Population dynamics of farmland ladybug resources and dominant species in Nyingchi,Tibet, China北大核心CSCD

捕食性瓢虫是重要的天敌昆虫,有利于害虫的生物防治.为查清西藏林芝地区农田瓢虫资源与种群现状,明确优势种类及种群动态和规律,对林芝不同生态区域的青稞、小麦、油菜3种作物农田开展瓢虫资源调查研究,同时选取固定样地定期进行种群动态分析.结果显示:林芝地区农田瓢虫分为2个亚科4个族10个属,共13种,其中11种为捕食性瓢虫.主要优势瓢虫种类为横斑瓢虫、多异瓢虫、二星瓢虫.其中横斑瓢虫在全部调查样地中均有分布,在农田中总体优势度指数、相对多度为最高.3种优势瓢虫在不同作物中种群动态变化规律存在差异,其中横斑瓢虫虫口密度长期高于其余优势瓢虫,且与蚜虫密度曲线有较为明显的重合现象.横斑瓢虫种群密度峰值主要集中在6月中旬至7月上旬,但在不同作物农田中具体峰值时期存在差异.可见,林芝地区农田不同种类瓢虫之间有较大数量差异,在不同生态区域与作物环境下具有不同的种群特征,但是优势瓢虫种类与种群规律较为明确,可用于农田蚜虫生物防治;结果可为保护当地重要昆虫资源及开展生物防治提供基础数据支撑.(图4表6参23)     

江苏沿海地区转Bt基因抗虫棉对棉田昆虫种群的影响

2004-2005年,在江苏沿海地区采用系统调查与面上普查相结合的方法,比较分析转Bt基因抗虫棉(中棉所44)与常规棉(中棉所17)2类棉田昆虫种群的差异.结果表明,与常规棉田相比,Bt棉田棉铃虫、玉米螟、金刚钻、棉小造桥虫等鳞翅目害虫种群数量显著降低,而盲蝽象、红蜘蛛、棉蚜、烟粉虱等非靶标刺吸式害虫种群数量显著增加;蜘蛛、瓢虫等捕食性天敌种群数量显著增加,而棉铃虫的寄生性天敌种群数量则显著下降.转Bt基因抗虫棉对棉田昆虫种群的影响在数年间保持相对稳定的状态.     

几种天敌对麦蚜蜜露的行为反应

麦长管蚜和禾谷缢管蚜蜜露的主要糖分为果糖、葡萄糖、蔗糖及两种未知糖分．其中前者以蔗糖含量最高，后者则不含蔗糖．其游离氨基酸种类基本相同，但后者蜜露中未鉴定出苏氨酸；除丙氨酸和组氨酸外，麦长管蚜中各类氨基酸的含量明显高于禾谷缢管蚜，其中单头麦长管蚜日分泌氨基酸量以亮氨酸和丙氨酸最高，分别达到了0．204 7ng和0．137 7ng，而禾谷缢管蚜以丙氨酸和亮氨酸最高，分别达到了0．154 3ng和0．102 5ng．随着蜜露含量的增加，各天敌的搜索与滞留时间显著延长，但逐渐趋于平缓，基本符合逻辑斯蒂增长．燕麦蚜茧蜂在两种蚜虫蜜露上的搜索与滞留时间差异显著，而瓢虫与草蛉类的搜索与滞留时间差异不显著，说明蜜露对捕食性和寄生性天敌的影响不同．图3表1参13     

