The structure of feeding behavior in a phytophagous insect (Hylobius abietis)

Analysis of the feeding behavior of animals using such a high temporal resolution that meals can be defined may improve our understanding of the mechanisms regulating feeding. Meals can be distinguished in an ethologically meaningful manner by using the ‘meal criterion’, the shortest non‐feeding interval between feeding bouts recognized as meals. However, such a criterion has only been determined for a few insect species. Applying a recent method developed for assessing meal criteria for vertebrates, we determined the meal criterion for Hylobius abietis (L.) (Coleoptera: Curculionidae) based on data from video recordings of single individuals feeding on seedlings of Norway spruce, Picea abies (L.) Karst. (Pinaceae). The pine weevil is an economically important pest insect, because it feeds on the stem bark of planted conifer seedlings. Weevils had 4–5 meals per day. Each meal lasted about 24 min during which about 13 mm² of bark per meal were removed. Females had longer total meal durations and longer non‐feeding intervals within meals than males. Girdling seedlings did not affect the weevils' feeding properties. The size of meals was significantly correlated with the duration of non‐feeding intervals before and after them. This study is one of few describing the feeding behavior of an insect at a temporal resolution that allows individual meals to be distinguished. With more meal‐related data from insects available, differences in meal properties may be interpreted based on phylogeny, ecology, and physiology. Our results may also assist in the setup and interpretation of studies of plant‐insect interactions, and facilitate the evaluation and development of methods to protect plants against herbivores.     

植食性昆虫唾液效应子和激发子的研究进展

植食性昆虫与寄主植物通过协同进化形成了复杂的防御和反防御机制.本文系统综述了昆虫唾液效应子和激发子在植物与昆虫互作中的作用及机理.昆虫取食中释放的唾液激发子被植物识别而激活植物早期免疫反应,昆虫也能从口腔分泌效应子到植物体内抑制免疫;抗性植物则利用抗性(R)蛋白识别昆虫无毒效应子,启动效应子诱导的免疫反应,而昆虫又进化...     

Molecular Interrogation of the Feeding Behaviour of Field Captured Individual Insects for Interpretation of Multiple Host Plant Use

The way in which herbivorous insect individuals use multiple host species is difficult to quantify under field conditions, but critical to understanding the evolutionary processes underpinning insect–host plant relationships. In this study we developed a novel approach to understanding the host plant interactions of the green mirid, Creontiades dilutus, a highly motile heteropteran bug that has been associated with many plant species. We combine quantified sampling of the insect across its various host plant species within particular sites and a molecular comparison between the insects'' gut contents and available host plants. This approach allows inferences to be made as to the plants fed upon by individual insects in the field. Quantified sampling shows that this “generalist” species is consistently more abundant on two species in the genus Cullen (Fabaceae), its primary host species, than on any other of its numerous listed hosts. The chloroplast intergenic sequences reveal that C. dilutus frequently feeds on plants additional to the one from which it was collected, even when individuals were sampled from the primary host species. These data may be reconciled by viewing multiple host use in this species as an adaptation to survive spatiotemporally ephemeral habitats. The methodological framework developed here provides a basis from which new insights into the feeding behaviour and host plant relationships of herbivorous insects can be derived, which will benefit not only ecological interpretation but also our understanding of the evolution of these relationships.     

Arbuscular mycorrhizal fungi affect phytophagous insect specialism

The majority of phytophagous insects eat very few plant species, yet the ecological and evolutionary forces that have driven such specialism are not entirely understood. The hypothesis that arbuscular mycorrhizal (AM) fungi can determine phytophagous insect specialism, through differential effects on insect growth, was tested using examples from the British flora. In the UK, plant families and species in the family Lamiaceae that are strongly mycorrhizal have higher proportions of specialist insects feeding on them than those that are weakly mycorrhizal. We suggest that AM fungi can affect the composition of insect assemblages on plants and are a hitherto unconsidered factor in the evolution of insect specialism.     

