Selection of aphid prey by Adalia bipunctata L. and Coccinella 7-punctata L

Larvae and adults of Adalia bipunctata L. and Coccinella 7-punctata L. seemed unable to detect and avoid feeding on unsuitable or toxic aphids, e.g. larvae of A. bipunctata fed on the highly toxic Megoura viciae, even when given the choice of a suitable aphid. Apparent preferences were not always for the most suitable food. Field cage experiments demonstrated the preference of adult A. bipunctata and C. 7-punctata for different habitats, the former ovipositing at the shrub level (4 ft.) and the latter feeding and ovipositing on plants near ground level.     

The effects of different aphid foods on Adalia bipunctata L. and Coccinella 7-punctata L

The influence of different aphid foods on larval development and adult fecundity of Adalia bipunctata L. and Coccinella 7-punctata L. was investigated. Certain aphids such as Myzus persicae Sulz. and Acyrthosiphon pisum Harris were suitable for both species. Megoura viciae Buckt., was toxic to A. bipunctata but not to C. 7-punctata. Aphis fabae Scop., although a common natural prey of A. bipunctata, slowed larval development, partly because it was nutritionally unsuitable. Fecundity of adults fed on A. fabae was also reduced to less than half. Larvae and adults of C. 7-punctata developed and reproduced as well on A. fabae as on other suitable aphids. C. 7-punctata caught aphids more quickly than A. bipunctata. Larvae of both species given relatively unsuitable prey fed more slowly than normal and consumed less of each aphid. The toxic aphid M. viciae was rejected by A. bipunctata after a short period of feeding.     

Habitat preferences of aphidophagous coccinellids [Coleoptera]

From May to July 1982 and 1983, coccinellids were sampled in habitats that differed in aphid density, insolation, and host plant type. The number of adults ofCoccinella 7-punctata (CS),C. 5-punctata (CQ),Propylea 14-punctata (PQ),Adonia variegata (AV),Adalia bipunctata (AB),A. 10-punctata (AD), andCalvia 14-guttata (CA) were recorded. AB, AV and CS preferred high, while CQ tolerated low aphid density. CQ, CS, AB and AV preferred sunny, while AD and CA tolerated shaded conditions. CS and AV preferred herbaceous plants, AD and CA large plants, particularly trees, AB showed little specialization, CQ preferred trees early in the season and sparse herbaceous plants later. PQ appeared to be a generalist with a wide tolerance of all these factors, but with a tendency to move from trees to herbaceous plants as the season progressed. Habitats with a high abundance of a species were assumed to be those with on optimum combination of the preferred conditions. There were slight differences in the breadth of habitat preferences, and a little habitat overlap between species. The tendency to aggregate was greater in AB than in other species. Annual variations in species abundance influenced the number of habitats occupied, but not the abundance in the favoured places.     

猪源乳酸杆菌与益生元组合筛选及其体外发酵特性

【目的】对3株乳酸杆菌和4种寡糖类益生元进行组合筛选,并探究其对猪结肠微生物体外发酵特性的影响。【方法】将3株乳酸杆菌(罗伊氏乳杆菌L45、植物乳杆菌L47和罗伊氏乳杆菌L63)分别添加至以菊粉(inulin)、低聚果糖(FOS)、低聚半乳糖(GOS)或乳果糖(lactulose)为唯一碳源的培养基中,结合菌株24 h的生长活性和产酸特性,筛选出最优组合;进一步利用体外发酵技术探究所筛选合生元组合对微生物和发酵特性的影响。【结果】L45和L63分别以FOS和Lactulose为碳源发酵时的生长曲线与葡萄糖相似,L47发酵Inulin和FOS的ΔOD600显著高于葡萄糖(P<0.05),且L47发酵Inulin产生的乳酸是葡萄糖的1.20倍,L47+FOS和L47+Inulin组合效应较好。体外发酵结果表明,与对照组相比,L47+FOS和L47+Inulin降低了发酵液中螺旋体门(Spirochaetes)的相对丰度,提高了乳杆菌属(Lactobacillus)和双歧杆菌属(Bifidobacterium)的相对丰度;L47+Inulin和L47+FOS显著提高了总短链脂肪酸含量(P<0.05);与L47+Inulin组相比,L47+FOS组乙酸和丁酸含量更高(P<0.05)。【结论】L47+FOS与L47+Inulin具有较好的组合效应,且具有改善猪结肠体外发酵的能力,提示L47+FOS和L47+Inulin作为合生元的发展潜力,两种组合在体内情况的效果有待深入研究。     

The potential of predators in natural control of aphids in wheat: Results of a ten-year field study in two German landscapes

