中红侧沟茧蜂的生活史

中红侧沟茧蜂 (Microplitis mediator)同蜜蜂、胡蜂和蚂蚁等昆虫同属于膜翅目昆虫 ,但它过着一种截然不同的生活 ,是棉铃虫、粘虫等大害虫肝里的“蛔虫”,是过着拟寄生生活的寄生蜂。也许你有在棉田附近踏青的经验 ,你的注意力或许会被眼前 1个飞舞的蚂蚁所吸引 ,那可能并不是 1只会飞的蚂蚁 ,很可能是 1只刚从茧中蜕变出来的中红侧沟茧蜂。这只雌性的寄生蜂只有 3mm,有 1对很显眼的长触角 ,体色淡黄 ,姿态优美。吮吸花蜜 ,这是它成年生活的惟一食物和饮料。与此同时 ,它也在散放着召唤异性的信息——性信息素 ,在不远处有 1只同它一样羽化…     

斑痣悬茧蜂的寄主种间选择性及其子代蜂发育适合度表现

为检验基于经典搜寻理论的最优膳食模型的预测——产卵雌蜂应该选择最适于子代蜂发育的寄主种进行产卵,本研究以斑痣悬茧蜂(Meteorus pulchricornis)及其寄主斜纹夜蛾(Spodoptera litura)和粘虫(Mythimna separata)的幼虫为材料,在控制寄主体型大小和龄期影响的基础上,分别在体型大小相近和日龄相同的3个水平上观察了斑痣悬茧蜂对2种寄主幼虫的选择偏好,并观察了子代蜂生长发育适应度表现。在观察期(1h)内,当2种寄主幼虫的体型相近或者龄期相同的情况下,斑痣悬茧蜂对粘虫的产卵器刺扎次数以及寄生率(用结茧率表示)均高于斜纹夜蛾;而在斜纹夜蛾幼虫体内发育出的子代蜂茧重和体型均大于粘虫,成蜂寿命无显著差异。最后,对斑痣悬茧蜂的寄主选择和子代发育表现不一致现象进行了讨论。     

斑痣悬茧蜂的寄主辨别能力及其影响因素

为评价斑痣悬茧蜂Meteorus pulchricornis (Wesmael)的寄主辨别能力及其影响因素, 采用双选试验（斜纹夜蛾2龄寄主幼虫, 健康∶被寄生=5∶5）, 观察了寄生经历（无寄生经历、 有1次寄生经历、 有1次过寄生经历）和寄主被首次寄生后的间隔时间（1 - 7 d）对斑痣悬茧蜂在健康寄主和被寄生寄主之间的选择; 为探究斑痣悬茧蜂是否能够辨别寄主斑块质量, 观察了斑痣悬茧蜂连续3次访问不同质量寄主斑块（被寄生寄主∶健康寄主分别为 2∶8, 5∶5和 8∶2）时的产卵刺扎次数。对选择频次进行的分析表明, 寄主被首次寄生后的间隔时间和寄生蜂的寄生经历均对过寄生发生有显著影响(P<0.05), 过寄生概率随寄主首次被寄生后的间隔时间延长而降低; 有寄生经历的寄生蜂发生过寄生的概率低于无寄生经历的寄生蜂。用Cox比例风险模型对寄主辨别时间进行的分析表明, 发生过寄生的风险随寄主被初次寄生后间隔时间的延长而减小, 也因寄生蜂具有过寄生经历而减小。斑痣悬茧蜂在连续3次访问不同质量寄主斑块中, 产卵刺扎次数随寄主斑块的质量提高而显著增多。据此推论, 斑痣悬茧蜂不仅能够辨别被寄生寄主, 而且能够辨别含有被寄生寄主的寄主斑块。     

