大草蛉对草地贪夜蛾捕食潜能研究

草地贪夜蛾Spodoptera frugiperda JE Smith于2018年底至2019年初入侵我国后,迅速扩散,并在半年内对西南地区的玉米生产造成为害。田间调查和观测研究表明,田间虽然可见该害虫的天敌,但由于天敌种群数量低,无法形成有效控害的模式。为研究大草蛉对草地贪夜蛾的控害潜能,本研究进行了捕食功能反应试验。结果表明,大草蛉成虫对草地贪夜蛾卵以及大草蛉3龄幼虫对草地贪夜蛾1龄幼虫的捕食效应均能够很好的拟合HollingⅡ功能反应模型。其中,大草蛉成虫对贪夜蛾卵的理论日最大捕食量、瞬时攻击率和处理时间分别为1115.56头、1.004和0.0009 d。大草蛉幼虫对贪夜蛾低龄幼虫的理论日最大捕食量、瞬时攻击率和处理时间分别为358头、1.074和0.003 d。结果表明大草蛉具备对草地贪夜蛾卵和低龄幼虫进行有效控害的潜力,为应用天敌昆虫防治草地贪夜蛾提供了理论依据。     

不同龄期的大草蛉对桃蚜的捕食作用

大草蛉Chrysopa pallens(Rambur)是我国分布较广、捕食能力较强的天敌昆虫。为明确大草蛉对桃蚜Myzus percicae潜在的控制能力,在室内研究了大草蛉不同龄期幼虫和成虫对桃蚜的捕食作用,以及种内干扰对大草蛉捕食的影响。结果表明：25℃恒温条件下,大草蛉成虫和幼虫对桃蚜的捕食功能反应可拟合HollingⅡ圆盘方程,在24 h内大草蛉成虫、1龄幼虫、2龄幼虫和3龄幼虫对桃蚜理论最大捕食量分别为370.4头、21.5头、112.4头和217.4头。大草蛉成虫和幼虫对桃蚜的捕食量均随着猎物密度的增加而增加,当桃蚜数量增加到150头后,大草蛉成虫和幼虫捕食量的增加速度明显减缓。成虫及幼虫对桃蚜的搜寻效应随着猎物密度的增加而降低,内干扰作用随着大草蛉虫龄的增加而增强。试验结果表明大草蛉对桃蚜具有较强的控害能力,对研究桃蚜生物防治技术有重要参考价值。     

亚非草蛉的生物学及其对柑桔潜叶蛾幼虫的捕食效应研究

在实验室条件下,亚非草蛉的平均发育历期为:卵期3.1天,幼虫8.9天,成虫寿命雌虫101.7天、雄虫61.8天,产卵前期8.4天。每雌虫平均产卵量400.3粒。最大产卵量746粒。产卵高峰期为羽化后的16—24天。亚非草蛉对湿度的适应范围较广,但幼虫的死亡率与湿度的关系大。 亚非草蛉幼虫一生捕食柑桔潜叶蛾幼虫数平均为149.1头,其日捕食量随龄期的增大而增加。温度对草蛉幼虫的捕食效应具有显著的影响,在35℃时达到最高的捕食效应,而在15℃以下和40℃以上,则受到明显的限制。湿度对草蛉捕食潜叶蛾幼虫的影响呈Iogistic曲线。草蛉对潜叶蛾幼虫密度的功能反应属HollingⅠ型反应。草蛉幼虫对其自身密度的功能反应可用Watt模型模拟。草蛉对潜叶蛾幼虫的捕食作用率随捕食者个体间的相互干扰作用的增加而下降,两者之间的关系随草蛉幼虫数的增加呈幂函数下降曲线。 田间观察及室内试验结果表明,亚非草蛉是柑桔潜叶蛾的一种重要的捕食性天敌。     

棉田草蛉发生规律的研究

草蛉成虫和幼虫能捕食粮、棉、果、树、蔬菜等作物上的多种害虫的多种虫态,是较有利用前途的天敌昆虫。为了摸清各种因子对棉田草蛉种群数量的影响,为保护和利用草蛉提供依据,我们从1974至1976年先后在汉阳、天门、广济、襄阳等县,对草蛉的田间生态作了一些调查和观察,现整理于下。     