莲草直胸跳甲幼虫在黄瓜和豇豆上的安全性表现

莲草直胸跳甲(Agasicles hygrophila)为引进我国控制入侵种喜旱莲子草(Alternanthera philoxeroid es)的专食性天敌.它在主要植物上是否安全直接影响到其生防价值和生态安全.对前人已研究过的且对莲草直胸跳甲有影响的非靶标植物进一步研究,从莲草直胸跳甲的趋性、取食及非靶标植物对幼虫的寿命长短、生长发育的影响等指标筛选出黄瓜(Cucumis sativus)、豇豆(Vigna unguiculata)等植物,并采用涂抹汁液饲喂法、全汁液饲喂法和植物表皮毛数量与类型测定、植物表皮毛处理等方法来研究目标植物对莲草直胸跳甲幼虫的致死原因.结果显示:莲草直胸跳甲对豇豆、黄瓜叶片有趋性和轻微取食现象,且其幼虫在豇豆叶片上聚集性死亡,因此其幼虫对黄瓜、豇豆是安全的.莲草直胸跳甲幼虫取食豇豆、黄瓜叶片汁液48 h内存活率为100%,豇豆叶片表皮毛为钩状,且其背面表皮毛的数量最多,为139±14.11,其中幼虫在豇豆叶片背面死亡率最高,为53.33%±0.09%.2龄幼虫在豇豆叶片背面的脱离率最小,为6.67%±0.03%,去除豇豆叶片表皮毛以后,幼虫在豇豆叶片上的脱离率为100%.综上,豇豆、黄瓜叶片汁液对莲草直胸跳甲幼虫生存影响不显著,钩状表皮毛对莲草直胸跳甲幼虫有致死作用,表明非靶标植物的物理性状在引进天敌昆虫适应性上为不利因素.     

柿树被日本龟蜡蚧危害后挥发物的变化及其对红点唇瓢虫的引诱作用

研究了柿树(DiospyroskakiL.f.)受日本龟蜡蚧(CeroplastesjaponicusGreen)危害后,体内释放出的挥发性物质对天敌昆虫红点唇瓢虫(ChilocoruskuwanaeSilvestri)的招引作用.Y形嗅觉仪测定结果表明,瓢虫趋向受害枝叶的百分率为74.17%,明显大于趋向未受害枝叶的20.00%,t检验证明,二者间差异极显著;而受害轻微枝叶挥发物对红点唇瓢虫的诱导作用与未受害枝叶的诱导效果相比没有显著差异;说明日本龟蜡蚧对柿树的危害可诱导树体挥发性物质发生改变,增加了对红点唇瓢虫的引诱作用.经气相色谱/质谱联用仪(GC/MS)分析发现,柿树未受害枝叶挥发物共有29种组分,烃类物质的相对含量占92.98%;受害枝叶释放出的挥发物组分有32种,烃类物质的相对含量增加到97.15%,另外减少了3种醇类化合物和2种烷烃类化合物,同时合成了8种新的组分,包括4种烃类、3种萜类和1种酮类.这些新合成的化合物极有可能在不同程度上参与了对瓢虫的招引作用.本文揭示了柿树受日本龟蜡蚧危害后,诱导其挥发出对天敌昆虫有引诱作用的化学信息素,为进一步试验确定有效成分和人工筛选模拟引诱剂,开辟生物防治新途径提供了基础依据.图1表2参16     

转基因抗虫水稻生态安全性研究进展

我国转基因抗虫水稻的商业化种植已成为国内外广泛关注的热点问题.本文系统综述了转基因抗虫水稻的遗传转化、基因漂流、靶标害虫的抗性风险、对非靶标生物和稻田节肢动物群落的影响以及B t杀虫蛋白在土壤中的残留等方面的研究进展.现有研究表明,B t水稻对二化螟、三化螟和稻纵卷叶螟等主要靶标害虫具有较高的抗性水平,对稻飞虱、叶蝉、捕食性天敌等非靶标生物的生长发育和稻田节肢动物群落的稳定性无明显影响.靶标害虫的抗性和转基因水稻与杂草稻、野生稻之间的基因漂移风险是转基因抗虫水稻商业化种植的主要环境安全问题.参60     

