者的交互作用对含盐量的影响差异显著。     

不同封育年限荒漠草原土壤有机碳矿化及温度敏感性

为了解宁夏荒漠草原土壤有机碳矿化对气候变化和封育禁牧措施的响应,该研究选取未封育(FY0)、封育5年(FY5)、9年(FY9)和12年(FY12)的荒漠草原为研究对象,采用室内培养碱液吸收法,分别在5、15、25和35℃条件下对不同封育年限的荒漠草原0—20 cm土壤进行76 d的培养,探讨了不同温度条件下各封育年限荒漠草原土壤有机碳的矿化动态及其温度敏感性(Q_(10))。结果表明:不同封育年限荒漠草原土壤有机碳矿化速率在不同温度条件下随培养时间的增加变化趋势基本相同,均在活跃期(0—13 d)迅速达到峰值,随后急剧下降,至惰性期(14—76 d)趋于平稳;不同温度条件下,荒漠草原土壤有机碳累积矿化量随封育年限延长的变化趋势不尽相同,在5℃和35℃培养条件下以封育9年的荒漠草原最高,分别为5.875 mg·g-1和7.587 mg·g~(-1)(P0.05),15℃和25℃培养条件下各封育年限荒漠草原之间差异不显著;一级动力学方程可较好地拟合不同封育年限荒漠草原土壤有机碳矿化特征,其潜在矿化量在不同培养温度下的变化范围为4.105—8.834mg·g~(-1),以封育5年的荒漠草原25℃处理条件下土壤有机碳潜在矿化量最大;随培养温度的增加,不同封育年限荒漠草原土壤有机碳累积矿化量总体呈波动性变化;未封育荒漠草原土壤有机碳矿化对温度的变化最为敏感,温度敏感性系数Q_(10)值为1.998,显著高于其他封育年限荒漠草原(P0.05)。综上,禁牧封育可改变荒漠草原土壤有机碳的矿化动态,并减弱其对温度变化的敏感性,从土壤碳蓄积的角度考虑,宁夏荒漠草原以封育9年以上为宜。     

塔克拉玛干4种荒漠植物气体交换与环境因子的关系初探

研究了4种荒漠植物）胡杨，疏叶骆驼刺，头状沙拐枣，多枝柽柳）气体交换的季节变化及其与环境因子的关系。结果：（1）外界环境因子中，无论是对光合速率还是蒸腾速率，光照强度都是最重要的主导因子，其次是气温，大气湿度与植物的蒸腾速率成负相关，影响程度因不同植物及其环境因子的情况而有所不同。（2）在气温越高的地方，荒漠植物的温度生态位（包括最适温度和极限温度）也随之增高。（3）水分胁迫影响气温和叶温的差异，4种植物都能调整其叶温，使之低于沙漠地区的极度高温。     

转Cry1Ie基因玉米和转CP4-剧SPS基因大豆对斑马鱼的生态毒性

为评估转Cry1Ie基因抗虫玉米和转CP4-EPSPS基因耐除草剂大豆对鱼类的生态毒理效应,以斑马鱼(Danio rerro)为受试动物,配制4种分别含有转基因玉米、转基因大豆以及相应非转基因亲本的试验饲料,并以商业饲料为对照,通过98 d喂养实验,调查斑马鱼的摄食、生长、繁殖和抗氧化酶活性,分析不同喂养阶段斑马鱼的组织病理和敏感蛋白mRNA表达水平.结果 表明:抗虫转基因玉米和耐除草剂转基因大豆对斑马鱼的生长表现、肝脏、肠道和性腺的组织病理、产卵量和受精卵孵化率均无显著影响.转基因大豆组斑马鱼肝脏中的超氧化物歧化酶(SOD)活性显著高于非转基因大豆组和商业饲料组,且雄鱼显著高于雌鱼(P＜0.05).斑马鱼脏器组织中敏感蛋白mRNA的表达水平,没有随时间呈现明显的规律性变化,喂养时间与组别和性别之间存在显著的交互作用.试验饲料组斑马鱼的生长表现、肝脏中SOD活性以及mRNA表达量与商业饲料组相比有显著差异,可能与饲料的适口性和营养成分上的差异有关.总体上看,转Cry1Ie基因抗虫玉米和转CP4-EPSPS基因耐除草剂大豆对斑马鱼没有明显的生态毒性效应.     