中华通草蛉和大草蛉幼虫对黑刺粉虱若虫的捕食功能反应

【目的】为了研究中华通草蛉Chrysoperla sinica(Tjeder)幼虫和大草蛉Chrysopa pallens(Rambur)幼虫对黑刺粉虱Aleurocan spinfetus(Quaintance)若虫的捕食作用。【方法】在室内(25±1)℃条件下对2种草蛉的捕食功能反应模型进行了评估,并对2种草蛉的3龄幼虫的种内干扰作用和自身密度作用的反应方程进行了拟合。【结果】2种草蛉的捕食功能均属于HollingⅡ反应模型,捕食量均随黑刺粉虱若虫密度的增加而增加。中华通草蛉和大草蛉的自身密度方程分别为E=0.753 0×P~(–0.134 8)和E=0.697 5×P~(–0.164 6),种内干扰作用方程分别为A=2.362 6×P~(–0.231 8)和A=2.429 6×P~(–0.225 6)。【结论】中华通草蛉和大草蛉对黑刺粉虱均具有较好的捕食作用。     

饥饿对大草蛉雄成虫捕食作用的影响

对不同饥饿程度大草蛉雄成虫捕食作用影响的研究表明,饥饿不能改变大草蛉雄成虫捕食作用功能反应类型,饥饿对捕食量影响不显著;大草蛉雄成虫对麦二叉蚜的捕食量（Ｎａ）随着时间（ｔ）的变化,其模型为Ｎａ＝１００／１＋ｅ＾－０．３０８８－０．０９９６ｔ;大草蛉雄成虫在２４ｈ内的捕食速率（Ｖ）与其时间段（ｘ）的关系为Ｖ＝６．７１１７ｘ＾－０．７９２８;大草蛉雄成虫喜好选择捕食麦二叉蚜的低龄若蚜。     

不同虫态及虫龄大草蛉与七星瓢虫之间的集团内互作

【目的】为明确新疆棉田棉蚜 Aphis gossypii 捕食性天敌之间的集团内捕食效应及其对蚜虫数量的控制作用。【方法】本研究以优势天敌昆虫大草蛉 Chrysopa pallens 和七星瓢虫 Coccinella septempunctata 为对象,以棉蚜为猎物,在温室中利用盆栽棉花,首先观察了2种天敌昆虫之间各虫态及虫龄配对的19个处理在无蚜植株上共存24 h后的存活数,然后观察了2种天敌昆虫配对处理下棉苗上棉蚜数量随时间的变化趋势。【结果】在无蚜棉株上2种捕食性天敌昆虫共存24 h后的存活结果表明：（1）在发育阶段相同的配对组合中,若是成虫则均存活,若是１龄幼虫则大草蛉存活较多,若是末龄幼虫则七星瓢虫存活较多;（2）在有卵的组配中,除七星瓢虫卵不被大草蛉成虫所捕食外,其他5个组配处理中卵均被捕食;（3）在有蛹的配对组合中,除七星瓢虫蛹被大草蛉末龄幼虫捕食外,其他处理下蛹均不被捕食;（4）在成虫与幼虫的配对组合中,七星瓢虫成虫捕食较多的大草蛉1龄幼虫,但不捕食大草蛉末龄幼虫,而大草蛉成虫与七星瓢虫1龄或末龄幼虫之间不发生捕食;(5）在不同龄期幼虫的配对组合中,大草蛉末龄幼虫捕食七星瓢虫1龄幼虫,而七星瓢虫末龄幼虫捕食大草蛉1龄幼虫。在有蚜植株上2种捕食性天敌共存对棉蚜数量具有不同的控制作用：（1）2种捕食昆虫的幼虫各自单独存在（对照）下,蚜虫密度随时间而降低;（2）大草蛉幼虫与七星瓢虫幼虫或成虫配对处理下,棉蚜密度随时间而增大;（3）大草蛉成虫与七星瓢虫幼虫或成虫配对处理下,棉蚜密度随时间而减小。【结论】研究结果说明,大草蛉与七星瓢虫之间存在集团内捕食,但２种天敌共存对棉蚜的控制作用取决于大草蛉虫态, 若大草蛉为幼虫,可使蚜虫密度增大,若为成虫,则使蚜虫密度减小。     