植物表面蜡质对植食性昆虫的影响研究进展

植物表面蜡质的最初角色是防止植株体内水分的散失和外界水分的进入,其分布的部位、化学成分和结构的复杂性与复杂的生态角色相对应.植物表面蜡质的物理化学特性能够抵抗各种各样生物与非生物侵害,这些侵害包括真菌病害、植食性昆虫、太阳射线、冻结温度等.植物表面蜡质还是植物、植食性昆虫及其捕食者和寄生者相互作用的竞技场,其特有的化学成分和形态学特征赋予它特有的生态机能,这些机能之一便是植物与植食性昆虫之间相互作用的媒介.植物表面蜡质的物理结构和数量能够影响植食性昆虫的附着和移动.表面蜡质可通过影响天敌对植食性害虫的捕食,从而间接影响植食性害虫的行为.表面蜡质提取物和单一的蜡质成分能够刺激或者抑制植食性昆虫产卵、活动和取食.烷烃、蜡酯、游离脂肪醇和酸等脂肪族化合物是表面蜡质的主要成分,在植食性昆虫选择寄主植物中,长链脂肪族化合物起着尤为重要的作用;芳香族化合物也影响昆虫对寄主植物的选择.植食性昆虫较少在光滑蜡质少表现型的作物上取食,在光滑蜡质少表现型的作物上,表面蜡质的数量少,化学组分和形态学特征也不同.研究光滑蜡质少作物抗虫的分子生物学机制,有助于阐明植物表面蜡质在植物与昆虫之间所起的作用.表面蜡质的理化特性能够改变害虫与寄主植物间的相互作用,具有重要的农业影响,已成为一个活跃的研究领域.     

四川道孚县芒苞草生境的植物群落结构和土壤元素含量

芒苞草(Achanthoclamys bracteata P.C.Kao)是分布于横断山区局部狭小区域的一种单型科植物,在指示植物系统进化和地理环境变迁中具有十分重要的作用和地位.对四川省道孚县鲜水河流域的两个芒苞草分布地点(麦粒山和亚卓山)进行了群落学特征和土壤学研究.芒苞草生境群落类型为温性干旱河谷灌丛和草地,上接亚高山云冷杉针叶林.麦粒山芒苞草生境为毛莲蒿-矮嵩草-芒苞草群落;而亚卓山灌丛草地类型为川滇蔷薇-毛莲蒿-西南野古草-芒苞草群落,亚卓山草地则以西南野古草、直芒草、金发藓等为优势种.物种多样性指数以灌丛最高,亚卓山草地物种多样性在中海拔处出现极小值,海拔越高,芒苞草单株重量越轻,中海拔位置处的地上地下生物量比值(2.06±0.17)最大.土壤元素含量以铝和铁最丰富,而磷和钾的含量分别为(8 873.5±1463.3)mg kg-1和(431.1±180.4)mg kg-1,比该区域的平均值低.芒苞草多生长在有岩石出露的地方,在道孚县的分布区域局限在鲜水河河谷地带.芒苞草强烈的生境选择作用以及河谷地带强度较大的人为活动,是威胁芒苞草生存的主要因素.图5表3参24     

花椒农林复合生态系统的简化对某些相关因子的影响

对单一种植和复合种植两种模式的花椒林地(即有草模式和无草模式)进行了相关生态因子的对比调查,以评价现存花椒林单一模式的合理性．结果表明,在单一种植模式下,花椒林的高度、地径和冠幅虽显著优于复合模式,但是病虫害严重;两种模式中土壤含水率均是随土层厚度的增加而增大,但是变幅有较大差异：复合模式的变幅较稳定,为7．59%～23．79％;而单一模式的变化较剧烈,为4．73％～49．72％,复合模式的土壤含水率显著高于单一模式．复合模式的昆虫种类、多样性、丰富度和均匀度也明显高于单一模式,其中单一模式中的肉食性和寄生性昆虫种类低于复合模式,而植食性蚜虫数量则高于复合模式,暗示单一模式中天敌的栖境和资源以及特定的食草昆虫与有益菌缺少．讨论认为,杂草在花椒林生态系统中起着重要的生态作用,现存的单一种植模式虽然对花椒的生长和产量有利,但却是以牺牲农林系统的可持续发展以及生物多样性为代价的．表3参9。     

