光周期对小地老虎生长发育及繁殖的影响

【目的】探明光周期对小地老虎Agrotis ypsilon(Rottemberg)生长发育及繁殖的影响。【方法】在实验条件下观察了5个光周期(0L︰24D,8L︰16D,12L︰12D,16L︰8D和24L︰0D)下小地老虎的生长发育和繁殖情况。【结果】随着光照时间增加,小地老虎生长速度加快,发育历期缩短,孵化率、存活率、羽化率、产卵量先增大后降低。其卵、幼虫、蛹和成虫的最适光周期分别为12L︰12D或16L︰8D、16L︰8D、0L︰24D以及12L︰12D。综合来说,光周期16L︰8D最适合小地老虎的生长发育。【结论】研究结果初步揭示了不同光周期对小地老虎生长发育及繁殖状况存在显著的影响,并且不同虫态对光周期变化也呈现不同的变化规律。     

不同性比对小菜蛾繁殖及田间种群数量的影响

不同雌雄比对小菜蛾Plutella xylostella(L.)繁殖的影响以及性诱剂对田间种群的控制效果研究试验结果表明:随雌雄比的提高,雌蛾的产卵量减少,孵化率降低,在1∶1,4∶1状态下平均单雌产卵量分别为79.33粒和76.03粒,平均孵化率为89.03%和78.44%,在13∶1状态下平均单雌产卵量为36粒,平均孵化率仅为46.05%,全雌状态下所产的卵无一孵化。田间应用性诱剂也可有效降低虫口数量。     

自然条件下福寿螺繁殖特性

为了弄清福寿螺在自然条件下的繁殖特性,在湖南省资兴市水稻田内进行了为期3年的人工养殖试验.结果表明:福寿螺在湘南自然条件下1年可发生不完全3代.第1代、第2代和第3代(越冬代)雌螺的平均性成熟期分别为59.3、45.4和213.0 d.雄螺的平均性成熟期比雌螺早4.3d.福寿螺的自然性比(♀∶♂)为1.54:1.每次交配持续时间平均为19.2h,但并非每次交配后都会产卵.田间福寿螺月产卵块数与月平均气温呈显著正相关(r=0.756).福寿螺卵块的平均孵化期(d)与日平均气温(℃)呈显著负相关(r=-0.980),其线性回归方程为y=-0.726x+23.064.福寿螺卵块的平均孵化期为20.7d,平均孵化率为44.1％.雌螺与雄螺的平均寿命分别为2.40和1.98 a.平均每头雌螺一生可产卵13764粒,可繁殖幼螺6070头.     

温度对中型指环虫产卵和孵化的影响

指环虫病是严重影响鱼类养殖的寄生虫病.为了有效控制指环虫病,实验研究了寄生在金鱼(Carassius auratus)鳃部的中型指环虫(Dactylogyrus intermedius)卵、纤毛幼虫的形态,以及在离体条件下温度对其产卵和孵化的影响.成熟的中型指环虫虫卵大部分为梨形,长30 μm左右,后端有一个卵柄.纤毛幼虫呈圆筒状,两端稍尖,眼点两对;后吸盘具有若干对小锚钩;在前部、中部和尾部分别具有一圈纤毛.实验研究了4℃、10℃、22℃、30℃和35℃条件下中型指环虫的产卵和孵化情况,在4℃条件下,中型指环虫基本不产卵也不孵化;在其他4个温度条件下,产卵量随着温度的升高而增加,其平均产卵量分别为3.30、4.10、4.13和4.24枚/虫.统计结果显示:在35℃条件下的产卵量明显高于10℃(P＜0.05),其他温度条件下的平均产卵量没有显著性差异.中型指环虫的产卵速率随着温度的升高而加快,产卵维持的时间分别为4d、23h、15h和llh.孵化率在22℃时最高,为72.7％,在30℃和35℃的孵化率为50％左右,卡方检验显示:4种温度下的孵化率之间没有显著性差异p＞0.05);随着温度的升高,孵化速率逐渐加快,而孵化时间和纤毛幼虫的存活时间则缩短,平均孵化时间分别为24d、3d、42h和26h,纤毛幼虫的最长存活时间分别为4d、3d、56h和34h.结果显示,当水温为22℃时,中型指环虫的产卵数量和纤毛幼虫的存活时间都比较高,且孵化率最高,表明该温度条件较适合中型指环虫的种群增长.     

