基于宏基因组的储粮害虫嗜卷书虱共生微生物多样性及功能分析

孤雌生殖的嗜卷书虱Liposcelis bostrychophila是储粮生态系统中易发害虫的优势种群之一,其共生微生物影响着嗜卷书虱L. bostrychophila的生物学特性。本文通过宏基因组测序技术和生物信息技术,分析了嗜卷书虱L. bostrychophila共生微生物的多样性及功能。结果表明：共鉴定出10门51属146种;变形菌门和厚壁菌门为菌群的优势门,平均相对丰度分别为90.05%和9.21%;立克次氏体属和葡萄球菌属为菌群的优势属,平均相对丰度分别为88.99%和9.03%。嗜卷书虱L. bostrychophila成虫体内微生物参与的碳水化合物代谢通路和复制与修复通路的丰度最高,平均相对丰度分别为9.0%和6.8%,表明嗜卷书虱L. bostrychophila体内共生微生物在宿主取食后协助碳水化合物的代谢,以及参与宿主部分DNA的复制和损失修复。本文系统揭示了嗜卷书虱L. bostrychophila共生微生物多样性及功能,以期能以共生微生物为切入点寻找储粮书虱的绿色防控提供有效途径。     

Effects of controlled atmosphere and DDVP on population growth and resistance development by the psocid, Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae)

The effects of controlled atmosphere (CA) and DDVP on population growth and resistance development by the psocid, Liposcelis bostrychophila Badonnel, were studied in the laboratory. Results indicated that the population of L. bostrychophila increased rapidly under natural conditions; after 11 weeks, this population had increased 48.1-fold at 28°C, 80% relative humidity (r.h.). Exposure to CA (35% CO₂, 1% O₂) or DDVP (Dichlorvos, 0.3 mg/ml) alone failed to control the population growth. After 11 weeks, populations increased 4.3- and 9.1-fold, respectively. However, alternating exposure to CA and DDVP provided a significant increase in mortality as compared to those exposed to CA or DDVP alone. The results of bioassay showed that both populations exposed to CA and DDVP developed a low but significant resistance to CA and DDVP, respectively. After six exposures, the level of resistance to CA and DDVP increased 1.8- and 2.0-fold, respectively. Probit analysis did not show an appreciable increase in slope value of either population in spite of continuous exposures, indicating considerable heterogeneity of these psocids in response to CA or DDVP and suggesting a greater potential for the development of higher levels of resistance. It is suggested that alternating CA with insecticides could be an important management measure for psocids in storage.     

Substrate selection by Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae): effects of insect extracts and biodeteriorated book-paper

A series of experiments was conducted to observe the selection by groups of booklice among substrates impregnated with extracts of booklice or between biodeteriorated book paper and paper free of apparent contamination. Sequential extracts of booklice were prepared from fresh and lyophilised samples in hexane and 80% methanol and applied to glass-fibre discs. At 10,000 ppm all extracts resulted in more insects on a control disc. Furthermore, all 1000 ppm extracts resulted in more insects on the blank discs, with the exception of a 1000 ppm 80% methanol extract of freeze-dried booklice. These data indicated that compounds extracted from booklice deter conspecifics. At lower concentrations (?100 ppm), exposure to extracts either resulted in significantly fewer non-selecting insects (100 ppm, freeze-dried hexane or methanol), equivalent to the distribution in control groups, or effectively even distribution between the blank and treated disc and the Petri dish. Short-term experiments, over 5 min, using the most repellent extract and concentration (80% methanol extract of fresh material, 10,000 ppm) indicated that insects from the culture are deterred from moving onto a treated disc rather than an untreated disc. Subsequent experiments using book paper showed that booklice were unable to select between three identically treated pieces of paper. However, exposure to biodeteriorated book-paper that had been incubated for 8 days (i8) as one of the three choices caused a significant reduction in the numbers of insects selecting un-incubated paper, sterilised paper or i8-paper: most insects remained in the dish. These data are discussed in relation to their significance in the habitats infested with populations of Liposcelis bostrychophila.     