In the present study, we investigated the natural control of aphids by predators in wheat fields in a low (L) and high-input cropping region (H) of Germany during a 10-year period. Data for the statistical analyses were obtained from weekly after the start of aphid emergence. The mean annual aphid indices, calculated as the sum of Sitobion avenae (Fabr.), Rhopalosiphum padi (L.), Metopolophium dirhodum (Walk.)(Homoptera: Aphididae), were 30.4 and 81.5 × 103 aphid days per m2, for L and H, respectively. Nine predator fractions were analysed: Coccinella septempunctata L., adults (1) and larvae (2), Propylea quatuordecimpunctata (L.) (Coleoptera: Coccinellidae) adults (3) and larvae (4), syrphid larvae (mostly Episyrphus balteatus [De Geer] (Diptera: Syrphidae)) (5), Chrysoperla carnea Steph. (Neuroptera: Chrysopidae) larvae (6), and adult carabids (7), staphylinids (8) and spiders (9). The two sites were comparable in terms of the mean size of the overall predator community, expressed in predator units (PU): 4.9 PU/m2 (L) vs. 5.4 PU/m2 (H). Most predator fractions responded numerically to increasing aphid densities. The numerical response was strongest in syrphid larvae, scarcely detectable in adult coccinellids, and virtually non-existent in epigeic arthropods. Multiple regression models revealed indirect relationships between the weekly overall predator community densities (PU/m2) and individual predator fractions (individuals/m2) and absolute rates of aphid density increase (individuals/m2) one or two weeks after baseline. A site-independent reduction of the aphid density increase to nil (y = 0) was observed at 3.9 to 4.2 PU/m2. Consequently, the 2.7 times higher aphid density at H cannot be attributed to the presence of fewer predators or lower effects of the overall predator community or of any individual predator fraction.     

Biological control ofAphis pomi [Hom.: Aphididae] ofAphidoletes aphidimyza [Dip.: Cecidomyiidae]; a predator-prey model

Predation ofAphis pomi DeGeer [Hom.: Aphididae] byAphidoletes aphidimyza (Rondani) [Dipt.: Cecidomyiidae] was simulated in Michigan apple orchards using a computer and output validated against field data collected from sleeve cages enclosing aphid infested apple terminals. Lower and upper temperature thresholds for development were 2.9 and 35°C for nymphs ofA. pomi with a mean immature developmental period of 162.3 heat units. Median survivorship of adultA. pomi was 364.3 heat units with an average fecundity of 60.7 offspring per female.A. aphidimyza egg and larval lower threshold and developmental periods were 10.5 and 25.5, 8.1°C and 65.5 heat units, respectively. Larval functional response showed Type II behavior with a y-asymptote of 45 aphids killed per predator. Multiple generation model runs performed under different initial predator: prey densities indicated that current critical predator: prey ratios used in the field for control decisions may underestimate predator efficacy.      

香菇复配氨基酸培养基优化及其对香菇菌丝生长生理的影响

[背景]L-氨基酸能够提供香菇生长发育的部分养分需求,利用外源添加氨基酸的方式对香菇生长基质进行优化,对于香菇产业的增产提质具有积极的发展意义.[目的]利用外源添加丙氨酸(Ala)、丝氨酸(Ser)和天冬酰胺(Asn)的方式改善培养基成分,并探究复配氨基酸促进香菇生长的可能代谢途径.[方法]在三因素三水平上,通过响应面...     

土壤不同镉水平对马缨丹生长及其抗氧化酶活性的影响

采用盆栽试验方法,分别设置0(对照,不添加镉)、30、60、90、120、150、180、210mg·kg-1共8个土壤镉处理水平,研究土壤不同镉水平对马缨丹(Lantana comara L.)生长及其抗氧化酶活性的影响,以探讨马缨丹对镉胁迫的生理响应机制。结果显示:(1)随着土壤镉处理浓度的升高,马缨丹干重呈先升高后降低的趋势,30mg·kg-1镉处理能促进植株的生长,而浓度高于60mg·kg-1时显著抑制马缨丹的生长。(2)马缨丹叶片和根系中O-·2产生速率、H2O2和MDA含量及电解质渗漏率均随土壤镉处理浓度的升高和胁迫时间的延长逐渐升高,胁迫90d时,叶片和根系中O-·2产生速率、H2O2和MDA含量及电解质渗漏率分别在镉浓度高于60和30mg·kg-1时显著低于对照。(3)叶片和根系抗氧化酶SOD、POD、APX和CAT活性随着土壤镉处理浓度的增加大体呈先升高后降低的趋势,并在镉浓度分别高于90和60mg·kg-1时,叶片和根系抗氧化酶活性显著低于对照。研究表明,低浓度镉处理土壤能促进马缨丹植株生长,而高浓度镉处理土壤显著降低了马缨丹体内抗氧化酶活性,导致活性氧大量积累,引起严重的膜脂过氧化伤害,从而显著抑制马缨丹植株的生长。     

