Abstract:草地贪夜蛾Spodoptera frugiperda是世界十大害虫之一，其入侵和为害对我国的农业生产构成了重大的威胁。草地贪夜蛾寄主范围广，对多种化学药剂和转Bt玉米产生抗性，随着抗药性及农药安全问题的加剧，迫切需要新型防治方法。本文对昆虫种群遗传调控技术，如性连锁平衡致死系统、构建杂交不育平衡致死品系，以及干扰昆虫生殖特性的方法，如控制昆虫性别、干扰昆虫生长发育的关键基因、调整性信息素比例等进行了综述。基于草地贪夜蛾玉米型和水稻型2个品系的杂种不育和交配障碍等生殖隔离现象，探讨了种群遗传调控和生殖特性干扰在草地贪夜蛾防控中的应用前景。以昆虫生殖为切入点，为昆虫不育技术在草地贪夜蛾上的应用提供理论依据。

Abstract:Objective To reveal possible genetic variation among Spodoptera frugiperda populations in three provinces of central and southern China, trace the invasion source and spread pathway of S. frugiperd , and provide the theoretical basis and genetic information for effectively controlling this insect.Method The samples of S. frugiperda were collected from Guangdong, Guangxi and Hunan of China. Haplotype analysis was carried out using CO I and Tpi gene markers. Nine microsatellite (SSR) markers were used to analyze the genetic diversity and genetic structure of S. frugiperda populations. Results Expect that two samples of S. frugiperda populations from Zhangjiajie of Hunan were characterized to be CO I corn strain and one sample to be hybrid strain, other samples were CO I rice train. The results of SSR markers showed that lower genetic diversity was detected for each population compared with those in South America populations, and the genetic differentiation across populations was no significant. However, the genetic distance was the nearest between Guangdong Dongguan population and Hunan Zhangjiajie population, and the farthest between Guangdong Dongguan population and Guangxi Nanning population.Conclusion There is no significant relationship between genetic distance and geographic distance. The genetic structure analysis helps to speculate on the role of weather background field, geographical isolation and human transmission in the process of S. frugiperda spread. S. frugiperda invading in central-south China might be original from multiple locations. The short time of S. frugiperda colonization in the invasive lands leads to the low genetic diversity. No obvious genetic differentiation has formed at present.

Abstract:Objective Different molecular markers were used to identify the host types of Spodoptera frugiperda which invaded Guangzhou, in order to monitor the diffusion of insect sources and to offer forecasting and early warning of insect conditions.Method The host types of S. frugiperda collected from maize plants in Guangzhou were identified using three COI gene markers (COI-A, COI-B and COI-C) and the Tpi gene marker. The identification results were compared. Result Based on sequence alignment and haplotype analysis, S. frugiperda samples invading Guangzhou were identified as the "rice strain" using COI-A,COI-B and COI-C markers. A sample was identified to be the hybrid of S. frugiperda and Mythimna separate using COI-A marker. S. frugiperda samples invading Guangzhou were identified as the "corn strain" using the Tpi gene marker, and the 126th and 127th bp were GA/AT heterozygous.Conclusion The COI-A marker has relatively strong ability of species identification as it can identify the hybridization events between S. frugiperda and other close related species. Tpi marker can be used to identify host types of S. frugiperda. Combining the two markers will improve the identification accuracy. The development of microsatellite markers or functional gene markers related to host feeding would enable precise identification of the host types.

Abstract:Objective To evaluate the toxicity and control effect of azadirachtin to Spodoptera frugiperda and provide a technical reference for prevention and control of Spodoptera frugiperda.Method The toxicity and field control effect of azadirachtin on Spodoptera frugiperda were determined by soaking leaf method and spraying method.Result Under indoor condition, the LC₅₀ values of 2^nd and 3^rd instar larvae were 0.59 and 0.46 mg/L respectively, when treated with 0.3% azadirachtin EC after seven days; At seven days after treated with 40% azadirachtin dry powder, the LC₅₀ values of 2^nd and 3^rd instar larvae were 0.93 and 0.79 mg/L respectively; At three days after treated with 0.3% azadirachtin EC, the AFC₅₀ values of 2^nd and 3^rd instar larvae were 0.30 and 0.12 mg/L respectively; At three days after treated with 40% azadirachtin dry powder, the AFC₅₀ values of 2^nd and 3^rd instar larvae were 0.53 and 0.30 mg/L respectively. When 0.3% azadirachtin EC was diluted 500 times and sprayed on corn, the control effects on S. frugiperda reached 24.83%, 50.34% and 75.50% after 1, 3 and 7 days respectively.Conclusion Azadirachtin has good toxicity and antifeedant activity, and the control effect on S. frugiperda is better at seven days after treatment. Azadirachtin has a broad application prospect in controlling S. frugiperda.

