Comparative laboratory evaluation of the acute and chronic toxicology of diflubenzuron,hexaflumuron and teflubenzuron against II instar desert locust (Schistocerca gregaria) (Orthoptera: Acrididae)

The acute and chronic toxicities of three benzoylphenyl ureas, diflubenzuron, hexaflumuron and teflubenzuron were assessed under laboratory conditions against two-day-old second (II) instar Desert Locust, Schistocerca gregaria (ForskÅl) nymphs. Following exposure by ingestion of a single precise dose applied to short pieces of spring barley, nymphs were monitored for two moults until the fourth (IV) instar. Analysis of acute response data gave three significantly different LD₅₀ statistics (P < 0·05), 68·0, 26·6 and 0·71 μg per nymph respectively for diflubenzuron, hexaflumuron and teflubenzuron. The probit regression slopes also differed significantly, indicating distinct tolerance distributions for the three compounds, the narrowest response being to diflubenzuron and the widest range of response being to teflubenzuron. The timing of death was found to vary between the compounds; most nymphs died during the first moult following treatment with either hexaflumuron or teflubenzuron. However, the majority of nymphs that died after exposure to diflubenzuron did so after completing the first moult after treatment, but before the second. The mean development times of nymphs during the II and especially third (III) instars were significantly longer (P < 0·05) than those of the controls following exposure to diflubenzuron and hexaflumuron. Teflubenzuron had no significant effect (P < 0·05) on the duration of the II instar. The potential of the three compounds to control S. gregaria populations in the field is discussed with particular reference to the timing and nature of acute and chronic responses.     

Sterols that modify moulting in insects

The development of insects is under the control of a steroid hormone, ecdysone. This paper reviews suicide substrate type inactivators designed to inhibit the biosynthesis of ecdysone. Several series of acetylenic derivatives of cholesterol were synthesized and their biological effects on the prothoracic glands of the locust were investigated in vitro, enabling structure-activity relationships to be studied. Information on the ability of brassinosteroids, a series of plant growth regulators, to inhibit ecdysteroid activities of insects is discussed as a precursor to a study of brassinosteroid ecdysone mimics.     

西伯利亚龟象取食对荞麦不同抗感品种生化物质的影响

为探讨抗虫和感虫荞麦品种对西伯利亚龟象Rhinoncus sibiricus取食的反应, 选择抗虫品种‘蒙0207’‘晋苦6’和感虫品种‘蒙0208’‘晋苦2’, 研究害虫不同程度(轻度、中度和重度)取食情况下, 荞麦叶片中营养物质(可溶性蛋白和可溶性糖)和次生代谢物质(单宁、总酚和类黄酮)含量, 防御酶［过氧化氢酶(CAT)、苯丙氨酸解氨酶(PAL)］以及蛋白酶抑制剂［胰蛋白酶抑制剂(TI)、胰凝乳蛋白酶抑制剂(CI)］活性的变化, 以及西伯利亚龟象体内主要解毒酶活性的变化。结果表明, 西伯利亚龟象取食48 h后, 各处理组荞麦叶片中可溶性性蛋白、可溶性糖、单宁、总酚和类黄酮的含量以及PAL、CAT、TI、CI活性均有增加。在供试的4个荞麦品种中, 抗虫品种被取食后可溶性蛋白和可溶性糖含量上升幅度较感虫品种更大, 感虫品种被取食后单宁含量,PAL、TI、CI活性上升幅度较抗虫品种更大。在不同取食程度下, 抗虫品种中的TI和CI活性均显著高于感虫品种。西伯利亚龟象成虫取食抗虫荞麦品种后体内羧酸酯酶(CarE)和谷胱甘肽S-转移酶(GSTs)活性均显著高于取食感虫品种的个体。研究结果表明, 西伯利亚龟象取食能诱导荞麦抗虫性物质含量的变化, 但对荞麦抗性品种与感虫品种的影响不同。     

种植油菜对‘玉露香梨’坐果及果实品质的影响

为明确梨树行间种植油菜在改善梨果品质方面的作用,本试验比较了行间清耕和行间种植油菜处理下梨园土壤养分和访花昆虫情况,分析了梨果实坐果率、脱萼率及果实品质。结果表明,行间种植油菜较行间清耕处理显著提高了梨园土壤中速效磷和速效钾含量,增幅为36.6%和11.2%,此外可以增加昆虫特别是蜜蜂的访问量,减少金龟子的访问量;与行间清耕+自然授粉相比,行间种植油菜+自然授粉与人工授粉处理均可显著提高梨坐果率和脱萼率,增加果实重量和减小果实偏斜率;同时,行间种植油菜+自然授粉处理下梨果实可溶性固形物和总糖含量均最高,达13.83%和9.45%。行间种植油菜可以提高梨园土壤营养和授粉昆虫的数量,增加梨坐果和改善果实品质。     

云南曲靖和蒙自万寿菊主栽区有害生物调查与分析

近年来, 我国万寿菊单一种植规模不断扩大, 有害生物的发生越发严重, 影响万寿菊产量与品质, 造成较大的经济损失。关于万寿菊有害生物调查, 前人报道多集中于吉林、海南、黑龙江、贵州、甘肃、山西等地, 对云南万寿菊主产区的有害生物缺乏系统调查。因此, 本次研究在全国最大的万寿菊种植区和近两年来万寿菊叶黄素含量最高的种植区, 即曲靖市沾益区和蒙自市冷泉镇进行有害生物系统调查, 发现曲靖地区万寿菊主要病害有褐斑病和枯萎病; 主要害虫包括美洲斑潜蝇、斜纹夜蛾、棉铃虫等10种; 主要杂草有粗毛牛膝菊、鬼针草、马唐、千针苋等19种。蒙自地区万寿菊主要病害有褐斑病和炭疽病; 主要害虫包括美洲斑潜蝇、四斑长跗萤叶甲、棉铃虫等9种; 主要杂草有粗毛牛膝菊、马唐、尼泊尔蓼、细柄野荞麦等13种。     