南亚热带不同植被根际微生物数量与根际土壤养分状况

研究了包括尾叶桉、广东凤丫蕨、柳叶竹、大叶相思、青皮、木荷、湿地松在内的7种南亚热带不同植物植被下土壤根际微生物与根际养分状况及其相关关系。结果表明,根际环境对细菌有明显的正效应,对放线菌和真菌有正、负两方面的影响,但对根际微生物总量具有根际效应明显;在南亚热带森林生态系统中.在植物的某些生长季节,微生物的根际效应与土壤养分的根际效应一致     

克螨特和霸螨灵及其混剂在水中的光降解

研究了克螨特、霸螨灵在几种水体中的光降解以及 2种农药之间的光敏化或光猝灭效应。结果表明 ,在 3 0 0W高压汞灯光照处理时 (试验试管距光源 8cm) ,克螨特和霸螨灵都极易降解 ,克螨特的光解半衰期为 9.0 6min ,霸螨灵的光解半衰期仅为 1 .4 8min。克螨特在不同水体中的光解率为 :重蒸馏水 >鱼塘水 >河水 >井水 ,霸螨灵的光解率为 :井水 >重蒸馏水 >鱼塘水 >河水 ;2种农药在现采水、过滤水、灭菌水中的光解率依次降低。克螨特和霸螨灵混剂在重蒸馏水中互为光猝灭剂 ,在井水、河水和塘水中霸螨灵对克螨特有极显著的光敏化作用 ,而克螨特对霸螨灵有极显著的光猝灭效应。克螨特、霸螨灵在pH 5和 pH 9缓冲液中光解率比之在 pH 7缓冲液中稍快 ,光猝灭效应也较强烈。在重蒸馏水中太阳光照处理时 ,克螨特和霸螨灵互为光敏剂 ,而高压汞灯下则互为光猝灭剂。     

内蒙古荒漠草原短花针茅叶片功能性状对不同草地经营方式的响应

植物叶片功能性状对不同草地经营方式的适应是一种有效地生态对策。短花针茅(Stipa breviflora)是亚洲中部暖温性荒漠草原的主要建群种,通过调查生长良好的不同龄级短花针茅叶性状,试图揭示荒漠草地利用模式与植物生态响应机制。该研究测量自然叶高(LNH,leaf natural height)、叶长(LL,leaf length)、叶鲜质量(LFW,leaf fresh weight)、叶干质量(LDW,leaf dry weight)、自然叶宽(LW,leaf width)、叶缘距(LED,leaf edge distance)、叶直立度(leaf erection index,LEI)、叶卷曲度(leaf rolling index,LRI)和叶干物质含量(leaf dry matter content,LDMC)等叶性状指标。结果表明,(1)短花针茅的LNH、LL、LFW、LDW、LW、LED等叶性状在灌溉草地几乎都显著大于放牧草地和围封草地。(2)LEI、LFW为生境干扰响应的敏感性状;LW、LDMC为生境干扰响应的惰性性状。(3)Pearson相关分析结果可知,放牧对短花针茅叶性状影响最大。研究认为,短花针茅叶片功能性状对不同草地经营方式的的适应对策,是通过对不同性状的权衡,充分利用环境资源来完成的。     

Variability in herbivore-induced odour emissions among maize cultivars and their wild ancestors (teosinte)

Summary. Maize plants respond to caterpillar feeding with the release of relatively large amounts of specific volatiles, which are known to serve as cues for parasitoids to locate their host. Little is known about the genetic variability in such herbivore-induced plant signals and about how the emissions in cultivated plants compare to those of their wild relatives. For this reason we compared the total quantity and the qualitative composition of the odour blend among eleven maize cultivars and five wild Zea (Poaceae) species (teosinte), as well as among the offspring of eight Zea mays mexicana plants from a single population. Young plants were induced to release volatiles by mechanically damaging the leaves and applying oral secretions of Spodoptera littoralis (Lepidoptera: Noctuidae) caterpillars to the wounded sites. Volatiles were collected 7 h after treatment and subsequently analysed by gas chromatography. The total amounts of volatiles released were significantly different among maize cultivars as well as among the teosintes. Moreover, striking differences were found in the composition of the induced odour blends. Caryophyllene, for instance, was released by some, but not all varieties and teosintes, and the ratios among monoterpenes and sesquiterpenes varied considerably. The offspring of different mother plants of the Z. m. mexicana population showed some variation in the total amounts that they released, but the composition of the odour blend was very consistent within the population of this teosinte species. We discuss the ecological significance of these findings in terms of specificity and reliability of induced plant signals for parasitoids.     

