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Dehydration-responsive element-binding (DREB) transcription factors are important abiotic stress tolerance related genes, and some reports on the roles of DREB have primarily addressed herbal plants. To explore the abiotic stress tolerance role of DREB (ThDREB) from Tamarix hispida, a ThDREB gene with a complete ORF of 783 bp that encodes a 28.74 kDa protein with 260 amino acids, was isolated and functionally annotated. ThDREB expression was highly induced by NaCl, PEG, NaHCO3 and CdCl2 treatments, and the highest expression level (369.2-fold of control) was found for the roots that were under NaCl stress for 6 h. The tobacco plants that were transformed by ThDREB were conferred with higher germination rates, fresh weights and root lengths than the wild type (WT) tobacco plants under NaCl and mannitol treatments. The total chlorophyll content (tcc), superoxide dismutase (SOD) and peroxidase (POD) activities were also higher in the transgenic lines in comparison with the WT, and the malondialdehyde (MDA) and H2O2 content, electrolyte leakage (EL) rate and ROS as tracked by staining were generated to a lesser degree in ThDREB transgenic plants than in the WT under NaCl and mannitol stress. Furthermore, the transient overexpression analysis of ThDREB in T. hispida also improved plant salt and drought tolerance in comparison with the empty vector-transformed lines. Our results indicated that ThDREB expression could effectively improve tolerance to salt and drought stress by enhancing the antioxidase activity that keeps the ROS at a low accumulation level and makes them easy to scavenge.

Eukaryotic translation initiation factor 1A (eIF1A) functions as an mRNA scanner and AUG initiation codon locator. However, few studies have clarified the role of eIF1A in abiotic stress. In this study, we cloned eIF1A (TheIF1A) from Tamarix hispida and found its expression to be induced by NaCl and polyethylene glycol (PEG) in roots, stems, and leaves. Compared to control, TheIF1A root expression was increased 187.63-fold when exposed to NaCl for 6 h, suggesting a potential abiotic stress response for this gene. Furthermore, transgenic tobacco plants overexpressing TheIF1A exhibited enhanced seed germination and a higher total chlorophyll content under salt and mannitol stresses. Increased superoxide dismutase, peroxidase, glutathione transferase and glutathione peroxidase activities, as well as decreased electrolyte leakage rates and malondialdehyde contents, were observed in TheIF1A-transgenic tobacco and T. hispida seedlings under salt and mannitol stresses. Histochemical staining suggested that TheIF1A improves reactive oxygen species (ROS) scavenging in plants. Moreover, TheIF1A may regulate expression of stress-related genes, including TOBLTP, GST, MnSOD, NtMPK9, poxN1, and CDPK15. Moreover, a 1352-bp promoter fragment of TheIF1A was isolated, and cis-elements were identified. Yeast one-hybrid assays showed that ThDof can specifically bind to the Dof motif present in the promoter. In addition, ThDof showed expression patterns similar to those of TheIF1A under NaCl and PEG stresses. These findings suggest the potential mechanism and physiological roles of TheIF1A. ThDof may be an upstream regulator of TheIF1A, and TheIF1A may function as a stress response regulator to improve plant salt and osmotic stress tolerance via regulation of associated enzymes and ROS scavenging, thereby reducing cell damage under stress conditions.

The ethylene response factor (ERF) genes are a subfamily of transcription factors containing a single AP2/ERF domain, which play crucial roles in plant development and response to biotic and abiotic stresses. In the present study, 16 ERF genes (named ThERF1–ThERF16) were isolated from Tamarix hispida, and their expression in response to salt, drought and ABA treatment was investigated using real-time RT-PCR. The results showed that all 16 ERFs are expressed in root, stem and leaf tissues, but the individual transcript levels vary strongly in roots, stem or leaves. Among these ThERFs, ThERF1 is the most abundant in roots, stems and leaves, indicating that it may play a more important physiological role than the other ThERF genes. The 16 ThERF genes are all highly differentially expressed in leaves, stems or roots under salt and drought stress, demonstrating that they are involved in the salt and drought stress responses. Under ABA treatment, expression of the ThERF genes was mainly down-regulated in roots, but induced in leaves or stems, suggesting that they are also involved in the ABA stress response. These results strongly suggest that ThERFs are abiotic stress response genes that may play important roles in the stress tolerance of T. hispida.

