蝶蛹金小蜂寄生对菜粉蝶和玉带凤蝶蛹血细胞数量和组成的影响

以血球计数板较系统地考查了菜粉蝶和柑桔凤蝶雌雄蛹被蝶蛹金小蜂寄生后浆血细胞和颗粒血细胞数量的时间动态变化,以明确该蜂寄生对其寄主血细胞数量和组成的影响.结果表明,菜粉蝶蛹被寄生后,其血细胞总数除寄生后2天外均极显著高于同期未寄生蛹,最多的约高出20倍;除被寄生后0.5和5天的寄生蛹的血细胞组成与同期未寄生蛹无显著差异外,寄生后1～ 4 天雌雄寄生蛹的浆血细胞所占比例均显著低于同期未寄生蛹,而颗粒血细胞所占比例则反之.玉带凤蝶寄生蛹的血细胞总数在寄生后0.5 ～ 3天与同期未寄生蛹相比均无显著差异,但寄生后4 ～ 5天却显著升高,最多的约高出3倍;寄生后0.5 ～ 5天的寄生蛹浆血细胞所占比例均显著低于同期未寄生蛹,而颗粒血细胞所占比例恰反之.可见,该蜂寄生在一定时间内不仅能引起其两种寄主血细胞总数和颗粒血细胞所占比例明显增高,而且能导致浆血细胞所占比例明显下降.     

寄生蜂的外竞争和内竞争作用

寄生蜂之间的竞争作用是影响昆虫群落的大小、结构和稳定性的主要因素之一,也是影响寄主种群密度变化和生防系统有效性的关键因素。寄生蜂之间的竞争可发生在搜索寄主的成蜂之间(外竞争,extrinsic competition),亦可发生在同一寄主体内同时发育的幼虫之间(内竞争,intrinsic competition)。全面、深入地了解寄生蜂的种间和种内竞争互作关系、影响竞争结果的主要因素和竞争作用对寄主控效的影响等可为害虫生物防治体系中天敌的选择和管理提供依据,为建立持续有效的害虫生防体系奠定基础。本文首先从寄生蜂成蜂搜寻、定位寄主的能力和寄主识别的能力两个方面对寄生蜂成蜂的竞争能力进行了综述,其次又从物理攻击和生理抑制两个方面对寄生蜂幼虫的竞争能力进行了综述,最后指出了科学、全面、深入地阐明农业生态系统中多种寄生蜂间的相互作用关系的必要性。     

苹果树腐烂病室内快速评价方法的研究

 腐烂病是我国苹果树上一种严重的树干皮层腐烂病害,本研究拟探索快速、可靠、稳定及操作简便的病害室内评价方法。在"富士"苹果离体叶片、嫩梢、果实和枝条上造成不同伤口,强致病菌株03-8接种,25℃保湿培养后调查发现,不接菌对照有、无伤口均不发病;各种伤口接种病原菌均能发病,但伤口类型对病害影响很大。叶片正面较反面更有利于发病,叶片正面1针和10针的刺伤发病无明显差异;嫩梢叶痕接种较刺伤接种发病轻;果实表面针刺1针和10针及去除果皮造成伤口对发病影响大,差异显著;枝条烫伤接种后10d发病明显而其它材料在接种后1.5~2d即可发病。进一步用4个致病力不同的菌株验证评价方法的可靠性和稳定性,发现接种完全展开叶、嫩梢和枝条均可以充分显示不同菌株之间的致病力差异,但前两者重复性好、试验周期短、鉴定效率高,且操作简便、材料易得,因此建议用离体叶片或嫩梢作为材料,针刺1针接种,25℃保湿培养2d后调查,作为室内准确、快速评价苹果树腐烂病的方法,该方法可用于筛选抗病材料、评价分离株的致病性和药剂的防病效果等。     

瑞香狼毒素对菜粉蝶幼虫的拒食活性及其作用机制

瑞香狼毒素1,5-二苯基-3-羟基-1-戊酮,是本室从杀虫植物瑞香狼毒中分离得到的一个高活性化合物。本文研究了该活性成分对菜粉蝶幼虫的拒食作用和对乙酰胆碱酯酶(AChE)活性的影响。采用浸渍叶碟饲喂法测得:在48h时瑞香狼毒素对3龄幼虫的非选择性和选择性拒食作用的拒食中浓度(AFC50)分别为15.1mg/L和16.9mg/L。采用点滴法测得瑞香狼毒素对5龄幼虫的拒食作用的拒食中量(AFD50)为0.565μg/头。瑞香狼毒素对AChE活性的抵制率高达78.5%,表明该活性成分可显著抑制AChE活性。     

快速检测单头柑橘木虱体内黄龙病病原

本研究通过采用简易的柑橘木虱制样方法,利用PCR检测技术在单头柑橘木虱体内检测到黄龙病病原,并利用XbaⅠ限制性内切酶将从柑橘木虱体内扩增的黄龙病病原16SrDNA酶切成520bp和640bp两个片段,证实了木虱体内黄龙病病原为亚洲种。本研究成功地建立了一套快速检测柑橘木虱体内黄龙病病原的方法,可为检疫工作者和相关研究人员提供重要参考。     

A simple method for monitoring the respiratory rhythm in intact insects and assessing the neurotoxicity of insecticides

A simple, non-invasive method, for the monitoring of the respiratory rhythm of insects was developed. The insect was restrained and a force displacement transducer attached to one abdominal segment of the dorsal region was used to monitor the respiratory rhythm. Although the method was applied to four species of insects, the main study focused on the yellow mealworm beetle, Tenebrio molitor, due to the simplicity of the recorded respiratory rhythm. In this case, the recorded rhythmic activity represents the synchronised contraction of the dorsal abdominal muscles, driven by the respiratory central pattern generator (CPG). This non-invasive method allows prolonged and stable recording of the respiratory rhythm. The records showed a decrease in the amplitude and the duration in the rhythmic contractions to about 25 and 31% of the initial values, respectively, in the first 7 h of continuous recording. The respiratory rhythm was strongly influenced by the presence of the CO₂, creating the CO₂-reflex. In the beginning of the application of CO₂, there was total inhibition of the respiratory rhythm and then there was a gradual increase in the tension developed by the dorsal abdominal muscles. Using this recording method, it was possible to quantify the function of the respiratory CPG, measuring the amplitude of the respiratory contractions, under normal conditions and in the presence of insecticides. The insecticides imidacloprid and deltamethrin of certain quantities were diluted in the appropriate solvent to make 50, 100 and 500 ng per insect, and were applied to the cuticle, topical application, of the immobilized insect, while recordings of the respiratory rhythm were made continuously.