斌吉吉 斌吉吉
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农业昆虫中的重要目 第一节:直翅目 Orthoptera 其取之希腊文σρθσδ直(straight )+πτερα翅(wing)的意思 包括蝗虫、蟋蟀、螽斯、蝼蛄等种类昆虫。属有翅亚纲、渐变态类。广泛分布于世界各地,以热带地区种类较多。一、形态特征 体中至大形。仅少数种类小形,口器为典型咀嚼式,触角长,多为丝状。前翅革质,后翅膜质,翅脉多平直。(一) 头部 多数种类为下口式,少数穴居种类为前口式。上领发达,强大而坚硬。复眼大而突出,单眼一般2—3个,少数种类缺单眼。多数种类触角丝状,有的长于身体,有的较短;少数种类触角为剑状或锤状。(二) 胸部 前胸特别发达,背板常向背面隆起呈马鞍形,中、后胸愈合。前翅狭长、革质,停息时覆盖在体背,称为覆翅;后翅膜质,臀区宽大,停息时呈折扇状纵褶于前翅下。有些种类的翅退化成鳞片状。有的前翅较宽,雄性在肘—臀脉区特化成发音构造,两前翅相互磨擦发音(如螽斯、蟋蟀、蝼蛄等)。部分种类前足特化成开掘足(如蝼蛄),多数种类后足形成跳跃足(如蝗虫、蟋蟀、螽斯)。(三) 腹部 腹部一般ll节,少数仅见8—9节,第11腹节较退化,分成背面的肛上板和两侧的肛侧板。具尾须l对,短而不分节或长丝状。雌虫产卵器一般都很发达,仅蝼蛄等无特化的产卵器。 多数种类雄虫常具发音器,以翅相互磨擦发音,或以后足腿节内侧的音齿与前翅相互磨擦发音。能发音的种类常具听器,螽斯、蟋蟀、蝼蛄等的听器位于前足胫节基部,或显露,或呈狭缝形;蝗虫类的听器位于腹部第1节的两侧,近似月牙形。口器咀嚼式
科学家发现昆虫停止呼吸是为避免吸氧过量 《自然》杂志刊登最新发现———  为什么昆虫会“例行公事”地一次中断好几分钟的呼吸?这是一个困扰生物学者数十年的问题。最近,一项关于昆虫呼吸系统的新研究将揭开谜底:昆虫停止呼吸是为了避免因吸入过量氧气而造成的损害。  这是一个同以往的理论完全不同的新角度。  UCI大学和德国洪堡大学的研究人员提出,蝗虫、飞蛾、蝴蝶、某些类型的果蝇、甲虫和臭虫等昆虫会周期性地关闭自身的呼吸系统,以达到避免吸入过量氧气的目的,从而防止自己因为吸氧过多而使身体组织受到伤害。  蒂莫西·布拉德利是UCI大学生态学和生物进化学的教授,斯蒂芬·赫兹是德国洪堡大学生理学助理教授,他们二人在《自然》杂志2005年第3期上发表了他们这项最新发现。  为了保护身体,昆虫都会选择间歇性的“停止呼吸”。  昆虫呼吸系统的构造能够适应自身在不同环境中活动的需要。比如,蝗虫在飞行时身体处于最活跃的状态。当蝗虫在休息或者不那么活跃的时候,如果它仍然保持着和飞行时一样的氧吸入量,将会造成体内氧含量过剩,会引起氧化性损害的组织损害。因此,为了保护自己的身体,很多像蝗虫这样的昆虫都会选择间歇性的停止呼吸。  布拉德利说,为了使体内的氧含量浓度降低到一个生理学上的安全值,大多数昆虫会停止呼吸,它们通过充分地减少体内气体交换来达到这个目的。他的假设说明,昆虫的呼吸模式会根据环境的不同而改变。  这项研究对于以往的理论是个极大挑战。  以往存在两种解释昆虫间隔性停止呼吸的说法。  一种说法是,这样不连续的呼吸是为了减少水分的流失。  另一种说法是,当昆虫处于地下时,间隔性停止呼吸可以帮助它们摆脱呼吸的副产品———二氧化碳。和在地下矿井里工作的矿工一样,处于地下的昆虫也会面对高浓度的二氧化碳和极低的氧气含量,为了寻求更好的空气流通条件,它们不得不选择间隔性的呼吸。如果说氧气的实质是保证昆虫体内的细胞产生能量,那么昆虫体内二氧化碳的移动则起到了非常重要的保护作用,可以使它们的身体组织免于受到有毒物质的侵害。  同样道理,空气中的氧气浓度过高对人体是有毒害作用的。  研究这个问题,就不得不提到氧气与生物体的关系问题。众所周知,氧气是生命之源。但是吸入的氧气过量也会导致生物体死亡。身体组织暴露在活性很强的氧分子中,会使蛋白质、脂类和DNA受损,促使细胞死亡、加快衰老。  对于人类自身而言,我们的身体必须向组织提供氧气,但是身体也必须保证其组织能够避免过量氧气导致的氧化性损伤。这种损伤和年龄的增长密切相关。或许正是因为这个原因,市场上才会出现众多具有防氧化作用的化妆品,帮助人们对抗岁月的痕迹。空气中的氧气浓度过高对人体是有毒害作用的。  事实上,近十年来的观察发现,果蝇在高氧含量的空气环境中生存,其寿命也会缩短。