Abstract:Objective To investigate the predation potential of the natural enemies, Harmonia axyridis, to Spodoptera frugiperda.Method The predation behavior of H. axyridis was observed in laboratory, and the predation abilities of H. axyridis adults and the 4^th instar larvae to the 1^st and 2^nd instar larvae of S. frugiperda were evaluated.Result The predatory behaviors of H. axyridis on S. frugiperda larvae included five behaviors of stationary, searching, testing, feeding and crawling. H. axyridis adult appeared three pairs of feet grasping its prey when preying on the 3^rd instar larva of S. frugiperda. The predation function responses of H. axyridis adults and the 4^th instar larvae to the 1^st and the 2^nd instar larvae of S. frugiperda were accorded with the Holling II model. For the 1^st instar larvae of S. frugiperda, the maximum daily predation amounts of adults and the 4^th instar larvae of H. axyridis were 196.08 and 161.29 individuals respectively, the rates of instantaneous attack were 1.390 6 and 1.451 4 respectively, and the handling time were 0.005 1 and 0.006 2 days respectively. For the 2^nd instar larvae of S. frugiperda, the maximum daily predation amounts of adults and the 4^th instar larvae of H. axyridis were 65.36 and 41.84 individuals respectively, the rates of instantaneous attack were 1.145 7 and 1.271 0 respectively, and the handling time were 0.015 3 and 0.023 9 days respectively. The predation abilities of H. axyridis adults to S. frugiperda larvae were stronger than those of the 4^th instar larvae of H. axyridis.Conclusion H. axyridis has certain potential control ability on S. frugiperda and can be used for the prevention and control of S. frugiperda.

Abstract:Objective To provide a basis for studying the structural function and pathogenic mechanism of highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV). Method Fragments of the whole genome of HP-PRRSV JXA1 strain were cloned into the modified low copy vector pOKq with reverse genetics technique. The CMV promoter and BGH termination signal peptide were added into the terminals of the viral genome. The FseI restriction site, as a genetic marker locus, was introduced at the 510th nucleotide of the whole genome of the virus by mutation. DNA-launched approach was used for viral rescue and the biological properties of rescued viruses were analyzed.Result The full-length cDNA clone of the constructed PRRSV JXA1 strain was infectious. The virus was successfully rescued and named rJXA1. The genetic marker was successfully introduced into the rescued virus. The rescued virus and parental virus had similar growth curves with reaching the maximum titer at 72 h after infection.Conclusion The reverse genetic platform of the JXA1 strain has been successfully constructed, which will lay a foundation for further research on the pathogenesis, gene function and vaccine development of PRRSV.

Abstract:Objective To construct a recombinant Lactococcus lactis expression system of phage lysine Cp51, and study its antibacterial activity against Clostridium perfringensin type A in vitro.Method Phage lysin Cp51 gene was inserted into the prokaryotic expression vector PNZ8148, and then the recombinant vector PNZ8148-Cp51 was constructed and transformed into L. lactis NZ9000. Nisin was used to induce expression of soluble protein Cp51. The antibacterial activity of the recombinant protein against C. perfringens type A was detected by kinetic turbidimetric assay in vitro. The inhibitory effect of recombinant L. lactis on the proliferation of C. perfringens type A was tested by mixed cultivation.Result The recombinant phage lysin Cp51 was successfully expressed in L. lactis and the Cp51 gene was 1 268 bp in length. The recombinant protein had strong antibacterial activity against C. perfringens type A at the concentration above 1 μg·mL^-1 in vitro. The recombinant L. lactis also had certain inhibitory effect on C. perfringens type A with the number of C. perfringens decreased from 9×10⁹ CFU·mL^-1 to 9×10⁸ CFU·mL^-1 after mixed cultivation.Conclusion Recombinant L. lactis expressing phage lysin Cp51 which against C. perfringens type A has been successfully constructed, which provides a basis for further optimization of expression and clinical application.

