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农药亚致死剂量对小菜蛾及其天敌优姬蜂的影响 总被引：12，自引：0，他引：12
作者总结了在农业生态系统中农药亚致死剂量对害虫天敌影响的四条通径。在模拟农药—作物—小菜蛾—优姬蜂的生态系统中,系统地分析了农药—小菜蛾—优姬蜂种群动力学,用生命表技术,以控制效应(CE)来评判系统中农药亚致死剂量对小菜蛾和优姬蜂种群的影响,以及在农药亚致死剂量影响下,优姬蜂对小菜蛾种群的控制作用。结果表明,农梦特亚致死剂量对优姬蜂的控制效应大于对小菜蛾的控制效应,受农梦特亚致死剂量影响的优姬蜂仍能对小菜蛾种群起一定的控制作用。 相似文献
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棉铃虫齿唇姬蜂的寄生对棉铃虫体内主要代谢物质的影响 总被引：1，自引：0，他引：1
寄生蜂是调节寄主害虫种群数量的一个重要因子。棉铃虫齿唇姬蜂Campoletis chorideaeUch-ida是棉铃虫Helicoverpa arm igeraHübner和烟青虫Helicoverpa assultaGuenée的主要寄生性天敌,对两种害虫的田间自然控制起着非常重要的作用。本文选取棉铃虫齿唇姬蜂-棉铃虫系统为研究对象,从齿唇姬蜂的寄生对棉铃虫体内主要代谢物质的影响等方面进行了研究。试验结果显示,棉铃虫齿唇姬蜂的寄生使棉铃虫幼虫组织中糖原含量发生了明显的变化,与未被寄生的同龄棉铃虫幼虫相比,被寄生幼虫组织中的糖原含量下降了近一倍,被寄生的棉铃虫幼虫血淋巴和虫体组织中蛋白质、脂肪的含量均显著下降。 相似文献
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小菜蛾重要寄生蜂——半闭弯尾姬蜂在中国的地理分布 总被引：4，自引：0，他引：4
半闭弯尾姬蜂Diadegma semiclausum是小菜蛾Plutella xylostella的一种主要寄生蜂,在气温较温和的地区可对小菜蛾种群起到明显控制作用.文献中未见该蜂在中国自然分布的记录.在北京、山东、河南、山西、宁夏、新疆等地采得的一种弯尾姬蜂与澳大利亚引进的半闭弯尾姬蜂形态特征一致.对中国北京和澳大利亚昆士兰两地的弯尾姬蜂种群进行了杂交试验,种群间正交、反交和回交的子代数和雌性比与种群内交配的无显著差异,表明这两个地理种群在生殖上完全亲和,属同种.这是首次以形态学和遗传学证据证明半闭弯尾姬蜂这一重要天敌在中国广泛分布. 相似文献
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为了明确颈双缘姬蜂Diadromus collaris（Gravenhorst）触角感受器的种类及分布,本试验对雌、雄蜂触角及感受器进行了扫描电镜观察。结果表明,颈双缘姬蜂触角具有毛形感受器、刺形感受器、锥形感受器、板形感受器和腔锥形感受器等5种感受器,其中毛形感受器分2种类型,锥形感受器分6种类型。毛形感器在雌蜂的触角上分布多于雄蜂,锥形感受器11只分布于雄蜂的触角上,而锥形感受器IⅡ、Ⅳ、V和Ⅵ及腔锥形感受器仅分布在雌蜂上,板形感器在雄蜂的触角上分布多于雌蜂。本文对5类感受器的形态进行了详尽描述,并与其它寄生蜂的感受器进行了比较,同时对各类型感受器的功能进行了探讨。 相似文献
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棉铃虫齿唇姬蜂触角感器的扫描电镜观察 总被引：7，自引：2，他引：7
棉铃虫齿唇姬蜂雌雄蜂触角上感器的扫描电镜观察结果显示，共发现毛形感器、板形感器、钟形感器、锥形感器、Bohm氏鬃毛和刺形感器6类感器，分别对这6类感器的类型与形态进行了详细描述，并对各种感器的功能进行了深入的分析和讨论。 相似文献
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2016年-2019年采用马来氏网监测昆明晋宁区十字花科蔬菜小菜蛾与半闭弯尾姬蜂成虫种群动态,结果表明:两者发生趋势基本一致,半闭弯尾姬蜂与小菜蛾具有跟随现象。小菜蛾和半闭弯尾姬蜂成虫全年有1～2个发生高峰期,半闭弯尾姬蜂成虫出现峰值滞后小菜蛾成虫峰值20～32 d。2016年-2019年半闭弯尾姬蜂发生高峰期分别在7月12日-8月30日、7月2日-8月21日、6月30日-8月31日、5月20日-6月10日,夏秋季寄生率明显高于冬春季,7月15日-10月30日半闭弯尾姬蜂寄生率在42.00%～87.21%,春季至夏初田间半闭弯尾姬蜂数量和寄生率较低,夏秋季是人工田间释放半闭弯尾姬蜂的最佳时期,研究结果为半闭弯尾姬蜂田间保护应用提供依据。 相似文献
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小菜蛾弯尾姬蜂室内批量繁殖的技术 总被引：7，自引：0，他引：7
报道小菜蛾弯尾姬蜂室内批量繁殖工艺技术。实验室温度：20℃－25℃，光照：L：D12：12，相对温度：65％－70％，40m^2温室面积用于栽培甘蓝。在此条件下，每周可生产2000头－3000头小菜蛾弯尾姬蜂，可田间释放寄生蜂防治小菜蛾15亩－20亩。 相似文献
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基于微波遥感技术的干旱监测指数及其应用研究——以三江源区为例 总被引：1，自引：0，他引：1
以三江源区为研究区,基于AMSR-E的亮度温度数据获得了微波极化差异指数(MPDI)、比值干旱指数(DI)和多时相微波干旱指数(PI),并分别对这3种指数进行了干旱监测有效性检验。为了获得研究区全区监测效果更好的干旱指数,对MPDI、DI和PI指数进行融合,最终获得的综合微波干旱指数(SDI)与土壤湿度数据和降水数据都存在很好的相关性,对比单个指数时监测干旱的有效性也得到了提高。最后,应用SDI指数对三江源区21世纪以来的干旱情况进行了监测研究。结果表明:基于AMSR-E的综合微波干旱指数(SDI)能有效的对干旱进行监测,充分发挥了被动微波遥感数据的优势,具有一定的应用价值,为后续利用多源的多传感器的微波遥感数据监测干旱的相关研究奠定了基础。 相似文献
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以北京师范大学陕西省靖边县榆林风沙科学野外实验站自动气象站2007-2009年的降雨、风速和风向数据为基础,分析沙漠-黄土过渡带风水复合侵蚀营力的特征。结果表明：① 研究区年内降雨量≥12 mm的降雨事件主要分布在5-9月,月平均降雨侵蚀力8月最大,为318.24 MJ·mm/(hm2·h·a),年平均降雨侵蚀力为510.08 MJ·mm/(hm2·h·a);② 该区西北风占主导地位,东南风次之,累计频率分别为43.8%和16.21%;起沙风主要集中在3-6月,其频率分别为19.34%、12.34%、20.5%、12.39%;③ 研究区年平均输沙势（DP）、合成输沙势（RDP）分别为228.76 VU、41.73 VU,合成输沙方向（RDD）为141.17°,方向变率指数（RDP/DP）为0.2,起沙风变率较大,属于中等风能环境,沙物质向东南偏南方向输移。 相似文献