中红侧沟茧蜂在粘虫体内的发育 及畸形细胞发生

中红侧沟茧蜂Microplitis mediator的初产卵因受雌蜂产卵器的机械挤压,在形态上有别于未产出的卵,这种机械挤压激活了蜂卵的胚胎发育。产卵后 6 h,胚带和浆膜层开始分化,20 h胚胎成形,包裹在单层细胞的浆膜层内。32～34 h,幼蜂孵化,顶部的浆膜层立即分散形成畸形细胞,尾部的浆膜层则逐渐释放细胞。1龄幼蜂具一对角质的颚,用来消灭同种竞争者。寄生后108～113 h,1龄幼蜂蜕皮进入2龄。2龄幼蜂为无头型,尾囊发达。成熟的畸形细胞(受寄生日龄6天)表面密布微绒毛,细胞内部高尔基体丰富,内质网发达,细胞核多分支。在高尔基体的两侧和细胞膜附近分布了大量的分泌小池。     

一种中红侧沟茧蜂畸形细胞分泌的寄生特异蛋白

SDS-PAGE电泳表明,黏虫Pseudaletia separa-ta、棉铃虫 Helicoverpa armigera、小地老虎 Agrotisypsilon的幼虫受中红侧沟茧蜂Microplitis mediator寄生后,血淋巴中都出现一个98.6 kDa的寄生特异蛋白(p98.6)。畸形细胞(teratocytes)的体外培养发现,p98.6是由来自中红侧沟茧蜂胚胎浆膜层的畸形细胞分泌的。这一结果将为研究寄生蜂的寄生生理和畸形细胞在协调寄生蜂和寄主关系中的作用打下基础。     

中红侧沟茧蜂多分DNA病毒基本特征研究

本文首次报道中红侧沟茧蜂 (Microplitismediator)雌蜂卵巢中存在多分DNA病毒 (MicroplitismediatorPlolyd navirus,MmPDV) ,初步研究了MmPDV形态和基本生理生化特征。利用蔗糖密度梯度超速离心分离纯化了MmPDV粒子 ,电镜负染显示PDV粒子分三段 ,带有一明显的尾部结构 ,大小约为 130× 35nm ;SDS PAGE电泳条带较多 ,至少可以分辨出 2 6个电泳条带 ,表明病毒粒子衣壳蛋白复杂 ;琼脂糖凝胶电泳显示MmPDV基因组至少由大小不同、丰度不等的 14个DNA分子组成 ,用 6种内切酶 (EcoRI,HindIII,BssHII,PstI,BamHI,BglI)酶切MmPDV基因组后 ,估算出MmPDV基因组大小约为 10 8kb。用雌蜂输卵管萼液注射小地老虎幼虫 ,注射后的小地老虎体重和龄期发育动态表明 ,MmPDV具有抑制寄主生长发育的生理功能     

中红侧沟茧蜂触角感受器的扫描电镜观察

利用扫描电镜对中红侧沟茧蜂Microplitis mediator的触角感受器进行了观察,发现了6个类型的感器,分别为毛形感器、板形感器、刺形感器、钟形感器、锥形感器、腔锥形感器。其中,毛形感器具有2种形态,锥形感器具有4种形态。钟形感器仅分布于雌蜂的触角上,锥形感器Ⅲ和Ⅳ仅分布于雄蜂的触角上。结合感受器的形态、分布和已报道的触角电位反应数据,对各感受器的功能进行了推测。     

中红侧沟茧蜂滞育诱导和滞育茧的冷藏

中红侧沟茧蜂Microplitis mediator (Haliday)是夜蛾科害虫低龄幼虫的重要寄生蜂。田间实验表明,在冀中地区秋季田间条件下,当日平均气温为21.5℃、日平均光照时间为12 h 33 min时,少数个体进入滞育;当气温降至17.9℃以下、日光照时间缩短到11 h 45 min以下时,全部个体进入滞育。室内模拟实验结果表明,在17～26℃、光照时间10～14 h范围内,随着温度的降低和光照时间的缩短,滞育率明显提高。高温能抵消短光照对滞育诱导的影响,在26℃下,短光照不能诱导滞育。因此,低温和短光照是诱导该种天敌昆虫滞育的主要因子。中红侧沟茧蜂感受滞育信号的敏感期为低龄幼虫期,以预蛹（茧）进入滞育。低龄幼虫感受滞育信号以后,需要在滞育环境中发育到老熟幼虫才能全部进入滞育。将室内诱导的滞育茧在4℃左右环境条件下冷藏240天,成蜂的羽化率和寄生能力与没有冷藏的非滞育茧差异不显著;冷藏300天,滞育茧仍有81.4%可以正常羽化。本项研究结果为中红侧沟茧蜂的规模化、标准化生产提供了科学的依据。     