Abstract:Objective To investigate the effect of feed restriction on mammary gland development of pubertal mice and explore the involved mechanisms,and provide a scientific basis for nutritional regulation during mammary gland development of animals.Method Twenty-four 4-week-old C57BL/6J female mice were randomly divided into the control group and feed restriction group. The trial lasted for four weeks. The body weight, feed intake and water intake were recorded weekly, and the body imaging and body composition of mice were examined before the end of the trial. At the end of the trial, the mouse mammary gland was collected and weighed. The blood was collected and the levels of insulin-like growth factor (IGF-1) and estradiol (E2) in serum were measured. The mammary gland development was observed and assessed by using whole-mount staining and the numbers of mammary gland terminal end bud (TEB) and duct branches were analyzed. Immunofluorescence staining was used to detect the expression of proliferating cell nuclear antigen (PCNA) in the mammary gland tissue of pubertal mice.Result The body weight, body weight gain, average daily feed intake and average daily energy intake of mice in feed restriction group were significantly lower than those of mice in control group (P<0.001), while the water intake of feed restriction group was significantly higher than that of control group (P<0.05). Feed restriction had no effect on muscle and fat contents. In addition, feed restriction significantly decreased the mammary gland weight by 29%(P<0.05), with no effect on mammary gland index. The results of whole-mount staining showed that feed restriction significantly inhibited the development of mammary gland, with significant lower number of TEB and duct branches (P<0.05). Furthermore, feed restriction significantly reduced the serum level of IGF-1 by 34%(P<0.05), with no influence on serum E2 level. Feed restriction significantly inhibited PCNA protein expression in the mammary gland of pubertal mice.Conclusion Feed restriction significantly inhibits mammary gland development of pubertal mice, which might be associated with the decreased level of IGF-1 in serum and expression of proliferation-associated protein PCNA in mammary gland tissue.

Abstract:Objective To construct the overexpression vector and RNAi vector for porcine FSTL1 gene, and investigate the role and mechanism of FSTL1 gene on the differentiation of porcine preadipocytes.Method We constructed the overexpression vector and RNAi vectors of FSTL1 gene, transfected the vectors into porcine preadipocytes, and then induced differentiation of preadipocytes. Triglyceride content and the mRNA expression levels of adipocyte differentiation-associated genes were measured.Result The cDNA sequence of porcine FSTL1 gene was successfully cloned, the length of open reading frame was 924 bp, and the sequence has been submitted to GenBank with the login ID of KF021281. The overexpression vector pcDNA3.1-FSTL1 and the RNAi vectors pSilencer 4.1-491 and pSilencer 4.1-530 of the porcine FSTL1 gene were successfully constructed. Overexpressed FSTL1 gene promoted triglyceride content in porcine preadipocytes, whereas triglyceride content was reduced after FSTL1 gene was interfered. FSTL1 up-regulated the mRNA expression level of PPARγ2, AP2 genes by 73% and 113% respectively, and down-regulated LPL, Adiponectin and FASN genes by 44%, 79%, and 16% respectively.Conclusion The FSTL1 gene promotes the differentiation of porcine preadipocytes through up-regulating the mRNA expression of PPARγ2 and AP2 genes and down-regulating LPL, Adiponectin and FASN genes, and increases triglyceride content in porcine preadipocytes.