昆虫几丁质酶及其在植物抗虫品种改良中的应用

几丁质是昆虫外壳和围食膜的重要组成成分 ,在适当的时期昆虫分泌适量的几丁质酶降解几丁质以保证昆虫的正常生长。植物几丁质酶能够抵御病原菌的入侵 ,但是对昆虫没有明显的效果 ,而昆虫几丁质酶基因在转基因植物中的组成型表达却对昆虫具有明显的抗性。本文综述了昆虫几丁质酶的特性 ,阐述了昆虫几丁质酶及其在植物抗虫方面应用的研究进展。     

Does mother know best? The preference–performance hypothesis and parent–offspring conflict in aboveground–belowground herbivore life cycles

1. A substantial amount of research on host‐plant selection by insect herbivores is focused around the preference–performance hypothesis (PPH). To date, the majority of studies have primarily considered insects with aboveground life cycles, overlooking insect herbivores that have both aboveground and belowground life stages, for which the PPH could be equally applicable. 2. This study investigated the factors influencing the performance of the root‐feeding vine weevil (Otiorhynchus sulcatus) larvae and whether this was linked to the oviposition behaviour of the maternal adult living aboveground. 3. Maternal insects feeding aboveground reduced root biomass by 34% and increased root carbon by 4%. Larvae feeding on plants subjected to aboveground herbivory had reduced mass. Irrespective of the presence of maternal herbivory, larval mass was positively correlated with root biomass. 4. Larval mass was also reduced by conspecific larvae, previously feeding on roots (19% reduction). However, the mechanism underpinning this effect remains unclear, as in contrast to maternal herbivory aboveground, prior larval feeding did not significantly affect root biomass or root carbon concentrations. 5. Maternal insects did not distinguish between plants infested with larvae and those that were free of larvae, in terms of their egg‐laying behaviour. Conversely, maternal insects tended to lay eggs on plants with smaller root systems, a behaviour that is likely to negatively affect offspring performance. 6. The PPH is not supported by our findings for the polyphagous vine weevil feeding on the host plant raspberry (Rubus idaeus), and in fact our results suggest that there is the potential for strong parent–offspring conflict in this system.     

The impact of arbuscular mycorrhizal fungi on tomato plant resistance against Tuta absoluta (Meyrick) in greenhouse conditions

The symbiotic relationship between plants and arbuscular mycorrhizal fungi (AMF) improves plant growth and increases its resistance to pests and diseases. Mycorrhizal fungi are among the specialized fungi associated with the rhizosphere and are completely dependent on plant organic carbon. In this research tomato, Solanum lycopersicum L. was used as the host plant to evaluate the interaction effects between inoculation of tomato plant with AMF and feeding of tomato leaf miner, Tuta absoluta (Meyrick). In addition, plant growth parameters and growth rate of insect were assessed. The mycorrhizal treatment included a mixture of four fungal species (Funneliformis mosseae, Rhizophagus intraradices, R. irregularis and Glomus iranicus). The results of the experiment showed that tomato plant roots were well colonized (66.29%) by AMF and there was a significant mutual relationship between the insects feeding on the plants and the fungi. Feeding by the insects on plants inoculated with the fungus increased percentage of colonization by AMF in plants infested with the insect as compared to the control plants. The results also indicated that growth parameters and phosphorus content of the plants inoculated with fungi significantly increased compared to the control group. Moreover, significantly lower growth rate and consumption index observed in the T. absoluta larvae were fed on the leaves of plants treated with AMF compared to leaves of plants not inoculated with AMF.     