Restoration of flavonols and isoflavonoids in Ugni molinae subjected to a reciprocal transplant experiment in a domestication framework

Plant domestication can modify flavonoid concentration, generating a decrease in plants subjected to cultivation, but when cultivated plants are transferred to their original wild area, flavonoids can be recovered. In this framework, a native shrub from Chile, Ugni molinae, has been domesticated due to their high phenolic composition. We hypothesised that plant domestication results in a decrease of flavonoid in cultivated plants, and that when they are exposed to a reciprocal transplant experiment, the flavonoid content can be recovered. Hence, a reciprocal transplant experiment for analysing the flavonoids of cultivated plants transferred to their original wild environments was carried out. Methanolic leaf extracts from two cultivated ecotypes and their respectively wild ancestors were collected for flavonoid analysis. Four flavonols and two isoflavonoids were identified and quantified by liquid chromatography. Results showed differences in flavonoids concentrations between wild (290?µg/g) and cultivated (160?µg/g) plants. Furthermore, when wild plants were transferred to cultivated areas, a reduction in flavonoids of 80?µg/g was observed. Moreover, rutin was the most abundant compound (36.09%) detected by chromatography in Mehuín wild plants. Our results showed that cultivated plants transferred to their respective wild environment presented a capacity of recover myricetin, daidzin and genistin content.     

Conservation impacts of commercial cultivation of endangered and overharvested plants

Overharvesting is one of the greatest threats to species survival. Farming overharvested species is a conservation strategy that can meet growing market demand and conserve wild populations of the target species. This strategy is compatible with the international community's desire to uphold the right of local communities to use biological resources to support their livelihoods. However, studies investigating whether farming can alleviate poaching pressure have focused almost exclusively on animals. To address the shortfall in plant-focused studies, we compiled information on commercial cultivation of threatened plants to assess its conservation benefits. Because China's rising middle class has rapidly intensified demand for wildlife products, we searched the scientific literature published in Chinese (China National Knowledge Infrastructure and Baidu) and in English. We found 32 reports that contained data on 193 internationally or nationally threatened plant species that were under commercial cultivation. These reports showed that cultivations of 82% of the 193 species were sustained by collecting whole plants from the wild periodically or continuously. Although based on a small sample size, species that were maintained in cultivation only through artificial propagation or seeds collected in the wild were likely associated with a reported reduction in wild harvesting of whole plants. Even so, results of correlation analyses suggested that production system, scale, and when a species began being cultivated had little effect on conservation status of the species, either globally or in China. However, species brought into cultivation relatively recently and on a smaller scale were more likely to have undergone a reduction in collecting pressure. Farming of nonmedicinal plants was most problematic for species conservation because wild plants were laundered (i.e., sold as cultivated plants). For effective conservation, policy to guide cultivation operations based on the target species’ biological characteristics, cultural significance, market demand, and conservation status is needed.     

Are soil mite assemblages structured by the identity of native and invasive alien grasses?

Associations between plants and animals in aboveground communities are often predictable and specific. This has been exploited for the purposes of estimating the diversity of animal species based on the diversity of plant species. The introduction of invasive alien plants into an ecosystem can result in dramatic changes in both the native plant and animal assemblages. Few data exist at the species level to determine whether belowground animal assemblages share the same degree of association to plants. The hypotheses that soil mites (Acari) form assemblages specifically associated with different native grass species in an unmanipulated natural ecosystem and that invasive alien grasses will impact soil mite assemblage composition in this setting were tested. Soil mites sampled beneath five native and two invasive alien species of grasses at the Konza Prairie Biological Station, Kansas, USA, were similarly abundant, species rich, diverse, and taxonomically distinct. No mite species had affinities for a specific grass species. There was no evidence from analysis of similarity, canonical correspondence analysis, or a nonparametric assemblage analysis that the assemblage composition of soil mites was specific to grass species. Results suggest that soil mite assemblages were more related to characteristics of the plant assemblage as a whole or prevailing soil conditions. The most recent invasive alien grass did not support a successionally younger mite fauna, based on the ratio of mesostigmatid to oribatid mites, and neither of the two invasive grasses influenced mite assemblage structure, possibly because they had not yet substantially altered the soil environment. Our results suggest that extrapolations of soil mite diversity based on assumptions of plant specificity would be invalid.     

Leaf quality, predators, and stochastic processes in the assembly of a diverse herbivore community

Ecological communities are structured by both deterministic, niche-based processes and stochastic processes such as dispersal. A pressing issue in ecology is to determine when and for which organisms each of these types of processes is important in community assembly. The roles of deterministic and stochastic processes have been studied for a variety of communities, but very few researchers have addressed their contribution to insect herbivore community structure. Insect herbivore niches are often described as largely shaped by the antagonistic pressures of predation and host plant defenses. However host plants are frequently discrete patches of habitat, and their spatial arrangement can affect herbivore dispersal patterns. We studied the roles of predation, host plant quality, and host spatial proximity for the assembly of a diverse insect herbivore community on Quercus alba (white oak) across two growing seasons. We examined abundances of feeding guilds to determine if ecologically similar species responded similarly to variation in niches. Most guilds responded similarly to leaf quality, preferring high-nitrogen, low-tannin host plants, particularly late in the growing season, while bird predation had little impact on herbivore abundance. The communities on the high-quality plants tended to be larger and, in some cases, have greater species richness. We analyzed community composition by correlating indices of community similarity with predator presence, leaf quality similarity, and host plant proximity. Birds did not affect community composition. Community similarity was significantly associated with distance between host plants and uncorrelated with leaf quality similarity. Thus although leaf quality significantly affected the total abundance of herbivores on a host plant, in some cases leading to increased species richness, dispersal limitation may weaken this relationship. The species composition of these communities may be driven by stochastic processes rather than variation in host plant characteristics or differential predation by insectivorous birds.     

