川西亚高山森林不同恢复途径物种组成和群落结构动态变化

川西亚高山森林作为西南林区主体,是长江上游的生态屏障,该区域植被恢复方式主要为人工恢复和自然恢复,比较不同恢复方式下森林的物种组成和群落结构动态变化,对于川西亚高山森林恢复与重建有重要的意义,可以为制定合理的森林管理策略提供科学依据。基于茂县山地生态系统定位研究站不同恢复模式形成的的华山松人工林、油松人工林和自然恢复的次生林野外调查数据,分析了2005-2020年乔、灌、草三个层次的群落结构特征和多样性。结果表明:(1)不同恢复途径下,乔木层物种数都呈现增加趋势,华山松人工林、油松人工林、自然恢复的次生林乔木层物种数分别增加了11种、7种、8种;(2)华山松人工林中华山松重要值从48.06%降低到31.1%,乡土阔叶树种四川蜡瓣花进入乔木层,2020年重要值增大至21.62%,油松人工林中油松重要值逐渐降低,从43.59%降至29.76%;自然恢复的次生林中,乡土树种锐齿槲栎逐渐成为第一优势种,2020年重要值增至19.9%。(3) 华山松人工林、油松人工林和自然恢复的次生林中,温带区系成分分别占总属数的71.43%,80.77%和84%,温带区系特征明显。(4)华山松人工林和油松人工林乔木层径级结构均为偏正态分布;而自然恢复的次生林径级分布呈倒"J"形,以小径级个体为主。(5)不同林型的乔木层高度在15年间呈现增加的趋势,具体表现为油松人工林>华山松人工林>自然恢复的次生林。(6)乔木层Shannon-wiener指数和 Simpson指数均表现为自然恢复的次生林显著大于两个人工林,丰富度指数和均匀度指数表现为油松人工林最大;灌木层4个多样性指数均表现为油松人工林最大;草本层的丰富度指数、Shannon-wiener 指数和 Simpson 指数均表现为油松人工林较大,均匀度指数没有显著差异。结论:人工林恢复速度大于自然恢复的次生林,但自然恢复的次生林更新能力更强,且更有利于多样性的保存。两个人工林逐渐由常绿针叶林演替为以常绿针叶树为主的针阔混交林,自然恢复的次生林演替为以常绿阔叶树为主的针阔混交林。     

民勤绿洲荒漠过渡带人工梭梭种群年龄结构及动态

基于野外样地调查数据,通过分析静态生命表、存活曲线、动态指数等参数,结合时间序列模型,研究了人工梭梭种群年龄结构动态,旨在预测人工梭梭种群演替趋势,为退化人工梭梭种群恢复与重建提供理论依据。结果表明：(1)民勤绿洲荒漠过渡带人工梭梭种群的年龄结构近似于“金字塔”型,幼龄林个体占总物种数的90.1%;(2)人工梭梭种群存活曲线趋近于Deevey-Ⅱ型,为稳定型种群。不同区域人工梭梭种群的第Ⅰ、Ⅱ、Ⅲ龄级个体死亡率和消失率最高;(3)动态量化结果显示人工梭梭种群总体均表现为增长型,对外界干扰敏感性较强;(4)时间序列预测分析表明,在未来2、4个龄级时间后,种群Ⅱ、Ⅳ龄级个体数量大幅度增加,人工梭梭种群发展趋势较好。民勤绿洲荒漠过渡带人工梭梭种群为稳定增长型种群,种群具有一定的自然更新能力。针对该种群幼龄个体死亡率较高的问题,未来建议加强对第Ⅰ、Ⅱ、Ⅲ龄级幼株的精准抚育管理,通过人为辅助措施提高幼苗的保存率,促进人工梭梭林的可持续发展。     

In vitro rearing of Ooencyrtus nezarae (Hymenoptera: Encyrtidae), an egg parasitoid of Riptortus pedestris (Hemiptera: Alydidae)

Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) is a polyphagous egg parasitoid of various true bugs, including Riptortus pedestris (Fabricius) (Hemiptera: Alydidae), a major pest of soybean and fruit trees in northeastern Asia. This study was conducted to develop artificial host eggs containing insect haemolymph for mass rearing of O. nezarae. The haemolymph of Chinese oak silkworm (Antheraea pernyi Guérin-Méneville) pupae was found to be most suitable for artificial eggs for the complete development of O. nezarae. Among 764 parasitoid eggs laid in artificial eggs, 49.2% successfully developed to adult parasitoids. The developmental time in artificial eggs was delayed by 3–5 days relative to that observed in natural host eggs; however there was no significant difference in the length of hind tibia between adults that emerged from artificial and natural host eggs. Moreover, new generations that emerged from artificial eggs reproduced on all egg types offered (either natural or artificial eggs). We propose that the artificial eggs developed herein can therefore be an effective means for mass rearing O. nezarae.     

In search of artificial domatia for predatory mites

Banker plants can enhance biological pest control by providing both floral resources and appropriate oviposition sites, e.g. through acarodomatia, to predator species. The use of materials mimicking domatia i.e. artificial domatia may be an economically favourable alternative to the use of banker plants bearing domatia. The aim of the present study was to identify materials that are able to host eggs of the Neoseiulus californicus predatory mite but not those of the Tetranychus urticae pest mite. In a laboratory experiment, the oviposition of predatory and phytophagous mites were compared in Petri dishes containing leaves. The different modalities compared were (i) natural domatia of Viburnum tinus or (ii) one of twelve potential artificial domatia materials. The overall oviposition response of predatory mites to all artificial domatia was similar to that of the natural domatia. The oviposition of the Tetranychus urticae pest mite did not increase in response to the artificial domatia. Five artificial domatia hosted as many eggs of the predatory mite as observed in the natural domatia. The effect of the physical properties of artificial domatia was also tested and N. californicus was found to favour the artificial domatia that had high heat retention capacities for oviposition. Three of these artificial domatia were tested on rose plants in a greenhouse experiment; none of which enhanced the biological control on the plants under these conditions. The present study highlights the difficulty in identifying and using suitable artificial domatia as substitutes to banker plants in biological pest control efforts.     

Fitness consequences of artificial diets with different macronutrient composition for the predatory bug Orius majusculus

The commercial production of Orius spp. (Hemiptera: Anthocoridae), including Orius majusculus (Reuter), relies on the use of eggs of Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) as rearing diet. However, E. kuehniella eggs have become an expensive fodder thus increasing the price of these key biological control agents. The use of artificial diets potentially decreases the production costs. In this regard, establishing a link between dietary composition and fitness could advance the development of an optimum alternative artificial diet for these predatory insects. The aim of the current study was to test the effect of six artificial diets with different macronutrient composition on the development and reproductive fitness of O. majusculus when compared with the effect of E. kuehniella eggs. In general, nymphal survival was not affected by diet, whereas development was slightly delayed on artificial diets. However, female body mass and fecundity were significantly lower on all of the artificial diets compared with the E. kuehniella eggs diet, suggesting that artificial diets were of inferior quality. Within artificial diets, females fed the viable diet with highest content in lipid laid more eggs than those raised on the most protein-rich diets. We found there was some variation in carcass composition between the O. majusculus fed the various diets, but these variations did not match the differences found in the fitness parameters measured.     

