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1.
Atmospheric change and species invasions are arguably two of the most important factors affecting the long‐term sustainability of natural ecosystems. We examined the independent and interactive effects of atmospheric carbon dioxide (CO2) and tropospheric ozone (O3) on the foliar quality of two host species and performance of an invasive folivorous insect. Trembling aspen (Populus tremuloides) and paper birch (Betula papyrifera) were grown at the Aspen FACE research site in northern Wisconsin, USA, under all combinations of ambient and elevated CO2 and O3. We measured the effects of elevated CO2 and O3 on aspen and birch phytochemistry and on the survivorship, development time, growth, and fecundity of the gypsy moth (Lymantria dispar). Elevated CO2 had little effect on, whereas elevated O3 altered, the composite phytochemical profiles of aspen and birch. Nutritional quality in aspen and birch leaves was marginally affected by elevated CO2 and reduced by elevated O3. Both gases increased concentrations of phenolic and structural compounds in aspen and birch. Elevated CO2 offset reduced foliar quality under elevated O3, but only in aspen, and to a greater extent later than earlier in spring. Elevated CO2 generally had beneficial effects on, while elevated O3 detrimentally affected, gypsy moth performance. Elevated CO2 ameliorated most of the reductions in gypsy moth performance under elevated O3. Our findings suggest that atmospheric change can alter foliar quality in gypsy moth hosts sufficiently to influence gypsy moth performance, but that these responses will depend on interactions among CO2, O3, and tree species. Our findings also contrast with those of earlier studies at Aspen FACE, indicating that foliar quality responses to environmental change are likely influenced by tree stand age and longevity of exposure to pollutants to the extent that they affect plant‐herbivore interactions differently over decadal time spans. 相似文献
2.
REBECCA E. FORKNER ROBERT J. MARQUIS JOHN T. LILL JOSIANE LE CORFF 《Ecological Entomology》2008,33(2):276-285
Abstract. 1. Specialization on ephemeral resources (e.g. new leaves) should produce large annual variation in herbivore population size when the timing of availability of those resources is unpredictable. Despite considerable evidence for impacts of synchrony with budburst on survival of larval Lepidoptera, previous studies of adult Geometridae and Noctuidae found no correlations between insect phenology and population variability.
2. We surveyed larval Lepidoptera feeding on Quercus alba and Q. velutina in Missouri from 1993 to 2003 and examined population variability, measured as the coefficient of variation of population density (CV), in a subset of abundant species. We compared CV values among species whose larvae feed only in spring, early summer, mid-summer, late summer, or all season. We predicted that univoltine species whose larvae eclose and complete development in spring during leaf expansion would have higher variability than species feeding later in the season, having multiple generations, or having longer development times.
3. As predicted and consistent with hypotheses, spring-feeding species had CV values 32% higher than species feeding in summer months. Coefficients of variation were also 34% higher in leaf-rolling and mining guilds compared with free-feeders, suggesting that mobile species may compensate for asynchrony with budburst by dispersing to higher quality plants or plant parts. Multivoltine species, however, did not differ from univoltine species in population variability.
4. Our results suggest that asynchrony with plant phenology and factors that might exacerbate it, such as climate change, will have the largest impacts on the dynamics of spring-feeding Lepidoptera, particularly species with limited mobility. 相似文献
2. We surveyed larval Lepidoptera feeding on Quercus alba and Q. velutina in Missouri from 1993 to 2003 and examined population variability, measured as the coefficient of variation of population density (CV), in a subset of abundant species. We compared CV values among species whose larvae feed only in spring, early summer, mid-summer, late summer, or all season. We predicted that univoltine species whose larvae eclose and complete development in spring during leaf expansion would have higher variability than species feeding later in the season, having multiple generations, or having longer development times.