Root tissue is the primary site of perception for stress from soil, and is the main tissue involved in stress response. Tamarix hispida is a woody halophyte that is highly tolerant to salt and drought stress, but little information available about gene expression in roots in response to abiotic stress. In this study, eight transcriptomes from roots of T. hispida treated with NaHCO3 for 0, 12, 24 and 48 h (two biological replicates were set at each time point) were built. In total, 47,324 unigenes were generated, and 6,267 differentially expressed genes (DEGs) were identified. There were 2,510, 3,690, and 2,636 genes significantly differentially expressed after stress for 12, 24 and 48 h, respectively. Co-expressed DEGs were clustered into ten classes (P

Basic helix-loop-helix (bHLH) transcription factors (TF) comprise a large group of proteins that are involved in many developmental and physiological processes in plants. In this study, a bHLH gene (PkbHLH2), along with its promoter, was cloned from Populus koreana Rehd. A PkbHLH2 promoter::GUS gene fusion construct was generated to investigate the expression of PkbHLH2. The results demonstrated that PkbHLH2 was expressed mainly in leaf stalks, leaf veins and roots. Yeast one-hybrid assays showed that a bZIP gene product (PkbZIP2) can bind specifically to the ABA-responsive elements (ABRE) that exist in the promoter region of PkbHLH2, regulating the expression of PkbHLH2. In addition, the “GC” of the ABRE core motif “ACGTG” was very important for PkbZIP2 recognition, because its mutation to “TT” completely prevented the interaction between PkbZIP2 and ABRE. Furthermore, both PkbHLH2 and PkbZIP2 can be up-regulated by abscisic acid (ABA) and osmotic stress, and share similar expression patterns when exposed to ABA and osmotic stress. These results suggest that PkbZIP2 is an upstream regulator of PkbHLH2, which can control the expression of PkbHLH2 through an ABA-dependent signaling pathway.

All plant shoot tips contain apical meristems, an area that differentiates into multiple cell and tissue types and is critical to the development of the above ground plant body. To study the development of birch (Betula platyphylla Suk.), we constructed a transcriptome from the young shoot tips of birch by using the Solexa method. In total, 40,780 tentative unique genes (TUGs) were generated. Among these, 29,939 genes showed significant (>1E5) sequence similarity with proteins in the NR-database. Gene ontology (GO) classification suggested that 6,945 TUGs were categorized as involved in biological processes, 10,639 TUGs were grouped into encoding cellular components, and 6,159 TUGs were assigned to roles involving molecular function group. Our results showed that the GO subgroup of genes involved in binding and those involved in metabolic processes are most abundant in terms of molecular functions and biological processes, respectively. Furthermore, the most abundant genes in the transcriptome are β-N-acetylhexosaminidase, ribosomal protein L44, thioredoxin H, light-harvesting complex I protein, S-adenosylmethionine decarboxylase, NADP-dependent glyceraldehyde-3-phosphate dehydrogenase, and tonoplast proton pump. The expression profiles of some abundant genes were studied during a 1-year growth period using real-time RT-PCR. The results showed that their expression altered significantly during the growth stages, suggesting that they play active roles in shoot development.