光照强度与光周期对虎斑乌贼胚胎发育的影响

为探究光照对虎斑乌贼受精卵孵化的影响,确定其胚胎发育的最佳光照条件,本研究采用单因子试验方法,分析了不同光照强度(10、30、50、70、90 μmol·m^-2·s^-1)和光周期L∶D(24 h∶0 h、18 h∶6 h、12 h∶12 h、6 h∶18 h、0 h∶24 h)对虎斑乌贼胚胎发育的影响.结果表明: 不同光照强度对虎斑乌贼胚胎发育的孵化率、卵黄囊断裂率、培育周期、初孵幼体体质量与胴长均影响显著;而对孵化周期和幼体出膜7 d后存活率无显著影响.其中孵化率、培育周期、初孵幼体体质量与胴长随着光照强度的增强先增大后减小,而卵黄囊断裂率则逐渐增大.最适光照强度为30 μmol·m^-2·s^-1,此光照强度下孵化率为(90.0±4.1)%,卵黄囊断裂率为(7.3±1.5)%,培育周期为(25.50±0.35) d,孵化周期为(8.10±0.89) d,初孵幼体体质量为(0.213±0.011) g,胴长为(1.013±0.022) cm,出膜7 d后存活率为(97.1±4.0)%.不同光周期对虎斑乌贼胚胎发育的孵化率、培育周期、孵化周期均影响显著,而对卵黄囊断裂率、初孵幼体体质量、胴长和幼体出膜7 d后存活率无显著影响.其中孵化率和孵化周期随着光照时间的增加呈现先增大后减小的变化.最适光周期为LD(12 h12 h),此光周期下孵化率达(88.7±1.8)%,卵黄囊断裂率为(8.7±1.8)%,培育周期为(25.00±0.50) d,孵化周期为(7.00±3.20) d,初孵幼体体质量为(0.209±0.005) g,胴长为(0.998±0.026) cm,出膜7 d后存活率为(96.8±7.1)%.说明弱光照强度30 μmol·m^-2·s^-1和半日光照强度L∶D(12 h∶12 h)更有利于虎斑乌贼的胚胎孵化.在实际生产中,应避免阳光直射,采取适当的遮光措施.     

光照时间和冷藏对桃小食心虫生长发育和繁殖的影响

研究了光照时间和冷藏对桃小食心虫各虫态生长发育和繁殖的影响.结果表明,随着光照时数的延长,各虫态历期基本呈缩短趋势,光照时间对幼虫滞育率影响最为明显,15 h滞育率最低,无论是光照延长还是缩短,幼虫滞育率都会明显增加.其它重要生命参数如单雌产卵量、幼虫体重、孵化率、脱出率和羽化率等最高点多集中在光照13～17 h,所以,桃小食心虫生长发育和繁殖的最佳光照时间为15 h左右.冷藏时间对蛹历期、成虫寿命和卵历期影响均不明显,但冷藏7 d后羽化率、单雌产卵量及孵化率均呈下降趋势,蛹和卵不易长时间低温存放.     

光周期和LED光源对茄二十八星瓢虫成虫行为的影响

【目的】探明光周期和LED光源对茄二十八星瓢虫Henosepilachna vigintioctopunctata成虫取食、移动、交配和产卵等行为的影响,为该害虫的预测预报和综合治理提供科学依据和技术指导。【方法】在光期光源为白色日光灯,光照强度约为500 lx, RH 75%±2%条件下观察并记录了30℃时6个不同光周期(16L∶8D, 15L∶9D, 14L∶10D, 13L∶11D, 12L∶12D和11L∶13D)下茄二十八星瓢虫成虫取食、移动、交配和产卵行为;26℃时暗期以不使用光照(12L∶12D)为对照,使用红、黄、蓝、绿和白光5个不同LED光照(分别记为12L∶12R, 12L∶12Y, 12L∶12B, 12L∶12G和12L∶12W)下茄二十八星瓢虫成虫取食、移动、交配和产卵行为。【结果】当光照时长从13 h延长至16 h时,茄二十八星瓢虫成虫取食频次有增加的趋势;当光照时长从12 h延长至15 h时,产卵量有增加的趋势。光周期为14L∶10D和13L∶11D时,成虫取食频次(分别为45.25和25.00次/5对)显著低于其他光周期下,光周期11L∶13D下产卵量(仅有7.25粒/5♀)显著低于其他光周期下。蓝光处理组取食频次(112.50次/5对)显著高于黄光和绿光处理组(分别为77.0和66.25次/5对);黄光和绿光处理组产卵量(分别为261.50和285.50粒/5♀)显著高于对照组。【结论】延长光照时间,茄二十八星瓢虫成虫取食频次和产卵量均有增加趋势;暗期使用蓝光时成虫取食频次增加,而使用黄光和绿光时则产卵量增加。光周期和LED光源对其移动和交配行为影响不显著。     