3. As predicted and consistent with hypotheses, spring-feeding species had CV values 32% higher than species feeding in summer months. Coefficients of variation were also 34% higher in leaf-rolling and mining guilds compared with free-feeders, suggesting that mobile species may compensate for asynchrony with budburst by dispersing to higher quality plants or plant parts. Multivoltine species, however, did not differ from univoltine species in population variability.
4. Our results suggest that asynchrony with plant phenology and factors that might exacerbate it, such as climate change, will have the largest impacts on the dynamics of spring-feeding Lepidoptera, particularly species with limited mobility. 相似文献
3.
Abstract. 1. The strength or density dependence of pairwise species interactions can depend on the presence or absence of other species, especially potential mutualists.
2. The gall wasp Disholcaspis eldoradensis induces plant galls that secrete a sweet honeydew from their top surfaces while the wasp larvae are active. These galls are actively tended by Argentine ants, which collect the honeydew and drive off parasitoids attempting to attack the gall wasp.
3. When ants were excluded, the total rate of parasitism by seven species of parasitoids increased by 36%, and the rate of gall-wasp emergence decreased by 54%.
4. The total percentage parasitism was affected by gall density when ants were excluded but not when ants were unmanipulated, suggesting a change in parasitoid functional responses due to ant tending.
5. In addition, excluding ants significantly altered the proportions of different parasitoid species that emerged from galls; one parasitoid species increased from 1% to 34%, and another decreased from 46% to 19%.
6. The invasive Argentine ants studied are capable of maintaining the mutualism with the gall wasps that evolved in the presence of different ant species and also act as a selective filter for the local community of generalist parasitoids trying to attack this gall species. 相似文献
2. The gall wasp Disholcaspis eldoradensis induces plant galls that secrete a sweet honeydew from their top surfaces while the wasp larvae are active. These galls are actively tended by Argentine ants, which collect the honeydew and drive off parasitoids attempting to attack the gall wasp.
3. When ants were excluded, the total rate of parasitism by seven species of parasitoids increased by 36%, and the rate of gall-wasp emergence decreased by 54%.
4. The total percentage parasitism was affected by gall density when ants were excluded but not when ants were unmanipulated, suggesting a change in parasitoid functional responses due to ant tending.
5. In addition, excluding ants significantly altered the proportions of different parasitoid species that emerged from galls; one parasitoid species increased from 1% to 34%, and another decreased from 46% to 19%.
6. The invasive Argentine ants studied are capable of maintaining the mutualism with the gall wasps that evolved in the presence of different ant species and also act as a selective filter for the local community of generalist parasitoids trying to attack this gall species. 相似文献
4.
Field surveys of cynipid gall-inducer occurrences on Quercus species were conducted in Florida, North Carolina, and Pennsylvania, USA. All cynipids demonstrated strong host species and organ fidelity. One result of this specialization is effective niche partitioning among cynipids. The host-association patterns of these specialist herbivores should reflect similarities among oaks, thus we clustered oak species according to their cynipid distributions. Cynipids distinguished small differences among their hosts. A dendrogram of oak species based on cynipid distributions was largely congruent with botanical arrangernents. Cynipid occurrences offer information helpful to resolving some aspects of oak systematics. Collaborative efforts between taxonomic botanists and entomologists will be useful in resolving a variety of plant and insect systematic problems. 相似文献
5.