It is well known that plant heat shock proteins (HSPs) play important roles both in response to adverse environmental conditions and in various developmental processes. However, among plant HSPs, the functions of tree plant HSPs are poorly characterized. To improve our understanding of tree HSPs, we cloned and characterized an HSP gene (ThHSP18.3) from Tamarix hispida. Sequence alignment reveals that ThHSP18.3 belongs to the class I small heat shock protein family. A transient expression assay showed that ThHSP18.3 protein was targeted to the cell nucleus. Treatment of Tamarix hispida with cold and heat shock highly induced ThHSP18.3 expression in all studied leaves, roots and stems, whereas, treatment of T. hispida with NaCl, NaHCO(3), and PEG induced ThHSP18.3 expression in leaves and decreased its expression in roots and stems. Further, to study the role of ThHSP18.3 in stress tolerance under different stress conditions, we cloned ThHSP18.3 into the pYES2 vector, transformed and expressed the vector in yeast Saccharomyces cerevisiae. Yeast cells transformed with an empty pYES2 vector were employed as a control. Compared to the control, yeast cells expressing ThHSP18.3 showed greater tolerance to salt, drought, heavy metals, and both low and high temperatures, indicating that ThHSP18.3 confers tolerance to these stress conditions. These results suggested that ThHSP18.3 is involved in tolerance to a variety of stress conditions in T. hispida.

In this study, the additive effects of a late embryogenesis abundant (LEA) gene and a basic leucine zipper (bZIP) gene on salt and osmotic stress in Tamarix plants were analyzed. The constructs containing one or both of the LEA and bZIP genes were transformed into tobacco. Northern blot analysis showed the genes were overexpressed under the control of the CaMV 35S promoter in both dual and single gene-transgenic tobacco lines. The effects of salt and osmotic stress in transgenic tobacco plant were investigated. Following exposure to NaCl, mannitol, and PEG6000 stress, dual gene-transgenic lines showed higher seed generation and growth rates than single gene-transgenic lines and the wild-type. In response to NaCl stress, the dual gene-transgenic lines showed lower malondialdehyde and higher leaf chlorophyll content than single gene-transgenic lines and the wild-type. These results suggested that the co-expression of LEA and bZIP resulted in an additive enhancement of stress tolerance in dual gene-transgenic tobacco.

H+-ATPase subunit c (VHA-c) is involved in the adaptation to environmental stresses, including salt, drought, and heavy metals. However, it remains unclear whether VHA-c can induce a physiological response related to stress tolerance. To investigate this possibility, we generated transgenic tobacco lines overexpressing a V-ATPase subunit c (LbVHA-c1) gene from Limonium bicolor (Bunge) Kuntze. Compared with wild-type (WT) tobacco, superoxide dismutase (SOD) and peroxidase (POD) activities in the transgenic plants were significantly enhanced under salt stress conditions. The level of malondialdehyde (MDA) in the transgenic plants was significantly lower than that in WT plants grown under salt stress conditions. Moreover, the transgenic plants displayed obviously better growth than the WT plants under salt stress. These results suggest that LbVHA-c1 may confer stress tolerance through enhancing POD and SOD activities, and by protecting membranes from damage by decreasing lipid peroxidation under salt stress.

Plant peroxidases (PODs) have been ascribed a variety of biological functions, including hydrogen peroxide detoxification, lignin biosynthesis, hormonal signaling, and stress response. In the present study, ten POD genes, including three ascorbate peroxidases (class I PODs) and seven secretory peroxidases (class III PODs), were cloned from Tamarix hispida. The roles of the ten POD genes were addressed under different abiotic stress conditions, and gene expression profiles in roots, stems, and leaves were evaluated using real-time quantitative reverse-transcribed polymerase chain reaction. Our results showed that the relative abundance of the PODs was markedly different in roots, stems, and leaves, indicating that POD activity differs in these three organs. ThPOD1 and ThPOD8 were the most and least abundant, respectively, in all organs. The expression profiles in response to abiotic stresses were organ specific. All of the genes were highly induced by drought, salt, salt–alkaline, CdCl2, and abscisic acid (ABA) treatments in at least one organ. Five ThPOD genes were induced in roots, stems, and leaves under all of the studied stress conditions, indicating that they are closely associated with abiotic stress. Our results demonstrate that the ten plant peroxidases are all expressed in leaves, stems, and roots, that they are involved in different abiotic stress responses, and that they are controlled by an ABA-dependent stress signaling pathway.