中红侧沟茧蜂寄生对粘虫幼虫取食及生长发育的影响

【目的】为明确中红侧沟茧蜂Microplitis mediator(Haliday)寄生对粘虫Mythimna separata(Walker)幼虫取食和发育的影响及评价其田间应用价值。【方法】比较研究了中红侧沟茧蜂寄生不同日龄粘虫对粘虫幼虫取食量和发育的影响。【结果】被寄生的粘虫4、6、8日龄幼虫与未被寄生的同龄期幼虫取食量差异达极显著水平。被寄生的4、6、8日龄粘虫幼虫间的取食量差异不显著。被寄生的幼虫,5 d前体重缓慢上升,之后缓慢下降,所有被寄生的幼虫均不能化蛹。4、6、8日龄粘虫幼虫被寄生后,中红侧沟茧蜂幼虫在其体内的发育历期不同,不同日龄间差异显著,随着日龄的增大显著缩短。【结论】表明该蜂不仅能有效地控制粘虫当代危害,而且在很大程度上能够抑制粘虫的种群数量。     

斑痣悬茧蜂寄生对甜菜夜蛾幼虫取食和食物利用的影响

为研究甜菜夜蛾Spodoptera exigua幼虫被斑痣悬茧蜂Meteorus pulchricornis寄生后的取食以及食物利用情况,在室内采用重量法测定了甜菜夜蛾4龄幼虫被寄生后取食量、体重增加量、营养指标的变化。结果表明：被寄生甜菜夜蛾幼虫的取食量、生长率和食物利用效率等明显受到抑制,幼虫被寄生后第3-6 d 取食量显著小于未被寄生幼虫,寄生后第4 d 的幼虫取食量只有正常幼虫的29.89%,第5 d只有48.69%。幼虫在寄生后的第3-5 d体重增加量显著小于未被寄生幼虫,分别为正常幼虫的21.51%,38.87%和14.42%,相对生长率则也显著低于后者。被寄生甜菜夜蛾幼虫的营养利用表现也明显不同于未被寄生幼虫,反映生长和代谢效率的食物利用率（ECI）和食物转化率（ECD）均显著降低,而反映吸收效率的近似消化率（AD）则提高。虽然在寄生后第4 d出现了相反的现象,其原因可能在于第4 d取食量明显减少,而体重仍在增加。本研究表明,斑痣悬茧蜂寄生明显抑制寄主甜菜夜蛾幼虫的取食、食物利用效率和生长。     

斑痣悬茧蜂寄生、发育和生殖特征与寄主幼虫日龄的关系

【目的】“圆屋顶形”假说认为,对单寄生性姬蜂和茧蜂适合度而言,中间龄期幼虫寄主的品质高于更早和更晚龄期幼虫。该假说得到许多研究支持,但这些研究常以寄主幼虫脱皮划分虫龄,很少观测生殖特征,从而难以确切和全面描述适合度随寄主生长发育变化而变化的关系。本研究旨在检验“圆屋顶形”假说。【方法】本研究以斜纹夜蛾Spodoptera litura不同日龄幼虫为寄主,观测斑痣悬茧蜂Meteorus pulchricornis寄生和发育特征,并测定成蜂生殖力。【结果】线性回归分析表明,雌蜂对中间日龄寄主幼虫的寄生率大于对两端日龄寄主幼虫的寄生率;蜂卵至成虫的存活、成虫体型大小及其生殖力（产卵量）等适合度相关特征均表现出中间日龄寄主幼虫处理大于两端日龄幼虫处理。【结论】研究结果支持“圆屋顶形”假说。     