Jeffery S. Bale Gregory J. Masters Ian D. Hodkinson Caroline Awmack † T. Martijn Bezemer Valerie K. Brown ‡ Jennifer Butterfield Alan Buse John C. Coulson John Farrar John E. G. Good Richard Harrington Susane Hartley § T. Hefin Jones Richard L. Lindroth Malcolm C. Press Ilias Symrnioudis Allan D. Watt John B. Whittaker 《Global Change Biology》2002,8(1):1-16
This review examines the direct effects of climate change on insect herbivores. Temperature is identified as the dominant abiotic factor directly affecting herbivorous insects. There is little evidence of any direct effects of CO2 or UVB. Direct impacts of precipitation have been largely neglected in current research on climate change. Temperature directly affects development, survival, range and abundance. Species with a large geographical range will tend to be less affected. The main effect of temperature in temperate regions is to influence winter survival; at more northerly latitudes, higher temperatures extend the summer season, increasing the available thermal budget for growth and reproduction. Photoperiod is the dominant cue for the seasonal synchrony of temperate insects, but their thermal requirements may differ at different times of year. Interactions between photoperiod and temperature determine phenology; the two factors do not necessarily operate in tandem. Insect herbivores show a number of distinct life‐history strategies to exploit plants with different growth forms and strategies, which will be differentially affected by climate warming. There are still many challenges facing biologists in predicting and monitoring the impacts of climate change. Future research needs to consider insect herbivore phenotypic and genotypic flexibility, their responses to global change parameters operating in concert, and awareness that some patterns may only become apparent in the longer term. 相似文献
6.
Cook JM Rokas A Pagel M Stone GN 《Evolution; international journal of organic evolution》2002,56(9):1821-1830
Abstract.— Gall-inducing insects have especially intimate interactions with their host plants and generally show great specificity with regard to both the host-plant species and the organ (e.g. flower, leaf) galled. However, the relative roles of shifts between host species and between host-plant organs in the diversification of gall-inducers are uncertain. We employ a novel and general maximum-likelihood approach to show that shifts between host-plant organs occur at a significantly greater rate than shifts between host oak sections in European Andricus gallwasps. This suggests that speciation has more often been associated with gall location shifts than with colonization of new host-plant species, and implies that it may be easier for gall-inducers to colonize new plant organs than new plant species.
Andricus gallwasps have complex life cycles, with obligate alternation of sexual and parthenogenetic generations. Our phylogenetic analyses show that a life cycle with both generations galling white oaks (section Quercus ) is ancestral, with a single shift of the sexual generation onto black oaks (section Cerris ) to generate a clade with a novel host-alternating life cycle. This new life cycle provided the opportunity for further speciation, but may have also increased the risk of extinction of one or both generations by the demographic requirement for co-existence of both host-plant groups. In summary, it appears that Andricus gallwasp radiation may be a two-level process. Speciation events often involve shifts in gall location on the same host species. However, there are only so many ways to gall an oak, and rare shifts to new oak sections may contribute greatly to long-term diversification by opening up whole new adaptive zones. 相似文献
Andricus gallwasps have complex life cycles, with obligate alternation of sexual and parthenogenetic generations. Our phylogenetic analyses show that a life cycle with both generations galling white oaks (section Quercus ) is ancestral, with a single shift of the sexual generation onto black oaks (section Cerris ) to generate a clade with a novel host-alternating life cycle. This new life cycle provided the opportunity for further speciation, but may have also increased the risk of extinction of one or both generations by the demographic requirement for co-existence of both host-plant groups. In summary, it appears that Andricus gallwasp radiation may be a two-level process. Speciation events often involve shifts in gall location on the same host species. However, there are only so many ways to gall an oak, and rare shifts to new oak sections may contribute greatly to long-term diversification by opening up whole new adaptive zones. 相似文献
7.