Feeding by Hessian fly [Mayetiola destructor (Say)] larvae does not induce plant indirect defences

Abstract.  1. Recent research has addressed the function of herbivore-induced plant volatiles in attracting natural enemies of feeding herbivores. While many types of insect herbivory appear to elicit volatile responses, those triggered by gall insects have received little attention. Previous work indicates that at least one gall insect species induces changes in host-plant volatiles, but no other studies appear to have addressed whether gall insects trigger plant indirect defences.
2. The volatile responses of wheat to feeding by larvae of the Hessian fly Mayetiola destructor (Say) (Diptera: Cecidomyiidae) were studied to further explore indirect responses of plants to feeding by gall insects. This specialist gall midge species did not elicit a detectable volatile response from wheat plants, whereas a generalist caterpillar triggered volatile release. Moreover, Hessian fly feeding altered volatile responses to subsequent caterpillar herbivory.
3. These results suggest that Hessian fly larvae exert a degree of control over the defensive responses of their host plants and offer insight into plant-gall insect interactions. Also, the failure of Hessian fly larvae to elicit an indirect defensive response from their host plants may help explain why natural enemies, which often rely on induced volatile cues, fail to inflict significant mortality on M. destructor populations in the field.     

Perception of insect feeding by plants

The recognition of phytophagous insects by plants induces a set of very specific responses aimed at deterring tissue consumption and reprogramming metabolism and development of the plant to tolerate the herbivore. The recognition of insects by plants requires the plant’s ability to perceive chemical cues generated by the insects and to distinguish a particular pattern of tissue disruption. Relatively little is known about the molecular basis of insect perception by plants and the signalling mechanisms directly associated with this perception. Importantly, the insect feeding behaviour (piercing‐sucking versus chewing) is a decisive determinant of the plant’s defence response, and the mechanisms used to perceive insects from different feeding guilds may be distinct. During insect feeding, components of the saliva of chewing or piercing‐sucking insects come into contact with plant cells, and elicitors or effectors present in this insect‐derived fluid are perceived by plant cells to initiate the activation of specific signalling cascades. Although receptor–ligand interactions controlling insect perception have yet not been molecularly described, a significant number of regulatory components acting downstream of receptors and involved in the activation of defence responses against insects has been reported. Some of these regulators mediate changes in the phytohormone network, while others directly control gene expression or the redox state of the cell. These processes are central in the orchestration of plant defence responses against insects.     

用现代分子生物学方法揭示植物与昆虫的相互关系

昆虫与植物之间相互关系的研究由来已久。1 964年Ｅｈｒｌｉｃｈ和Ｒａｖｅｎ提出了协同进化 (ｃｏｅｖｏ ｌｕｔｉｏｎ) [1 ] 的概念后 ,更大大促进了植物与昆虫相互关系的研究。马世骏高度重视这一领域的研究 ,指出协同进化的观点是研究生物进化的方法论的基础之一[2 ] 。钦俊德对昆虫与植物的关系作了系统的论述和总结[3] 。以往研究昆虫与植物之间的相互关系 ,主要依靠分析昆虫的习性与相关植物的外部形态和内含次生物质之间的关系 ,辅以数学手段及计算机工具来进行 ,虽然取得了大量卓有成效的成果 ,但都还未能直接从绝大多数生物的遗传…     

The ‘mother knows best’ principle: should soil insects be included in the preference–performance debate?

Abstract.  1. Few entomological studies include soil-dwelling insects in mainstream ecological theory, for example the preference–performance debate. The preference–performance hypothesis predicts that when insect herbivores have offspring with limited capacity to relocate in relation to a host plant, there is a strong selection pressure for the adult to oviposit on plants that will maximise offspring performance.
2. This paper discusses the proposition that insect herbivores that live above ground, but have soil-dwelling offspring, should be included in the preference–performance debate. Twelve relevant studies were reviewed to assess the potential for including soil insects in this framework, before presenting a preliminary case study using the clover root weevil ( Sitona lepidus ) and its host plant, white clover ( Trifolium repens ).
3. Maternal S. lepidus preferentially oviposited on T. repens plants that had rhizobial root nodules (which enhance offspring performance) rather than T. repens plants without nodules, despite plants having similar foliar nutritional quality. This suggests that adult behaviour above ground was influenced by below-ground host-plant quality.
4. A conceptual model is presented to describe how information about the suitability for offspring below ground could underpin oviposition behaviour of parental insects living above ground, via plant- and soil-mediated semiochemicals. These interactions between genetically related, but spatially separated, insect herbivores raise important evolutionary questions such as how induced plant responses above ground affect offspring living below ground and vice versa.     

