【作者】 晁云飞；

【导师】 李欣； 白素芬；

【作者基本信息】 河南农业大学 ， 农业昆虫与害虫防治， 2010， 硕士

【摘要】 本文以世界性蔬菜重要害虫-小菜蛾Plutella xylostella (Linnaeus)及其两种优势内寄生蜂-菜蛾啮小蜂Oomyzus sokolowskii Kurdjumov和菜蛾盘绒茧蜂Cotesia vestalis(Kurdjumov)为研究对象,通过构建小菜蛾-菜蛾盘绒茧蜂和小菜蛾-菜蛾啮小蜂两个寄生体系,对“调节型”和“顺从型”寄生蜂成功发育的生理基础进行了比较研究。取得以下研究结果:一、菜蛾啮小蜂的个体发育在室温25±1℃,相对温度60%-80%,光周期L14 : D10,光照强度1000-1500 lux的培养条件下,研究了菜蛾啮小蜂的个体发育过程。该蜂胚胎发育历经44h-48h。孵化后的蜂幼虫经历一次明显的蜕皮,明显存在两个虫龄。整个幼虫期6-8d。老熟幼虫的化蛹过程可以划分为初期、中期和后期3个阶段,蛹期8-9d。羽化出的成虫在不饲喂任何食物的情况下,发育4d后开始死亡。菜蛾啮小蜂从产卵到羽化为成虫历经16-18d。二、寄生不同虫龄小菜蛾对菜蛾啮小蜂生物学特性的影响寄主昆虫的质量显著影响其体内寄生蜂的生长发育,选择适合的寄主虫龄是成功繁蜂的关键。本研究以小菜蛾重要的幼虫--蛹跨期寄生蜂菜蛾啮小蜂为研究对象,在室内(25±1)℃研究了1龄、2龄、3龄、4龄初和4龄末小菜蛾幼虫被寄生后,对菜蛾啮小蜂生物学物性的影响。结果表明:寄生各个虫龄小菜蛾的啮小蜂从卵到羽化的发育历期、羽化后成蜂寿命没有明显的差异。寄生不同虫龄小菜蛾羽化出的啮小蜂的性比只在3龄末和4龄末之间存在显著性差异,寄生4龄末小菜蛾育出的雄蜂比例最高。菜蛾啮小蜂对各虫龄小菜蛾幼虫产卵寄生没有表现出明显的偏好性,但相比2龄和4龄小菜蛾幼虫,3龄末小菜蛾幼虫仍是较适合的寄主,寄生3龄末小菜蛾幼虫羽化出的啮小蜂个体最大。三、离子色谱法测定寄生后小菜蛾血淋巴游离氨基酸采用离子色谱法测定了小菜蛾末龄幼虫、预蛹及被菜蛾盘绒茧蜂寄生后,血淋巴中游离氨基酸组成和含量。共检测到17种氨基酸,其中组氨酸、脯氨酸和丙氨酸是主要的种类。随着小菜蛾幼虫的生长,血淋巴中氨基酸总量明显增加,发育到预蛹时,总量下降,表明虫体内氨基酸代谢途径因变态的即将发生而产生了变化。被菜蛾盘绒茧蜂寄生后,小菜蛾幼虫血淋巴中游离氨基酸总量显著增加,导致多数氨基酸种类含量增加,表明该蜂有效地调节了寄主的蛋白质和氨基酸代谢,使之朝着有利于自身发育的方向发展。但是,当蜂幼虫完成在寄主体内的发育时,小菜蛾血淋巴中氨基酸总浓度明显下降,说明该蜂有效地获取了寄主中的氨基酸营养。对这些氨基酸种类的识别将可为今后该蜂大规模的的人工化培养提供极有价值的信息。四、小菜蛾两种内寄生蜂种间竞争机制通过构建模式系统,阐明寄生蜂种间竞争的内在机制,可以为天敌的正确引种提供理论依据。本文以2龄末小菜蛾幼虫为寄主昆虫,分别选取小菜蛾两种内寄生蜂菜蛾盘绒茧蜂Cotesia vestalis和菜蛾啮小蜂Oomyzus sokolowskii以不同的寄生顺序和时间间隔寄生同一寄主以形成多寄生。在室内25℃下,比较了这两种蜂的种间竞争能力,并对其采取的竞争机制进行了分析。当种间竞争发生后,育出的茧蜂数最多,小蜂数极少。影响这两种蜂种间竞争结果的原因首先取决于它们的物理攻击能力,茧蜂的1龄幼虫有发达的角质上颚,而小蜂缺乏;同时,与这两种寄生蜂各自携带的寄生因子如多分DNA病毒(polydnavirus PDV)、畸形细胞或毒液等对寄主生长发育的调控至关重要。茧蜂的寄主调控能力最强,它拥有的PDV和毒液能显著延长寄主的幼虫期,这样的寄主环境造成小蜂不能发育成功。而且,小蜂先寄生的多寄生寄主死亡率明显升高也是造成小蜂数减少的重要原因。更多还原