Abstract. 1. Community level oak–tannin–insect patterns have been largely unexplored since Paul Feeny's ground‐breaking research. Two hypotheses were tested for Quercus velutina and Q. alba in the Missouri Ozarks: abundance and richness of leaf‐chewing herbivores are negatively correlated with foliar condensed tannin concentrations and variation in condensed tannin concentrations explains variation in herbivore community structure. 2. In 2001, foliar condensed tannins in the understorey and canopy of these two oak species were quantified simultaneously with censuses of herbivores in May, during leaf expansion, and in June and August, when leaves were fully expanded. Thirty‐eight of the 134 species encountered had densities sufficient to be analysed individually (n = 10). Of those, Acronicta increta (Noctuidae) and Attelabus sp. (Curculionidae), both oak specialists, were negatively correlated with condensed tannins in the canopy of Q. alba. One additional specialist, Chionodes pereyra (Gelechiidae), was marginally negatively correlated with condensed tannins in the understorey of Q. velutina. Understorey species richness of May Q. velutina herbivores was negatively correlated with condensed tannins, as were total canopy insect density and species richness of August herbivores on Q. alba. 3. Principal component analysis (PCA) of insect abundances indicated that understorey and canopy Q. velutina and Q. alba had different communities of leaf‐chewing insects. Furthermore, condensed tannin levels contributed significantly to variation in PCA scores for Q. velutina, explaining 25% of the total variation. 4. Overall, these results indicate that specialists were more likely than generalists both to correlate negatively with condensed tannins and to occur in lower tannin habitats; abundance and richness of both early and late season fauna correlated negatively with tannins; and species were more likely to correlate negatively with condensed tannins when feeding on Q. alba than on Q. velutina and when feeding in the canopy than in the understorey. Future studies of tannin–insect interactions should manipulate leaf quality in combination with manipulations of other factors that likely influence community structure. 相似文献
8.
Stephanie L. Sopow Joseph D. Shorthouse Ward Strong Dan T. Quiring 《Ecology letters》2003,6(2):102-105
Abstract We report that a chemical stimulus from a herbivore, a galling insect, changes plant morphology and physiology to benefit the herbivore. Previous studies could not determine whether insect galls are induced by mechanical or chemical stimuli because feeding and oviposition both occurred at the site of gall formation. We report that the mouthparts of a spruce‐galling insect, Adelges cooleyi, were inserted in stem phloem cells far from induced galls, that tissues between mouthparts and galls appeared normal, and that the ability to initiate galls was inversely correlated with distance from buds (potential gall sites). Thus the effects of chemical stimuli were unambiguously separated from any mechanical influence of probing stylets or ovipositors. Our results strongly suggest that galls were induced by a chemical stimulus transported to buds via vascular tissue and that its efficacy was dose‐dependent. 相似文献
9.
10.
Amanda K. Weaver Glen Ray Hood Michael Foster Scott P. Egan 《Ecology and evolution》2020,10(18):10207-10218
Complex interactions within multitrophic communities are fundamental to the evolution of individual species that reside within them. One common outcome of species interactions are fitness trade‐offs, where traits adaptive in some circumstances are maladaptive in others. Here, we identify a fitness trade‐off between fecundity and survival in the cynipid wasp Callirhytis quercusbatatoides that induces multichambered galls on the stem of its host plant Quercus virginiana. We first quantified this trade‐off in natural populations by documenting two relationships: a positive association between the trait gall size and fecundity, as larger galls contain more offspring, and a negative association between gall size and survival, as larger galls are attacked by birds at a higher rate. Next, we performed a field‐based experimental evolution study where birds were excluded from the entire canopy of 11 large host trees for five years. As a result of the five‐year release from avian predators, we observed a significant shift to larger galls per tree. Overall, our study demonstrates how two opposing forces of selection can generate stabilizing selection on a critical phenotypic trait in wild populations, and how traits can evolve rapidly in the predicted direction when conditions change. 相似文献
11.
In the Mamora cork oak forest (Morocco), oophagous predators of the gypsy mothLymantria dispar (L.) (Lepidoptera: Lymantriidae) are one of the main mortality factors influencing pest population dynamics. The predators destroy egg masses more by disrupting their cohesiveness than by predation. From 1987 to 1990, the impact of oophagous enemies significantly contributed to the collapse of a localized gypsy moth outbreak. Variation of egg mass dislocation intensity was greater between trees than among the different strata of a tree. The number of gypsy moth egg masses and egg predator attacks increased when oaks were large and unhealthy. Forest degradation probably explains why egg mass destruction rates were so high (60 to 90% of the eggs) in the infested forest. Oophagous predators find food and shelter under the dehiscent bark of unhealthy cork oaks. 相似文献
12.