异色瓢虫不同光环境下的交配行为

光照条件是影响昆虫生长发育及生理行为变化的重要环境因子之一。以重要的捕食性天敌异色瓢虫为研究对象,借助动物行为自动观察系统对其在不同光照强度、光周期和光波长下的交配行为及繁殖力进行了分析研究。结果显示:(1)异色瓢虫的各交配行为和繁殖能力在有光和黑暗处理间具有显著差异;(2)异色瓢虫的求偶行为不受光照强度变化的影响,而交配持续时间及交配间隔时间在高光照强度下均显著短于低光照强度。尽管异色瓢虫的累积产卵量在不同光照强度间未见显著性差异,但是其幼虫孵化率随光照强度的增强显著降低;(3)异色瓢虫在光照时间较长的条件下表现出较高的交配求偶欲望,交配持续时间及交配间隔时间随光照时间的延长而缩短,其累积产卵量和幼虫孵化率均随光照时间的延长而显著增加;(4)不同环境颜色对异色瓢虫的求偶行为没有显著影响,但是其交配持续时间及交配间隔时间随照射光波长的增加而显著降低,雌虫的累积产卵量和幼虫孵化率均在黄色(575 nm)和绿色(510 nm)条件下最高,且显著大于其它处理。结果表明异色瓢虫的交配受光照条件影响极为显著,为进一步深入研究异色瓢虫环境适应性及提升其在生物防治中大规模饲养中的扩繁效率提供了重要的理论依据。     

草地贪夜蛾人工饲料及饲养条件的优化

改良草地贪夜蛾Spodoptera frugiperda(J.E Smith)人工饲料配方及优化饲养条件,为草地贪夜蛾室内批量饲养奠定基础。利用不同人工饲料配方及制作工艺、不同温湿条件、对草地贪夜蛾进行群体饲养,研究其对草地贪夜蛾生长发育及繁殖的影响,并开展不同产卵介质对草地贪夜蛾成虫产卵量及卵孵化率的影响。结果显示,在温度27℃±0.5℃、相对湿度70%±5%、光周期L∶D=16 h∶8 h的人工气候箱中,采用饲料配方4进行幼虫群体饲养的效果最好,其发育历期最短,仅为27.1 d,幼虫存活率高达83.8%,化蛹率为91.2%,雌雄性比为1∶1.08,单雌产卵量为836粒。另外,草地贪夜蛾幼虫最喜食加热20 min的饲料,成虫于粉色塑料纸上产卵量最大。该饲料配方非常适宜草地贪夜蛾室内饲养,优化的饲养条件也为其室内规模化饲养提供参考。     

温度对柑橘始叶螨实验种群生长发育繁殖的影响

通过室内试验研究了温度对柑橘始叶螨Eotetranychus kankitus(Ehara)生长发育和繁殖的影响,组建了柑橘始叶螨在7种温度下(18、21、24、27、30、33℃和36℃)的实验种群生命表。结果表明,柑橘始叶螨的生长发育、繁殖和生命表参数在不同温度之间有显著差异。卵在36℃条件下不能正常孵化,其他6个温度对该螨的种群适合度有显著影响;发育历期与温度基本呈负相关;整个世代温度(T)和发育速率(V(G))拟合的线性日度方程和Logistic模型分别为V(G)=-0.037+0.004 T(R2=7.879)和V(G)=0.080/(1+EXP(7.402-0.363T))(R2=0.973);世代发育起点温度和有效积温分别为12.38℃和220.00d·℃;每雌产卵总量在27℃下最高,为73.4粒,18℃下最低,为35.3粒;卵的孵化率、幼、若螨的存活率在27℃下最大,分别为99.75%、96.18%和97.54%,18℃下最小,分别为99.01%、94.05%和93.15%;在6种温度下内禀增长力r m值分别为0.0372、0.0757、0.1024、0.1195、0.1469、0.1427;净增值率R o分别为9.3241、16.0162、16.6874、20.4564、21.1958、8.8142。由此推断,21—30℃是柑橘始叶螨生长发育和繁殖的最适温度范围。     