Pollution tolerance and distribution pattern of plants in surrounding area of coal-fired industries

Higher concentration of SO2 and particulate matters was reported in surrounding areas of coal-fired industries which influences the distribution pattern of plants. Sensitive plant species are abolished from such areas, however, only pollution tolerant species survive under stress conditions. The present study was designed to investigate the vegetation composition around coal-fired industries i.e. brick industries. To categorise plants as sensitive or resistant air pollution tolerance index (APTI) value was calculated. Out of 99 plants studied, Ricinus communis with APTI 81.10 was found to be the most resistant wild plant showing uniform distribution at all the polluted sites. On the other hand, Lepidium sativum with APTI 5.27 was recorded as the most sensitive plant and found to be present only at the less polluted sites.     

Cooperative web sharing against predators promotes group living in spider mites

I examined spider mite cooperative web sharing against predation as a factor promoting group living. Tetranychus urticae and Tetranychus kanzawai infest leaf surfaces under webs made of silk threads. Experimental observation of predation by the predatory mite Euseius sojaensis on spider mites of different group sizes revealed that fewer spider mites were preyed upon when the web-building period before the attack was prolonged, suggesting that established webs help protect spider mites. Moreover, per capita predation on spider mites was diluted in larger groups. This was not due to predator satiation but seemingly because webs had been completed while the initial prey was consumed. Spider mites lived more closely together in the presence of a predator, showing that the degree of group living is facultative. In the presence of a preceding spider mite with an established web, a newcomer spider mite gain protection by taking residence in the established webs; sharing the web was not disadvantageous for the preceding mite. The proportion of individuals preyed upon did not differ between preceding and newcomer mites, suggesting that there was no interference against the latter. These interactions were consistent between heterospecific spider mites. Because there was no detectable indirect interaction between mites sharing fresh webs, cooperative web sharing seemed to be a major force promoting group living in the spider mites. Moreover, the distances between spider mites did not differ between heterospecific and conspecific groups, demonstrating that mites living together do not distinguish between species; hence, heterospecific mites may cooperate and live together in the same manner as conspecifics.     

Tracing individual movements of aphids reveals preferential routes of population transfers in agroecosystems.

Agricultural pests are not restricted to crops, but often simultaneously or successively use different cultivated and uncultivated hosts. Nevertheless, the source-sink role of cultivated and uncultivated habitats in the life cycle of crop pests remains poorly understood. This is largely due to the difficulty of tracking displacements of small organisms in agricultural landscapes. We used stable-isotope ratios in order to infer the natal host plant of individuals of the English grain aphid Sitobion avenae colonizing wheat fields in autumn. We showed that among the numerous plant sources of S. avenae, maize, which has been intensively grown in western France since the 1960s, provided most aphids that attack wheat fields early in autumn. This study illustrates how insect pests respond to land-use changes within a relatively short period of time, rapidly acquiring a new host that in turn affected their population biology considerably by playing a pivotal role on their annual life cycle.     

An overlooked side effect of nest-scattering behavior to decrease predation risk (Acari: Tetranychidae,Stigmaeidae)

The number of nests containing egg masses a female makes over her lifetime and the pattern of scattering nests vary among species in a genus of nest-weaving spider mites (Stigmaeopsis). We hypothesized that the scattered nests of small nest builders have a previously overlooked indirect effect in that the void nests created after predation take on a new role as hindering devices that effectively decrease predator searching efficiency. First, we demonstrated that the experimental design used in this study is a good reflection of the nest distribution pattern of Stigmaeopsis takahashii (an intermediate-sized nest builder) in the field. Using this species as a model, we tested how different nest-scattering patterns affect the predator to examine how scattering may indirectly provide an anti-predation strategy by increasing a predators searching time. Next, we observed how artificially arranged void nests disturb predatory behavior in both starved and fully fed predator females and showed that void nests have a strong hindering effect on predators. Thus, we concluded that the nesting behavior of this mite species not only has anti-predator effects but must also have a stabilizing effect on predator–prey interaction systems at the population level.