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近年来关中西部冬小麦收获后耕地撂荒现象(简称秋季撂荒)日益严重。以凤翔、岐山、扶风三县为例,选取2000—2020年间9个年份春季和秋季各1期Landsat影像,运用CART决策树分类法提取9个年份秋季耕地撂荒的时空变化特征,并通过实地问卷调查探究其影响因素及驱动机制。结果表明：研究区秋季耕地撂荒主要分布在凤翔县西南部、岐山县中部以及三县北部临近山区的地带,凤翔县中部和扶风县中部秋季撂荒程度较轻;2000年以来研究区耕地秋季撂荒呈波动上升趋势,其中2000—2007年间撂荒面积逐步增加,2007—2013年间有所回落,2013—2020年间又迅速攀升,2020年撂荒范围最广,撂荒率达64.64%。近20 a研究区秋季撂荒地块由小规模零星分布逐渐转为大规模集中分布。灌溉条件是研究区秋季耕地撂荒的主要影响因素,且影响程度逐年上涨;经济区位、耕作半径和交通条件对撂荒率也有一定的影响,但影响程度逐年减小;耕地边际化是驱动研究区农户选择秋季撂荒的根本原因,劳动力短缺是研究区秋季撂荒的主要原因,灌溉缺乏、积温不足和耕地细碎化等农业生产条件不足是研究区秋季撂荒的直接原因。 相似文献
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Abdulrahim M AL-ISMAILI Moustafa A FADEL Hemantha JAYASURIYA L H Janitha JEEWANTHA Adel AL-MAHDOURI Talal AL-SHUKEILI 《干旱区科学》2021,13(4):388-396
This study aimed to explore the potential of developing a novel cooling system combining a greenhouse and an earth-tube heat exchanger(ETHE).In this system,greenhouse air is circulated through the underneath soil mass to use the deep-soil cooling effect.This was achieved through the following steps.First,soil temperature profile inside and outside the cultivated greenhouse was monitored for almost one year to study the possibility of using deep-soil coldness for cooling the greenhouse air.Second,a prototype ETHE was built to practically investigate the potential reduction in air temperature as the air flows inside the deep earth pipes.Third,a prototype greenhouse was erected to study the ETHE concept.Results from the first experiment revealed that soil temperature at a soil depth of 2.5 m inside the greenhouse offers good conditions to bury the ETHE.The soil temperature at this soil depth was below the maximum temperature(32℃)that most greenhouse crops can withstand.Results from the prototype ETHE showed a slight reduction in air temperature as it passed through the pipes.From the prototype of the integrated greenhouse and ETHE system,reduction in air temperature was observed as the air passed through the ETHE pipes.At night,the air was heated up across the ETHE pipes,indicating that the ETHE was working as a heater.We concluded from this study that greenhouses in arid climates can be cooled using the ETHE concept which would save a large amount of water that would otherwise be consumed in the evaporative coolers.Further investigations are highly encouraged. 相似文献
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BACKGROUND: In this study, the collecting efficiency of different samplers of airborne drift was compared both in wind tunnel and in field experiments. The aim was to select an appropriate sampler for collecting airborne spray drift under field conditions. RESULTS: The wind tunnel study examined three static samplers and one dynamic sampler. The dynamic sampler had the highest overall collecting efficiency. Among the static samplers, the pipe cleaner collector had the highest efficiency. These two samplers were selected for evaluation in the subsequent field study. Results from 29 individual field experiments showed that the pipe cleaner collector on average had a 10% lower collecting efficiency than the dynamic sampler. However, the deposits on the pipe cleaners generally were highest at the 0.5 m level, and for the dynamic sampler at the 1 m level. CONCLUSIONS: It was