Fungal isolates involved in biodeterioration of book-paper and their effects on substrate selection by Liposcelis bostrychophila (Badonnel) (Psocoptera: Liposcelididae)

The effects of fungi on the distribution of groups of Liposcelis bostrychophila were investigated. Two strains of Ulocladium botrytis were obtained from biodeteriorated book-paper and Eurotium amstelodami was isolated from the food used to culture L. bostrychophila. Isolated fungi were cultured on either paper sterilised with ethanol (paper) or on a malt-agar medium (medium). One strain or species was presented to groups of L. bostrychophila on a glass-fibre disc, with a blank disc as the other choice, and the number of insects on each disc and those free in the Petri dish was recorded after 12 h. In general a lower proportion of insects selected when one of the choices was either a 10,000 ppm extract of extract of U. botrytis cultured on malt-agar or one of the more dilute extracts of U. botrytis cultured on either medium. In contrast, extracts of both strains of U. botrytis (paper, 10,000 ppm) and E. amstelodami (malt-agar medium; 10,000; 1000 and 100 ppm) did not affect the proportion of insects that selected. With the exception of an extract of one of the strains of U. botrytis (paper; 10,000 ppm) significantly more selecting insects were found on the blank disc. A second set of experiments, in which extracts were applied to both discs, showed that L. bostrychophila did differentiate between the same fungus grown on paper or malt-agar medium and also between extracts of U. botrytis and E. amstelodami. It would appear that fungi grown on malt-agar medium are more repellent than fungi grown on paper and that E. amstelodami is preferred to U. botrytis. However, the selection of a substrate by L. bostrychophila very much depends on the context in which it is provided, i.e. the other choice.     

Comparative residual toxicities of carbaryl, deltamethrin and permethrin as structural treatments against three liposcelidid psocid species (Psocoptera: Liposcelididae) infesting stored commodities

Residual toxicities of carbaryl, deltamethrin and permethrin were evaluated as surface treatments on concrete (porous surface) and galvanized steel (non-porous surface) panels (0.3×0.3 m²) against adults of Liposcelis bostrychophila Badonnel, Liposcelis entomophila (Enderlein), and Liposcelis paeta Pearman. Residual toxicities of these chemicals were assessed at 30±1°C, 70±2% r.h., and a photoperiod of 12 : 12 h (L:D), one day after treatment (0 wk) and thereafter at wk 1, 2, 4, 6, 8, and then every 4 wk up to wk 40. Mortality was recorded after exposure periods of 6 h, and then every 24 h until end-point was achieved. Liposcelis bostrychophila was the most susceptible species to the three chemicals tested, followed by L. paeta, and L. entomophila. Deltamethrin on concrete and permethrin on steel were the most successful chemicals, whereas permethrin on concrete and carbaryl on steel were the least successful against all three species. We conclude that for long-term protection, none of the chemicals studied is suitable against any of the three psocid species on concrete storage surfaces. On steel surfaces, only permethrin would deliver long-term protection up to 40 wk against L. bostrychophila and L. paeta infestations. This chemical however, will fail to provide long-term control against infestations where L. entomophila is present.     

Influence of ambient temperature and relative humidity on changes in numbers of a natural population of Liposcelis entomophila (Enderlein) (Psocoptera: Liposcelididae)

Tobacco processing practices of humidifying rooms with mist and using steam to soften cured leaf, raise relative humidity (r.h.) and temperature in the rooms during February to March, creating conditions suitable for Liposcelis entomophila multiplication. High r.h. values and high temperatures in these buildings corresponded with the annual peak in booklice numbers. The number of booklice trapped in the period preceding the annual peak was found to be linearly related to cumulative degree-days calculated excluding days when r.h. and temperature were below 70% and 18 degrees C, respectively. Elevation of r.h. and temperature during processing also promotes fungal growth, making more food available for the booklice. It is suggested that L. entomophila numbers in tobacco processing buildings can be reduced by manipulating r.h. and temperature to levels below 70% and 18 degrees C, respectively.     

