联肼·乙螨唑对蔬菜优势叶螨产卵发育的影响及其田间防效

为明确新型复配杀螨剂联肼·乙螨唑对目前蔬菜田常发生的2种优势叶螨二斑叶螨Tetranychus urticae和截形叶螨T. truncatus的杀螨活性,于室内采用离体叶碟法测定其对这2种叶螨产卵及发育的影响,于室外采用活体植株评价该药剂对2种叶螨的田间防效。结果表明,经复配杀螨剂联肼·乙螨唑及其单剂处理2种叶螨雌成螨24 h后,死亡率为20.50%～54.98%,均显著高于清水对照;联肼·乙螨唑处理较清水对照显著降低了2种叶螨卵发育至若螨期的比率,联肼·乙螨唑处理后二斑叶螨和截形叶螨的若螨率分别为4.91%和1.63%。田间试验中联肼·乙螨唑对2种叶螨具有一定的速效性,药后3 d对二斑叶螨和截形叶螨的防效分别达95.74%和89.83%,药后7 d防效分别为98.03%和99.44%,显示了优良的防控效果及持效性。表明复配杀螨剂联肼·乙螨唑可用于田间蔬菜优势叶螨种群的高效防控。     

温度对截形叶螨生长发育和繁殖的影响

在室内15—35℃恒温条件下,截形叶螨的发育历期与温度呈负相关,在15、25和35℃下雌螨一代平均历期分别为32.13、9.02和5.64天;雌、雄螨一代发育起点温度分别为10.90和11.33℃,有效积温分别为135.42和110.47日度;不同温度对世代存活率及子代雌雄性比的影响无显著差异,但雌成螨的寿命及产卵期均随着温度的升高而缩短;30℃下内禀增长率(0.3298)、周限增长率(1.3907)、净增殖率(130.993)、日产卵量(10.98)及总产卵量(181.90)都最高,30℃是种群繁殖增长的最适温度。     

Influence of enteric helminths on the distribution of intestinal endocrine cells belonging to the diffuse endocrine system in brown trout,Salmo trutta L

The presence of intestinal helminths in the alimentary canal of brown trout, Salmo trutta L., can alter the number of cells that synthesize modulatory peptides. A total of 167 brown trout were collected from tributaries of the River Brenta (northern Italy), of which 119 (71.3%) specimens were infected with enteric helminths, 28 with the acanthocephalan Pomphorhynchus laevis Müller, 1776 with intensity of infection ranging from 1 to 162 (18.57 +/- 30.79) worms per host and 67 fish with the cestode Cyathocephalus truncatus Pallas, 1781. Intensity of infection with C. truncatus ranged from 1 to 85 (6.87 +/- 12.59) per fish. In 24 fish there were concurrent infections of both species of helminths. The caecal and middle regions of the intestine were the most heavily parasitized. Immunohistochemical tests showed a decrease in endocrine cells (ECs) of the diffuse endocrine system (DES) positive to gastrin, cholecystokinin-8, bombesin and secretin antisera in the intestine of the infected trout. The number of ECs immunoreactive to anti-glucagon serum did not show differences in the digestive tract of uninfected brown trout and in conspecifics parasitized with P. laevis. The density of cells containing glucagon-like material was low in the fish parasitized with C. truncatus. The results suggest that endoparasitic helminths induce alterations in the DES of infected S. trutta.     

Occurrence and present status of coastal dolphins (Delphinus delphis and Tursiops truncatus) in the eastern Ionian Sea

• 1. Boat surveys aimed at studying short‐beaked common dolphins and common bottlenose dolphins in eastern Ionian Sea coastal waters were conducted between 1993 and 2003. During 835 survey days, 24 771 km of total effort was distributed within an area of 480 km², resulting in 428 common dolphin and 235 bottlenose dolphin sightings.
• 2. Individual photo‐identification was performed extensively throughout this study, making it possible to monitor the number of animals seen in the study area each year and their long‐term residency patterns.
• 3. Common dolphins declined across the study period, from 2.18 encounters/100 km in 1997 to 0.40 encounters/100 km in 2003. In contrast, there was a relatively stable presence of bottlenose dolphins, some individuals showing high levels of site fidelity and others using the area only occasionally.
• 4. The local decline of common dolphins and the low density of bottlenose dolphins appeared to reflect the general status of these cetacean species in the wider Mediterranean region, where common dolphins were classified as endangered in the IUCN Red List in 2003.
• 5. Based on the available evidence, we infer that the present unfavourable status of common dolphins in eastern Ionian Sea coastal waters is largely a consequence of prey depletion.

Copyright © 2005 John Wiley & Sons, Ltd.     

温度对玉米截形叶螨生长发育的影响

在15℃－35℃恒温条件下，玉米截形叶螨Tetranychus truncatus的发育历期与温度呈负相关；雌、雄螨1代发育起点温度分别在12．60和12．65℃，有效积温各为137．78和121．52日度；25℃－35℃时卵孵化率和幼若螨存活率都较高，并且发育速率较快，该范围是截形叶螨生长发育的最适度。     

温度和光照长度对截形叶螨繁殖的影响

在自动控制温度和光照长度的小实验室内，采用二次回归通用设计，对截形叶螨的繁殖方面进行了研究，其结果表明：产卵高峰期和子代性比与温度和光照长度无关；产卵期随着温度的升高呈直线缩短的函数关系；日均产卵量随着温度的升高呈直线增加的函数关系，光照长度对日均产卵量呈开口朝下的抛物线函数关系；雌螨寿命在本试验范围内最短寿命为17天左右，最长寿命为69天左右.     

温度和光照长度对雄性截形叶螨生长发育的影响

采用二次回归通用设计的方法,对雄性截形叶螨生长发育进行了研究。结果表明：从完成一个世代的发育历期来看,温度的作用明显大于光照长度的作用;温度和光照长度之间存在正向互作关系,但不十分显著。在３３．４℃、１１．５３ｈ／ｄ光照条件下,完成一个世代所需的时间最短（４．８９ｄ）。     

保护地黄瓜截形叶螨种群动态的研究

截形叶螨在保护地黄瓜上的空间格局为聚集分布．分布的基本成分为个体群,聚集强度与叶螨的密度有关,随着密度的上升而下降;截形叶螨在保护地黄瓜上呈指数增长,模型为N1=1．3634e^0.31261(R=0．9174^**)。应用最优分割法将截形叶螨种群动态划分为3个阶段：初建期、发展期和高峰期。在种群初建期,截形叶螨开始迁入,数量较低,以扩散为主,分布不均匀,聚集强度较高;在发展期,截形叶螨种群不断扩散,分布日均匀,聚集强度逐渐下降;在高峰期,截形叶螨种群数量急剧增长到高峰,聚集强度继续下降,此阶段由于黄瓜接近成熟及受害枯萎．截形叶螨因缺少食物而数量急剧下降。     

Linking small pelagic fish and cetacean distribution to model suitable habitat for coastal dolphin species,Delphinus delphis and Tursiops truncatus,in the Greek Seas (Eastern Mediterranean)

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