Seasonal population dynamics of Typhlodromus pyri Scheuten (Acari, Phytoseiidae) in apple orchards in the region Meckenheim

Typhlodromus pyri Scheuten (Acari, Phytoseiidae) has been reported as the most important predator of the European red mite, Panonychus ulmi (Koch) (Acari, Tetranychidae) in apple culture. However, biological data on T. pyri was insufficient on important parameters like seasonal population dynamics and within-tree and on-leaf distribution in apple orchards in the region of Meckenheim, Germany. The purpose of the present work was, therefore, to obtain experimental data on these parameters of T. pyri from 2000 to 2002 in the apple orchards in this region. The results showed that overwintered females of T. pyri reactivate and start laying eggs between late March and early April. The mean daily number of the different stages of T. pyri per leaf peaked in July each year, where it ranged between 0.92–1.68 eggs, 0.81–1.41 nymphs, 0.64–1.32 females and 0.37–0.52 males. A significantly higher number of T. pyri individuals congregated in the bottom layer of trees (0.34–0.64 individuals/leaf) than in the middle and top layers (0.23–0.38 and 0.12–0.23 individuals/leaf, respectively). We found that 91.4–94.1% of the total eggs, 89.6–91.7% larvae, 73.0–76.5% nymphs, 60.5–64.6% adult females and 52.6–55.9% adult males concentrated their activities in the inner area of the leaf surface. More than 50% of the predatory mites congregated in the bottom layer in winter. Mean total density of the overwintering females in December of 2000,2001 and 2002 ranged between 10.6–14.2 females/5 cm twig in the bottom, 7.3–10.4 in the middle and 4.1–6.9 in the top layers of the apple trees. Mean total fecundity recorded over the 3 years was lowest in the overwintering generation with 31.8–37.6 eggs/female, highest in the June generation with 45.9–53.7 eggs/female, and intermediate in the August generation with 41.5–46.1 eggs/female. The overwintering generation was composed entirely of females, while the female to male ratio in the June generation was 2:1, and in the August generation 3:1. T. pyri overwinters as adult females in rough structures, cracks and crevices of twigs.     

Factors influencing mansonone induction in elm callus by culture filtrate elicitors of Qphiostoma ulmi

Mansonone F (phytoalexin) production in elm callus induced by elicitors of Ophiostoma ulmi is affLited by cultural and experimental conditions. These factors include different fun gal isolates, fungal culture age, elicitor concentration, the time of elicitor treatment, the callus cu Ytured with or without light and the callus subculturing frequency.     

瑞丽柠檬园红蜘蛛消长规律及药剂防治研究

在云南省瑞丽市进行了柠檬园红蜘蛛的消长规律及药剂防治研究。结果表明:柠檬红蜘蛛主要在11月至次年1月发生,其发生量在1月中旬达到高峰(2500~3000头/株);红蜘蛛在树冠北方、南方的发生量较多;柠檬园红蜘蛛的发生和为害与温度、湿度、食料、施肥、施药等因素关系密切;在7种供试药剂中,以4%螺螨酯悬浮剂、1.8%阿维菌素乳油和73%炔螨特乳油对红蜘蛛的防治效果较好,且对柠檬的嫩梢、花和幼果安全无害。     

兰州苹果园叶螨优势种演变原因其防治对策初探

通过对不同化学防治水平苹果园叶螨种群数量的调查、室内杀虫(螨)剂对叶螨相对毒性的测定以及对叶螨在苹果叶片上的分布及为害性状的考察表明:①频繁施用杀虫(螨)剂的果园.苹果全爪螨的种群数量明显大于李始叶螨种群数量;施用杀虫(螨)剂次数少的果园,李始叶螨的相对数量均高于苹果全爪螨;多年不喷洒杀虫(螨)剂的果园.李始叶螨种群数量占绝对的代势.②苹果全爪螨对三氯杀螨醇的扰性显著强于李始叶螨.③李始叶螨和苹果全爪螨在苹果叶片上存在着相互干扰.营养竞争等现象.进而证实田间大量使用三氯杀螨醇是促使兰州苹果园叶螨优势种演变的主要原因.并对压低苹果全爪螨发生基数和控制苹果园叶螨的防治对策进行探讨.     