Tamarix hispida, a woody halophyte, thrives in saline and saline-alkali soil. To better understand the gene expression profiles that manifest in response to saline-alkali stress, three cDNA libraries were constructed from leaf tissue of T. hispida plants that were well watered and exposed to NaHCO3 for 24 and 52 h. A total of 9,447 high quality expressed sequence tags (ESTs) were obtained from the three libraries. These ESTs represent 3,945 unigenes, including 986 contigs and 2,959 singlets. The numbers of unigenes obtained from the three libraries were 1,752, 1,558 and 1,675, respectively. The EST analysis was performed to compare gene expression in the three cDNA libraries; the transcripts responsive to NaHCO3 were identified. The differentially expressed transcripts were identified. The up-regulation genes were involved in a variety function areas, such as stress-related proteins, hormone signaling transduction, antioxidative response, transcriptional regulators, protein synthesis and destination, ion homeostasis, photosynthesis and metabolism. The results indicated that the response to NaHCO3 in T. hispida is a complex one, involving multiple physiological and metabolic pathways. Nine gene expression patterns were compared in response to NaHCO3 and NaCl using real time reverse transcription-polymerase chain reaction (RT-PCR). Gene expression trends were similar after a 24-h exposure to either NaCl or NaHCO3, however, great variability was found after a 52-h exposure, indicating that short-term responses to either salt may not be obviously different.

Twelve embryogenesis abundant protein (LEA) genes (namedThLEA-1 to -12) were cloned fromTamarix hispida. The expression profiles of these genes in response to NaCl, PEG, and abscisic acid (ABA) in roots, stems, and leaves ofT. hispidawere assessed using real-time reverse transcriptase-polymerase chain reaction (RT-PCR). TheseThLEAsall showed tissue-specific expression patterns in roots, stems, and leaves under normal growth conditions. However, they shared a high similar expression patterns in the roots, stems, and leaves when exposed to NaCl and PEG stress. Furthermore,ThLEA-1, -2, -3, -4, and-11were induced by NaCl and PEG, butThLEA-5, -6, -8, -10, and-12were downregulated by salt and drought stresses. Under ABA treatment, someThLEAgenes, such asThLEA-1, -2, and-3, were only slightly differentially expressed in roots, stems, and leaves, indicating that they may be involved in the ABA-independent signaling pathway. These findings provide a basis for the elucidation of the function ofLEAgenes in future work.

Late embryogenesis abundant (LEA) genes were confirmed to confer resistance to drought and water deficiency. An LEA gene from Tamarix androssowii (named TaLEA) was transformed into Xiaohei poplar ( Populus simonii × P. nigra) via Agrobacterium . Twenty-five independent transgenic lines were obtained that were resistant to kanamycin, and 11 transgenic lines were randomly selected for further analysis. The polymerase chain reaction (PCR) and ribonucleic acid (RNA) gel blot indicated that the TaLEA gene had been integrated into the poplar genome. The height growth rate, malondialdehyde (MDA) content, relative electrolyte leakage and damages due to salt or drought to transgenic and non-transgenic plants were compared under salt and drought stress conditions. The results showed that the constitutive expression of the TaLEA gene in transgenic poplars could induce an increase in height growth rate and a decrease in number and severity of wilted leaves under the salt and drought stresses. The MDA content and relative electrolyte leakage in transgenic lines under salt and drought stresses were significantly lower compared to those in non-transgenic plants, indicating that the TaLEA gene may enhance salt and drought tolerance by protecting cell membranes from damage. Moreover, amongst the lines analyzed for stress tolerance, the transgenic line 11 (T11) showed the highest tolerance levels under both salinity and drought stress conditions. These results indicated that the TaLEA gene could be a salt and drought tolerance candidate gene and could confer a broad spectrum of tolerance under abiotic stresses in poplars.