CAMILLE PARMESAN 《Global Change Biology》2007,13(9):1860-1872
New analyses are presented addressing the global impacts of recent climate change on phenology of plant and animal species. A meta‐analysis spanning 203 species was conducted on published datasets from the northern hemisphere. Phenological response was examined with respect to two factors: distribution of species across latitudes and taxonomic affiliation or functional grouping of target species. Amphibians had a significantly stronger shift toward earlier breeding than all other taxonomic/functional groups, advancing more than twice as fast as trees, birds and butterflies. In turn, butterfly emergence or migratory arrival showed three times stronger advancement than the first flowering of herbs, perhaps portending increasing asynchrony in insect–plant interactions. Response was significantly stronger at higher latitudes where warming has been stronger, but latitude explained < 4% of the variation. Despite expectation, latitude was not yet an important predictor of climate change impacts on phenology. The only two previously published estimates of the magnitude of global response are quite different: 2.3 and 5.1 days decade−1 advancement. The scientific community has assumed this difference to be real and has attempted to explain it in terms of biologically relevant phenomena: specifically, differences in distribution of data across latitudes, taxa or time periods. Here, these and other possibilities are explored. All analyses indicate that the difference in estimated response is primarily due to differences between the studies in criteria for incorporating data. It is a clear and automatic consequence of the exclusion by one study of data on ‘stable’ (nonresponsive) species. Once this is accounted for, the two studies support each other, generating similar conclusions despite analyzing substantially nonoverlapping datasets. Analyses here on a new expanded dataset estimate an overall spring advancement across the northern hemisphere of 2.8 days decade−1. This is the first quantitative analysis showing that data‐sampling methodologies significantly impact global (synthetic) estimates of magnitude of global warming response. 相似文献
13.
ABSTRACT.
- 1 Larval gypsy moth Lymantria dispar (L.) mortality depends upon the number and type of plant species consumed as well as the sequence in which they are consumed.
- 2 When a two-species diet is composed of a favourable and an unfavourable species, larval mortality is higher on the two-species diet than on the diet of the favourable species alone.
- 3 When a two species diet is composed of a favourable and unfavourable coniferous species, larval mortality is higher on the single conifer species diet than on the two-species diet.
- 4 Two-species diets, in which one species is a conifer, produce individuals with a greater fecundity than diets of either species alone.
- 5 The influence of diets composed of two favourable species, on development, size and fecundity, depends both on the relative quality of each of the two plant species and which of the two is consumed by older instars.
14.
The protein content of tissues in cynipid galls (Hymenoptera: Cynipidae): Similarities between cynipid galls and seeds 总被引：1，自引：1，他引：1
Cynipid galls are examples of induced plant development, where the gall inducer is in control of cell differentiation and morphogenesis of a new plant organ. This study concentrates on the tissues of the larval chamber common to all cynipid galls. The protein content of the inner gall tissue was compared to that of non‐gall plant tissues. We investigated three oak and two rose galls and their respective host plants. Total protein signatures of inner gall tissues were different from those of non‐gall plant tissues, and among the five galls. N‐terminal sequences were obtained for two abundant proteins from the inner gall tissues of D. spinosa and A. quercuscalicis, which were common to all galls, at 62 and 43 kDa. Database queries suggest the 62 kDa protein to be homologous to a protein disulphide isomerase (PDI), and the 43 kDa protein to be homologous to NAD‐dependent formate dehydrogenase (FDH). A naturally biotinylated protein was detected at 33 kDa during Western analyses with streptavidin. Western analyses revealed the presence of the biotinylated protein and PDI in the inner gall tissues of all five galls, while FDH was only detected in A. quercuscalicis and A. fecundator. PDI was also common to all non‐gall tissues, while FDH was not detected in non‐gall tissues, and the biotinylated protein was only detected in seeds. The proteins identified in the inner gall tissue suggest that (a) inner gall tissues in some galls are under respiratory stress, and (b) cynipid gall formation might involve the ectopic expression of seed‐specific proteins. 相似文献
15.
