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一、桑螟危害特点 桑螟,俗称卷叶虫、青虫等,是我区桑园主要害虫之一.桑螟一、二龄幼虫在叶背叶脉分叉处及芽苞内取食,三龄幼虫吐丝缀成卷叶或叠叶,隐藏其中咀食叶肉.桑螟暴发时,可造成桑园片叶所剩无几,不仅影响产叶量,其排泄物还污染叶片,容易发生交叉感染引发蚕病. 相似文献
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一、桑螟危害特点桑螟,俗称卷叶虫、青虫等,是我区桑园主要害虫之一。桑螟一、二龄幼虫在叶背叶脉分叉处及芽苞内取食,三龄幼虫吐丝缀成卷叶或叠叶,隐藏其中咀食叶肉。桑螟暴发时,可造成桑园片叶所剩无几,不仅影响产叶量,其排泄物还污染叶片,容易发生交叉感染引发蚕病。二、桑螟发生规律桑螟发生正常年份,以南宁市为例,3月9日左右在田间可以见到第一代幼虫,以后每隔一个月发生一代,从5月份开始世代重叠,虫口密度急剧增加。7月份大部分桑园夏伐后,受食物和农事活动的影响,田间虫源大量被清除掉,少数桑螟转移到失管桑园或野桑上伏夏,9月中、下… 相似文献
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一、桑螟危害特点
桑螟，俗称卷叶虫、青虫等，是我区桑园主要害虫之一。桑螟一、二龄幼虫在叶背叶脉分叉处及芽苞内取食，三龄幼虫吐丝缀成卷叶或叠叶，隐藏其中咀食叶肉。桑螟暴发时，可造成桑园片叶所剩无几，不仅影响产叶量，其排泄物还污染叶片，容易发生交叉感染引发蚕病。 相似文献
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对海宁市桑螟的发生特点、变化趋势和家蚕微粒子病发生的关系进行了分析,结果表明：桑螟发生对家蚕微粒子病的发生影响较大,桑螟世代数的增加,加大了对春季蚕种生产的影响.桑螟幼虫期与养蚕期重叠,防治适期要求精准.根据桑螟容易暴发成灾,越冬环境复杂,成虫趋光性较强等特点,提出了冬春采取室内人工捕捉、回山消毒和封园治虫控制越冬基数,春季越冬代桑螟羽化期在桑园用灯光诱杀成虫,错峰饲养原蚕,春蚕期桑园中如暴发桑螟用24％溴虫腈悬浮剂2 000～3 000倍液进行防治等以春季蚕种生产防微“控毒”为目标的桑螟防治措施. 相似文献
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1999年以来,我县桑园秋季的主要害虫桑螟,一直影响着我县的蚕种和蚕茧生产。桑螟幼虫不仅与蚕争叶,而且使受害桑树叶质下降,蚕食下虫口叶后,蚕体抗逆性减弱而引发蚕病;桑螟还带有微粒子病,与蚕发生交叉感染。实践证明,当年秋季“桑园螟虫多,蚕室蚕病多”。笔者从1999年至2005年七年中对桑螟在我地暴发三次的过程进行了调查分析,对桑螟的预警有了更深的了解。1桑树害虫暴发的原因1.1虫源据调查,我地桑园内可查见的害虫达40多种,造成经济危害10余种,在同地区当年危害严重的至多2～3种。近几年来我县桑园秋季一直有桑螟的虫源存在,并在4、5代发… 相似文献
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桑螟（DiaphaniaPyloalisWalker）是我国蚕区夏秋期的主要害虫，不少年份7月下旬桑螟第2代幼虫密度并不高，8～9月间遇多雨湿润的气候，往往暴发成灾，严重影响秋蚕的饲养。笔者于1995年夏秋期进行了桑螟不同密度为害损失率和污染率的测定，制订防治指标，为控制桑螟暴发提供依据。1调查、测定与统计方法1.1第2代桑螟幼虫密度调查1995年7月底在牌头镇马家弄村，安华镇溪北村调查了桑螟发生程度较轻（一级）、中等（二级）、严重（三级）的桑园三块，以0．67hm2为1小区，重复3区，计9小区，共6hm2。1．2损失率与污染率测定。9月底先调查各… 相似文献
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Beran GW 《Preventive veterinary medicine》2008,86(3-4):198-207
When early people made their appearance, zoonotic infectious diseases were already waiting, but epidemic diseases did not appear in human history until people began to live in large numbers under conditions of close contact, mainly during the last 10,000 years. Disease has decimated urban populations, conquered armies, and disrupted society. The focus here is on (1) the plague of Athens and the Black Death; (2) smallpox, influenza, and rabies; (3) avian influenza prion diseases, and foot & mouth disease; and (4) emerging and re-emerging diseases. All have veterinary public health associations. In Athens, Greece, in 430 BC, when the Spartans ravaged the countryside, hordes crowded into Athens so that orderly movements, space in which to live, and adequate supplies of food became impossible. Crowding of any population fosters disease transmission; chaos and disorder enhance it all the more. Out of northern Egypt came a terrible plague from across