In this study, the function of a LEA gene (TaLEA1) from Tamrix androssowii in response to heavy metal stress was characterized. Time-course expression analyses showed that NaCl, ZnCl(2), CuSO(4), and CdCl(2) considerably increased the expression levels of the TaLEA1 gene, thereby suggesting that this gene plays a role in the responses to these test stressors. To analyze the heavy metal stress-tolerance mechanism regulated by TaLEA1, TaLEA1-overexpressing transgenic poplar plants (Populus davidiana Dode × P. bollena Lauche) were generated. Significant differences were not observed between the proline content of the transgenic and wild-type (WT) plants before and after CdCl(2) stress. However, in comparison with the WT plants, the TaLEA1-transformed poplar plants had significantly higher superoxide dismutase (SOD) and peroxidase (POD) activities, and lower malondialdehyde (MDA) levels under CdCl(2) stress. Further, the transgenic plants showed better growth than the WT plants did, indicating that TaLEA1 provides tolerance to cadmium stress. These results suggest that TaLEA1 confers tolerance to cadmium stress by enhancing reactive oxygen species (ROS)-scavenging ability and decreasing lipid peroxidation. Subcellular-localization analysis showed that the TaLEA1 protein was distributed in the cytoplasm and nucleus.

Peroxiredoxins (Prxs) are a recently discovered family of antioxidant enzymes that catalyze the reduction of peroxides and alkyl peroxides. In this study, four Prx genes (named as ThPrxII, ThPrxIIE, ThPrxIIF, and Th2CysPrx) were cloned from Tamarix hispida. Their expression profiles in response to stimulus of NaCl, NaHCO(3), PEG, CdCl(2) and abscisic acid (ABA) in roots, stems and leaves of T. hispida were investigated using real-time RT-PCR. The results showed that the four ThPrxs were all expressed in roots, stems and leaves. Furthermore, the transcript levels of ThPrxIIE and ThPrxII were the lowest and the highest, respectively, in all tissue types. All the ThPrx genes were induced by both NaCl and NaHCO(3) and reached their highest expression levels at the onset of stress in roots. Under PEG and CdCl(2) stress, the expression patterns of these ThPrxs showed temporal and spatial specificity. The expressions of the ThPrxs were all differentially regulated by ABA, indicating that they are all involved in the ABA signaling pathway. These findings reveal a complex regulation of Prxs that is dependent on the type of Prx, tissue, and the signaling molecule. The divergence of the stress-dependent transcriptional regulation of the ThPrx gene family in T. hispida may provide an essential basis for the elucidation of Prx function in future work.

Plant vacuolar H(+)-ATPase (V-ATPase) plays an important role in response to different adverse environmental conditions. In the present study, we cloned and characterized a V-ATPase c subunit gene (ThVHAc1) from Tamarix hispida. The deduced ThVHAc1 amino acid sequence lacks a signal peptide and ThVHAc1 is a highly hydrophobic protein with four transmembrane regions. A transient expression assay showed that the ThVHAc1-GFP fusion protein is expressed on onion epidermal endomembrane cells. Real-time RT-PCR demonstrated that ThVHAc1 gene expression was induced by NaCl, NaHCO(3), PEG and CdCl(2) stress in T. hispida roots, stems and leaves. Exogenous application of abscisic acid (ABA) also stimulated ThVHAc1 transcript levels in the absence of stress, suggesting that ThVHAc1 is involved in ABA-dependent stress signaling pathway. Furthermore, the transgenic yeast expressing ThVHAc1 increased salt, drought, ultraviolet (UV), oxidative, heavy metal, cold and high temperature tolerance. Our results suggested that the ThVHAc1 gene from T. hispida serves a stress tolerance role in the species.