Abstract:Objective To compare the differences between the effects of high oxygen concentration treating mehod (hyperoxia method) and traditional HCl treating method (HCl method) on prevention of diapause in silkworm (Bombyx mori) eggs, and investigate the application of hyperoxia method in transgenic technology system of silkworm.Method The bivoltine silkworm'Dazao' were treated by hyperoxia method and HCl method on the 20th hour after spawning. The hatching rate and incubation period were compared, and the best condition of hyperoxia method was investigated. The univoltine silkworm'Tuerqi' and transgenic bivoltine silkworm'Dazao'were treated by hyperoxia method. The effects of hyperoxia method and microinjection on blocking univoltine silkworm diapause were investigated.Result Hyperoxia method had similar dispause prevention effects with HCl method considering hatching rate and incubation duration. The best condition was treating 40 hours by 70% (φ) O₂ after spawning for 20 hours. Hyperoxia method could successfully prevent diapause in univoltine silkworm eggs. The hatching rate was (71±20)%. The hatching rate of micro-injected transgenic silkworm eggs treated by hyperoxia method approached (49±9)%, while that of control group was 0.Conclusion Hyperoxia method is a feasible new method for replacing HCl method in the future production, enables safe and environmental friendly prevention of diapause in silkworm eggs, solves key problems of diapause prevention in transgenic silkworm eggs, and improves breeding progress of transgenic silkworms.

Abstract:Objective To evaluate effects of Cd stress on seed germination and growth of seminal root and shoot in chromosome single-segment substitution lines (SSSLs) of Oryza glumaepatula after seed germination, screen for Cd-tolerant SSSLs, and identify QTLs related to Cd-tolerant characters in bud.Method The seed germination test was carried out using six varieties at CdCl₂ concentrations of 0, 30, 50, 100, 500 μmol·L^-1, and the proper treatment of CdCl₂ concentration and the related character indexes to evaluate CdCl₂ tolerance of SSSLs were determined. The lengths of seminal roots and shoots of experimental SSSLs were analyzed to screen for SSSLs with strong tolerance to CdCl₂ at P=0.01 level and identify QTLs related to Cd-tolerant characters.Result At the concentrations of 0, 30, 50, and 100 μmol·L^-1 CdCl₂, the seed germination rates of six varieties were distributed between 91%~95%, which were insignificant among different CdCl₂ concentrations. However, the growth of seminal roots and shoots were significantly inhibited by CdCl₂, and the significant differences were observed for the tolerance to CdCl₂ among different varieties. Using relative root length and relative shoot length on the 7th day after germination as tolerance indexes, at the concentrations of 50 and 100 μmol·L^-1, five relative root length QTLs including qRRL1-1, qRRL2-1, qRRL3-1, qRRL3-2 and qRRL6-1 were identified in eight SSSLs at P=0.01 level, the phenotypic contribution rates of additive effects ranged from 31.18% to 100.59%. Three relative shoot length QTLs including qRSL1-1, qRSL1-2, and qRSL2-1 were identified in five SSSLs, the phenotypic contribution rates of additive effects were 7.43%~18.95%.Conclusion SSSLs of O. glumaepatula carry Cd-tolerant QTLs at the germination period, which will be useful for exploring beneficial Cd-tolerant genes in rice.

Abstract:Objective To study biophysical property, loading morphology and loading mechanism of nanocarrier-gene complex prepared by magnetic nanoparticle (MNP) loading plasmind DNA, and lay a foundation for application of oriented editing technology based on magnetic nano carrier.Method MNP was used as gene carrier to prepare nanocarrier-gene complex MNP-pRGEB32 with plasmid DNA pRGEB32. The abilities of MNP loading and protecting pRGEB32 were analyzed. The particle size distribution, Zeta potential and loading morphology of MNP-pRGEB32 were investigated.Result MNP compressed, adsorbed and aggregated pRGEB32 through electrostatic interaction to form nanocarrier-gene complex. MNP could effectively load and protect pRGEB32.Conclusion MNP can be used as an ideal gene transfer carrier.