Density of an intraguild predator mediates feeding group size, intraguild egg predation, and intra- and interspecific competition

Intraguild predation (IGP) is common in most communities, but many aspects of density-dependent interactions of IG predators with IG prey are poorly resolved. Here, we examine how the density of an IG predator can affect feeding group size, IG egg predation, and the growth responses of IG prey. We used laboratory feeding trials and outdoor mesocosm experiments to study interactions between a social intraguild predator (larvae of the wood frog; Rana sylvatica) and its prey (spotted salamander; Ambystoma maculatum). Larvae of R. sylvatica could potentially affect A. maculatum by consuming shared larval food resources or by consuming eggs and hatchlings. However, successful egg predation requires group feeding by schooling tadpoles. We established from five to 1,190 hatchlings of R. sylvatica in mesocosms, then added either 20 A. maculatum hatchlings to study interspecific competition, or a single egg mass to examine IGP. Crowding strongly suppressed the growth of R. sylvatica, and IGP was restricted to the egg stage. In the larval competition experiment, growth of A. maculatum was inversely proportional to R. sylvatica density. In the predation experiment, embryonic mortality of A. maculatum was directly proportional to the initial density of R. sylvatica and the mean number of tadpoles foraging on egg masses. IGP on eggs reduced A. maculatum hatchling density, which accelerated larval growth. Surprisingly, the density of R. sylvatica had no overall effect on A. maculatum growth because release from intraspecific competition via egg predation was balanced by increased interspecific competition. Our results demonstrate that the density of a social IG predator can strongly influence the nature and intensity of interactions with a second guild member by simultaneously altering the intensity of IGP and intra- and interspecific competition.L . A. Burley and A. T. Moyer contributed equally to this work.     

Growth strategy of an emergent macrophyte, Typha orientalis Presl, in comparison with Typha latifolia L. and Typha angustifolia L.

The growth strategy of an emergent plant, Typha orientalis Presl, was examined in experimental ponds in comparison with two other Typha species distributed in Japan, Typha latifolia L. and Typha angustifolia L. T. orientalis showed the greatest ability of vegetative reproduction at the expense of growth in height. T. orientalis started to produce new ramets earlier than T. latifolia and T. angustifolia. These results suggest that T. orientalis should be a rather pioneer-like species and would be restricted to disturbed habitats.     

高通量测序分析甘肃高寒草原瑞香狼毒根内生菌群落结构特征研究

【背景】瑞香狼毒是我国天然草地退化的标志性植物之一,在入侵的过程中其根内微生物发挥着重要的作用,探究瑞香狼毒根内微生物群落对有益微生物资源的利用及生物防控瑞香狼毒具有重要意义。【目的】探究甘肃省祁连山东麓不同高寒草原毒性杂草瑞香狼毒根部内生真菌和细菌的组成、多样性等群落结构特征。【方法】通过Illumina MiSeq高通量测序技术对甘肃祁连山东麓不同高寒草原的瑞香狼毒根部内生菌组成及多样性进行分析。【结果】不同高寒草原瑞香狼毒根内子囊菌门(Ascomycota)在真菌中占优势地位;蓝细菌(Cyanobacteria)、变形菌门(Proteobacteria)、放线菌门(Actinobacteria)在根内生细菌中属于优势类群。G4样点的真菌和细菌OTU(OperationalTaxonomic Unit)数量和Shannon多样性指数均高于其他4个采样点。主坐标分析(Principal Coordinate Analysis,PCoA)表明,不同高寒草原瑞香狼毒根内生菌群落之间存在一定的差异。One-Way ANOVA分析结合Pearson相关性分析显示,不同样地瑞香狼毒真菌群落结构在属水平上相关性较小,而细菌在属水平存在一定的相关性。【结论】本研究为进一步开发利用瑞香狼毒内生真菌和细菌资源、阐明瑞香狼毒内生菌群的群落结构和生态功能提供理论参考。     

Adventitious shoot formation in cultures of 30-year-old Larix decidua,L. leptolepis,L. eurolepis,and L. laricina trees

Primordial shoot explants excised from buds of one Larix decidua tree, about 30 years old, produced more adventitious buds, elongating into shoots, when grown on half strength Litvay medium than when grown on other basal media. Thidiazuron and N₆-benzyladenine (BA) were equally effective in adventitious bud induction. In a comparative study of 30-year-old L. decidua, L. leptolepis, L. eurolepis, and L. laricina trees, explants from L. eurolepis and L. decidua produced a high number of cultures with adventitious buds that elongated into shoots; those from L. leptolepis were less productive, and those from L. laricina failed to form adventitious buds. The highest response was obtained with material collected in August and September, and in March and April; the lowest response occurred in explants from the October collection.     