Plant lipid transfer proteins (LTPs) are ubiquitous lipid-binding proteins that are involved in various stress responses. In this study, we cloned 14 unique LTP genes (ThLTP 1-14) from Tamarix hispida Willd. (Tamaricaceae) to investigate their roles under various abiotic stress conditions. The expression profiles of the 14 ThLTPs in response to NaCl, polyethylene glycol (PEG), NaHCO(3), CdCl(2) and abscisic acid (ABA) exposure in root, stem and leaf tissues were investigated using real-time RT-PCR. The results showed that all 14 ThLTPs were expressed in root, stem and leaf tissues under normal growth conditions. However, under normal growth conditions, ThLTP abundance varied in each organ, with expression differences of 9000-fold in leaves, 540-fold in stems and 3700-fold in roots. These results indicated that activity and/or physiological importance of these ThLTPs are quite different. Differential expression of the 14 ThLTPs was observed (> 2-fold) for NaCl, PEG, NaHCO(3) and CdCl(2) in at least one tissue indicating that they were all involved in abiotic stress responses. All ThLTP genes were highly induced (> 2-fold) under ABA treatment in roots, stems and/or leaves, and particularly in roots, suggesting that ABA-dependent signaling pathways regulated ThLTPs. We hypothesize that ThLTP expression constitutes an adaptive response to abiotic stresses in T. hispida and plays an important role in abiotic stress tolerance.

Basic leucine zipper proteins (bZIPs) are transcription factors that bind abscisic acid (ABA)-responsive elements (ABREs) and enable plants to withstand adverse environmental conditions. In the present study, a novel bZIP gene, ThbZIP1 was cloned from Tamarix hispida. Expression studies in T. hispida showed differential regulation of ThbZIP1 in response to treatment with NaCl, polyethylene glycol (PEG) 6000, NaHCO3, and CdCl2, suggesting that ThbZIP1 is involved in abiotic stress responses. To identify the physiological responses mediated by ThbZIP1, transgenic tobacco plants overexpressing exogenous ThbZIP1 were generated. Various physiological parameters related to salt stress were measured and compared between transgenic and wild type (WT) plants. Our results indicate that overexpression of ThbZIP1 can enhance the activity of both peroxidase (POD) and superoxide dismutase (SOD), and increase the content of soluble sugars and soluble proteins under salt stress conditions. These results suggest that ThbZIP1 contributes to salt tolerance by mediating signaling through multiple physiological pathways. Furthermore, ThbZIP1 confers stress tolerance to plants by enhancing reactive oxygen species (ROS) scavenging, facilitating the accumulation of compatible osmolytes, and inducing and/or enhancing the biosynthesis of soluble proteins.

Plant roots are the primary site of perception and injury for salinity stress. In order to characterize the complexity of adaptation to salty environments in roots of Tamarix hispida, a woody halophyte, expressed sequence tag (EST) analysis was performed. Three cDNA libraries were generated from root tissues of T. hispida that were exposed to 0.4 M NaCl for 0 (control), 24 and 48 h. A total of 7726 ESTs were generated from the three libraries, and were assembled into 1142 contigs and 3026 singletons. EST analysis was performed to compare gene expression in the three cDNA libraries. Ninety redundant unique transcripts responsive to NaCl treatment were identified. Of them, 21 genes were novel or of unknown function while others were involved in the functional activities, such as ROS scavenging, lipid metabolism, osmolyte biosynthesis, signal transduction, transport, lignin synthesis and homeostasis. The genes, including those for metallothionein-like protein, polyubiquitin, hypothetical protein, and glycine-rich cell wall structural protein, were abundant in the libraries and showed obvious up-regulation after NaCl treatments, suggesting important roles in NaCl tolerance. The results of this study may contribute to our understanding of the molecular mechanism of salt tolerance in the roots of plants.

With the principles and methodologies of geostatistics, this paper studied the spatial structure and space dependence of Contarinia sp. and its natural enemy Erigonidium graminicola in a jujube orchard at different date. The results indicated that the semivariogram of Contarinia sp. on 8 June, 27 August and 19 October could be described by spherical model, showing an aggregated spatial distribution with the ranges of spatial dependence being 26.3, 7.8 and 22.0 m, and the degrees of spatial dependence being 88.05%, 85.77% and 87.58%, respectively. The semivariogram of Erigonidium graminicola could be also described by spherical model, showing an aggregated distribution with the ranges of spatial dependence being 28.3, 22.5 and 22.2 m, and the degrees of spatial dependence being 90.09%, 87.96% and 85.72%, respectively. It is suggested that Erigonidium graminicola is the dominant natural enemy against Contarinia sp. population in the examined jujube orchard.