Residual toxicities and persistence of organophosphorus insecticides mixed with carbaryl as structural treatments against three liposcelidid psocid species (Psocoptera: Liposcelididae) infesting stored grain

Four organophosphorus insecticides, azamethiphos, fenitrothion, chlorpyrifos-methyl, and pirimiphos-methyl were each mixed with carbaryl and evaluated as structural treatments on concrete and galvanized steel panels (0.3×0.3 m) against adults of three liposcelidid psocids: Liposcelis bostrychophila Badonnel, L. entomophila (Enderlein), and L. paeta Pearman. Residual toxicities and persistence of these insecticide mixtures were assessed at 30±1°C, 70±2% r.h., and a photoperiod of 12:12(L:D) h from 1 day after treatment (0 week) and at weeks 1, 2, 4, 6, and 8, and then every 4 weeks up to week 40. Mortality was recorded at exposure periods of 6 h and then every 24 h until end-point was achieved. Significant enhancement in residual toxicities was observed in azamethiphos plus carbaryl against L. entomophila, and chlorpyrifos-methyl plus carbaryl and pirimiphos-methyl plus carbaryl against all three species on steel surfaces, compared with the individual effectiveness of these insecticides reported earlier. We conclude that combining carbaryl with either azamethiphos, chlorpyrifos-methyl, or pirimiphos-methyl as a structural treatment will provide long-term protection (up to 40 weeks) against infestation by all three psocid species on steel storage structures, whilst carbaryl with fenitrothion will give shorter protection (up to 8 weeks). On concrete structures, however, only azamethiphos plus carbaryl will provide long-term protection against L. bostrychophila (up to 28 weeks) and L. paeta (up to 16 weeks). None of the four insecticide mixtures studied would provide long-term protection against an L. entomophila infestation on concrete surfaces.     

我国胡麻育成品种的遗传多样性分析

为分析国内不同时期（1950-2010年）选育的96份胡麻品种遗传多样性,利用形态学标记和SRAP分子标记两种方法聚类,在欧氏距离5.77和遗传相似系数为0.69时都能将96份品种分为4个类群,但两种聚类结果在亚群的划分上存在差异,说明形态标记的基因型与SRAP标记检测出的位点相关性小。将96份胡麻品种的SRAP标记数据按品种不同育成年代和地区进行遗传多样性信息指数的计算发现,随着年代递进和育成品种增多,基因多样性增加,但随着品种选育目标越来越趋于一致,其遗传距离趋于相近,Shannon信息指数的增幅趋于平缓,对不同地区胡麻品种分析发现,Shannon指数的变化与品种数量有关,与地域的联系并不紧密,这与栽培种本身的广泛相互引种有关系。     

不同地域和寄主来源的核盘菌遗传多样性分析

为了解核盘菌[Sclerotinia sclerotiorum（Lib.）de Bary]遗传多样性和进化关系,利用SSR分子标记对采自不同地区和寄主来源的32个核盘菌分离物进行分析,17对SSR引物共检测到69个多态性位点,平均每对引物检测到4.06个位点。其中,引物AF377908-1/AF377908-2和AF377922-1/AF377922-2的等位变异数目最多,高达8个,而引物AF377903-1/AF377903-2和AF377925-1/AF377925-2的等位变异数目最少,为2个。17个SSR引物的多态性信息量（PIC）的平均值为0.56,引物AF377922-1/AF377922-2的PIC最高,为0.78。聚类分析显示,32个核盘菌分离物可划分为5个组群,来自同一地区的大部分核盘菌分离物聚在相同或相近的组内,表明核盘菌群体内的SSR遗传背景基本一致,而群体间的遗传变异较大。     