植物蛋白酶抑制素抗虫作用的研究进展

植物自身为抵抗昆虫等的为害,在长期进化过程中形成了复杂的化学防御体系,其中起主导作用的是一些植物化学物质。这些化合物能影响昆虫（或其它有机体）的生长、行为和群体生物学,因而又称为它感素（allelochemics）[1～3]。大多数它感素为植物的利己素,可以单一或协同对害虫起作用,构成植物的抗虫性。根据植物对昆虫取食的反应,可将植物的化学防御概括为两类：一类是组成型防御[4],即抗虫物质不依赖于昆虫的取食而存在于植物组织中;另一类是诱导型防御[5～9],即植物仅当昆虫取食时才大量合成抗虫物质。诱导型抗虫物质当然亦可以组…     

视觉信号在昆虫检测植物寄主中的作用

植物为数十万种昆虫提供各种资源,如食物、交配、产卵和躲避天敌的场所。目前对昆虫检测植物寄主的研究主要关注昆虫嗅觉系统和植物寄主挥发物之间的相互作用,对昆虫视觉系统发挥的作用关注较少。近年来,对昆虫视觉器官、光行为反应及分子生物学的研究表明,昆虫具有优异的视觉能力,能够辨别植物寄主的颜色、大小和轮廓,应该将视觉纳入昆虫检测植物寄主的研究中。昆虫能够利用视觉信号准确检测寄主,远距离时,主要依靠植物寄主轮廓检测寄主,近距离时,寄主的大小、颜色和形状发挥重要作用。利用昆虫视觉识别寄主的专一性研制诱捕装置,可为害虫的监测和防治提供一定的理论基础。     

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。     

Differential acquisition of chrysanthemum yellows phytoplasma by three leafhopper species

Chrysanthemum yellows (CY) phytoplasma has been transmitted with three leafhopper species: Euscelidius variegatus (Kirschbaum), Macrosteles quadripunctulatus (Kirschbaum) and Euscelis incisus (Kirschbaum): the first two species are reported as CY phytoplasma vectors for the first time. Leafhoppers were allowed to acquire the pathogen from the following source plants: Apium graveolens L., Catharanthus roseus L., Chrysanthemum carinatum Schousboe L. and C. frutescens L. DNA extracted from healthy or inoculative leafhoppers-exposed plants were analyzed by dot-blot and Southern hybridizations with a molecular probe constructed onto a fragment of European aster yellows phytoplasma DNA. The three leafhopper species were able to transmit CY phytoplasma after acquisition on chrysanthemum, but only M. quadripunctulatus and E. variegatus transmitted after feeding on periwinkle, and none acquired it from celery. All plant species tested were susceptible to CY, but while chrysanthemum and periwinkle were suitable for both inoculation and acquisition, celery did not seem to be a good source of phytoplasma for further inoculations. It is concluded that host plants influence leafhoppers' vectoring ability, possibly due to the different feeding behaviour of the insects on diverse plant species. Since CY, like several other phytoplasmas, can be transmitted by different insect species, it is likely that a close transmission specificity probably does not exist between phytoplasmas and their leafhopper vectors.     

Evolutionary dynamics of specialisation in herbivorous stick insects

Understanding the evolutionary dynamics underlying herbivorous insect mega‐diversity requires investigating the ability of insects to shift and adapt to different host plants. Feeding experiments with nine related stick insect species revealed that insects retain the ability to use ancestral host plants after shifting to novel hosts, with host plant shifts generating fundamental feeding niche expansions. These expansions were, however, not accompanied by expansions of the realised feeding niches, as species on novel hosts are generally ecologically specialised. For shifts from angiosperm to chemically challenging conifer hosts, generalist fundamental feeding niches even evolved jointly with strong host plant specialisation, indicating that host plant specialisation is not driven by constraints imposed by plant chemistry. By coupling analyses of plant chemical compounds, fundamental and ecological feeding niches in multiple insect species, we provide novel insights into the evolutionary dynamics of host range expansion and contraction in herbivorous insects.     