Abstract. 1. With respect to seasonal availability for herbivores, plants defended by synthesising qualitative compounds differ from those protected by accumulation of quantitative macromolecules, leaf toughness, and low water and/or nutrient content. While the palatability of the former plants remains relatively constant during the season, the palatability of the latter group decreases with leaf age.
2. It was hypothesised that in seasonal temperate environments, quantitative plant defences should restrict the annual numbers of insect generations. To test this hypothesis, European butterflies were used as a model, both non-corrected regressions and tests controlling for phylogeny were carried out, and potentially confounding factors such as body size or occurrence in short-season environments were treated as covariables.
3. Non-phylogenetically controlled regressions corroborated that butterflies feeding on quantitatively protected hosts (woody plants + grasses) form fewer generations than species feeding on qualitatively protected forbs. Plant defences fitted voltinism better than butterfly size, and remained significant even after controlling for short seasons. Using independent contrasts, feeding on woody plants plus grasses, and feeding on woody plants only, predicted fewer generations. These patterns, however, applied exclusively for foliage-feeding species.
4. The association between plant defences and voltinism represents a hitherto overlooked pattern in the ecology of temperate herbivores. It may explain why large insects tend to form fewer generations and feed on structurally complex hosts, and why some species remain monovoltine although they are not restricted by short season. 相似文献
2. It was hypothesised that in seasonal temperate environments, quantitative plant defences should restrict the annual numbers of insect generations. To test this hypothesis, European butterflies were used as a model, both non-corrected regressions and tests controlling for phylogeny were carried out, and potentially confounding factors such as body size or occurrence in short-season environments were treated as covariables.
3. Non-phylogenetically controlled regressions corroborated that butterflies feeding on quantitatively protected hosts (woody plants + grasses) form fewer generations than species feeding on qualitatively protected forbs. Plant defences fitted voltinism better than butterfly size, and remained significant even after controlling for short seasons. Using independent contrasts, feeding on woody plants plus grasses, and feeding on woody plants only, predicted fewer generations. These patterns, however, applied exclusively for foliage-feeding species.
4. The association between plant defences and voltinism represents a hitherto overlooked pattern in the ecology of temperate herbivores. It may explain why large insects tend to form fewer generations and feed on structurally complex hosts, and why some species remain monovoltine although they are not restricted by short season. 相似文献
16.
Studies that provide estimates of the form and magnitude of selection on herbivore traits at the level of individual plants in natural populations represent a vital step in understanding the interaction of selection and gene flow among host-affiliated insect populations when individual plants equate to differing selective regimes. We analyzed phenotypic selection on the trait gall size for a host-specific gall former at both the individual host plant and population level (across host plants) in each of two years. Linear and nonlinear selection and the fitness function relating gall size to the probability of survivorship in the absence of natural enemies were estimated for each level and year. Selection imposed by the host plant was observed in 19 of the 22 subpopulations monitored. At the population level, linear and nonlinear selection were evident each year. However, population-level estimates masked the significant heterogeneity in the form and direction of selection evident among plants each year. Heterogeneity among gall-former subpopulations is emphasized by our findings that selection varied from directional to stabilizing among plants and the majority of selection gradients estimated for individual plants did not fall within the 95% CIs of the population-level estimates. 相似文献
17.