北京山区河岸带植物群落种-面积关系

种-面积关系是群落生态学的基本问题之一,是了解植物群落结构的重要途径。为摸清北京山区河流河岸带植物群落调查最小样方面积,在北京市怀柔区怀九河河岸带沿线,采用基于河岸带立地条件逐步扩大样地面积的方法布设50个80m长样地,调查计算并拟合不同类型河岸带所需的最小样地面积。研究结果表明:北京市怀柔区怀九河河岸带植物种数255种,隶属于70科185属。通过聚类分析将怀九河河岸带分为自然河岸带、近自然河岸带、人工岸坡乔灌草河岸带、人工岸坡观赏性乔灌草河岸带、人工岸坡疏乔灌草干砌石河岸带和人工岸坡浆砌石河岸带6种类型。根据赤池信息量准则AIC可知自然河岸带、近自然河岸带、人工岸坡乔灌草河岸带和人工岸坡疏乔灌草干砌石河岸带优先选取S=c-ae~(-bA),人工岸坡观赏性乔灌草河岸带优先选取S=aA/(1+bA),人工岸坡浆砌石河岸带优先选取S=c/(1+ae~(-bA))。满足相同比例植物种调查,不同类型河岸带所需最小样地面积存在明显差异,当满足河岸带植物调查80%植物种时,人工岸坡浆砌石河岸带(84m~2)和自然河岸带(217m~2)所需样地面积较小,其次是人工岸坡疏乔灌草干砌石河岸带(362m~2),近自然河岸带(450m~2)和人工岸坡乔灌草河岸带(460m~2)所需样地面积相似,而人工岸坡观赏性乔灌草河岸带所需样地面积最大为571m~2。所得出的河岸带植物调查最小样地面积对于河岸带生物多样性保护和指导河岸带生态修复具有重要意义。     

Effects of two artificial diets on the development and reproduction of Tirathaba rufivena (Walker) (Lepidoptera: Pyralidae)

Growth, survival, fecundity, and nutrition of Tirathaba rufivena (Walker) fed on two artificial and one natural diet were studied at 29±1°C and 75±5% relative humidity. Larvae reared on the two artificial diets showed faster growth and development, higher pupal survival and weight, and higher adult fecundity than those reared on a natural diet of young coconuts, Cocos nucifera L. The relative growth rate, efficiency of ingested food conversion, and efficiency of digested food conversion in larvae fed on artificial diets were significantly higher than those of larvae fed on young coconuts. The relative consumption rate of larvae fed on artificial diets was significantly lower than that of larvae fed on young coconuts. T. rufivena showed no significant degradation in ability to propagate after being reared on the artificial diet for five successive generations. These results indicated that two artificial diets are suitable for mass rearing of T. rufivena.     

Settlement and Density of Juvenile Fish Assemblages in Natural, Zostera Capricorni (Zosteraceae) and Artificial Seagrass Beds

Few studies have validated the use of artificial seagrass to study processes structuring faunal assemblages by comparison with natural seagrass. One metric (fish recruitment) for evaluating the use of artificial seagrass was used in the present study. Settlement and recruitment of juvenile fish was estimated in natural, Zostera capricorni Aschers, and artificial seagrass in Botany Bay, NSW, over 6 consecutive days. Tarwhine, Rhabdosargus sarba, dominated the catch from both habitats, and there was no significant difference in abundance of recruits among the habitats. This was at least partly caused by large spatial and temporal variation in abundance. Daily abundances of R. sarba recruits suggested movement between seagrass beds, but could not be confirmed without tagging individual fish. Rhabdosargus sarba settlers were less abundant than recruits, but were also patchily distributed amongst natural and artificial seagrass beds. Most other species were also found in similar abundance in the two habitats, except stripey, Microcanthus strigatus, which was more abundant in artificial seagrass. Overall, fish assemblages in natural and artificial seagrass were similar. Artificial seagrass may therefore be useful for monitoring settlement and recruitment of juvenile fishes to disturbed habitats, to predict the success of habitat remediation. However, if artificial seagrass is used to model processes occurring in natural seagrass, it is necessary to consider species-specific responses to the artificial habitat.     

Comparison of fish assemblages among an artificial reef, a natural reef and a sandy-mud bottom site on the shelf off Iwate, northern Japan

Synopsis Fish assemblages at an artificial reef site, a natural reef site and a sandy-mud bottom site, on the shelf (depth 130 m) off Iwate Prefecture, northern Japan, were surveyed by using a bottom trammel net from May 1987 to March 1993. A total of 12 173 fishes of 48 species were recorded. Physiculus maximowiczi was dominant and comprised 69% of the total numerical abundance. Total fish number was lowest in March at all the 3 sites when P. maximowiczi migrated to deeper and warmer waters. Assemblage equitability and species diversity also varied seasonally in accordance with the abundance fluctuation of P. maximowiczi. P. maximowiczi, Alcichthys alcicornis and Hexagrammos otakii were more abundant at the artificial reef and natural reef sites, while Dexistes rikuzenius and Hemitripterus villosus were more abundant at the sandy-mud bottom site; total fish abundance was largest at the artificial reef site mainly due to the large number of P. maximowiczi. Species richness was similar among sites, but equitability, and consequently species diversity, was lowest at the artificial reef site. The main effect of the artificial reef seemed the attraction of P. maximowiczi from nearby bottoms, especially from natural rocky reefs; its large abundance determined the structure of the artificial reef fish community.     