一种由粉红粘帚霉引起的青稞根腐病

[背景]根腐病在青稞生产中的危害日趋严重,阻碍了青稞根腐病的有效防控及青海省青稞产业的发展。然而人们对青稞根腐病的研究甚少且病原菌不详。[目的]明确青稞根腐病发生的危害、病原及致病性,为青稞根腐病的防控提供理论依据。[方法]采用常规的组织分离法分离青稞根腐病病原,通过形态鉴定与分子鉴定结合的方法对病原进行鉴定,并采用烧杯水琼脂法测定其致病性。[结果]共分离得到4株青稞根腐病病原菌,鉴定为Clonostachys rosea,有较强的致病性且致病性差异显著,经柯赫氏法则验证为青稞根腐病病原菌,并且是一种新的青稞根腐病病原,该类根腐病也是一种新的根腐类病害,在国内外属首次发现。[结论]Clonostachys rosea可引起青稞根腐病且致病性强。     

Influence of Predator Presence and Prey Density on Behavior and Growth of Damselfly Larvae (Ischnura elegans) (Odonata: Zygoptera)

Foraging behavior is often determined by the conflicting benefits of energy gain and the risk of mortality from predation or other causes. Theory predicts that animals should have lower activity levels when either the risk of predation or the availability of resources in the environment is high. We investigated the adjustment of the behavior of I. elegans larvae to predator presence (Anax imperator) and prey density (Daphnia sp.) and their interaction in a completely crossed factorial experiment in the lab and the effect of behavior on growth. The foraging activity of the I. elegans larvae was significantly reduced in the presence of a free-swimming predator but not a caged predator. Abdominal movements were significantly reduced at a low prey density. Growth was significantly reduced by the presence of a free swimming predator and low prey densities. These results provide evidence that these damselfly larvae adjust their behavior to the presence of predators to increase their survival at the expense of reduced growth and development.     

Biology and development of <Emphasis Type="Italic">Laricobius kangdingensis</Emphasis> Zilahi-Balogh and Jelínek,a newly discovered predator of <Emphasis Type="Italic">Adelges tsugae</Emphasis>

The biology and temperature-dependent development of Laricobius kangdingensis Zilahi-Balogh and Jelínek (Coleoptera: Derodontidae), a newly described predator of hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae) were investigated and compared with a related HWA predator, L. nigrinus Fender, that has already been released. As with other Laricobius species, there are four larval instars. The female to male sex ratio was 1:1.1. Mean lifetime fecundity per female was 196.4 eggs and 97.9 eggs for the parental generation (P₁) and first filial generation (F₁), respectively. Developmental rates at 6, 9, 12, 15, and 18°C were studied between fall 2002 and spring 2004 and used to determine low temperature development thresholds for the egg (2.8°C), and larval (1.6°C) stages. The egg and larval thresholds are lower than those observed for L. nigrinus. Laricobius kangdingensis individuals completed development only at 12 and 15°C; however, the adults did not emerge from aestivation after pupation. Our results suggest that L. kangdingensis may be a promising addition to the complex of predators currently being reared for control of HWA. Laricobius kangdingensis is long-lived, exhibits high fecundity, and can complete development on North American HWA. However, further studies will be necessary to secure its clearance for release, and the source of high mortality in the laboratory must be identified in order to improve its survival for mass-rearing. Handling editor: Eric Lucas     

甲基营养菌MB200中mutS的缺失及高浓度甲醇和甲醛诱变

【背景】甲基营养菌(Methylobacterium)是一类能够以单碳或非C-C键低碳化合物(如甲烷、甲醇、甲醛等)为底物生长,并可生产多种代谢产物如氨基酸、工业酶和辅助因子、多羟基烷酸酯(polyhydroxyalkanoates,PHA)、多糖和类胡萝卜素等的革兰氏阴性细菌。【目的】通过突变甲基营养菌MB200的mutS基因,在胁迫条件下定向诱导,以获得可以耐受高浓度甲醇和甲醛的生产菌株。【方法】利用三亲本结合构建mutS基因缺失的高突变菌株MB200sTB,逐步提升培养液中甲醇、甲醛的浓度进行定向诱导突变,对获得的高耐受性突变株进行回补,分析菌株的生长情况。【结果】构建了mutS基因的缺失突变体MB200sTB,并且得到了高耐受甲醇和甲醛的菌株MB200sHBc和MB200sHBq。MB200sHBc与野生株MB200相比其甲醇耐受性得到了极显著的提高,甲醇耐受浓度从8g/L提升到44g/L,但生长量不受影响。MB200sHBq在以甲醛为0.45g/L的碳源条件下,生长量相较于野生型MB200提高了1.69倍。【结论】通过定向诱导缺失mutS基因的突变体,可获得具有生产应用潜力的...     