Relative resistance of transgenic tomato tissues expressing high levels of tobacco anionic peroxidase to different insect species.

Different parts of genetically transformed tomato (Lycopersicon esculentum L.) plants that express the tobacco anionic peroxidase were compared for insect resistance with corresponding wild type plants. Leaf feeding by first instar Helicoverpa zea and Manduca sexta was often significantly reduced on intact transgenic plants and/or leaf disks compared to wild type plants, but the effect could depend on leaf age. Leaves of transgenic plants were generally as susceptible to feeding damage by third instar Helicoverpa zea (Boddie) and Manduca sexta (L.) as wild type plants. Green fruit was equally susceptible to third instar larvae of H. zea in both type plants, but fruit of transgenic plants were more resistant to first instar larvae as indicated by significantly greater mortality. Basal stem sections were more resistant to neonate larvae of H. zea and adults of Carpophilus lugubris Murray compared to wild type plants as indicated by significantly greater mortality and/or reduced feeding damage. Thus, tobacco anionic peroxidase activity can increase plant resistance to insects in tomato, a plant species closely related to the original source plant species, when expressed at sufficiently high levels. However, the degree of resistance is dependent on the size of insect and plant tissue involved.     

Effects of non-native plants on the native insect community of Delaware

Due to the lack of a co-evolutionary history, the novel defenses presented by introduced plants may be insurmountable to many native insects. Accordingly, non-native plants are expected to support less insect biomass than native plants. Further, native insect specialists may be more affected by introduced plants than native generalist herbivores, resulting in decreased insect diversity on non-native plants due to the loss of specialists. To test these hypotheses, we used a common garden experiment to compare native insect biomass, species richness, and the proportion of native specialist to native generalist insects supported by 45 species of woody plants. Plants were classified into three groupings, with 10 replicates of each species: 15 species native to Delaware (Natives), 15 non-native species that were congeneric with a member of the Native group (Non-native Congeners), and 15 non-native species that did not have a congener present in the United States (Aliens). Native herbivorous insects were sampled in May, June, and July of 2004 and 2005. Overall, insect biomass was greater on Natives than Non-native Congeners and Aliens, but insect biomass varied unpredictably between congeneric pair members. Counter to expectations, Aliens held more insect biomass than did Non-native Congeners. There was no difference in species richness or the number of specialist and generalist species collected among the three plant groupings in either year, although our protocol was biased against sampling specialists. If these results generalize to other studies, loss of native insect biomass due to introduced plants may negatively affect higher trophic levels of the ecosystem.     

植物耐虫性的研究方法

本文介绍了植物耐虫性的研究方法,包括植物功能损失指数(耐虫指数)、产量损失率、植株被换害率、存活率、根系体积(受害程度)、植株和害虫干重、叶片叶绿素荧光特性、保护酶活性和主茎伤流液量等生理生化指标以及害虫的种群发展和取食行为等方法,并提出植物耐虫性机理的研究思路和方向.     

A bioassay for insect deterrent compounds found in plant and animal tissues

A general field bioassay for detecting biologically active compounds in plants and insects has been developed and tested for efficacy and sensitivity. Methanolic extracts, in sucrose solution, of 20 plant and six caterpillar species were offered to the ponerine ant Paraponera clavata and the feeding preferences observed. The bioassay resulted in the detection of nine plant and three caterpillar species with ant-deterrent extracts, and 11 plant and three caterpillar species with neutral or attractant extracts. All of the plants showing ant-deterrent characteristics which had been chemically investigated in our laboratory, or for which chemical literature was available, contained secondary metabolites of known deterrence. Both naturally occurring and artificial differences in chemical concentrations could be detected using the bioassay. The method provides a means of screening plants and insects for compounds that are insect anti-feedants or that can modify insect behaviour.