由此看来,和人类用化妆品对自己进行保护一样,昆虫停止呼吸实际上也是一种自我保护。  如果将这项研究应用于实际,对于虫害地区来说会是一个很好的消息。  布拉德利和赫兹接下来的工作是研究一个更加全面的昆虫呼吸模式。他们计划把现有的模式发展成为可以解释所有种类的昆虫呼吸行为的模式。他们还将继续研究那些在已知呼吸模式之外的昆虫,比如沙漠甲虫。尽管我们已经知道昆虫对身体外部和内部的氧浓度有着准确的判断和适当的调节,但是我们并不了解这一切究竟是如何发生的,昆虫体内都有哪些组织和细胞参与到这个过程中。  世界上有很多国家和地区饱受虫害之苦,农业、林业等产业造成了很大的损失。如果具备了更多关于昆虫呼吸的知识,我们会更加清楚地知道何时使用杀虫剂能起到最佳效果,这将能有效地避免虫害造成的损失。  实验室  昆虫通过身体两侧的通气孔获得氧气  在实验中,研究人员把数根制造精细的管子插入蛾虫的通气孔,这不仅能测量出蛾虫释放的二氧化碳的量,还可以获得其气管中氧浓度的数据。这些管子直接把空气传送给体内细胞,以实现气体交换。利用一个呼吸运动计(一种在配备了空气流通系统的房间中测量呼吸运动的器械),研究人员观测了蛾虫的呼吸过程。在放置蛾虫的房间中,他们首先注入含有丰富二氧化碳的空气,然后测量出蛾虫自身排出二氧化碳的时间和数量。  布拉德利解释说,昆虫在自身呼吸系统中保持4到5千帕的氧浓度,比正常的大气氧浓度低4到5倍。这个现象是很有代表性的。在一个氧浓度正常的环境中,昆虫保持一段时间的呼吸,然后会像爆发一般的突然释放二氧化碳。在这之后,它会关闭自己的呼吸系统,避免吸入更多的氧气,使体内氧气含量维持在4到5千帕,这样的氧含量对于昆虫身体是有利的。在外界氧浓度较低的情况下,昆虫会长时间打开呼吸系统,而它关闭呼吸系统的时间是很短的。在与此相反的情况下,也就是在氧浓度较高的空气流动中,昆虫的呼吸系统会暂时开放,然后紧紧地关闭,并将持续很长一段时间。换句话说,昆虫进行氧气交换的活动十分活跃,并且它们的方式很特殊,就好像它们懂得测量周围空气中的氧浓度一样。布拉德利说,昆虫的行为说明它们的身体会自行调节内部的氧含量。
美制造出能飞翔的机器蝇 本领超过“007” 苍蝇总是不受人们欢迎的,但现在,美国五角大楼的高级官员们和许多生物研究所正在以前所未有的热情来关注这种不起眼的动物。日前,美国加州大学伯克利分校的科学家们宣称,他们已经利用仿生学原理制造出了世界上第一只能飞翔的“机器蝇”。苍蝇,动物世界的战斗机  苍蝇个头虽小,却能以40公里的时速飞行;如果发现情况,能在3%秒的瞬间迅速起飞;苍蝇飞行一整天却只消耗食物1/10克。加州大学伯克利分校的一位生物学家说:“苍蝇是所有飞虫中,飞行最稳定,机动性能最佳的。在动物世界,苍蝇就是喷气式战斗机。”  加州大学展示的这只机器蝇名叫“黑寡妇”,重量只有100毫克,身高不到3厘米。该项目负责人马特·金侬介绍说:“它在100米上空飞行,人们用肉眼几乎发现不了它,而它却可以拍出极为清晰的照片传回。”不过科学家表示,目前这只机器蝇飞得太快,不能自行控制方向。而他们理想中的机器蝇则应该飞得快慢自如,可以随时变换方向,而且会自行判断周围情况,躲在不为人知的角落。  机器蝇,未来的超级间谍  虽然机器蝇的研制目前还处于初级阶段,但其广泛的应用前景已引起多方关注。美国五角大楼对有望成为“微型间谍”的机器蝇极为重视,自1998年这项研究刚刚开始时就一直大力资助。他们设想,机器蝇可以帮助军方完成侦察阿富汗山洞或是寻找伊拉克秘密武器等艰巨任务。而在未来战争中,机器蝇甚至可以带上微型炸药,飞到敌方总部,将其指挥官炸死,或炸掉其指挥中心的所有仪器。总之,机器蝇将完成过去“007”远远完成不了的任务,成为名副其实的“超级间谍”。  研究人员说,在未来的机器蝇身上,将安装许多传感器和微型摄像机,因此他们能做的事情还有很多。比如可以用来发现森林火灾,在灾难中搜寻废墟中的幸存者。在太空探索中,机器蝇也大有可为。在未来登上新星球后,机器蝇可代替航天员,在各种复杂条件下完成拍照、摄影、取样等工作。  让机器蝇像苍蝇那样飞  尽管机器蝇的前景看好,但真正让它飞起来却很困难。苍蝇的翅膀上分布着20块功能不同的肌肉,如何模仿肌肉运动实现飞行,成为研究的重点。加州大学伯克利分校的研究人员用了4年、近2000个小时的研究时间,就是为了弄清苍蝇翅膀是如何工作的。研究人员做了30多个模型,最终,他们利用一种类似玻璃纸的原料聚酰亚胺,造出了只有10毫米长、3毫米宽、5微米厚的仿生翅膀。它能够每秒钟扇动150下,而且还让机器蝇实现了绑附在一根细线上的半自主飞行。科学家们说,他们希望在未来两年内让机器蝇像真苍蝇一样完成起飞、空中飞行和着陆等动作。  机器蝇研制的另一个难题是燃料和驱动问题。由于体积所限,未来机器蝇必须使用高效的微型驱动设备。麻省理工学院爱普斯坦教授的实验室正在开发微型涡轮喷气发动机,可用与生产计算机芯片相同的工具和技术,实现批量生产。专家说,未来的微型喷气发动机可望缩小到只有米粒大小,其动力却足以使机器蝇飞翔数天而不用着陆。