Needle morphological evidence of the homoploid hybrid origin of Pinus densata based on analysis of artificial hybrids and the putative parents,Pinus tabuliformis and Pinus yunnanensis

Genetic analyses indicate that Pinus densata is a natural homoploid hybrid originating from Pinus tabuliformis and Pinus yunnanensis. Needle morphological and anatomical features show relative species stability and can be used to identify coniferous species. Comparative analyses of these needle characteristics and phenotypic differences between the artificial hybrids, P. densata, and parental species can be used to determine the genetic and phenotypic evolutionary consequences of natural hybridization. Twelve artificial hybrid families, the two parental species, and P. densata were seeded in a high‐altitude habitat in Linzhi, Tibet. The needles of artificial hybrids and the three pine species were collected, and 24 needle morphological and anatomical traits were analyzed. Based on these results, variations in 10 needle traits among artificial hybrid families and 22 traits among species and artificial hybrids were predicted and found to be under moderate genetic control. Nineteen needle traits in artificial hybrids were similar to those in P. densata and between the two parental species, P. tabuliformis and P. yunnanensis. The ratio of plants with three needle clusters in artificial hybrids was 22.92%, which was very similar to P. densata. The eight needle traits (needle length, the mean number of stomata in sections 2 mm in length of the convex and flat sides of the needle, mean stomatal density, mesophyll/vascular bundle area ratio, mesophyll/resin canal area ratio, mesophyll/(resin canals and vascular bundles) area ratio, vascular bundle/resin canal area ratio) relative to physiological adaptability were similar to the artificial hybrids and P. densata. The similar needle features between the artificial hybrids and P. densata could be used to verify the homoploid hybrid origin of P. densata and helps to better understand of the hybridization roles in adaptation and speciation in plants.     

Biology and life table studies of the oriental tobacco budworm,Helicoverpa assulta (Lepidoptera: Noctuidae), influenced by different larval diets

Development, survivorship, pupal weight, oviposition, and life table parameters of the oriental tobacco budworm, Helicoverpa assulta Guenée, were evaluated in the laboratory on an artificial diet, pepper (Capsicum frutescens L.), and tobacco (Nicotiana tobacum L.). We found that the average developmental time of immature stages was longest on tobacco (36.2 d), intermediate on pepper (34.4 d), and shortest on artificial diet (33.5 d). Immature survival from egg to pupa varied from 31% on tobacco, 43% on pepper, and 74% on artificial diet. Pupal weight ranged from 197.4 mg/pupa on tobacco, 233.1 mg/pupa on pepper and 253.4 mg/pupa on artificial diet. The average numbers of eggs laid by adults reared as larvae on the artificial diet, pepper, or tobacco were 614, 421 and 334 eggs/female, respectively. Numbers of remaining eggs in ovaries of the adult females reared as larvae on the artificial diet, pepper, or tobacco were 16, 26, and 42 eggs/female, respectively. The longevity of adult females developed from larvae reared on the three diets was not significantly different, whereas the longevity of male adults from the larvae reared on artificial diet was longer (16.8 d) than that for males reared on tobacco (13.8 d) and pepper (13.3 d). The intrinsic, finite, gross, and net rates of increase were highest for females reared as larvae on artificial diet, lowest for females emerging from larvae reared on tobacco, and intermediate for females emerging from larvae reared on pepper. Generation times and doubling time of H. assulta were shortest for larvae fed artificial diet, intermediate from larvae reared on pepper, and longest from larvae reared on tobacco. We concluded that the artificial diet was the most suitable larval diet of H. assulta followed by pepper, and tobacco.     