Abstract:Objective To comprehensively analyze the effects of different ecological types of earthworm on soil aggregate distribution, water stability of aggregate and percentage of aggregate disruption (PAD) in South China, and provide scientific basis and theoretical support for utilizing earthworms to improve soil structure.Method The laboratory culture experiment was carried out in this study. Eisenia fetida, Pontoscolex corethrurus, Amynthas robustus and A. aspergillum were added in typical latosolic red soil and red soil in South China to study the impacts of different ecological species of earthworm on soil structure.Result Compared with the blank control, the addition of P. corethrurus, A. robustus and A. aspergillum significantly promoted the formation of large-aggregates (d > 2 000 μm) in two soil types (P < 0.05), The large-aggregate proportion in latosolic red soil increased respectively by 35.20%, 44.81% and 37.88%, and increased respectively by 14.92%, 25.31% and 20.18% in red soil. A. robustus significantly reduced the contents of water stable large-aggregates (d > 2 000 μm) and small-aggregates (250 μm ≤ d ≤ 2 000 μm) in latosolic red soil, but significantly increased the proportion of water stable micro-aggregates (d < 250 μm, P < 0.05), which was 37.84% higher than that of the blank control. The addition of four types of earthworms significantly increased PAD values in both two soil types (P < 0.05), and the PAD value in adding A. aspergillum treatment was the lowest. The results of principal component analysis showed that there were significant differences in the distributions and stabilities of soil aggregates under the action of different earthworms in two different soils (P < 0.05).Conclusion The impacts of different earthworm types in South China on latosolic red soil and red soil aggregate distribution and stability are different. The endogenic earthworm (P. corethrurus and A. robustus) has the best impact on the improvement of soil structure. The endo-anecic (A. aspergillum) had the least destructive impact on water stable soil aggregate.

Abstract:Objective To establish an accurate predicted model for free iron in soil based on visible and near infrared (vis-NIR) reflectance spectroscopy, provide a simple, rapid and economical method for soil free iron determination, and facilitate the pedogenesis and classification of soil.Method Soil samples in B horizon were collected from eighty-two upland soil profiles in Guangxi including ferralosols, ferrosols, argosols and cambosols. Chemical and spectral properties of soil samples were analyzed under laboratory condition. The correlation between spectral reflectance after transformation and free iron content in soils was analyzed. The predicted models of soil free iron were established by the method of partial least squares regression (PLSR) and stepwise multiple linear regression (SMLR) based on characteristic bands. The optimal model was determined by evaluating the coefficient of determination (R²), root mean square error (RMSE), and residual prediction deviation(RPD).Result Soil spectral curves had obvious characteristics of free iron absorption and reflection peaks near 457, 800 and 900 nm bands respectively. Free iron content in soils negatively correlated with the raw spectral reflectance. The correlation coefficient between spectral reflectance and free iron content in soils increased significantly after differential transformation of the raw spectrum. The predicted model of free iron content in soils established by the first-order differential spectral transformation and SMLR based on characteristic bands of 400-580 and 760-1 300 nm had the highest accuracy, R² and RPD of the verification set were 0.85, and 2.62 respectively, and RMSE was 8.41 g·kg^-1.Conclusion It is feasible to rapidly and cost-effectively predict free iron content in soils using vis-NIR spectral technology. Soil spectral reflectance of upland in Guangxi has a high correlation with soil free iron content. SMLR is a good method to establish the predicted model of soil free iron content.

Abstract:Objective To improve the adsorption capacity of bentonite for Cr (VI) in water.Method NaOH and chitosan were used for modifying bentonite. Alkali modified bentonite (B-NaOH), chitosan modified bentonite (B-CS) and chitosan-alkali modified bentonite (B-NaOH-CS) were obtained. Using sodium bentonite (B) as the control, we characterized physicochemical properties of three kinds of modified bentonite through infrared spectrometer, scanning electron microscope and specific surface area analyzer, and analyzed their adsorption capacities for Cr (VI).Result A strong N-H absorption peak and an enhanced C-H symmetric bending peak appeared in B-NaOH-CS. The surface sheet structure of B-NaOH-CS was curly dispersed, the interlayer pores increased, and the specific surface area was 1.2 times more than other bentonite. When the concentration of Cr (VI) was 50 mg·L^-1, the equilibrium adsorption capacity of B-NaOH-CS for Cr (VI) was 1.03 mg·g^-1, which was 1.84 and 1.26 times of B-NaOH and B-CS respectively. The quasi-second-order kinetic equation and Langmuir equation could more accurately describe adsorption process of bentonite for Cr (VI). Thermodynamic parameters of △H>0, △G<0 and △S>0 indicated the adsorption process of bentonite for Cr (VI) was endothermic, spontaneous and disordered. B-NaOH had the maximum adsorption capacity for Cr (VI) at pH=7.0, while B-CS and B-NaOH-CS at pH=3.0.Conclusion B-NaOH-CS has the best adsorption effect on Cr (VI). Modified bentonite plays an important role in Cr (VI) pollution remove.