祁连山北坡自然恢复杨桦林地植物功能型组成及其影响因素

依据生活型(乔木、藤本、灌木、半灌木、多年生禾草、多年生杂类草和一二年生草本)和水分生态型(旱生、旱中生、中生和湿生)将祁连山北坡次生杨桦林28个调查样地中的81个物种划分为18种植物功能型(Plant functiontypes,PFTs),并通过典范对应分析(CCA)方法研究植物功能型与环境因子间的关系.结果表明:自然恢复杨桦林地植物功能型主要集中在中生多年生杂类草(PFTs16)、湿生多年生杂类草(PFTs23)、旱中生多年生杂类草(PFTs9)和中生灌木(PFTs18)4个植物功能型上;乔、灌、草三层冠层特征和中生植物的大量出现,反映了群落植物生活型趋于复杂化和结构化,生态型逐渐向中生化方向演替的特点;土壤容重、有机碳和全氮含量主要影响植物的生活型分异特征,土壤含水量和林冠郁闭度是植物的水分生态型分异的主要环境因子,而坡位、坡度控制着群落植物总体分布格局的形成.图1表3参31     

Incorporating natural enemies in an economic threshold for dynamically optimal pest management

The control of pests by their natural enemies represents an important regulating ecosystem service that helps maintain the stability of crop ecosystems. These services, however, are often ignored in pest management decision making. In addition, the use of broad-spectrum insecticides can damage the populations of natural enemies, reducing the cost-effectiveness of insecticide investment if unaccounted for in treatment decisions.The existing literature on modeling of biological control of insect pests has generally focused on simulations of the population dynamics of pest and natural enemy species and the processes underlying pest control. But agriculture is a managed ecosystem where predator–prey relationships are heavily influenced by human managers. In modeling managerial choices, this study develops an intra-seasonal dynamic bioeconomic optimization model for insecticide-based pest management that explicitly takes into account both the biological control effect of natural enemies on pest density and the nontarget mortality effect of insecticides on the level of natural pest control supplied. The model captures predator–prey interactions, linking them to crop growth and yield damage functions, which in turn are evaluated in a dynamic optimization framework. We introduce a new decision rule for judicious insecticide decisions using a natural enemy-adjusted economic threshold. This threshold represents the pest population density at which insecticide control becomes optimal in spite of the opportunity cost of injury to natural enemies of the target pest. Using field data from Michigan, the model is applied to the case of soybean aphid (Aphis glycines, Matsumura), a recent invasive pest of soybean (Glycine max), whose management is of both economic and environmental importance to the North Central region of the United States. As illustrated by the numerical examples, such natural enemy-adjusted threshold is likely to lead to fewer recommendations for insecticide use than naïve models that ignore natural enemies, resulting in less insecticide use, while maintaining profitability for farmers that rely on chemical pest control methods.The bioeconomic model developed in this study can be used to conduct a wide variety of analyses such as identifying dynamically optimal spray strategies and estimating the implied economic value of natural control services. Furthermore, with the incorporation of inter-year carry-over factors, such as overwintering of pests and natural enemies, the current model can contribute to building multi-year models for studying long-term pest management.     

生态茶园建设与病虫害综合防治

综述了在茶树病虫害综合防治中生态学原理和农田生态系统科学理论的运用。强调以生态防治，即农业防治和生物防治为主，借助于各种农业技术和现代生物科学手段，在综合防治中尽量少用化学农药，以减少对环境的污染、农药残留及对天敌的伤害，维持茶园生态平衡。     

Insect fauna associated with sugarcane plantations in Sri Lanka

A survey conducted over 13 years (1986-1999) in sugarcane plantations in Sri Lanka to identify insects associated with sugarcane recorded a total of 103 insect species comprising Coleoptera (31 spp.), Dictyoptera (2 spp.), Diptera (5 spp.), 12 Heteroptera (12 spp.), Homoptera (18 spp.), Hymenoptera (7 spp.), Isoptera (3 spp.), Lepidoptera (13 spp.), Orthoptera (9 spp.), and one species each of Thysanoptera, Nuroptera and Trichoptera. Among them were forty-six species of sugarcane pests. In addition, 27 species of natural enemies of sugarcane pests belonging to the orders Coleoptera, Diptera and Hymenoptera were identified Epiricania melanoleuca (Fletcher) introduced into Sri Lanka from Pakistan in 1991 for the control of the sugarcane planthopper was also recorded. Five new pest species previously not recorded from sugarcane in Sri Lanka have been identified.     

Additive effects of vertebrate predators on insects in a Puerto Rican coffee plantation.