半干旱黄土小流域不同恢复方式对生态系统多功能性的影响

在黄土高原大规模退耕还林（草）背景下,植被恢复对生态系统功能会产生极大影响。以往研究多为比较不同恢复方式或植被类型的单一生态系统功能,对生态系统多功能性的研究亟待加强。因此,基于甘肃定西龙滩流域3种恢复方式（天然荒草、自然恢复、人工恢复）6种植被类型（长芒草草地、赖草草地、苜蓿草地、柠条灌丛、油松林、山杏林）38个样地调查数据,选取与土壤养分储存与循环、水源涵养、初级生产力、多样性维持等相关的23个功能指标利用平均值法量化生态系统多功能性。研究结果显示,（1）除营养物转化与循环功能外,其余土壤相关的生态系统功能在不同恢复方式与植被类型间均具有显著性差异（P<0.05）。人工恢复植被的土壤肥力显著高于自然恢复植被;人工恢复植被中土壤肥力从高到低依次为柠条灌丛、苜蓿草地、山杏林、油松林。自然恢复植被的水源涵养功能显著高于人工恢复植被。（2）除植物生长策略外,其余植物相关的生态系统功能在不同恢复方式与植被类型间均具有显著性差异（P<0.05）。人工恢复植被中地上初级生产力从高到低依次为山杏林、油松林、柠条灌丛、苜蓿草地,并显著高于自然恢复植被。人工恢复植被中植物养分吸收能力从高到低依次为苜蓿草地、柠条灌丛、油松林、山杏林,并显著高于自然恢复植被。自然恢复植被的物种多样性显著高于人工恢复植被。（3）生态系统多功能性在不同恢复方式与植被类型间均具有显著性差异（P<0.05）。生态系统多功能性表现为人工恢复植被高于自然恢复植被,但人工恢复植被的水源涵养功能与物种多样性均低于自然恢复植被,不利于生态系统的可持续发展。研究认为,在植被恢复具体实践中,应针对不同的恢复目标,根据各植被类型的功能特征,制定因地制宜的植被恢复战略。     

Influences of habitat complexity on the diversity and abundance of epiphytic invertebrates on plants

SUMMARY 1. The compound influence of habitat complexity and patch size on stream invertebrate assemblages associated with submerged macrophytes was investigated through field sampling of two natural macrophyte species with contrasting leaf morphologies (complex, Ranunculus yezoensis; simple, Sparganium emersum) and an experiment with two artificial plants with different levels of morphological complexity. 2. The artificial plant experiment was designed to separate the effects of habitat area (patch size) and habitat complexity, thus enabling a more rigorous assessment of complexity per se than in previous studies where only a single patch size was used. Simple and complex artificial plants were established with five different patch sizes corresponding to the range found in natural plants. 3. Invertebrates occurred on both complex and simple forms of natural and artificial plants at similar abundances with dipterans and ephemeropterans being predominant. Taxon richness was higher on structurally complex Ranunculus than on simple Sparganium and was similarly higher on the complex artificial plant than on the simple one, over the entire range of habitat patch sizes. Thus, architectural complexity affected the taxon richness of epiphytic invertebrates, independently of habitat scale. 4. On the natural plants there was no difference in the abundance (both number of individuals and biomass) of invertebrates between simple and complex forms, while on artificial plants more invertebrates occurred on complex than on simple forms. The amount of particulate organic matter, >225 μm (POM) and chlorophyll a showed mixed patterns on natural and artificial plants, suggesting that the availability of these resources is not an overriding proximate factor controlling invertebrate abundance on plants. The difficulty of extrapolating from experimental results involving use of artificial plants is discussed, especially when considering the relationship between habitat structure and the occurrence of epiphytic invertebrates on natural plants.     