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呵呵~大冬瓜又回来了 ``````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````燕````````````````````````````````````````````````````````燕燕燕``````````````````````````````````燕燕燕````````````燕燕燕````````````````````````````````````燕燕燕燕燕````````燕燕燕燕燕燕燕燕燕燕燕燕燕燕``````````````````燕燕````````燕燕燕````燕燕``````````燕燕燕``````````````````````````燕燕燕燕``````燕燕``````````燕燕``````````````````````````````燕燕````````燕燕````````燕燕燕````````````````````````燕``````````````燕燕燕燕``````````````````````````````````燕燕燕````````````燕燕燕燕``````````````````````````````燕燕燕燕````````````燕燕````燕燕``````````````````````````燕燕燕燕``````````燕燕燕````````燕燕燕燕````````````````燕燕燕燕````````燕燕燕燕燕````````````燕燕燕燕燕燕燕````````燕燕燕````````燕燕燕燕````````````````````燕燕燕燕````````````燕````````````燕````````````````````````````燕燕``````````````````````````````燕燕燕````````````````````````````````````````````````````燕燕燕````````````````````````````````````燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕````````燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕燕``````````````````````燕燕燕````````````燕燕燕````````````````````````````````````燕燕````````````燕燕燕````````````````````````````````````燕燕燕燕燕````````燕燕````````````````````````````````````````````燕燕燕燕燕燕燕燕``````````````````````````````````````````````````燕燕燕燕燕燕燕````````````````````````````````````````燕燕燕燕燕````燕燕燕燕燕燕````````````````````````燕燕燕燕燕燕燕燕``````````````燕燕燕燕燕````````````````燕燕燕燕燕燕燕````````````````````````燕燕``````````````````燕燕燕``````````````````````````````````````````````````````````````````````````````````````````````````````````
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