中红侧沟茧蜂寄生对寄主粘虫血淋巴糖类、脂类和蛋白质含量的影响

为揭示寄生蜂寄生对其寄主的生理调控机制, 室内对中红侧沟茧蜂Microplitis mediator寄生与未被寄生寄主粘虫Mythimna separata幼虫血淋巴中糖类、脂类和蛋白含量变化进行了测定。结果显示: 在滞育与非滞育条件下, 被寄生的粘虫血淋巴中糖原浓度均比未被寄生的粘虫高。滞育条件下寄生后12 d差异显著（P<0.05）, 被寄生粘虫糖原含量为7.93 μg/mL, 未被寄生粘虫糖原含量为4.70 μg/mL; 非滞育条件下寄生后6 d差异显著（P<0.05）, 被寄生粘虫糖原含量为14.35 μg/mL, 未被寄生粘虫糖原含量为5.47 μg/mL。海藻糖含量测定结果显示, 在滞育条件下寄生蜂对被寄生粘虫无明显影响, 而非滞育条件下影响效果差异显著（P<0.05）, 寄生后4 d被寄生粘虫海藻糖含量为46.82 μg/mL, 未被寄生粘虫含量为26.72 μg/mL。在滞育与非滞育两种条件下, 寄生与未被寄生寄主脂类和蛋白含量没有显著性差异。结果说明: 寄生蜂的存在使寄主血淋巴中的糖原含量增高; 非滞育条件是影响被寄生粘虫海藻糖含量变化主要因素; 粘虫对中红侧沟茧蜂的寄生表现相当强的适应性和忍受力。     

Host age preference of Microplitis mediator (Hymenoptera: Braconidae), an endoparasitoid of Mythimna separata (Lepidoptera: Noctuidae)

Microplitis mediator (Haliday) is a solitary endoparasitoid of larvae of the cotton bollworm, Helicoverpa armigera (Hübner) and the oriental armyworm, Mythimna = Leucania separata (Walker). The preference and suitability of different instars of M. separata for M. mediator were determined under laboratory conditions at a constant temperature of 26 ± 1 °C, 65 ± 5% RH and L14:D10 photoperiod. The selection coefficient revealed that M. mediator parasitized 1st to 4th instars, but preferred 2nd and 3rd instars. Seventy-one percent of parasitism was achieved within 24 h when the 2nd instars were used as hosts at a density of one parasitoid per 20 Larvae. Parasitoid egression and pupation were dependent on the host instar parasitized and occurred from the 1st through the 4th instar. The mean developmental time from egg to prepupae of M. mediator within 1st to 4th instars of the host was 8.27, 8.30, 8.30 and 9.20 days, respectively. Cocoon weights were lower when 1st and 2nd instars served as hosts rather than 3rd and 4th instars. The percentage of host larva that died before parasitoid egression declined as the age of the host increased, ranging from 26% to 2% for 1st–5th instars, respectively. The results of this study suggest that 2nd and 3rd instars of M. separata would be the best host stages for mass production of M. mediator in the laboratory and the best host instars to target for effective control in field releases.     

Performance of Microplitis tuberculifer (Hymenoptera: Braconidae) parasitizing Mythimna separata (Lepidoptera: Noctuidae) in different larval instars

The solitary parasitoid Microplitis tuberculifer (Wesmael) is an important biological control agent of various lepidopteran pests in Asia. We examined the preference of M. tuberculifer for different instars of its common host, Mythimna separata (Walker), host instar effects on parasitoid development, and the consequences of parasitism in different stages for growth and consumption of host larvae. The wasp successfully parasitized the first four larval instars of M. separata, but not the fifth, which appeared to be behaviorally resistant. First and second instars were parasitized at higher rates compared to thirds and fourths in no-choice situations, ostensibly due to longer handling times for the latter, but second instars were most preferred in a choice test that presented all stages simultaneously. Although later instar hosts yielded heavier cocoons, the fastest parasitoid development was obtained in second instars. Lower sex ratios were obtained from first instars as females appeared to lay a smaller proportion of fertilized eggs in small hosts. Both weight gain and food consumption of parasitized larvae were reduced significantly within 24 h of parasitism, regardless of the stage parasitized, and final body weights were less than 10% those of unparasitized larvae. Thus, M. tuberculifer has good potential as a biological control agent of M. separata, successfully parasitizing the first four larval instars and dramatically reducing plant consumption by the host in all cases.     