the Mediterranean Sea. The identity of the plague of Athens remains unsure, but the well-considered conclusion is Rift Valley Fever, a mosquito borne, viral zoonosis. The Black Death, also called the Plague, raged in Asia for centuries. In 1347, the Black Death was brought by a ship out of Asia to Sicily. The scenes of devastation were repeated throughout Europe, with 90% or more of the people dying in city after city. Influenza, too, has been a cause of periodic human epidemics, but the great pandemic of influenza occurred in the last months of World War I. In the years of highest occurrence, more than half the world's population became clinically infected. If veterinary public health had been born earlier, it could have led to elucidating the epidemiology of influenza and the plagues of Athens, Europe, and Asia. In turn, smallpox had also caused continual tragedy. In 1796, Edward Jenner began to harvest pustules of cowpox from children or infected cows and inject them into susceptible children. In 1980, the World Health Organization declared that smallpox had been eliminated from the world. Rabies, though, still strikes terror. A number of animal diseases, broadly termed emerging and re-emerging diseases, need surveillance because they have the potential to impact human health. From late in 2003 to 2007, the highly pathogenic H5N1 influenza virus in poultry infected at least 121 people and caused 62 deaths in four countries. The prion diseases, too, all have very high numbers in concentrated contacts. To control these diseases, veterinary public health is essential, with diagnosis, epidemiological surveillance, clinical manifestations, and prevention as primary measures. 相似文献
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Dekker A Dercksen D Snoep J van Wuyjckhuise L 《Tijdschrift voor diergeneeskunde》2007,132(18):695-701
On 26th of july 2007 a new case of bluetongue was notified in the Netherlands and on 2nd of august 2007 foot-and-mouth disease was diagnosed in Surrey, England, which raised the threat of having both infections simultaniously in one area. Bluetongue and foot-and-mouth disease have a different pathogenesis, but symptoms may resemble each other at a later stage of infection. The pathogenesis and possible clinical symptoms of both infections are discussed and illustrated with pictures. 相似文献
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在动物的异常行为中以刻板行为最为常见,而咽气癖又是马最常见的口部刻板行为之一。作者就咽气癖在生理方面和心智方面对马体产生的影响、行为基础、诱因的研究进展及常见的防治措施进行综述。 相似文献
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近几年,世界饲用添加剂市场增长较快,预计今后将进一步增长,据世界粮农组织(FAO)首领会议的倡议,到2015年,将使世界营养不良的人口削减一半,其间,肉制品将会以每年2％的速度增长,特别是加快猪肉和禽肉增长。这将促进世界添加剂,尤其是蛋氨酸和赖氨酸需求量的增加。 相似文献
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