大草蛉对桃蚜和夹竹桃蚜的捕食作用研究

大草蛉在我国分布广泛,能捕食多种农作物害虫。本试验首先研究了大草蛉一龄幼虫对桃蚜、大草蛉二龄幼虫对桃蚜和夹竹桃蚜的捕食功能反应。三个反应的最大捕食量Namax分别为144．93、303．03和151．51（头）,瞬时攻击率a分别为0．7428、0．8654和0．6644。大草蛉一龄幼虫有较强的种内干扰反应,随着捕食者密度的增加,捕食作用率（E）依次为0．2025、0．1185、0．0866、0．0694和0．0584;对桃蚜的捕食作用率（E）与自身密度（P）的函数关系式为E=0．2025P^-0.7727。在桃蚜和夹竹桃蚜的混合种群中,大草蛉二龄幼虫对桃蚜的选择效应大于夹竹桃蚜。     

天敌体内玉米蚜的CoⅡ标记检测

以玉米蚜Rhopalosiphum maidis Fitch及玉米田的捕食性天敌为研究对象,筛选1对特异扩增玉米蚜细胞色素氧化酶Ⅱ(COⅡ)基因序列片段的引物。种特异性检验表明,该引物只对玉米蚜基因组DNA具有扩增效果,对与其同域发生的其他种类不具扩增作用;室内以该引物检测喂食单头玉米蚜的异色瓢虫Harmonia axyridis(Pallas)成虫和大草蛉Chrysopa pallens(Rambur)成虫腹内靶标食物的衰变情况,结果表明,异色瓢虫成虫和大草蛉成虫阳性比率的半衰期分别为喂食后2·814和2·441h;对玉米田间捕食性天敌的检测结果表明,在所检测的6类群13种捕食性天敌中,大灰食蚜蝇幼虫、草蛉幼虫、异色瓢虫成虫和幼虫、龟纹瓢虫成虫和幼虫对玉米蚜的捕食作用检出率较高,大于40%。     

冀中农区大草蛉(Chrysopa septempunctata)栖息地选择

大草蛉(Chrysopa septempunctata)是华北农区的主要天敌昆虫,研究了作物主要生长季节大草蛉的分布动态及其对栖息地的选择取向,结果表明,(1)大草蛉对栖息生境有较强的选择性,明显趋向于田间杂草地生境;(2)大草蛉在田间草地带上的栖息较为稳定,且受田间草地带宽度的直接影响,宽度1m左右的草地带有更高的大草蛉密度;(3)林带对大草蛉分布显示出积极作用,其效应范围因林带结构不同表现各异;(4)作物生长后期林带逐渐成为大草蛉栖息的重要场所。     

Synthesis and luminescence properties of a blue-emitting Sr(3.5) Y(6.5) O(2) (PO(4) )(1.5) (SiO(4) )(4.5) :Eu(2+) phosphor

A novel blue‐emitting Sr_3.5Y_6.5O₂(PO₄)_1.5(SiO₄)_4.5:Eu²⁺ phosphor was synthesized via a solid‐state reaction. Powder X‐ray diffraction (XRD) analysis demonstrated that the Sr_3.5Y_6.5O₂(PO₄)_1.5(SiO₄)_4.5 host had a hexagonal crystal structure in the space group P6₃/m and unit cell parameters a = 9.418 Å, c = 6.900 Å. The as‐prepared phosphor showed a blue emission and all the main emission peaks were located at around 466 nm for different excitation wavelengths of 297, 333 and 391 nm. The temperature dependence of the photoluminescence property was investigated in the range 20–250 °C, and the emission intensity decreased to 71% of the initial value at room temperature on increasing the temperature to 150 °C. According to the classical theory of fluorescent thermal quenching, the activation energy (ΔE) for the thermal quenching luminescence of the as‐prepared Sr_3.45Y_6.5O₂(PO₄)_1.5(SiO₄)_4.5:0.05Eu²⁺ phosphor was determined to be 0.20 eV. Copyright © 2011 John Wiley & Sons, Ltd.     