Double-strand breaks on artificial chromosomes in yeast

Yeast artificial chromosomes composed primarily of bacteriophage λ DNA exhibit very low levels of meiotic crossing over compared with similarly sized intervals of natural yeast DNA. When these recombinationally quiet chromosomes were augmented with a 12.5 kb insert of sequences from yeast chromosome VIII, genetic studies demonstrated that the artificial chromosomes had acquired recombination properties characteristic of this region of chromosome VIII. On authentic yeast chromosomes, most meiotic recombination events are initiated at sites where the DNA is cleaved to create a double-strand break (DSB). This report describes physical analyses that were carried out to examine the relationship between DSB sites and the recombination behavior of the artificial chromosomes. The results show that DSBs are rare on these artificial chromosomes, except for the 12.5 kb insert. Mapping of the DSB sites shows that their positions correlate with the previously determined positions of DSB sites on chromosome VIII. Deletion of two characterized chromosome VIII DSB sites from the 12.5 kb insert on the artificial chromosome resulted in the loss of the predicted DSB fragments and a reduction in crossing over between artificial chromosomes. Received: 15 May 1998; in revised form: 26 September 1999 / Accepted: 18 November 1999     

人工固沙措施对沙丘沉积物特征及土壤养分的影响

为探明人工铺设尼龙网状固沙措施对风沙危害的影响,以腾格里沙漠东南部人工固定沙丘、两类自然流动沙丘以及防护林的地表沉积物和结皮为研究对象,研究沙丘不同位置、不同深度沉积物的颗粒组成、土壤有机质、有效氮、有效磷、有效钾含量等养分特征。结果表明:(1)人工固定沙丘和自然流动沙丘粒度组成和土壤养分含量都存在显著差异(P<0.5),沙障的防风,固沙和土壤改良作用明显。(2)人工固定沙丘各个地貌位置沉积物粒度频率曲线均出现三峰,反映了沙障对粉尘沉积物的拦截作用,体现了沙障对土壤理化性质的改良过程;分选性随风向逐渐变差,随着粒径变细而好;偏度和峰度明显高于其他。(3)整个研究区沉积物偏碱性,影响着土壤养分含量。人工固定沙丘养分含量最高,有效氮和有机质含量均为最大,有效磷和有效钾含量略低于对比林,其粉沙物质含量与养分含量成正比。(4)人工固定沙丘的沙丘迎、背风坡均有植被分布,并覆有土壤物理结皮,沉积物粒级分配较自然发育的流动沙丘分散,养分含量增加。由此可见,沙障对沙区的土壤环境和生态环境改善具有重要的影响。     

Artificial diets for the larval oak longicorn beetle, <Emphasis Type="Italic">Moechotypa diphysis</Emphasis> (Coleoptera: Cerambycidae)

The oak longicorn beetle, Moechotypa diphysis (Pascoe), is a pest of bed logs for shiitake mushroom and an invasive species on Japan’s main islands. I attempted to rear larvae of M. diphysis on two artificial diets consisting of a commercially available diet for silkworm plus dried yeast and sawdust of the sawtooth oak, Quercus acutissima Carruthers, or of Japanese beech, Fagus crenata Blume. Newly hatched larvae were inoculated on these artificial diets and reared at 25°C in the dark. More than 60% of larvae emerged as adults when fed with these diets. The weights of emerged adults fed on the artificial diets were heavier than those emerging from logs of Q. acutissima, their natural diet, in a field cage. These results demonstrate that the two artificial diets are useful for rearing M. diphysis larvae and can assist further studies on the development of this invasive species.     

Comparative Development and Performance of Artificially Reared versus Host-RearedDiapetimorpha introita(Cresson) (Hymenoptera: Ichneumonidae) Wasps

Diapetimorpha introita(Cresson) (Hymenoptera: Ichneumonidae), a native ectoparasitoid ofSpodopteraspp. pupae, was reared in the laboratory on an artificial diet devoid of any insect host components. Diet-reared wasps demonstrated a propensity to search for and parasitize natural hosts in a field cage trial. Longevity of the diet-reared wasps was comparable with the longevity of wasps reared on host pupae. Survival rate ofD. introitawas 61.3% when reared on diet and 76.3% when reared on host pupae. Wasps reared on the artificial diet had longer developmental times, reduced fecundity, and reduced adult weights compared to wasps reared on host pupae. These studies suggest that future research efforts should focus on increasing fecundity and weight of diet-reared wasps and decreasing the mortality and developmental time of wasps reared on the artificial diet. The ability to rearD. introitaon an inexpensive, artificial diet significantly enhances the potential of mass rearing this parasitoid for inundative releases againstSpodopteraspp.     