肥料减施下玉米-大豆间作对作物产量和昆虫群落组成及多样性的影响

为探究肥料减施下玉米-大豆间作对作物产量和昆虫群落组成及多样性的影响,在玉米、大豆单作及二者间作下施以标准肥料750 kg/hm~2和减半肥料375 kg/hm~2,于作物生长期调查田间昆虫群落组成及多样性,并在收获期对玉米和大豆进行测产。结果表明:与单作玉米相比,间作玉米在施用标准肥料下的百株生物量、百株籽粒重和千粒重分别显著增加78.33%、85.35%和38.71%,而在施用减半肥料下则分别显著增加90.91%、135.73%和33.33%;相同种植模式下,与施用标准肥料相比,减半肥料使单作玉米百株籽粒重显著降低22.45%。与单作大豆相比,在施用标准肥料下,间作大豆的百株籽粒重和千粒重分别显著降低49.47%和11.54%,在施用减半肥料下,间作大豆的百株生物量、百株籽粒重和千粒重分别显著降低73.94%、50.51%和17.39%;相同种植模式下,与施用标准肥料相比,减半肥料使大豆在单作和间作下的百株籽粒重分别显著降低65.02%和65.73%,使间作下大豆的百株生物量和千粒重分别显著降低73.14%和17.39%。与单作相比,间作均显著降低了标准肥料和减半肥料处理下玉米和大豆害虫群落的物种数、多样性指数和均匀度指数,还显著降低了标准肥料和减半肥料处理下玉米天敌昆虫群落的物种数和优势度指数以及大豆天敌昆虫群落的物种数和均匀度指数。表明玉米-大豆间作能有效提高玉米产量,降低虫害发生,但对大豆生产不利,而间作条件下减施肥料对玉米产量的影响更小。建议在田间生产中可将夏玉米和大豆间作种植,更有利于通过生态学方法控制田间害虫发生和增加作物总体产量。     

Modelling optimal timing and frequency of insecticide sprays for knockdown in preparation for other control measures

A modelling investigation was conducted into optimizing the number of sprays and inter-spray interval to reduce an insect population to a low level, for example, prior to pheromone trapping or the release of sterile males. The model population was age-structured and density-dependent. If spray mortality is 100% for each spray, then the ideal spraying schedule is easily determined from the durations of the various life stages. For spray mortality of less than 100%, a simulation was used to determine optimal spraying schedules. Relative length of the larval period, fertility rate and age to first oviposition were found to be the most important biotic parameters for this determination. Their importance is magnified as spray mortality decreases. The stage targeted by sprays and the percent mortality caused by each spray are also important in determining the required number of sprays. Using medfly (Ceratitis capitata Wiedmann) biotic parameters as an example when the spray targets adults, it appeared that neither the stage at which density-dependent mortality takes effect, nor the form of the adult survivorship curve are important in determining the optimal spray schedule.     

基于CiteSpace的昆虫性别决定基因研究现状与热点分析

为明确国内外昆虫性别决定基因研究的发展历程、研究热点及趋势,为未来研究方向提供参考与建议,本研究整理并筛选了1933—2022年中国知网（CNKI）和Web of Science(WOS)数据库收录的昆虫性别决定基因的论文,运用文献计量学分析软件CiteSpace对发文年代、关键词、作者和机构等进行可视化分析。结果表明：2001—2005年昆虫性别决定基因研究的发文量呈现上升趋势,发文量最多的国家是美国（446篇）,其次是中国（111篇）和日本（88篇）;国内外载文量最多的期刊分别是《昆虫学报》（9篇）和Genetics(94篇);通过关键词共现和聚类分析表明昆虫性别决定在国内外都是广泛关注的热点问题,且国内外研究方向大体一致,研究热点均集中在模式生物上;通过关键词共现和突现词分析发现利用昆虫性别决定基因进行害虫防治是未来研究的新趋势。     

一种从藤粉蝶分离的微孢子虫的生物学特性和分子系统发育研究

从广州市萝岗桑园周边捕捉到的野外昆虫藤粉蝶(Delias pasithoe)成虫体内分离到1株微孢子虫,经人工接种可在家蚕体内全身性寄生。用透射电子显微镜观察到该微孢子虫为双核,极丝11～12圈,极丝同型,基本符合Nosema属微孢子虫超微结构特征。该微孢子虫在其生活史发育过程中以偶倍数核为主,以二分裂方式增殖,形成双核孢子,发育周期为108 h。基于SSU rRNA和rRNA ITS序列的相似性比较和系统进化分析进一步证实该微孢子虫与Nosema属亲缘关系最近,应被分类为Nosema属‘true’Nosema亚群。     

Evaluation on resistance of 4 alfalfa （Medicago sativa ） cultivars to pea aphid （Acyrthosiphon pisum ）

在大田和室内条件下,采用大量蚜虫侵染幼苗法评价4个苜蓿（Medicagosativa）品种对豌豆蚜（Acyrthosiphonpisum）的抗性,以筛选出对豌豆蚜高抗的材料。结果表明,甘农5号（HA3）在大田和室内的抗性植株百分率均显著高于其他品种,分别为50．3％和48．9％,而猎人河的抗性植株百分率在大田和室内均较低,分别为4．0％和4．3％;4个苜蓿品种在大田的抗性级别为甘农5号高抗,甘农3号、金皇后、猎人河均为感虫,室内抗性级别为甘农5号抗虫,金皇后、甘农3号低抗,猎人河感虫。