Collagen-like triple helix formation of synthetic (Pro-Pro-Gly)10 analogues: (4(S)-hydroxyprolyl-4(R)-hydroxyprolyl-Gly)10, (4(R)-hydroxyprolyl-4(R)-hydroxyprolyl-Gly)10 and (4(S)-fluoroprolyl-4(R)-fluoroprolyl-Gly)10.

For the rational design of a stable collagen triple helix according to the conventional rule that the pyrrolidine puckerings of Pro, 4-hydroxyproline (Hyp) and 4-fluoroproline (fPro) should be down at the X-position and up at the Y-position in the X-Y-Gly repeated sequence for enhancing the triple helix propensities of collagen model peptides, a series of peptides were prepared in which X- and Y-positions were altogether occupied by Hyp(R), Hyp(S), fPro(R) or fPro(S). Contrary to our presumption that inducing the X-Y residues to adopt a down-up conformation would result in an increase in the thermal stability of peptides, the triple helices of (Hyp(S)-Hyp(R)-Gly)(10) and (fPro(S)-fPro(R)-Gly)(10) were less stable than those of (Pro-Hyp(R)-Gly)(10) and (Pro-fPro(R)-Gly)(10), respectively. As reported by B?chinger's and Zagari's groups, (Hyp(R)-Hyp(R)-Gly)(10) which could have an up-up conformation unfavorable for the triple helix, formed a triple helix that has a high thermal stability close to that of (Pro-Hyp(R)-Gly)(10). These results clearly show that the empirical rule based on the conformational preference of pyrrolidine ring at each of X and Y residues should not be regarded as still valid, at least for predicting the stability of collagen models in which both X and Y residues have electronegative groups at the 4-position.     

Role of tfdC(I)D(I)E(I)F(I) and tfdD(II)C(II)E(II)F(II) gene modules in catabolism of 3-chlorobenzoate by Ralstonia eutropha JMP134(pJP4)

The enzymes chlorocatechol-1,2-dioxygenase, chloromuconate cycloisomerase, dienelactone hydrolase, and maleylacetate reductase allow Ralstonia eutropha JMP134(pJP4) to degrade chlorocatechols formed during growth in 2,4-dichlorophenoxyacetate or 3-chlorobenzoate (3-CB). There are two gene modules located in plasmid pJP4, tfdC(I)D(I)E(I)F(I) (module I) and tfdD(II)C(II)E(II)F(II) (module II), putatively encoding these enzymes. To assess the role of both tfd modules in the degradation of chloroaromatics, each module was cloned into the medium-copy-number plasmid vector pBBR1MCS-2 under the control of the tfdR regulatory gene. These constructs were introduced into R. eutropha JMP222 (a JMP134 derivative lacking pJP4) and Pseudomonas putida KT2442, two strains able to transform 3-CB into chlorocatechols. Specific activities in cell extracts of chlorocatechol-1,2-dioxygenase (tfdC), chloromuconate cycloisomerase (tfdD), and dienelactone hydrolase (tfdE) were 2 to 50 times higher for microorganisms containing module I compared to those containing module II. In contrast, a significantly (50-fold) higher activity of maleylacetate reductase (tfdF) was observed in cell extracts of microorganisms containing module II compared to module I. The R. eutropha JMP222 derivative containing tfdR-tfdC(I)D(I)E(I)F(I) grew four times faster in liquid cultures with 3-CB as a sole carbon and energy source than in cultures containing tfdR-tfdD(II)C(II)E(II)F(II). In the case of P. putida KT2442, only the derivative containing module I was able to grow in liquid cultures of 3-CB. These results indicate that efficient degradation of 3-CB by R. eutropha JMP134(pJP4) requires the two tfd modules such that TfdCDE is likely supplied primarily by module I, while TfdF is likely supplied by module II.     