叶螨危害与苹果叶片无机营养关系初步研究

应用模糊聚类和统计分析方法研究了苹果叶片 P,K,Mo,Zn,Mn,Cu,B,Ca,Mg 和Fe 十种无机营养元素与苹果全爪螨和山楂叶螨危害的关系。结果表明:10种元素与不同果园或地域两种叶螨的发生比例及密度相关;在品种、树龄相同条件下10种元素含量的差异可能是制约叶螨发生的原因之一;苹果不同品种间10种营养元素含量的差异与苹果全爪螨密度有关;Mo,Fe,Mn 和 K 可能是影响两种叶螨发生危害的重要营养元素,它们在叶片上分布的不均匀性可能是导致两种叶螨在同一叶片上生态位分离的主要原因。     

不同柑桔种质资源对桔全爪螨酶活性及其对药剂敏感性的影响

采用生物测定和微量滴度酶标板法,研究了7种柑桔种质资源上桔全爪螨种群对炔螨特的敏感性及其体内羧酸酯酶(CarE)活性的变化。结果表明取食不同柑桔种质资源的桔全爪螨对炔螨特的敏感性不同,按其LC50从小到大依次排列为大浦、太田柑、天草、纽荷尔、枳壳、德尔塔和北碚447。其中在北碚447上种群的LC50是大浦上种群的6.96倍。生化分析表明,取食不同柑桔种质资源的桔全爪螨体内的羧酸酯酶活性不同,从低到高依次为大浦、太田柑、天草、纽荷尔、枳壳、德尔塔和北碚447。比较7个种群羧酸酯酶活性个体频率分布发现,北碚447和德尔塔种群中有更多的桔全爪螨个体向酶活性高的区域分布,且对药剂的敏感性与酯酶活性间存在显著的相关关系。     

桔全爪螨自然种群生命表及其分析的改进

通过系统调查和室内观察，采用平均历期法，组建以作用因子组配的桔全爪螨自然种群生命表。组配自然种群生殖力表，以内禀增长率（ｒｍ）等作为判断桔全爪螨种群数量发展趋势的指标。分析结果表明，在春季天敌对桔全爪螨种群数量的控制作用是明显的，但天敌作用不足以控制桔全爪螨种数量的增长，需辅助以其他措施进行控制。     

1％阿维·鱼藤新型乳油防治柑橘红蜘蛛田间药效试验

采用1％阿维·鱼藤新型乳油对柑橘红蜘蛛进行田间药效试验。结果表明,1％阿维·鱼藤新型乳油500、1000和1500倍液3个处理对活动螨态均具优异的杀灭效果,药后1d,500倍液处理组防效显著高于对照药剂200阿维·哒3000倍液处理,二者各为99．70%±0．30％和93．64%±2.29％;药后5d,1％阿维·鱼藤新型乳油500、1000和1500倍液3个处理对活动螨态的防效与对照药剂相当,4者防效均高达94．72％以上。此外,1％阿维·鱼藤新型乳油1500、1000和500倍3个处理均对柑橘红蜘蛛螨卵具一定的杀卵效果,其中500倍处理组的杀卵作用较好,校正杀卵率达80．59%±2．51％。     

束管食螨瓢虫对桔全爪螨的捕食作用研究

束管食螨瓢虫对桔全爪螨成螨，若螨，幼螨的功能反应是ＨｏｌｌｉｎｇⅡ型反应，对卵的反应为Ⅰ型反应；温度，空间异质性不改变功能反应的类型，只影响其参数。捕食者个体间的干扰系数随空间的增大而减小。饥饿程度强烈地影响着捕食行为，成虫在饱食后１．４ｈ内停止捕食。