Synopsis of the tribe Bocageeae (Annonaceae), with revisions of Cardiopetalum,Froesiodendron, Trigynaea,Bocagea, and Hornschuchia

The tribal name Bocageeae Endlicher is reestablished and the tribe is circumscribed on the basis of solitary internodal ebracteate pedicels that are articulated at the base, and pollen shed in polyads of eight or more grains. Septate anther locules, large pollen size, and seed appendages are prevalent in the tribe. Intectate pollen with free-standing columellae, rare in Annonaceae, occurs not only in the genusTrigynaea but also in some species ofBocagea andHornschuchia. As defined here, the Bocageeae include seven neotropical genera:Cymbopetalum, Porcelia, Bocagea, Cardiopetalum, Froesiodendron, Hornschuchia, andTrigynaea. The latter five genera are revised and the treatments include ten new species:Cardiopetalum plicatum, Froesiodendron urceocalyx, Hornschuchia lianarum, H. santosii, H. leptandra, Trigynaea cinnamomea, T. lanceipetala, T. triplinervis, T. lagaropoda, andT. axilliflora, all from tropical South America. A new combination,Froesiodendron longicuspe, changes the rank of that taxon from subspecies to species.Cardiopetalum surinamense is removed fromFroesiodendron and reassigned toCardiopetalum on the basis of its connate petals, dehiscent monocarps, and seeds with bilobed arils. A cladogram provides an explicit hypothesis of intergeneric relationships in the tribe. The new combinationOnychopetalum periquino, based onTrigynaea periquino, is made.     

Lack of relationship between gliding cyanobacteria and filamentous gliding heterotrophic eubacteria: comparison of 16S rRNA catalogues of Spirulina,Saprospira, Vitreoscilla,Leucothrix, and Herpetosiphon

Spirulina platensis and Spirulina maxima were characterized by 16S ribosomal RNA oligonucleotide cataloguing. Both species are highly related. They fall into the main group of the cyanobacteria, showing a remote relationship to Nostoc, Fischerella, Aphanocapsa, and also to Prochloron. Low similarity coefficients were found between the Spirulina species and certain organotrophic and sulfide oxidizing bacteria, viz. Saprospira grandis, Vitreoscilla stercoraria, Leucothrix mucor, Herpetosiphon aurantiacus, and Beggiatoa leptomitiformis, respectively. This result does not support the classical hypothesis that certain filamentous gliding bacteria are apochlorotic cyanobacteria.     

Location,expression and orientation of the putative chlororespiratory enzymes,Ndh and IMMUTANS,in higher-plant plastids

The chloroplasts of many plants contain not only the photosynthetic electron transport chain, but also two enzymes, Ndh and IMMUTANS, which might participate in a chloroplast respiratory chain. IMMUTANS encodes a protein with strong similarities to the mitochondrial alternative oxidase and hence is likely to be a plastoquinol oxidase. The Ndh complex is a homologue of complex I of mitochondria and eubacteria and is considered to be a plastoquinone reductase. As yet these components have not been purified to homogeneity and their expression and orientation within the thylakoid remain ill-defined. Here we show that the IMMUTANS protein, like the Ndh complex, is a minor component of the thylakoid membrane and is localised to the stromal lamellae. Protease digestion of intact and broken thylakoids indicates that both Ndh and IMMUTANS are orientated towards the stromal phase of the membrane in Spinacia oleracea L. Such an orientation is consistent with a role for the Ndh complex in the energisation of the plastid membrane. In expression studies we show that IMMUTANS and the Ndh complex are present throughout the development of both Pisum sativum L. cv Progress No. 9 and Arabidopsis thaliana (L.) Heynh. leaves, from early expansion to early senescence. Interestingly, both the Ndh complex and the IMMUTANS protein accumulate within etiolated leaf tissue, lacking the photosystem II complex, consistent with roles outside photosynthetic electron transport.Abbreviations PQ plastoquinone - PSI, PSII photosystem I, II     

