Host plant influences life cycle,reproduction, feeding,and vector competence of Thrips palmi (Thysanoptera: Thripidae), a vector of tospoviruses

Phytoparasitica - Thrips palmi, an important pest of vegetables and ornamentals, transmits several tospoviruses. Effect of tospovirus on host plant and vector is well studied. Little is known about...     

Evidence for resistance to Citrus tristeza virus in pomelo (Citrus maxima Merr.) grown in Darjeeling and Sikkim hills of India

Darjeeling and Sikkim hills of India are well known for production of mandarin orange (Citrus reticulata). The recent spread of Citrus tristeza virus (CTV) has threatened the citrus cultivation in this region. During a survey in Darjeeling and Sikkim hills, pomelo trees were recorded as CTV free. Since pomelo trees did not show any disease appearance, a study was undertaken to ascertain whether they are resistant to CTV infection or resistant to aphid feeding or both. Toxoptera citricida, the most efficient aphid vector and which is abundantly present in this region, did not feed on pomelo when other Citrus species such as mandarin, kagzi lime and rough lemon were available. Additionally, CTV isolates of Darjeeling and Sikkim hills were not transmissible to pomelo either by T. citricida or grafting. We report for the first time that pomelo is resistant to isolates of CTV present in this region.     

双毛细管静电雾化电场特性研究

为探究毛细管电极形成的空间电场对静电雾化过程的影响,建立了适用于单、双毛细管静电雾化的实验系统,并采用高速数码摄像机记录了无水乙醇的静电雾化过程,通过系统分析雾化图像获得了滴状、纺锤形、脉动锥射流、旋转锥射流、稳定锥射流和多股射流等典型的静电雾化模式;并依据锥射流雾化模式下对应的实验工况,利用静电场叠加原理与椭圆积分方法,对单、双毛细管静电雾化电极产生的空间电场进行了理论分析与数值计算。研究结果表明:单、双毛细管电极的轴线上电场强度最大,电场强度随着φ(空间中的任意一点P与毛细管轴线正向的夹角)的增大而减小,随着r(原点O与点P的距离)的增大而减小;与毛细管单电极相比,相同条件下,毛细管双电极中间区域的径向电场强度减小,轴向电场强度增大,非相干区域的电场强度均增大;毛细管双电极的空间电场的分布使得静电雾化产生的射流与雾滴群等呈现"八"字状,即偏离双毛细管几何对称面向外倾斜。