Effects of Helicoverpa armigera (Noctuidae, Lepidoptera) host stages on some developmental parameters of the uniparental endoparasitoid Meteorus pulchricornis (Braconidae, Hymenoptera)

A single choice test was performed to examine developmental strategies in the uniparental endoparasitoid Meteorus pulchricornis and its host, the cotton bollworm Helicoverpa armigera. The results support the dome-shaped model in which the fitness functions are 'dome-shaped' relative to size (and age) of host at parasitism. Older and, hence, larger host larvae were simply not better hosts for the developing parasitoids. Although parasitoid size (measured as cocoon weight and adult hind tibia length) was positively correlated with host instars at parasitism, parasitoids developing in larger hosts (L5 and L6) suffered much higher mortality than conspecifics developing in smaller hosts (L2-L4). Furthermore, egg-to-adult development time in M. pulchricornis was significantly longer in older host larvae (L4-L6) than in the younger. Performance of M. pulchricornis, as indicated by fitness-related traits, strongly suggests that the L3 host is the most suitable for survival, growth and development of the parasitoid, followed by both L2 and L4 hosts; whereas, L1, L5 and L6 are the least favourable hosts. The oviposition tendency of M. pulchricornis, represented by parasitism level, was not perfectly consistent with the performance of the offspring; L2-L4 hosts, although with the same parasitism level, had offspring parasitoids with differences in fitness-related performance. Larval development in Helicoverpa armigera was usually suspended, but occasionally advanced, in the final instar.     

Superparasitism behavior and host discrimination of Campoletis chlorideae (Ichneumonidae: Hymenoptera) toward Mythimna separata (Noctuidae: Lepidoptera)

The oriental army worm, Mythimna separata Walker (Lepidoptera: Noctuidae), was adopted as a host to keep Campoletis chlorideae Uchida (Hymenoptera: Ichneumonidae) populations in the laboratory, because it can be mass reared. However, wasp cocoon production in this system via single parasitism was not satisfactory. To improve the rearing efficiency of C. chlorideae on M. separata, we studied the effects of superparasitism on the offspring production of C. chlorideae, as well as the host discrimination ability of the adult wasps in the laboratory. The results showed that, compared with single parasitism, both double and quintuple parasitism significantly increased C. chlorideae cocoon production in M. separata without a significant effect on emergence, weight, or sex ratio of adult wasps at the P < 0.05 level. Host selection experiments suggested that C. chlorideae preferred to lay eggs on unparasitized hosts rather than freshly parasitized hosts but could distinguish neither the 24-h postparasitization hosts from the unparasitized hosts nor the freshly self-parasitized hosts from the conspecifically parasitized hosts. No-choice behavior tests indicated that C. chlorideae took significantly longer time to accept the freshly parasitized hosts containing more than two eggs compared with the unparasitized hosts. In the end, superparasitism behavior and its application in the mass rearing of this endoparasitoid are discussed.     

天然产物梣酮对粘虫围食膜的影响

【目的】梣酮是从芸香科植物白鲜Diatamnus dasycarpus根皮中分离出的一种化合物, 对试虫表现出胃毒活性。本研究旨在检测梣酮对粘虫Mythimna separata 6龄幼虫中肠围食膜的影响, 从而进一步阐明梣酮的杀虫作用机理。【方法】经活体及离体处理, 通过生化分析和扫描电镜观察等方法, 研究了梣酮处理对粘虫幼虫中肠围食膜糖含量, 蛋白质含量和组分以及围食膜表面结构的影响。【结果】梣酮(20 mg/mL)活体处理降低了粘虫6龄幼虫围食膜的蛋白质含量, 却使糖含量升高。活体(20 mg/mL梣酮)及离体(8 mg/mL梣酮)处理条件下, 围食膜糖含量分别为对照组的1.75倍及2.17倍。SDS-PAGE结果显示, 离体及活体条件下经梣酮处理, 围食膜部分蛋白质降解。围食膜解剖扫描电镜观察表明, 梣酮处理可造成围食膜微纤丝排列紊乱。【结论】天然产物梣酮处理对粘虫中肠围食膜的糖含量及蛋白质含量和组分有影响,且改变了围食膜表面结构。本研究为深入地研究梣酮杀虫作用机理奠定了基础。