Intraspecific Variation in Chemical Attraction of Rice to Insect Predators

The olfactory response of predators of the brown planthopper,Nilaparvata lugensStål, to different genotypes of rice (14 cultivars and breeding lines ofOryza sativaL. and 1 wild species,Oryza nivaraSharma et Shastry) was measured in an airflow olfactometer. Odor from rice plants attracted more females of the mirid predatorCyrtorhinus lividipennisReuter than plain air (control) on only 6 of the 15 rice genotypes. Orientation ofC. lividipennistoward volatiles of certain rice genotypes was apparent even when the plants were free of the brown planthopper. However, the predator distinguished between prey-infested and uninfested plants and preferred plants with eggs over plants with nymphs. The predator did not distinguish different stages of plant growth (vegetative, booting, or flowering). Plants artificially injured to simulate brown planthopper oviposition wounds were not as attractive to the predator as plants on which the planthopper had oviposited. The preassay preconditioning on the cultivar TN1 did not produce a predator bias for this genotype. This suggests that rearing effects or chemically mediated associative learning reported for some natural enemies did not influenceC. lividipennis'host response. Results with another predator, the coccinellidMicraspis hirashimaiSasaji, produced less consistent behavior. Planthopper-infested plants attracted more females ofM. hirashimaithan unifested plants in only 1 of the 12 rice genotypes evaluated. Implications for augmenting predators by rice cultivar selection and modification are discussed.     

Improving cultivated oats (A vena sativa L.) with alleles for vegetative growth index from A. sterilis L.

Summary Ten Avena sterilis L. lines of Mediterranean origin were crossed with six A. sativa L. cultivars from the North Central USA. Additionally, six intervarietal crosses were made among the A. sativa cultivars. F₂- derived lines from each cross type (interspecific and intraspecific) were evaluated for transgressive segregation for grain yield and several vigor traits. Mean percentages of transgressive segregates one LSD_0.05 above the high parent for vegetative growth index and biomass were 9.0% and 9.8%, respectively, from interspecific crosses, but only 4.5% and 2.9%, respectively, from intraspecific crosses. However, there were two and a half times more high transgressive segregates for grain yield from intra than from interspecific crosses. The maximum vegetative growth index among segregates from interspecific crosses was 0.2 q/day/ha greater than the highest segregate from intraspecific crosses. However, mean harvest index was reduced materially by the introgression of A. sterilis germplasm. Because there was no genetic association between vegetative growth index and harvest index, however, it should be possible to improve both harvest index and vegetative growth index and, thus, the grain yield of cultivated oats.Journal Paper No. J-11228 of the Iowa Agric. and Home Econ. Exp. Stn., Ames, IA 50011. Project 2447     

高产杀粉蝶菌素的链霉菌鉴定及其拮抗水稻白叶枯菌活性研究

【目的】为保证农业生产可持续性发展,研发和使用环境友好的生物农药受到全社会的高度重视。微生物代谢产物农药是我国目前应用最广的生物农药,也是未来发展绿色农药的一个重要方向。【方法】利用包含水稻白叶枯菌(Xanthomonas oryzae pv. oryzae, Xoo) PXO99A的NA培养基琼脂平板,从水稻根际土壤中筛选能抑制Xoo生长的链霉菌。通过高效液相色谱和质谱分析活性代谢产物的化学结构;采用剪叶法接种Xoo到水稻叶片后,再喷施杀粉蝶菌素溶液(0.1 g/L),2周后测定叶枯症状;采用响应面分析法优化高产杀粉蝶菌素的发酵培养基;采用PacBio SMRT测序平台+Illumina HiSeq X Ten平台开展全基因组测序。平均核苷酸一致性(average nucleotide identity,ANI)用于比较HSW2009与其他链霉菌在全基因组水平的亲缘关系。【结果】分离到一株对Xoo生长有强抑制活性的链霉菌HSW2009,其活性代谢产物为杀粉蝶菌素A1(piericidin A1,简称PIE);喷施PIE可以减轻Xoo在水稻叶片内的侵染;优化HSW2009高产PIE的发...