昆虫对植物次生物质的代谢适应机制及其对昆虫抗药性的意义

植物次生物质(plant secondary metabolites)对昆虫的取食行为、生长发育及繁殖可以产生不利影响,甚至对昆虫可以产生毒杀作用。为了应对植物次生物质的不利影响,昆虫通过对植物次生物质忌避取食、解毒代谢等多种机制,而对寄主植物产生适应性。其中,昆虫的解毒代谢酶包括昆虫细胞色素P450酶系（P450s）及谷胱甘肽硫转移酶（GSTs）等,在昆虫对植物次生物质的解毒代谢及对寄主植物的适应性中发挥了重要作用。昆虫的解毒酶系统不仅可以代谢植物次生物质,还可能代谢化学杀虫剂,因而昆虫对寄主植物的适应性与其对杀虫剂的耐药性甚至抗药性密切相关。昆虫细胞色素P450s和GSTs等代谢解毒酶活性及相关基因的表达可以被植物次生物质影响,这不仅使昆虫对寄主植物的防御产生了适应性,还影响了昆虫对杀虫剂的解毒代谢,因而改变昆虫的耐药性或抗药性。掌握昆虫对植物次生物质的代谢适应机制及其在昆虫抗药性中的作用,对于明确昆虫的抗药性机制具有重要的参考意义。本文综述了植物次生物质对昆虫的影响、昆虫对寄主植物次生物质的代谢机制、昆虫对植物次生物质的代谢适应性对昆虫耐药性及抗药性的影响等方面的研究进展。     

次生物质在植物与昆虫协同进化中的意义

次生物质是植物次级低谢的产物,它在植物与昆虫协同进化中起着主导作用。本文通过介绍次生物质在植物化学防御中的作用,昆虫对次生物质的适应及其利用等内容,阐述了次生物质在植物与昆虫协同进化中的意义。     

植物抗虫性次生物质的研究概况

综述了国内外与植物抗虫性有关的次生物质的主要类型和植物次生物质对昆虫的寄主选择、取食和产卵等作用的研究进展,对次生物质在生态系统中的作用也作了介绍,并展望了植物次生物质的应用前景。     

植食性昆虫选择寄主植物的奥秘

在自然的情况下,每一种植食性昆虫都各有其一定的寄生范围,单食性昆虫只取食某种植物,而多食性昆虫则选取固定的几十种到几百种植物。从识别的过程来说,昆虫不象高等动物那样,对食物的认识靠传教、靠经历、甚至靠思维;对昆虫视觉生理研究也表明：植食性昆虫的视觉在...     

昆虫对植物蛋白酶抑制素的诱导及适应机制

植物蛋白酶抑制素是植物重要的防御物质之一,一般是分子量较小的多肽或蛋白质,能够与昆虫消化道内的蛋白酶形成复合物,阻断或削弱蛋白酶对食物中蛋白的水解,使昆虫厌食或消化不良而致死。植物蛋白酶抑制素在植物体内一般是诱导表达的,昆虫取食危害后,导致某些植物在伤口产生一种寡聚糖信息素-蛋白酶抑制素诱导因子,蛋白酶抑制素诱导因子诱导叶片局部产生植物蛋白酶抑制素,并刺激产生信号物质系统肽,通过十八烷酸途径在一系列酶的作用下产生茉莉酸,茉莉酸与受体结合,活化植物蛋白酶抑制素基因。昆虫在长期取食植物蛋白酶抑制素后会在生理及行为上产生适应性而导致不敏感,适应方式主要包括：(1)改变肠道蛋白酶对蛋白酶抑制素的敏感性;(2) 水解蛋白酶抑制素;(3)过量取食及干扰产生蛋白酶抑制素的信号通道。由于昆虫能够对植物蛋白酶抑制素产生适应,因此合理利用植物蛋白酶抑制素的抗虫作用显得十分重要。     

植物次生物质的抗虫作用

植物适应环境的方式多种多样,其中通过影响体内代谢,形成千差万别的次生物质,来产生对逆境的抵抗,就是一个重要方面。一些次生物质,如树脂、橡胶、多胺、烟碱、黄酮、醌类、皂苷等,人们早就认识到它们在人体内可以发挥许多重要的药理作用,是一些植物药所以能治疗疾病的有效成分,但对于它们在植物体内所行使的生理功能,长时期并不十分清楚,以致以往人们一般都认为它们不过是植物在进行各种代谢的途径中所形成的废弃物质。随着科学的发展,人们通过长期观察和各种试验逐渐证明,次生物质是植物长期进化的产物,在植物适应环境、提高竞争能力方面起着十分重要的作用。本文仅就次生物质在植物抵抗     

植物抗虫性次生物质的研究概况

综述了国内外与植物抗虫性有关的次生物质的主要类型和植物次生物质对昆虫的寄主选择、取食和产卵等作用的研究进展,对次生物质在生态系统中的作用也作了介绍,并展望了植物次生物质的应用前景。     

Global Change Effects on Plant Chemical Defenses against Insect Herbivores

This review focuses on individual effects of major global change factors, such as elevated CO2, Oa, UV light and temperature,on plant secondary chemistry. These secondary metabolites are well-known for their role in plant defense against insect herbivory. Global change effects on secondary chemicals appear to be plant species-specific and dependent on the chemical type. Even though plant chemical responses induced by these factors are highly variable, there seems to be some specificity in the response to different environmental stressors. For example, even though the production of phenolic compounds is enhanced by both elevated CO2 and UV light levels, the latter appears to primarily increase the concentrations of fiavonoids. Likewise, specific phenolic metabolites seem to be induced by O3 but not by other factors, and an increase in volatile organic compounds has been particularly detected under elevated temperature. More information is needed regarding how global change factors influence inducibility of plant chemical defenses as well as how their indirect and direct effects impact insect performance and behavior, herbivory rates and pathogen attack. This knowledge is crucial to better understand how plants and their associated natural enemies will be affected in future changing environments.     

