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Locusta migratoria tibetensis(Chen),a unique subspecies of migratory locust in Tibetan Plateau,has caused serious damage in recent years,and the study of its aggregation mechanism can be the basis for its ecological management.In this paper,we investigated the components of the fecal extract of this pest by gas chromatography-mass spectroscopy(GC-MS) and evaluated its bioactivity by a self-made "Y" olfactometer as well as electroantennograms.The results showed that the fecal extract bioactivities of different extract methods to solitary and gregarious fourth-instar nymphs differed,and that ethyl alcohol extraction was the best method for extracting fecal extracts of L.migratoria tibetensis.The bioactivity of fecal extracts increased with instars,and the gregarious adult locusts had the strongest bioactivity.The taxis ratio of solitary locusts to the fecal extracts of solitary and gregarious nymphs was more than that of gregarious locusts to the fecal extract of nymphs.In detail,we detected 35 components in the fecal extract of L.migratoria tibetensis by GC-MS,where we found that the main constituents were cyclohexanol,2,5-dimethyl pyrazine,2,6,6-trimethyl-2-cyclohexene-1,4-dione,nonanal,benzyl alcohol,(E)-3,7,11,15-tetramethyl-2-hexadedcen-1-ol,3-phenylbutan-2-ol,and 2,2′-methylenebis(6-tert-butyl-4-methylphenol).The components and their relative contents differed among the different developmental stages of fecal extracts.Adult female feces contained the most components,while that of solitary nymphs had the fewest.Some of the components of L.migratoria tibetensis were the same as the components of aggregation pheromone of Locusta magratoria manilemsis(Meyen).The electrophysiological responses of L.migratoria tibetensis to single artificially synthesized chemical compounds(concentration range 0—4 μL/mL) can be divided into three types.For the first type,the electrophysiological responses got the maximum value with the content of 2 μL/mL.For the second one,the electrophysiological responses to the same chemical compound differed among the developmental stages.And for the last type,the electrophysiological responses increased with the concentration of the compound.This paper reported the first study of the fecal extracts of L.migratoria tibetensis,however,further research is also needed to clarify the aggregation mechanism of this economically-important pest. more...

The principle of polarized 3D display is introduced.To deduce the principle of the parallax resulted from polarized 3D display by using Jones matrix,the most accurate retardation value is obtained finally.A kind of compensation film with the negative wavelength dispersion property is applied to the polarized 3D display.In this paper,there are two polarizers and two compensation films composited in the optical system to imitate the parallax pheno-menon made by polarized 3D display.The transmission of the test system can be measured by UV-2450,and the retardation value and the wavelength dispersion property of the compensation film can be measured by the RETS-100.With applying the compensation film with negative wavelength dispersion,the polarized 3D display will produce a better parallax so that there will be less or no demands on the watching pose,which makes more convenient for users as well as the good 3D display performance. more...

The delayed and irregular germination of Quercus seeds can negatively influence seedling quality and growth.The might be explained by several factores,including mechanical strength of the pericarp,secondary metabolites(e.g.tannins and polyphenols),plant hormones especially abscisic acid(ABA) and indoleacetic acid(IAA),and germination inhibitors.These chemicals produced in plants can prevent the seed germination of themselves or other species.The inhibitory substances in aqueous extracts of pericarp tissue which increased with acorn development have been found by Blanche.Moreover,the presence of inhibitory substances has also been confirmed in the pericarp of mature Quercus nigra acorns.However,the study on whether the germination inhibitors contained in different parts of oak acorns is still lacking.Acorns were divided into three parts: pericarp,cotyledon(cutting off 2/3 of the distal end of acorns) and embryo(here including embryo and 1/3 cotyledon around it).Then they were oven-dried(30°C),crushed and passed through 1-mm sieve.Subsequently,they were extracted in 80% methanol extracts and vacuum concentrated to 1 g/mL,some of which were diluted to 0.5 g/mL.In order to verify if the inhibitory substance in different parts of acorns can lead to delayed and uneven germination,germination percentage and root and shoot length of Beassica pekinensis seeds were investigated which cultivated in a Sanyo growth cabinet and watered by distilled water,80% methanol extracts and the extraction phase of methanol,of petroleum ether,of aether,of ethyl acetate,and of water from the acorn embryo,cotyledon and pericarp with concentrations of 1.0g and 0.5g dry acorn weight per ml methanol(g/mL).The results showed that(1) the germination percentage,shoot and root length of B.pekinensis seeds watered by 1.0 g/mL methanol extracts from embryo,cotyledon and pericarp of Q.variabilis,Q.aliena var.acuteserrata,Q.mongolica,Q.palustris and Q.acutissima seeds were significantly lower than those from control,and the inhibitory effect of germination rates gradually decreased,and 0.5 g/mL methanol extracts from embryo,cotyledon of Q.variabilis acorns reduced the germination percentage of B.pekinensis seeds,while no significant difference was detected in germination percentage of B.pekinensis seeds between those from pericarp of all tree species acorns and the control;(2) methanol extracts from embryo,cotyledon and pericarp of Q.robur and Q.×fangshanensis remarkably reduced shoot and root length of B.pekinensis seeds,but little response in germination percentage;(3) the inhibitory effect of Methanol extracts from embryo,cotyledon and pericarp declined in turn,with higher concentration of methanol extract having stronger inhibitory intension for each section of seeds;(4) the inhibitory strengthen of extraction phase of methanol among 5 extraction phases,was larger than that of extraction phase of ethyl acetate,resulting in the lowest germination rate,shoot or root length of B.pekinensis seeds,meanwhile,negative effects was observed in other extraction phases.The fact of extracted substances having stronger inhibitiory effect on the length of root and shoot than on the germination percentage of B.pekinensis,indicating that the inhibitors of oak seeds mainly restrict germination of root and shoot themselves,which could be the cause of the irregular germination. more...