Novel phenylanthraquinones,isofuranonaphthoquinones, homoisoflavonoids,and biflavonoids from African plants in the genera Bulbine,Scilla, Ledebouria,and Rhus

The sale of non-cultivated plants poses a real threat to the survival of a large number of plant species. On the other hand, the fact that a given plant has become a traded item is an important lead in the effort to investigate plants for the purpose of discovering novel secondary metabolites that may have marketable properties. This report is largely based on the investigations of plants collected from vendors of medicinal plants. The identification is based on botanical specimens derived from the purchased plant parts either by growing them in a garden or through micropropagation using tissue culture techniques. Bulbine species yielded novel phenyl anthraquinones and isofuranonaphthoquinones, which were found to exhibit antiparasitic and antioxidant properties. Scilla nervosa subsp. rigidifolia and Ledebouria graminifolia yielded twenty homoisoflavonoids and two xanthones. Bulbs derived from tissue culture based specimens of L. graminifolia contained all the compounds isolated from the marketed samples. Some of the homoisoflavonoids were found to possess activity against colon and breast cancer cell lines. Rhus pyroides furnished six novel bichalcones some of which exhibited insect antifeedant, cytotoxic and antiproliferative activities. Structures of the compounds described in this report were elucidated by spectroscopic means including HRMS and 1D-, and 2D-NMR experiments. Interconversion of some of the phenyl anthraquinones was accomplished as part of their structure proof. The total synthesis of three of the biflavonoids was achieved using a synthetic route which involves a microwave irradiation promoted Ulmann synthesis. This revised version was published online in June 2006 with corrections to the Cover Date.     

Ribotyping of 16S and 23S rRNA genes and organization of rrn operons in members of the bacterial genera Gemmata,Planctomyces, Thermotoga,Thermus, and Verrucomicrobium

The number of organization of rrn genes of two members of the order Planctomycetales, Planctomyces limnophilus and Gemmata obscuriglobus, as well as three species from other bacterial phyla, namely Thermotoga maritima, Thermus aquaticus and Verrucomicrobium spinosum were examined by Southern blot hybridization analysis of restricted DNA with labeled 16S- and 23S rRNAs. Ribotyping analysis revealed that two species contain unlinked 16S- and 23S rRNA genes. Planctomyces limnophilus possessed two unlinked rrn genes which were separated from each other by at least 4.3 kb, and Thermus aquaticus had to unlinked 16S and 23S rRNA genes, separated from each other by at least 2.5 kb. Gemmata obscuriglobus exhibited five genes for which the organization could as yet not be determined because of the complex hybridization patterns. In the other two species, rrn genes clustered in operons. Thermotoga maritima had a single gene for each rRNA species which were separated by not more than 1.5 kb, while Verrucomicrobium spinosum had four copies of probably linked 16S and 23S rRNA genes with a maximal distance between 16S and 23S rRNA genes of 1.3 kb.     

Isolation,Biological Properties,and Spatial Structure of Antibiotic Loloatin A

A peptide antibiotic with cyanolytic activity was isolated from the IGM52 strain of the Brevibacillus laterosporus Gram-positive spore-forming bacteria. By ¹H NMR spectroscopy, this antibiotic was identified as loloatin A, a cyclic decapeptide cyclo(-Asn-Asp-Tyr-Val-Orn-Leu-D-Tyr-Pro-Phe-D-Phe-). The spatial structure of loloatin A in solution was determined.     