Population growth and development of the psocid Liposcelis obscura (Psocodea: Liposcelididae) at constant temperatures and relative humidities

The effects of nine temperatures (22.5, 25.0, 27.5, 30.0, 32.5, 35.0, 37.5, 40.0, and 42.5 °C) and four relative humidities (RHs; 43, 55, 63, and 75%) on the population growth and development of the parthenogenetic Liposcelis obscura Broadhead (Psocodea: Liposcelididae) were investigated in laboratory studies. Results showed that L. obscura did not survive at 43% RH at all temperatures tested. At 55% RH, L. obscura survived at 22.5, 25, and 27.5 °C; none survived at 42.5 °C and ≤63% RH. Population growth was highest at 40.0 °C and 75% RH, where population increase was 216-fold from an initial population of five adult females. Liposcelis obscura has three-to-five nymphal instars, and the percentages of individuals with three, four, and five instars were 52, 41, and 7%, respectively. Temperature-dependent developmental equations were developed for L. obscura eggs, individual nymphal, combined nymphal, and combined immature stages. Liposcelis obscura populations grew much faster at 30–42.5 °C and 75% RH. Based on the equation for total developmental time, the predicted optimal development temperature is 39.2 °C and development was completed in 14.0 d. The upper developmental threshold was estimated as 47.1 °C. The lower developmental threshold was estimated as 14.7 °C. These data provide a better understanding of L. obscura population dynamics and can be used to develop effective management strategies for this psocid.     

Morphological and molecular identification of Liposcelis corrodens (Heymons, 1909) (Psocodea: Liposcelididae) as the first record from China

Liposcelis corrodens (Psocodea: Liposcelididae) is recognized as one species of common stored product pests, however, it has not been reported in China. In this study, we identified Liposcelis specimens collected from a maize reserve depot in China as Liposcelis corrodens based on morphological and molecular methods. The identification of L. corrodens and keys to the stored Liposcelis species of Group IID were reported. The mitochondrial gene cytochrome c oxidase I (mtDNA COI) of the specimens was sequenced and used as a DNA barcode to conduct molecular identification and phylogenetic analyses with other Liposcelis species of Group IID from different geographical populations. This is the first record of L. corrodens in China and it will be useful for the further studies of taxonomy and management of stored booklice.     

Response of different population sizes to traps and effect of spinosad on the trap catch and progeny adult emergence in Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)

Tribolium castaneum is a major pest in stored products throughout the world. Male T. castaneum adults produce aggregation pheromone 4,8-dimethyldecanal (4,8 DMD) which is synthetically developed and available for monitoring T. castaneum populations but low trapping by 4,8 DMD is reported. Effects of biorational insecticides on orienting to pheromone and progeny production is shown but such tests using spinosad has areas for further discovery. Therefore the objective of this research was to determine the effect of population size and spinosad exposure on the trap catch and progeny production in T. castaneum adults. In the first experiment, T. castaneum adults were released at different population sizes and the attraction to the pheromone traps was determined. The second experiment tested attraction of T. castaneum adults pre-exposed to spinosad to the pheromone traps. In the third experiment, progeny production of T. castaneum adults exposed to spinosad was assessed. The trapping of T. castaneum is increased at high population sizes and pre-exposure to spinosad while progeny was reduced on exposure to spinosad showing sex-based effects. This study concludes with management opportunities for different population levels of T. castaneum through effects of spinosad on pheromone perception and progeny production.     