Mechanisms of adaptation to environmental stress in the pest species Locusta migratoria tibetensis Chen were investigated with respect to the effects of temperature and ultraviolet(UV) radiation on its antioxidant system.The effects of low temperature(5—20 ℃),high temperatures(30—45 ℃),and UV radiation on the activities of antioxidant enzymes and on the malondialdehyde(MDA) content of L.migratoria tibetensis adults were measured.At low temperatures,decreasing from 20 ℃ to 5 ℃,the activities of superoxide dismutase(SOD),peroxidase(POD),and catalase(CAT),and the MDA contents of the adult integument and alimentary canal all increased.The activities of SOD,POD and CAT also increased at high temperatures,increasing from 30 ℃ to 35 ℃.However,all enzyme activities decreased significantly when the temperature exceeded 35 ℃.The effects of radiation were examined at three wavelengths,ultraviolet-A(UV-A),ultraviolet-B(UV-B),and visible light.POD and CAT activities increased progressively during increasing exposure to radiation at all three wavelengths(the magnitudes of the changes were in the order: UV-B treatment UV-A treatment visible light treatment).UV-A and UV-B produced greater changes in the SOD activity of adult locusts than did visible light,during 24h and 72h exposures.Both UV-A and UV-B radiation caused a marked increase in the MDA content of the body wall,indicating a time-dependent induction of lipid peroxidation.Maximal contents of MDA were 0.72 nmol/g FW in the female integument,0.88 nmol/g FW in the female alimentary canal,0.66 nmol/g FW in male integument and 0.94 nmol/g FW in the male alimentary canal after exposures of 72 h UV-B,72 h UV-A,72 h UV-A,and 72 h UV-B,respectively.Thus,adult L.migratoria tibetensis are able to endure low temperatures(5—20 ℃) by protecting themselves from damage by reactive oxygen species but are unable to endure temperatures exceeding 35 ℃,which disturb the insects′ antioxidant enzyme system.The increased activities of antioxidant enzymes of L.migratoria tibetensis under UV-A and UV-B stress represent important adaptations to the environment of the Qinghai-Tibet Plateau,which is characterized by intense ultraviolet irradiation. more...

Biological community structures have long been used to assess the impact of human activity on running waters.Compared to macroinvertebrates and fish community,periphyton community was infrequently used as indicator of stream conditions because of the large number of species and the need for taxonomic expertise.However,periphyton is valuable indicator of stream health because they are relative simple to collect and response rapidly and predictably to changes in stream chemistry and habitat quality.In the present work,we investigated the community structure of periphyton and characteristics of environmental factors among 69 sample sites in Taizi River Basin of Liaoning Province,Northeast China.Using the periphyton assemblages,we assessed stream conditions of Taizi River Basin based on Qualitative Habitat Evaluation Index(QHEI),Diatom Bioassessment Index(DBI) and Periphyton Index of Biological Integrity(P-IBI). The results indicated that the dominant species of periphyton in Taizi River Basin were Melosira varians,Diatoma vulgare,Cymbella tumida,C.hustedtii,Navicula cryptocephala,Gomphonema olivaceum,Achnanthes minutissima,Synedra acus,S.ulna,S.ulna oxyrhynchus,Nitzschia palea,Cocconeis placentula,Scenedesmus quadricauda,Oscillatoria tenuis and Phormidium tenus.There was great difference in the periphyton community structure in Taizi River Basin.Based on principal component analysis,conductivity,suspended solid,velocity,total dissolved solid,hardness,alkalinity,ammonia nitrogen,nitric acid nitrogen and total nitrogen were the main environmental factors in Taizi River Basin.Canonical correspondence analysis showed that conductivity,total dissolved solids and total nitrogen significantly influenced the community structure of periphyton in Taizi River Basin. The metrics of DBI were species richness,diversity index,tolerance index,sensitive species and similarity of community,and the metrics of QHEI were epifaunal substrate,embeddedness,velocity,sediment deposition,channel flow status,channel alteration,frequency of riffles,bank stability,vegetative protection and riparian vegetative zone width.The merits of P-IBI were filtered with box-plots analysis and correlation analysis,and the ultimate index merits of P-IBI were total genera of green algae,relative species richness of sensitive diatoms,relative richness of diatom taxons,relative richness of blue-green algae taxons,percent of Nitzschia,percent of Oscillatoria,percent of motile diatoms,percent of diatoms with handle,Chlorophyll a content of periphyton and cell density of periphyton. The results of stream condition assessment based on DBI,P-IBI and QHEI were in consensus in Taizi River Basin,although assessment results of some tributary were not in compatible.The results of stream condition assessment showed that upstream area of Taizi River Basin were in excellent ecological integrity,while,the downstream area of Taizi River Basin were in severe impairment.The results of correlation analysis showed that there were significant correlations among the scores of DBI,P-IBI and QHEI in sample sites of Taizi River Basin,and moreover,significant correlations were also detected between scores of DBI,P-IBI,QHEI and conductivity,total dissolved solid and total nitrogen.In the paper,we also discussed the relationship between periphyton community structure and environmental factors,and moreover,we evaluated the merit and deficiency of DBI,P-IBI and QHEI in the assessment of stream conditions of Taizi River Basin. more...