【Abstract】 In the present paper, we compared the phsiological effects of parasitization on diamondback moth, Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae), the most important crucifer pest worldwide, parasitized by two major endoparasitoids, the“regulator”Cotesia vestalis (Haliday) (Hymenoptera: Braconidae) or the“conformer”Oomyzus sokolowskii Kurdjumov (Hymenoptera: Eulophidae). The major results are summarized as follows.1.The ongeny of Oomyzus sokolowskiiThe ongeny of Oomyzus sokolowskii was observed at 25±1℃, RH 60%-80%, photoperiod of 14 h light and 10 h dark with light intensity of 1000-1500lux, under lab conditions. The development period required for the embryo of O. sokolowskii is forty-four to forty-eight hours. After hatching, the larvae undergoes a obviously molting, it has two larval instars. The duration of larval stage was 6-8 d. The final larvae enters pre-pupal stage after ceasing feeding. The whole pupal stage was divided into three phases. The pupal period was 8-9 d. After emergence, the longevity of adult was only 4 days without feeding any food. The developmental time for O. sokolowskii from egg batch to adult emergence was 16-18 days.2.The effect of host instar on biological characters of Oomyzus sokolowskii, a larval-pupal parasitoid of Plutella xylostellaHost insect quality significantly influences the progeny fitness of endoparasitoid wasps. Choosing the suitable host instar and size will be useful for developing augmenting parasitoids as biological control agents. In present paper, we investigated the effects of host different instar and size on biological characters of Oomyzus sokolowskii (Kurdjumov), an important larval-pupal endoparasitoid of Plutella xylostella L. in the laboratory at (25±1)°C. The results showed that parasitoids developing in different host instars did not exhibit significant differences in development time, and adult longevity was almost the same. The proportion of male wasps that emerged from the late fourth instar hosts was significantly higher than for the late third instar larvae. In choice experiment, the wasp did not show any differences to four larval instars, the number of egg laid per host, indicating almost the same host suitability among different larval instars. However, the late third instar larvae was the most suitable host compared with the other instars for parasitoid, because the biggest wasp emerged from them. 3.Determination of free amino acids in the hemolymph of parasitized Plutella xylostella by ion chromatographyChanges in free amino acids were analysed in hemolymph of fourth instar larvae, prepupae and parasitized Plutella xylostella larvae by ion chromatography. Seventeen primary amino acids were detected among which histidine, proline and alanine were the predominant free amino acids at all stages. The concentration of total amino acids increased significantly with the age of larvae. However, the amount declined with the larvae entering the prepupal phase. This suggested that changes in amino acid metabolism occurred. After parasitization by Cotesia vestalis, the concentration of total amino acids increased significantly compared with synchronous non-parasitized controls. The parasitism resulted in increased levels of most of the amino acids. This parasitoid strongly redirected host protein and amino acid metabolisms to make the host nutritional environment suitable to its development. At the end of the immature development of this parasitoid, we observed a very significant decline in total amino acid contents. This suggested that C. vestalis used these amino acids effectively to ensure its larval development. The definition of a suitable artificial diet according to our results for in vitro mass production of this parasitoid in the future is necessary and helpful.4.The mechanisms of inerspecific competition between two endopatasitoids of diamondback mothIt can provide important theory basis for introduction of exotic natural enemies to control insect pests by establishing an ideal host-parasitoid model systems to clarify the mechanisms of interspecific competition between endoparasitoids. The interspecific competitive capacity between Oomyzus sokolowskii and Cotesia vestalis was studied using the 2nd instar larvae of Plutella xylostella as the host at 25℃in the laboratory. Different time intervals between parasitism and two parasitoid sequences were chosen. C. vestalis outcompeted O. sokolowskii from the multiparasitized host irrespective of whether it parasitized first or second. The one reason for this result was that C. vestalis can physically attack O. sokolowskii using advanced scleritized mandibles in multiparasitized host. Compared with C. vestlis, O. sokolowskii lack mandibles. The another reason for this result was that these two endoparasitoids regulated the host in different ways. C. vestalis has polydnaviruses, venom and teratocytes, whereas O. sokolowkii only has venom. The braconid has stronger regulatory ability on host than eulophid. In the presence of polydnaviruses and venom of C. vestalis, the duration of host larval stage was prolonged and could not pupate. Under this host physiological state, O. sokolowkii could not successfully develop. Furthermore, the high mortality of host parasitized by O. sokolowkii first lead to great reductions of eulophid.更多还原