concluded from the wind tunnel part of the study that the amount of drift collected on the static collectors had a more strongly positive correlation with increasing wind speed compared with the dynamic sampler. In the field study, the difference in efficiency between the two types of collector was fairly small. As the difference in collecting efficiency between the different types of sampler was small, the dynamic sampler was selected for further measurements of airborne drift under field conditions owing to its more well‐defined collecting area. This study of collecting efficiency of airborne spray drift of static and dynamic samplers under field conditions contributes to increasing knowledge in this field of research. Copyright © 2011 Society of Chemical Industry 相似文献
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基于黑河下游额济纳旗地区的Quickbird影像,采用决策树(Decision Tree)、人工神经网络(Artifi-cial neural net,ANN)及支持向量机(Support Vector Machine,SVM)方法对干旱区植被信息进行提取。对三种方法的精度进行评价,结果显示:决策树分类得到的结果零碎,总体分类精度为84.87%;ANN法较决策树方法适宜度高,总体分类精度为91.87%;纹理信息辅助的SVM法取得效果最好,总体分类精度可达96.53%。试验中发现使用高分辨率影像提取干旱区植被种类信息时,大窗口的纹理特征辅助效果较好,但是分类结果的边界出现失常,随着纹理窗口越大,失常的范围也越大。 相似文献
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Hassink J Platz K Stadler R Zangmeister W Fent G Möndel M Kubiak R 《Pest management science》2007,63(2):171-179
The potential for short-range transport via air, i.e. volatilisation from the area of application and subsequent deposition on adjacent non-target areas, was investigated for the fungicide fenpropimorph in a wind tunnel system and under outdoor conditions in a higher-tier field study. Fenpropimorph 750 g L(-1) EC was applied post-emergence to cereal along with a reference standard lindane EC. Stainless steel containers of water were placed at different distances downwind of the application area to trap volatile residues during a study period of 24 h following application. Meteorological conditions in the wind tunnel as well as on the field were constantly monitored during the study period. The wind tunnel system was a partly standardised system on a semi-field scale, i.e. wind direction and wind speed (2 m s(-1)) were constant, but temperature and humidity varied according to the conditions outside. In the field experiment, the average wind speed over the 24 h study period was 3 m s(-1) and no rainfall occurred. Three different measuring lines were installed on the non-target area beside the treated field to cover potential variations in the wind direction. However, no significant differences were observed since the wind direction was generally constant. Fenpropimorph was detected in minor amounts of 0.01-0.05% of the applied material in the wind tunnel experiment. Even at a distance of 1 m beside the treated field, no significant deposition occurred (0.04% of applied material after 24 h). In the field, less than 0.1% of the applied fenpropimorph was detected at 0 m directly beside the treated field. At 5 m distance the deposition values were below 0.04%, and at 20 m distance about 0.01%. In general, the amounts of deposited fenpropimorph detected in the partly standardised wind tunnel system and the higher-tier field study were in good agreement. 相似文献