Abstract:Objective To identify the species of biocontrol strains and analyze their control efficiency to cereal cyst nematodes (Heterodera avenae).Method Biocontrol fungus A1 and B1 were identified according to morphological characters, rDNA-ITS sequence alignment and analysis of phylogenetic tree. The control effects of the fermentation broths of strain A1 and B1 against cysts, eggs and the second-stage juveniles (J2) and pot control effects against cereal cyst nematodes were determined.Result Strain A1 and B1 were identified as Aspergillus parasiticus and Trichoderm longilbrachiatum respectively. The mycelium parasitic rates of A1 and B1 on nematode cysts were over 80.00% at 14 days after treatment. At 12 days after treatment, the inhibition rates of the fermentation broths of A1 and B1 on egg hatching were 63.98% and 67.56% respectively. The corrected mortality rates of J2 at 72 hours after treatment were 68.14% and 92.98% respectively. At 90 days after treatment with 3% fungus fertilizer, pot experiment results showed that cyst reduction rates of A1 and B1 were 31.71% and 36.04%, the root lengths of wheat plants increased by 28.82% and 59.62%, and the plant heights increased by 20.38% and 21.43%, respectively.Conclusion Strain A1 and B1 have control effects on cereal cyst nematodes and are worthy of development and utilization.

Abstract:Objective To study carbon (C) content, storage and allocation in seedling organs of Cinnamomum camphora cultivated in four different densities under nitrogen (N) and phosphorus (P) additions, and provide information for forest C storage and allocation under the background of N deposition and P addition.Method The 1-year-old C. camphora seedlings were used as test materials. NH₄Cl and NaH₂PO₄·2H₂O were selected to simulate atmospheric N deposition and P addition, respectively. N and P additions were performed with four different levels (control, N, P, and N+P). The N and P addition amounts per year in N, P, and N+P treatments were 40 g·m^-2 NH₄Cl, 20 g·m^-2 NaH₂PO₄·2H₂O and 40 g·m^-2 NH₄Cl + 20 g·m^-2 NaH₂PO₄·2H₂O, respectively. Seedlings were planted in four different densities (10, 20, 40 and 80 seedlings·m^-2).Result C contents in roots, stems and branches of seedlings in all treatments had no significant difference. N and N+P treatments increased C content of leaves. With the increase of planting density, C content of leaves tended to decrease. The N and P additions increased C storage per seedling and C storage in unit area. C storage per seedling decreased with the increase of planting density.Conclusion C storage of leaves per seedling and C storage in unit area decreases with the increase of planting density. C storage percentage of stems increases in high cultivation density treatment. The effect of N+P treatment on C storage per seedling and C storage in unit area is greater than that of single N or P addition.

Abstract:Objective To design a root heating system suitable for dwarf crops, so as to solve the problem that potted crops in greenhouse without heating equipment in the Yangtze river delta region are vulnerable to low temperature and cold damage in winter.Method A nested double-layer cultivation pot was designed. The interlayer was filled with insulating fat foaming agent. Two silicone rubber heating plates of 80 W/m² and 15 cm×12 cm were placed in the substrate of the cultivation pot. The heating plate was controlled by STM32 MCU, which output signals to the solid state relay for heating power control. Fuzzy PID control algorithm was used to control the temperature of the crop root area to the set value in real time.Result The relative error of root zone temperature control did not exceed 5%. Under the condition of continuous low temperature (average temperature below 5℃ for a week), when the root zone set temperature was 15, 20 and 25℃, the average daytime temperature of the aboveground parts with 30-35 cm height of crops increased by 1.4, 2.6 and 3.7℃ respectively compared with the control group, while their average night temperature increased by 2.1, 2.9 and 4.0℃ respectively. Compared with the common pot, the pots with root zone temperature of 15, 20, 25℃ saved electric energy by 24.2%, 25.3% and 23.8% respectively.Conclusion Under the condition of continuous low temperature, our system can not only effectively increase the temperature of crop root zone, but also can heat up the aboveground part of crop. Under certain conditions, our system can alleviate the effects of cold stress on winter crop growth.