Based on the principles of community ecology and by the method of fuzzy clustering, this paper studied the temporal and quantitative dynamics of the arthropod community and sub-community in jujube orchard (Feidong 2003), aimed to utilize natural enemy resources for pest control. There were 52 species of arthropod belonging to 47 families in the orchard. Arachnida and Cecidomyidae had a higher relative abundance than other families being 0.3465 and 0.2309, respectively. The individuals of the arthropod community were the highest on 8 June and 21 September. The total community and pests-neutral insect sub-community could be clustered into 4 clusters, respectively. For total community, the clusters (T = 0.92) were those on 22 March, 6 April, 22 November, and on other dates, and for pests-neutral insect sub-community, they (T = 0.94) were those on 22 March, 6 April, 8 June, and on other dates. The natural enemy sub-community could be clustered into 3 clusters (T = 0.94), i. e., those on 22 March, on 6 April, and on other dates. The results of cluster analysis partly reflected the seasonal differences of total community and sub-community, while the temporal overlaps of cluster results reflected the complexity of community structure.

Investigations on the spatial construction and distribution of Myzus persicae and Erigonidium graminicola in a plum orchard were conducted from March 2003 to November 2003. The results indicated that the semivariogram of Myzus persicae could be described by spherical model, except on June 27 and November 22, which should be described by lined model, and that of Erigonidium graminicola could be described by spherical model, except on May 21, May 31, October 19 and November 22, which should be described by lined model. It could be concluded that the amount and spatial distribution of Erigonidium graminicola was closely related to those of Myzus persicae.

In this paper, twelve investigations were conducted on the structural feature of arthropod community in a plum orchard, and a cluster analysis was made on the temporal dynamics of the community. The total community could be clustered into 5 clusters (D = 0.2000), i.e., that in March, in June, in July, in November, and in other months. The natural enemy and pest-neutral sub-communities could be also clustered into 5 clusters, respectively. For natural enemy sub-community, the clusters (D = 0.2000) were that in March, in July, in August, in September and October, and in other months, and for pest-neutral sub-community, they (D = 0.1000) were that in April, in July, in June, in November, and in other months. The results of cluster analysis partly reflected the seasonal differences of total community and sub-communities, while the temporal overlaps of cluster results reflected the complexity of community structure. Based on the optimization cut-apart, both the total community and the sub-communities were divided into 5 stages, i.e., 6 April as the first stage, 27 April to 8 June as the second stage, 27 June to 27 August as the third stage, 21 September to 19 October as the forth stage, and 22 November as the fifth stage.

In this paper, the relevancy of Aphis gossypii with its natural enemies was studied by using grey systematic analysis. The results showed that the major natural enemies of Aphis gossypii were Tetragnathidae (0.8607), Therdion octomaculatum (0.8058), Therdion octomaculatum (0.7989), Haramonia aiyridis (0.7881) and Chrysopa sepetempunctata (0.7758). As for the daily total predation, the natural enemies which highly associated with the ideal dominant natural enemies were Erigonidium graminicola (0.8975), Tromobidiidae (0.8132), Propylacea japonica (0.7806) and Chrysopa sepetempunctata (0.7669); while for the quantity, Erigonidium graminicola (0.8482), Chrysopa sinica (0.7533), Tetragnathidae (0.7532), Therdion octomaculatum (0.7411) and Chrysopa sepetempunctata (0.7716) were the major natural enemies. According to the relational grade of the individuals between various natural enemies and ideal dominant natural enemies, the major natural enemies were Erigonidium graminicola (0.8461), Tromobidiidae (0.7325), Propylacea japonica (0.6983), Chrysopa sepetempunctata (0.6815) and Chrysopa sinica (0.6757). The species having0.9567 horizontal and vertical niche overlaps with Aphis gossyppii were Erigonidium graminicola, Chrysopa sepetempunctata and Tetragnathidae, while the temporal niche overlaps between Erigonidium graminicola, Chrysopa sepetempunctata, tetragnathidae and Aphis gossyppii were0.4020. It could be concluded that the main natural enemies of Aphis gossyppii were Erigonidium graminicola, Chrysopa sepetempunctata and Tetragnathidae.