Adaptive Patch Searching Strategies in Fragmented Landscapes

The search strategies dispersers employ to search for new habitat patches affect individuals’ search success and subsequently landscape connectivity and metapopulation viability. Some evidence indicates that individuals within the same species may display a variety of behavioural patch searching strategies rather than one species-specific strategy. This may result from landscape heterogeneity. We modelled the evolution of individual patch searching strategies in different landscapes. Specifically, we analysed whether evolution can favour different, co-existing, behavioural search strategies within one population and to what extent this coexistence of multiple strategies was dependent on landscape configuration. Using an individual-based simulation model, we studied the evolution of patch searching strategies in three different landscape configurations: uniform, random and clumped. We found that landscape configuration strongly influenced the evolved search strategy. In uniform landscapes, one fixed search strategy evolved for the entire spatially structured population, while in random and clumped landscapes, a set of different search strategies emerged. The coexistence of several search strategies also strongly depended on the dispersal mortality. We show that our result can affect landscape connectivity and metapopulation dynamics. Co-ordinating editor: N. Yamamura     

Eicosanoid Signaling in Insects: from Discovery to Plant Protection

Prostaglandins (PGs) and related eicosanoids are signal moieties derived from arachidonic acid and two other C20 polyunsaturated fatty acids. They were discovered in the 1930s in the context of mammalian reproductive physiology; PGs were associated with the prostate gland, hence their name, and they stimulate uterine smooth muscle contraction. Determining PG chemical structures in the early 1960s and demonstrating that they mediate many human pathophysiological events in the 1970s stimulated intensive research over the following decades in universities, governments and the private sector. Interest in the biological significance of PGs in insects arose in the 1970s and 1980s, which opened a new research frontier. PGs act in reproduction, releasing egg-laying behaviors in some species and signaling egg-maturation events in the Drosophila and silk moth models. They act in insect immunity, mediating and coordinating cellular and humoral responses to wounds, infection and invasion. PGs act in ion transport physiology in insect Malpighian tubules and recta. These compounds also mediate physiological trade-offs between insect immunity and reproduction. Finally, they are central players in the molecular ecology of interactions between blood-feeding insects and their vertebrate hosts. Some PG functions are critical at specific, crucial moments in insect lives, moments we consider ‘emergencies,’ such as the immediate reactions to infection. Certain microbial species have keyed into insect PG signaling and they evolved mechanisms to disable insect immune reactions to infection by inhibiting key enzymes in PG biosynthesis. We provide proof-of-principle that RNA interference treatments designed to silence genes in PG signaling disrupts insect immunity. In this review we describe the history, chemistry and biology of PGs. We use this background to argue that because PGs and other eicosanoids act in emergency situations, they are visible targets for development and deployment of novel insect pest management technologies.     

Seasonal variation in the glucosinolate content of North American Brassica nigra and Dentaria species

Concentrations of glucosinolates in the leaves of the woodland cruciferous herbs Dentaria laciniata, D. diphylla and D. maxima declined during the 1974 growing season but generally equalled or exceeded the levels found in the foliage of Brassica nigra, a crucifer of neighbouring open habitats. The superior quality of Dentaria foliage for certain crucifer-feeding insects does not seem to result from an unusually low concentration of glucosinolates. The qualitative and quantitative compositions of glucosinolates in the leaves and rhizomes of D. maxima were found to be intermediate between the corresponding values for D. laciniata and D. diphylla. This finding is consistent with a hybrid origin for D. maxima.     

木本植物的构型及其在植物生态学研究的进展

一般认为 ,木本植物的植株结构由枝系和根系两个亚系统构成[5,3 8] 。其地上部分的枝或茎的顶端分生组织和侧生分生组织通过不断重复的、持续的活动产生新的分枝 ,构成了复杂的枝系结构和多样的形态特征。传统的植物学研究中曾以树木的形态特征作为植物形态学、分类学和植被类型划分的依据。由于植物种群生态学中构件理论的提出[6,4 1] ,人们已经意识到植物体的各构件单元之间的关系和等级结构 ,认为木本植物地上部分存在着两种尺度的整合 ,即各构件单元在枝条水平上的整合以及各枝条构成的冠幅复合体[1,2 1] 。植物体不同的枝系特征以及枝…     

Differential defoliation of Eucalyptus grandis arises from indiscriminant oviposition and differential larval survival

1 The influence of six open-pollinated families (OPFs) of Eucalyptus grandis on both the growth and development of larvae and the oviposition preference of a paropsine chrysomelid ( Paropsis atomaria ) was investigated. The OPFs had previously been identified as differing in their susceptibility to defoliation by P. atomaria in forestry progeny trials.
2 Oviposition preference for resistant and susceptible foliage was tested using binary choice tests. These tests did not demonstrate any significant preference for either resistant or susceptible open-pollinated material indicating that adult host preference for susceptible trees was not a likely cause of differential defoliation.
3 Quantification and analysis of growth and development parameters for all larval stages of P. atomaria showed that feeding on genetic material identified as resistant resulted in a significant reduction of relative growth rate of first instar larvae and an alteration to normal feeding behaviour. There was also a trend towards increased larval mortality on resistant E. grandis .
4 We argue that although the magnitude of these effects was minor, interactions with additional biotic and abiotic sources of mortality in the field have the potential, when magnified over successive generations, to result in significant variation in defoliation of host genotypes in the field.