A variety of studies have established the value of shaded coffee plantations as habitat for birds. While the value of birds as biological controls in coffee has received some attention, the interactions between birds and other predators of insects have not been tested. We used exclosures to examine the effects of vertebrate predators on the arthropods associated with coffee, in particular the coffee leafminer (Leucoptera coffeella) and the flatid planthopper Petrusa epilepsis, in a shaded coffee plantation in Puerto Rico. We used a 2 x 2 factorial design with four treatments: exclusion of birds, lizards, birds and lizards, and control (no exclusion). Abundance of insects > 5 mm increased when birds or both birds and lizards were removed. Birds and lizards had an additive effect for insects < 5 mm and for all insects combined. Coffee leafminers showed a weak response to removal of predators while planthopper abundance increased significantly in the absence of avian predators. Arthropod predators and parasitoids did not differ significantly between treatments. Our findings suggest that vertebrate insectivores have an additive effect on insects in coffee and may help control abundances of some coffee pests. Equally important, we present evidence suggesting that they do not interfere with other known natural enemies of coffee pests.     

Population regulation by enemies of the grass Brachypodium sylvaticum: demography in native and invaded ranges

The enemy-release hypothesis (ERH) states that species become more successful in their introduced range than in their native range because they leave behind natural enemies in their native range and are thus "released" from enemy pressures in their introduced range. The ERH is popularly cited to explain the invasive properties of many species and is the underpinning of biological control. We tested the prediction that plant populations are more strongly regulated by natural enemies (herbivores and pathogens) in their native range than in their introduced range with enemy-removal experiments using pesticides. These experiments were replicated at multiple sites in both the native and invaded ranges of the grass Brachypodium sylvaticum. In support of the ERH, enemies consistently regulated populations in the native range. There were more tillers and more seeds produced in treated vs. untreated plots in the native range, and few seedlings survived in the native range. Contrary to the ERH, total measured leaf damage was similar in both ranges, though the enemies that caused it differed. There was more damage by generalist mollusks and pathogens in the native range, and more damage by generalist insect herbivores in the invaded range. Demographic analysis showed that population growth rates were lower in the native range than in the invaded range, and that sexually produced seedlings constituted a smaller fraction of the total in the native range. Our removal experiment showed that enemies regulate plant populations in their native range and suggest that generalist enemies, not just specialists, are important for population regulation.     

Additive effects of aboveground polyphagous herbivores and soil feedback in native and range-expanding exotic plants

Plant biomass and plant abundance can be controlled by aboveground and belowground natural enemies. However, little is known about how the aboveground and belowground enemy effects may add up. We exposed 15 plant species to aboveground polyphagous insect herbivores and feedback effects from the soil community alone, as well as in combination. We envisaged three possibilities: additive, synergistic, or antagonistic effects of the aboveground and belowground enemies on plant biomass. In our analysis, we included native and phylogenetically related range-expanding exotic plant species, because exotic plants on average are less sensitive to aboveground herbivores and soil feedback than related natives. Thus, we examined if lower sensitivity of exotic plant species to enemies also alters aboveground-belowground interactions. In a greenhouse experiment, we exposed six exotic and nine native plant species to feedback from their own soil communities, aboveground herbivory by polyphagous insects, or a combination of soil feedback and aboveground insects and compared shoot and root biomass to control plants without aboveground and belowground enemies. We observed that for both native and range-expanding exotic plant species effects of insect herbivory aboveground and soil feedback added up linearly, instead of enforcing or counteracting each other. However, there was no correlation between the strength of aboveground herbivory and soil feedback. We conclude that effects of polyphagous aboveground herbivorous insects and soil feedback add up both in the case of native and related range-expanding exotic plant species, but that aboveground herbivory effects may not necessarily predict the strengths of soil feedback effects.     

