长棒四节蚜小蜂空间分布型及其抽样技术的研究

长棒四节蚜小蜂是杨圆蚧的重要天敌，为一种自然控制能力很强的寄生小蜂。用频数分布法、聚集度指标法研究其空间分布型，结果表明为聚集分布，分布的基本形式系一般的负二项分布。根据Ｉｗａｏ的统计方法，利用Ｎ＝１／Ｄ＾２（α＋１／ｘ↑－＋β－１）公式，计算在各种虫口密度下的最适抽样数。     

杨圆蚧生命表的研究

为了搞清各种环境因子对杨圆蚧种群数量的影响,我们从1984年—1986年在黑龙江省绥化市,进行了杨圆蚧自然种群生命表的研究。 通过生命表的研究,了解了杨圆蚧[Quadraspidiotus gigas(Thiem et Gerneck)]种群数量变动及影响因子,得出了种群趋势指数(Ⅰ)值,它是预测次代害虫发生量的依据。经过二个世代的研究结果,由于各种因子的作用,特别是黄胸扑虱蚜小蜂[Prospaltella gigas Tshumakova]以下简称蚜小蜂)的寄生,1984—1985年(Ⅰ)值为0.16,1985—1986年(Ⅰ)值为0.49,种群数量连续下降。使种群数量保持在比较低的水平。 通过生命表的研究,不但了解了种群数量变动的趋势,而且还发现了杨圆蚧的天敌,尤其是蚜小蜂,对杨圆蚧的控制能力非常强,从2龄雌若虫到交尾后的雌成虫都可以被蚜小蜂寄生,寄生率很高,因此,对蚜小蜂应加以保护和利用。     

杨圆蚧主要寄生性天敌营养和保存技术研究

为了增强寄生性天敌对杨圆蚧的控制力，对杨圆蚧主要寄生性天敌营养和保存技术进行了研究。结果表明：给杨圆蚧的主要寄生性天敌－－黄胸扑虱蚜小蜂和长角异鞭蚜小蜂，提供２０％糖水和２０蜂蜜可延长其寿命和产卵量、增强其活力，有效地控制杨圆蚧的危害。用低温和无光的条件保存小蜂成虫，既可有效地延长黄胸扑虱蚜小蜂的寿命。又可避免在保存期间产卵。长时间在低温（４℃）和无光条件下贮存小蜂将影响小蜂的活力和产卵量。建议低     

杨圆蚧利它信息素和小蜂阻止产卵信息素对小蜂控制力的影响

寄主对寄生性天敌具有引诱作用和寄生小蜂分泌产卵信息素．是保证小蜂对寄主有较高的控制力的必要条件，研究发现杨圆蚧中存在着有利于长棒四节蚜小蜂和黄胸扑虱蚜小蜂寻找寄主和产卵的一类化学物质——利它信息素．主要存在于杨田蚧的介壳中．是一类具有水溶性特征的化台物．可帮助长棒四节蚜小蜂和黄胸扑虱蚜小蜂进行寄主的定位和辨识。因此可以保证在寄主低密度条件下．成功地进行寄主定位．对寄主进行有效的控制。长棒四节蚜小蜂和黄胸扑虱蚜小蜂在寄主杨圆蚧一龄固定若虫体上产卵后．留下可以阻止同种的其它个体或异种的个体进行寄主检查和产卵的物质．即产卵标速信息素。这样便极大地减少了杨田蚧之间复寄生现采的发生．确保了杨圆蚧若虫体内的小蜂有充足的营养．也使小蜂利用有限的卵．控制尽可能多的寄主．使杨圃蚧和小蜂保持在一定的种群水平。     

昆明地区伪角蜡蚧寄生蜂空间分布研究*

 通过田间调查和室内饲养,昆明地区伪角蜡蚧的寄生性天敌有5种,其中蜡蚧扁角跳小蜂和绵蚧阔柄跳小蜂是主要寄生蜂,占寄生蜂总数的88.1%。寄生蜂的平均寄生率为13.4%。寄生蜂在大叶黄杨上部枝条的寄生率高于下部;阴面寄生率高于阳面和中间。伪角蜡蚧寄生蜂的种群空间分布用聚集度指标,Taylor幂法则和IWAO的m^*-m回归分析法进行分析,得出伪角蜡蚧寄生蜂为聚集分布。     

橡副珠蜡蚧及其两种寄生蜂的空间分布型

为了研究橡胶林中橡副珠蜡蚧及其两种寄生蜂的空间分布型,对橡胶林区的橡副珠蜡蚧成蚧、若蚧及副珠蜡蚧阔柄跳小蜂和斑翅食蚧蚜小蜂进行调查,利用聚集度指标法和Taylor幂法则分析橡副珠蜡蚧成蚧、若蚧以及副珠蜡蚧阔柄跳小蜂和斑翅食蚧蚜小蜂种群的空间分布型。结果表明:聚集度指标法和Taylor幂法则分析得出的结论相同,即橡副珠蜡蚧成蚧、若蚧、副珠蜡蚧阔柄跳小蜂和斑翅食蚧蚜小蜂的空间分布型为聚集分布,其中,橡副珠蜡蚧成蚧与副珠蜡蚧阔柄跳小蜂、橡副珠蜡蚧若蚧与斑翅食蚧蚜小蜂的空间分布型相吻合。     