Induction of in vitro flowering in Dendrobium Madame Thong-In (Orchidaceae) seedlings is associated with increase in endogenous N(6)-(Delta (2)-isopentenyl)-adenine (iP) and N (6)-(Delta (2)-isopentenyl)-adenosine (iPA) levels

We analysed the endogenous cytokinin levels of Dendrobium Madame Thong-In seedlings grown in vitro during vegetative and flowering-inductive periods. HPLC was used to fractionate the extracts and radioimmunoassay (RIA) was used for assay of zeatin (Z), dihydrozeatin (DZ), N(6)-(Delta(2)-isopentenyl)-adenine (iP) and their derivatives. Coconut water used in experiments was found to contain high level (>136 pmol ml(-1)) of zeatin riboside (ZR). Protocorms and seedlings cultured in medium with coconut water were found to contain 0.5-3.9 pmol g(-1) FW of the cytokinins analysed. Seedlings (1.0-1.5 cm) cultured in flowering-inductive liquid medium containing 6-benzyladenine (BA, 4.4 muM) and coconut water (CW, 15%) contained up to 200 and 133 pmol g(-1) FW of iP and iPA, respectively. These levels were significantly higher than all other cytokinins analysed in seedlings of the same stage and were about 80- to 150-folds higher than seedlings cultured in non-inductive medium. During the transitional (vegetative to reproductive) stage, the endogenous levels of iP (178 pmol g(-1) FW) and iPA (63 pmol g(-1) FW) were also significantly higher than cytokinins in the zeatine (Z) and dihydrozeatin (DZ) families in the same seedlings. Seedlings that grew on inductive medium but remained vegetative contained lower levels of iPA. The importance of the profiles of iP and its derivatives in induction of in vitro flowering of D. Madame Thong-In is discussed.     

Biology of Bactrocera (Zeugodacus) tau (Walker) (Diptera: Tephritidae)

The biology of the fruit fly Bactrocera tau, an important horticultural pest, was studied under laboratory conditions at 25°C and 60–70% relative humidity on Cucurbita maxima. The duration of mating averaged 408.03 ± 235.93 min. After mating, the female fly had a preoviposition period of 11.7 ± 4.49 days. The oviposition rate was 9.9 ± 8.50 eggs and fecundity was 464.6 ± 67.98 eggs/female. Eggs were elliptical, smooth and shiny white, turning darker as hatching approached, and measured 1.30 ± 0.07 mm × 0.24 ± 0.04 mm. The chorion has polygonal microsculpturing and is species-specific with polygonal walls. The egg period lasts for 1.3 ± 0.41 days. The duration of the larval period is 1.2 ± 0.42, 1.7 ± 0.48 and 4.0 ± 0.94 days for first, second and third instars, respectively. Pupation occurs in the sand or soil and pupal periods are 7.0 ± 0.47 days. The life cycle from egg to adult was completed in 14.2 ± 1.69 days; the longevity of mated females and males was 130.33 ± 14.18 and 104.66 ± 31.21 days, respectively. At least two to three generations were observed from June 2008 to June 2009.     

The helix-coil transitions of poly (dA)-poly (dT) and poly (dA-dT)-poly (dA-dT)

Helix–coil transition curves are calculated for poly (dA) poly(dT) and poly (dA-dT) poly (dA-dT) using the integral equation approach of Goel and Montroll.⁵ The transitions are described by the loop entropy model with the exponent of the loop entropy factor, k, remaining an arbitrary constant. The theoretical calculations are compared with experimental transition curves of the two polymers. Results indicate that the stacking energies for these two polymers differ by about 1 kcal/mole of base pairs. Also, a fit between theory and experiment was not possible for k > 1.70.     

Spectroscopic investigations of Er(3+) :CdO-Bi(2) O(3) -B(2) O(3) glasses

This article reports on the optical properties of Er³⁺ ions doped CdO–Bi₂O₃–B₂O₃ (CdBiB) glasses. The materials were characterized by optical absorption and emission spectra. By using Judd–Ofelt theory, the intensity parameters Ω_λ (λ = 2, 4, 6) and also oscillatory strengths were calculated from the absorption spectra. The results were used to compute the radiative properties of Er³⁺:CdBiB glasses. The concentration quenching and energy transfer from Yb³⁺–Er³⁺ were explained. The stimulated emission cross‐section, full width at half maximum (FWHM) and FWHM × values are also calculated for all the Er³⁺:CdBiB glasses. Copyright © 2011 John Wiley & Sons, Ltd.