Damage potential of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) on cocoa beans: Effect of initial adult population density and post infestation storage time

The effect of different initial adult population densities of Tribolium castaneum (Herbst) at several post infestation storage times on the final adult population density, the percentage of damaged beans, the percentage of weight loss, and the weight of insect feeding residues on cocoa beans was investigated in laboratory experiments. Both factors interactively had highly significant (P < 0.01) effects on variables assessed. The highest mean final adult population density of 129.7 ± 4.6 was recorded in samples infested with the highest initial adult population density and stored for 150 d, while the least mean adult population density of 10.8 ± 0.54 was recorded on samples infested with the lowest initial adult population density in samples stored for 30 d. The highest percentage damaged cocoa beans 51.0 ± 1.21% was recorded in samples infested with the highest initial adult population density, while the least mean percentage damaged beans of 16.9 ± 1.26% was also recorded on samples infested with the lowest initial adult population density. Similar trends of means were recorded for all the remaining variables. Correlation between factors was significant and positive. Multiple and simple linear regressions analyses were also significant (P < 0.01) and all equations fitted the regression models and perfectly described the relationship between the independent and the dependent variables. Our results show that T. castaneum can impact negatively on both the quantity and quality of stored cocoa within just 30 days of infestation, with the impact increasing with increasing population density and post infestation storage time.     

添加营养物对椭圆食粉螨的种群增殖及体内营养物质的影响

椭圆食粉螨是仓储粮食和经济作物的重要害螨之一,也是储粮害虫天敌马六甲肉食螨规模扩繁的优势猎物,椭圆食粉螨高质量和规模化饲养是推动储粮害虫捕食螨防生防技术应用的保障。为了提高椭圆食粉螨扩繁效率,研究对椭圆食粉螨饲料进行优化,采用在麦麸中添加酵母粉、糖和氨基酸物质的方式,筛选出3种添加物组合的最优比例,在此条件下测定椭圆食粉螨体内营养成分含量变化,初步分析添加物对体内营养成分的影响。结果表明,啤酒酵母粉、绵白糖、L-缬氨酸3种添加物在饲料中分别作为单一因素,添加质量分数分别为15%、20%、1%时,椭圆食粉螨种群密度最大值增长倍数较大,分别为5.84、2.02和1.74倍。通过正交实验进行优化,筛选出3种添加物混合添加的最优组合,当添加质量分数为啤酒酵母粉15%、绵白糖17%、L-缬氨酸1%时,椭圆食粉螨种群增长最大。最优组合饲养条件下椭圆食粉螨体内营养成分含量显著提升,游离脂肪酸、可溶性糖和蛋白的增长幅度分别为652%、96%和71%。研究为提高椭圆食粉螨的饲养效率提供参考,服务于马六甲肉食螨规模化饲养,推动储粮害虫捕食螨天敌防控技术的应用。     

Effects of albusin B (a bacteriocin) of Ruminococcus albus 7 expressed by yeast on growth performance and intestinal absorption of broiler chickens--its potential role as an alternative to feed antibiotics

BACKGROUND: Bacteriocins with antimicrobial activity are considered as potential alternatives to antibiotics. The aim of this study was to investigate the effect of albusin B (bacteriocin) of Ruminococcus albus 7 expressed by yeast on the growth performance of broiler chickens. Ninety 1‐day‐old healthy broiler chickens were randomly divided into three groups: control, albusin B (2.5 g kg^?1) and nosiheptide (2.5 mg kg^?1, antibiotic control). Growth performance and intestinal functions were measured at 5 weeks of age. RESULTS: Albusin B‐supplemented broilers showed increased body weight gain compared with control broilers (54.7 ± 5.3 vs 48.5 ± 6.1 g day^?1 per bird, P < 0.05). Broilers supplemented with nosiheptide had a less developed mucosal layer than broilers in the other two groups. Compared with the control group, broilers supplemented with albusin B or nosiheptide showed increased mRNA expression of sGLT1, GLUT2 and PEPT1 in the jejunum (P < 0.05). The faecal Lactobacillus count was higher in the albusin B group than in the other two groups (P < 0.05). CONCLUSION: Albusin B supplementation increased intestinal absorption and elevated the faecal Lactobacillus count, thereby promoting the growth performance of broiler chickens. These improvements resulting from albusin B supplementation provide evidence of potential alternatives to antibiotics in broiler chicken feed. Copyright © 2011 Society of Chemical Industry