Evaluating the impacts of multiple generalist fungal pathogens on temperate tree seedling survival

Host-specific mortality driven by natural enemies is a widely discussed mechanism for explaining plant diversity. In principle, populations of plant species can be regulated by distinct host-specific natural enemies that have weak or nonexistent effects on heterospecific competitors, preventing any single species from becoming dominant and thus promoting diversity. Two of the first steps in exploring the role of natural enemies in diversity regulation are to (1) identify potential enemies and (2) evaluate their levels of host specificity by determining if interactions between any one host and its enemy have equivalent survival impacts on co-occurring host species. We developed a bioinformatics framework to evaluate impacts of potential pathogens on seedling survival, for both single and multiple infections. Importantly, we consider scenarios not only if there are specialist pathogens for each plant, but also when generalist pathogens have differential effects on multiple host species, and when co-infection has species-specific effects. We then applied this analytical framework to a field experiment using molecular techniques to detect potential fungal pathogens on co-occurring tree seedling hosts. Combinatorial complexity created by 160 plant-fungus interactions was reduced to eight combinations that affect seedling survival. Potential fungal pathogens had broad host ranges, but seedling species were each regulated by different combinations of fungi or by generalist fungi that had differential effects on multiple plant species. Soil moisture can have the potential to shift the nature of the interactions in some plant-fungal combinations from neutral to detrimental. Reassessing the assumption of single-enemy-single-host interactions broadens the mechanisms through which natural enemies can influence plant diversity.     

Computer simulation applied to the biological control of the insect Aphis gossypii for the parasitoid Lysiphlebus testaceipes

In integrated pest management (IPM), biological control is one of the possible options for the prevention or remediation of an unacceptable pest activity or damage. The success of forecast models in IPM depends, among other factors, on the knowledge of temperature effect over pests and its natural enemies. In this work, we simulated the effects of parasitism of Lysiphlebus testaceipes (Cresson, 1880) (Hymenoptera: Aphidiidae) on Aphis gossypii (Glover, 1877) (Hemiptera: Aphididae), a pest that is associated to crops of great economic importance in several parts of the world. We made use of experimental data relative to the host and its parasitoid at different temperatures. Age structure was incorporated into the dynamics through the Penna model. The results obtained showed that simulation, as a forecast model, can be a useful tool for biological control programs.     

Linking fruit traits to variation in predispersal vertebrate seed predation, insect seed predation, and pathogen attack

The importance of vertebrates, invertebrates, and pathogens for plant communities has long been recognized, but their absolute and relative importance in early recruitment of multiple coexisting tropical plant species has not been quantified. Further, little is known about the relationship of fruit traits to seed mortality due to natural enemies in tropical plants. To investigate the influences of vertebrates, invertebrates, and pathogens on reproduction of seven canopy plant species varying in fruit traits, we quantified reductions in fruit development and seed germination due to vertebrates, invertebrates, and fungal pathogens through experimental removal of these enemies using canopy exclosures, insecticide, and fungicide, respectively. We also measured morphological fruit traits hypothesized to mediate interactions of plants with natural enemies of seeds. Vertebrates, invertebrates, and fungi differentially affected predispersal seed mortality depending on the plant species. Fruit morphology explained some variation among species; species with larger fruit and less physical protection surrounding seeds exhibited greater negative effects of fungi on fruit development and germination and experienced reduced seed survival integrated over fruit development and germination in response to vertebrates. Within species, variation in seed size also contributed to variation in natural enemy effects on seed viability. Further, seedling growth was higher for seeds that developed in vertebrate exclosures for Anacardium excelsum and under the fungicide treatment for Castilla elastica, suggesting that predispersal effects of natural enemies may carry through to the seedling stage. This is the first experimental test of the relative effects of vertebrates, invertebrates, and pathogens on seed survival in the canopy. This study motivates further investigation to determine the generality of our results for plant communities. If there is strong variation in natural enemy attack among species related to differences in fruit morphology, then quantification of fruit traits will aid in predicting the outcomes of interactions between plants and their natural enemies. This is particularly important in tropical forests, where high species diversity makes it logistically impossible to study every plant life history stage of every species.     

低山丘陵区农业景观格局对害虫-捕食性天敌食物网的影响

农业集约化导致景观破碎化、均质化程度加深.景观斑块的组成及合理布局带来的农业景观高异质性是维持区域生物多样性的关键.该文选择具有典型低山丘陵地貌的辽宁省建平县为研究区,在食物网水平上探究区域农业景观格局对生物多样性的影响.选取20个样区,在明晰区域景观特征、分析害虫-捕食性天敌食物网结构的基础上,采用回归分析和最优模型...