Identification of b,c, and d cytochromes in the membrane of Vitreoscilla

Cytochromes b, c, d, and o were identified by spectroscopic analysis of respiratory membrane fragments from Vitreoscilla sp., strain C1. Carbon monoxide difference spectra of the reduced membranes had absorption maxima at 416, 534, and 571 nm (ascribed to cytochrome o) and 632 nm (cytochrome d). Derivative spectra of the pyridine hemochromogen spectra of the membranes identified the presence of b- and c-type cytochromes in Vitreoscilla. The cyanide binding curve of the membranes was biphasic with dissociation constants of 2.14 mM and 10.7 mM which were assigned to cytochrome o and cytochrome d, respectively. Membranes bound carbon monoxide with dissociation constant 3.9 M, which was assigned to cytochrome o. Cytochrome c ₅₅₆ and a NADH-p-iodonitrotetrazolium violet reductase component were partially purified from Vitreoscilla membranes.Abbreviations INT p-iodonitrotetrazolium violet - RMF respiratory membrane fragments - K _d dissociation constant - CHAPS 3-[(3-cholamido propyl) dimethylammonio]-1-propanesulfonate - DOC sodium deoxycholate - PAGE polyacrylamide gel electrophoresis - SDS sodium dodecyl sulfate     

Dispersibility, cost and allometry of tumblers (Combretum, Combretaceae) and parachutes (Leucadendron, Proteaceae) of different size

Fall rates of tumblers ofCombretum and of parachutes ofLeucadendron are shown to be generally high (> 1.8 ms^–1). Tumblers contribute up to 77% of the mass of the dispersal unit and parachutes upto 22%. This implies that they are relatively expensive and inefficient in comparison with other propagule types. Morphometric analyses confirm previous findings that species with large seeds also have the largest dispersal structures, but the lowest dispersibility. Finally, there is a correlation between the sizes of these propagules and their associated leaf-size, confirming other studies that link the relative sizes of various plant attributes.     

Introduction,distribution, spread,and impacts of exotic freshwater gastropods in Texas

We examined the patterns of distribution, vectors of introduction, and potential ecological impacts of freshwater exotic species in Texas over the last 45 years. Currently, five species of exotic gastropods are established: channeled-type applesnail (Pomacea insularum), red-rim melania (Melanoides tuberculatus), quilted melania (Tarebia granifera), giant rams-horn snail (Marisa cornuarietis), and Chinese mysterysnail (Cipangopaludina chinensis). In contrast to the northern part of the US, where shipping appears to be the most important vector for the introduction of aquatic invasive species, aquarium and ornamental trade dominated among unintentional vectors of introduction of all freshwater exotics in Texas, resulting in different patterns of distribution, spread, and ecological impacts. The rate of spread of exotic gastropods in Texas varied from 39 waterbodies colonized over 18 years for P. insularum to only three waterbodies during last 45 years for C. chinensis. Four of five exotic gastropods were found in highly vulnerable aquifer-fed springs and rivers, which contain numerous endemic and endangered species. The fifth species, Pomacea insularum, is an agricultural pest. Potential negative ecological effects of exotic gastropods include impacts on wetlands and wetland restoration, competitive exclusion of native snails, and the introduction of exotic parasites, trematodes, which could infect fish and waterfowl, including federally protected species. Aquifer springs with stable temperature regimes are refuges for both cold and warm intolerant species. Handling editor: D. Dudgeon     

Synthesis, characterization, and antibacterial activity of N,O-quaternary ammonium chitosan

N,N,N-Trimethyl O-(2-hydroxy-3-trimethylammonium propyl) chitosans (TMHTMAPC) with different degrees of O-substitution were synthesized by reacting O-methyl-free N,N,N-trimethyl chitosan (TMC) with 3-chloro-2-hydroxy-propyl trimethyl ammonium chloride (CHPTMAC). The products were characterized by ¹H NMR, FTIR and TGA, and investigated for antibacterial activity against Staphylococcus aureus and Escherichia coli under weakly acidic (pH 5.5) and weakly basic (pH 7.2) conditions. TMHTMAPC exhibited enhanced antibacterial activity compared with TMC, and the activity of TMHTMAPC increased with an increase in the degree of substitution. Divalent cations (Ba²⁺ and Ca²⁺) strongly reduced the antibacterial activity of chitosan, O-carboxymethyl chitosan and N,N,N-trimethyl-O-carboxymethyl chitosan, but the repression on the antibacterial activity of TMC and TMHTMAPC was weaker. This indicates that the free amino group on chitosan backbone is the main functional group interacting with divalent cations. The existence of 100 mM Na⁺ slightly reduced the antibacterial activity of both chitosan and its derivatives.