瓢虫隐尾跳小蜂的初步研究

报道了红点唇瓢虫的重要内寄生天敌瓢虫隐尾跳小蜂的生活史，生活习性以及对寄主的影响和防治方法等。经在黑龙江省大庆地区调查表明，对其寄主红点唇瓢虫的寄生率可高达８２％，平均寄生率为５４％，是影响红点唇瓢虫种群数量的主导因子，因而导致红点唇瓢虫对杨圆蚧的控制力大幅度下降。     

瓢虫隐尾跳小蜂Homalotylus flaminius (Dalman) 的初步研究

报道了红点唇瓢虫的重要内寄生天敌瓢虫隐尾跳小蜂的生活史、生活习性以及对寄主的影响和防治方法等。经在黑龙江省大庆地区调查表明，对其寄主红点唇瓢虫的寄生率可高达８２％，平均寄生率为５４％，是影响红点唇瓢虫种群数量的主导因子，因而导致红点唇瓢虫对杨圆蚧的控制力大幅度下降。     

枣大球蚧和球蚧蓝绿跳小蜂空间分布型吻合程度

采用多个聚集度指标和回归分析法对枣大球蚧Eulecaniumgigantea及其主要天敌球蚧蓝绿跳小蜂Blastothrixsericae的空间分布格局进行研究。各聚集度指标均表明：枣大球蚧及其球蚧蓝绿跳小蜂在空间上的分布格局均是聚集分布;Taylor幂法则、1wao的回归分析法也表明：枣大球蚧及其球蚧蓝绿跳小蜂在空间上的分布格局也是聚集分布,且聚集强度随种群密度的升高而增加;这种分布形式的一致性,有力地提高了天敌对寄主的自然控制能力。表3参10     

小蜂对杨圆蚧的趋性及杨圆蚧挥发物分析

采用四臂式嗅觉仪测定了长棒四节蚜小蜂和黄胸扑虱蚜小蜂对杨圆蚧1龄固定若虫的虫体、介壳、虫体与介壳复合体的趋性。结果表明，介壳和虫体与介壳复合体对两种小蜂具有较强的吸引力。两种小蜂对气味源的剂量都比较敏感。采用敢相色谱－质谱联机分析方法，分析了杨圆蚧1龄固定若虫虫体及介壳所释放的挥发性物质的成分和各组分所占比例，分析表明，虫体和介壳中释放出的挥发性物质均含有9个组分，但这9个组分在虫体和介壳挥发物中的比例略有变异。     

西宁地区麦油田蚜虫蚜茧蜂田间寄生率调查初报

对我省西宁地区麦、油田内蚜虫蚜茧蜂的寄生率进行了调查,调查结果表明,麦田蚜茧寄生率在5.66%~8.39%之间,油菜田蚜茧蜂寄生率在7.83%~21.19%,油菜田蚜茧蜂的田间寄生率明显高于麦田蚜茧蜂的寄生率。     

一种新的淡水等足类--细角鳃虫的寄生行为

珠江水系西江的局部支流近年出现了严重危害网箱养殖和江河鱼类资源的寄生虫病害,初步鉴定该虫隶属于甲壳纲、等足目、鳃虫科、细角鳃虫属(RocinelaLeach),是国内新发现的淡水鱼类寄生虫。文章就该虫对麦鲮的寄生行为进行了研究,结果表明:该虫具很强的寄生能力,240 min内累积感染率达90%。对寄生部位具一定的选择性,以寄生在鳃腔比例最大(55.5%),胸鳍基部(25.9%)次之。对麦鲮具较强的致死效应,23 h的累积死亡率为16.7%。吸血后体长(L)显著增长,而体宽(W)基本无变化。从寄主身上主动脱落的虫体,其L和L/W的增值比(%)均显著高于因使寄主致死而被动脱落的虫体(P<0.05);而仍在寄主身上的虫体,其L和L/W的增值比(%)则因各自摄食量的不同而存在较大差异。     

Virulence and local adaptation of a horizontally transmitted parasite

Parasites are thought to maximize the number of successfully transmitted offspring by trading off propagule production against host survival. In a horizontally transmitted microparasitic disease in Daphnia, a planktonic crustacean, increasing geographic distance between host and parasite origin was found to be correlated with a decrease in spore production and virulence. This finding indicates local adaptation of the parasite, but contradicts the hypothesis that long-standing coevolved parasites are less virulent than novel parasites. Virulence can be explained as the consequence of balancing the positive genetic correlation between host mortality and strain-specific spore production.     