Based on the principles of community ecology and by the method of fuzzy clustering, this paper studied the temporal and quantitative dynamics of the arthropod community and sub-community in megranate orchard, aimed to utilize natural enemy resources for pests control. The results showed that both of total community and natural enemy sub-community could be grouped into 4 clusters, and non-natural enemy sub-community could be grouped into 3 clusters. This clustering reflected the complexity of the community structure. The optimal cut-apart could divide the total community and sub-community into 3 stages, i. e., April-August, September-October, and November.

This study showed that the diversity index of total arthropod community in peach orchards was significantly correlated to the diversity index of both phytophages (r = 0.9480) and predators sub-communities (r = 0.7855), and the two sub-communities were correlative (r = 0.6741). It was also significantly correlated to the evenness index of total community (r = 0.7870), but not correlated to the evenness index of both sub-communities. The diversity index (H') of total community was significantly correlated to the ratio of predators individuals (Sd) and phytophages individuals (Sz) (r = 0.8112) and of species (Ss) and individuals (Si) (r = 0.9188), but not correlated to the ratio of predators (Spl) and phytophages (Szl).

The spatial structure and spatial correlativity of Aphis gossypii and Erigonidium graminicola populations during different periods were investigated by geostatistic methods. The results showed that the semivariogram of A. gossypii appeared as spherical type, indicating its spatial pattern was an aggregated type with a range of 7.33-12.40 cm, while that of E. graminicola was also fitted into spherical model, indicating an aggregated spatial arrangement with a range of 6.47-20.88 cm. The amount and spatial distribution of E. graminicola were closely related to those of A. gossypii, suggesting that E. graminicola was the dominant natural enemy influencing A. gossypii population.

Investigations on the Erythroneura sudra and Erigonidum graminicola populations in three layers (upper, middle and lower) and four directions (east, south, west and north) of peach tree crown showed that both of them had aggregated spatial distributions in these 7 part, because 5 parameters used to analyze the distribution reached required standard. Each insect was attracted by the others, as the parameter (alpha) in Iwao formulation m* = alpha + beta x - (1971) was positive. The average density of aggregation was the biggest in its middle layer and east direction, and the smallest in its lower layer and south direction. The biggest average density of aggregation appeared in mid-September.

Investigations on structure of arthropod community in peach gardon were conducted with the principal component analysis, the optimal sorting method and fuzzy clustering analysis. The results showed that more obvious main factors and temporal patterns exist in the community. Dealing with the population dynamics of 55 species of arthropods by fuzzy clustering analysis and taking lambda = 0.47, we divided the community into four stages. The number of pests and their natural enemies was divided into three parts by the optimal sorting method. The dominant species of pests and their natural enemies were demonstrated by the principal component analysis.

The spatial construction and distribution of Erythroneura sudra and Erigonidum gramimicola at different periods were investigated with geostatisics. The results showed that the semivariogram of Erythroneura sudra was described by spherical model, indicating an aggregated spatial arrangement. The range was 25.71-37.14 m. The semivariograms of Erigonidum graminicola was fitted by spherical model too, also indicating an aggregated spatial arrangement, and its range was 25.12-44.06 m. The amount and spatial distribution of Erigonidium graminicola was closely related to that of Erythroneura sudra. It reveals that Erigonidium graminicola is the dominant natural enemies influencing the population of Erythroneura sudra.