Effects of artificial plant cover on plant colonization of a bare peat surface

Abstract. This paper describes the effect of artificial plant cover on plant colonization of a bare peat surface, resulting from peat harvesting. Plant species colonization was compared on plots supplied with plastic models simulating Vaccinium vitis-idaea plants and plots without this artificial cover. After two growing seasons, species composition and total biomass of the established plant cover were similar in the two plot types. However, the number of established seedlings in the plots with artificial cover was significantly higher than that in the plots without cover. Out of 13 species observed four differed significantly in their performance on the two plot types. Betula spec. had both higher seedling numbers and higher biomass on the test plots; Deschampsia cespitosa had a higher biomass, whereas the seedlings were too numerous to be counted; Salix phylicifolia had higher seedling numbers. On the contrary, the number of seedlings of Epilobium angustifoliwn was lower on plots with artificial cover. It is suggested that colonization by Betula, D. cespitosa and S. phylicifolia was facilitated mainly by the improved microclimatic and soil moisture conditions under the artificial plant cover. On the other hand, germination of E. angustifolium may be negatively influenced by the increased shade on the test plots.     

Effect of diet and mating status on ovarian development and oviposition in the polyphagous predator Macrolophus caliginosus (Heteroptera: Miridae)

The mirid bug Macrolophus caliginosus is commercially reared on eggs of Ephestia kuehniella, constituting an effective but expensive factitious food. Artificial diets can decrease the rearing costs of this natural enemy, but developing and evaluating an artificial diet is a very time-consuming activity. In the current study, development and reproduction of M. caliginosus on two artificial diets based on egg yolk were investigated. The artificial diets resulted in longer development and lower adult weights, but survival was comparable with that of control insects fed E. kuehniella eggs. Reproductive potential of the predator reared on factitious and artificial foods was assessed using a dissection method. The influence of nymphal food on fecundity was less important than that of adult food. Adults fed E. kuehniella eggs had a preoviposition period of about 4 days, whereas adults offered only plant material started laying eggs about 7 days after emergence. Ovarian scores at day 7 were higher for females fed E. kuehniella eggs than for those given access only to a tobacco leaf. Ovarian scores were not significantly affected by mating status. In a final test, a parallel comparison of two methods for assessing reproductive response to diet was made. Here, adult couples were offered one of four diets: E. kuehniella eggs, one of two artificial diets or no food. Half of the females were dissected and the other half was held for determining lifetime oviposition. Females fed E. kuehniella eggs had superior ovarian scores and laid more eggs than those fed either artificial diet or those given no extra food. A good correlation (r = 0.97) was obtained between ovarian scores and oviposition data, indicating that dissecting females after 1 week provides a reliable estimate of fecundity as affected by diet quality. Rapid reproductive assessments as used in the current study will help to increase the rate of development of artificial diets and may contribute to more cost effective production methods for augmentative biological control agents.     

Bacterial communities in predatory mites are associated with species and diet types

The symbiotic bacterial communities of phytophagous arthropods are affected by host species and feeding habits, but such effects have been poorly studied in natural enemies. Here, we investigated the entire bacterial microbiome of two species of predatory mites, Neoseiulus californicus and Neoseiulus barkeri, feeding on three types of diets (artificial diet, pollen and their natural prey, the spider mite Tetranychus urticae) by high-throughput sequencing of the 16S rRNA gene. We found that the bacterial diversity of predatory mites feeding on artificial diet was significantly different from pollen and spider mite feeding groups in both N. californicus and N. barkeri, while bacterial diversity also differed strikingly between the two species even when feeding on the same artificial diet. This finding suggests that the bacterial community of predatory mites is determined by both species and diet. Alphaproteobacteria and Gammaproteobacteria were the two dominant bacterial classes in both predatory mite species, except for N. californicus feeding on artificial diet. The bacterium Bosea sp. was detected in all samples as the core microbial species in predatory mites. Additionally, we discuss whether Bradyrhizobiaceae and Rhodobacteraceae bacteria could be used as probiotics in the artificial diet of N. californicus for better mass rearing.