Leishmania RNA virus controls the severity of mucocutaneous leishmaniasis

Mucocutaneous leishmaniasis is caused by infections with intracellular parasites of the Leishmania Viannia subgenus, including Leishmania guyanensis. The pathology develops after parasite dissemination to nasopharyngeal tissues, where destructive metastatic lesions form with chronic inflammation. Currently, the mechanisms involved in lesion development are poorly understood. Here we show that metastasizing parasites have a high Leishmania RNA virus-1 (LRV1) burden that is recognized by the host Toll-like receptor 3 (TLR3) to induce proinflammatory cytokines and chemokines. Paradoxically, these TLR3-mediated immune responses rendered mice more susceptible to infection, and the animals developed an increased footpad swelling and parasitemia. Thus, LRV1 in the metastasizing parasites subverted the host immune response to Leishmania and promoted parasite persistence.     

Manipulation of host hepatocytes by the malaria parasite for delivery into liver sinusoids

The merozoite stage of the malaria parasite that infects erythrocytes and causes the symptoms of the disease is initially formed inside host hepatocytes. However, the mechanism by which hepatic merozoites reach blood vessels (sinusoids) in the liver and escape the host immune system before invading erythrocytes remains unknown. Here, we show that parasites induce the death and the detachment of their host hepatocytes, followed by the budding of parasite-filled vesicles (merosomes) into the sinusoid lumen. Parasites simultaneously inhibit the exposure of phosphatidylserine on the outer leaflet of host plasma membranes, which act as "eat me" signals to phagocytes. Thus, the hepatocyte-derived merosomes appear to ensure both the migration of parasites into the bloodstream and their protection from host immunity.     

云南花卉寄生线虫初步调查*

 2001～2004年，从云南各地161种寄主上采集的321份样品中，初步鉴定出花卉寄生线虫21个属。其中，螺旋属（Helicotylenchus Steiner, 1945），根结属(Meloidogune Goeldi,1892)，真滑刃属(Aphelenchus Bastian, 1865)，盘旋属(Rotylenchus Filipjev, 1936)，拟鞘线虫属（Hemicriconemoides Chitwood &; Berchfield, 1957），短体属(Pratylenchus Filipjev, 1936)，丝尾垫刃属（Filenchus Andrassy, 1954），矮化属(Tylenchorhynchus Cobb, 1913)，盾状线虫属(Scutellonema Andrassy, 1958)和小环线虫属（Criconemella De Grisse &; Loof, 1965）寄主范围较宽，分布较广泛，是云南花卉的重要寄生线虫。     

Controlling and coordinating development in vector-transmitted parasites

Vector-borne parasites cause major human diseases of the developing world, including malaria, human African trypanosomiasis, Chagas disease, leishmaniasis, filariasis, and schistosomiasis. Although the life cycles of these parasites were defined over 100 years ago, the strategies they use to optimize their successful transmission are only now being understood in molecular terms. Parasites are now known to monitor their environment in both their host and vector and in response to other parasites. This allows them to adapt their developmental cycles and to counteract any unfavorable conditions they encounter. Here, I review the interactions that parasites engage in with their hosts and vectors to maximize their survival and spread.     

Sex determination in malaria parasites

A century ago, W. G. MacCallum identified distinct male and female forms in malaria parasites of both birds and humans. Since then, scientists have been puzzled by the high female-to-male ratios of parasites in Plasmodium infections and by the mechanism of sex determination. The sex ratio of malaria parasites was shown to become progressively more male as conditions that allow motility and subsequent fertilization by the male parasites become adverse. This resulted from an increased immune response against male gametes, which coincides with intense host erythropoietic activity. Natural and artificial induction of erythropoiesis in vertebrate hosts provoked a shift toward male parasite production. This change in parasite sex ratio led to reduced reproductive success in the parasite, which suggests that sex determination is adaptive and is regulated by the hematologic state of the host.     

Brood parasitic cowbird nestlings use host young to procure resources

Young brood parasites that tolerate the company of host offspring challenge the existing evolutionary view of family life. In theory, all parasitic nestlings should be ruthlessly self-interested and should kill host offspring soon after hatching. Yet many species allow host young to live, even though they are rivals for host resources. Here we show that the tolerance of host nestlings by the parasitic brown-headed cowbird Molothrus ater is adaptive. Host young procure the cowbird a higher provisioning rate, so it grows more rapidly. The cowbird's unexpected altruism toward host offspring simply promotes its selfish interests in exploiting host parents.     

Intracellular parasite invasion strategies

Intracellular parasites use various strategies to invade cells and to subvert cellular signaling pathways and, thus, to gain a foothold against host defenses. Efficient cell entry, ability to exploit intracellular niches, and persistence make these parasites treacherous pathogens. Most intracellular parasites gain entry via host-mediated processes, but apicomplexans use a system of adhesion-based motility called "gliding" to actively penetrate host cells. Actin polymerization-dependent motility facilitates parasite migration across cellular barriers, enables dissemination within tissues, and powers invasion of host cells. Efficient invasion has brought widespread success to this group, which includes Toxoplasma, Plasmodium, and Cryptosporidium.