Abstract. Three related species of oak gall wasps, Andricus corruptrix (Schlechtendal), A. kollari (Hartig) and A. lignicola (Hartig) have entered Britain since the introduction of Turkey oak, Quercus cerris L. in 1735. Their lifecycles involve alternating generations between an agamic generation on the native oak species (Q. petraea, Q. robur and their hybrid Q. x. rosacea), and a smaller, sexual generation on the alien Q. cerris. In examining the distributions of these insects and Q. cerris, we hypothesized that: (1) the invasion will spread more rapidly in places where both host trees are equally abundant than through regions where one of the tree species is substantially less common than the other; (2) interspecific competition between these bud‐galling species will lead to a negative correlation between their abundances at a particular site; (3) differential recruitment of natural enemies from the native hymenopteran fauna will slow the rate of spread in a species‐specific manner. A. kollari arrived nearly 200 years ago and is now found throughout the British Isles, wherever Turkey oak is grown. A. lignicola and A. corruptrix have been here for 30 years, after establishing in S.E. England. A. lignicola is in its final rapid stages of range expansion across England, southern Scotland and N.E. Scotland. A. corruptrix is just beginning to spread through Central and S.W. England. It has occupied proportionally fewer sites behind its invasion front than have the other two species, but is no less abundant at these sites. Nevertheless, distance leaps of up to 50 km were identified in A. lignicola in N.E. Scotland, and the possibility of long‐distance transport of infected trees through the horticulture and forestry trades remains. The co‐occurrence of mature individuals of both host Quercus species does appear to have increased their rates of colonization in A. lignicola and A. corruptrix. There is no evidence, however, to suggest that interspecific competition between the three alien gall formers is an important factor in determining their distributions and abundance within their invaded ranges. All three species have recruited parasitoids and inquilines rapidly from the native fauna; attack rates were highly variable, but showed no evidence of density dependence across sites. 相似文献
18.
19.
Silicon (Si) is one of the most abundant elements in the earth's crust, although its essentiality in plant growth is not clearly established. However, the importance of Si as an element that is particularly beneficial for plants under a range of abiotic and biotic stresses is now beyond doubt. This paper reviews progress in exploring the benefits at two‐ and three‐trophic levels and the underlying mechanism of Si in enhancing the resistance of host plants to herbivorous insects. Numerous studies have shown an enhanced resistance of plants to insect herbivores including folivores, borers, and phloem and xylem feeders. Silicon may act directly on insect herbivores leading to a reduction in insect performance and plant damage. Various indirect effects may also be caused, for example, by delaying herbivore establishment and thus an increased chance of exposure to natural enemies, adverse weather events or control measures that target exposed insects. A further indirect effect of Si may be to increase tolerance of plants to abiotic stresses, notably water stress, which can in turn lead to a reduction in insect numbers and plant damage. There are two mechanisms by which Si is likely to increase resistance to herbivore feeding. Increased physical resistance (constitutive), based on solid amorphous silica, has long been considered the major mechanism of Si‐mediated defences of plants, although there is recent evidence for induced physical defence. Physical resistance involves reduced digestibility and/or increased hardness and abrasiveness of plant tissues because of silica deposition, mainly as opaline phytoliths, in various tissues, including epidermal silica cells. Further, there is now evidence that soluble Si is involved in induced chemical defences to insect herbivore attack through the enhanced production of defensive enzymes or possibly the enhanced release of plant volatiles. However, only two studies have tested for the effect of Si on an insect herbivore and third trophic level effects on the herbivore's predators and parasitoids. One study showed no effect of Si on natural enemies, but the methods used were not favourable for the detection of semiochemical‐mediated effects. Work recently commenced in Australia is methodologically and conceptually more advanced and an effect of Si on the plants' ability to generate an induced response by acting at the third trophic level was observed. This paper provides the first overview of Si in insect herbivore resistance studies, and highlights novel, recent hypotheses and findings in this area of research. Finally, we make suggestions for future research efforts in the use of Si to enhance plant resistance to insect herbivores. 相似文献
20.
Kirsten M. Prior Dylan G. Jones Shannon A. Meadley-Dunphy Susan Lee Alyson K. Milks Sage Daughton Andrew A. Forbes Thomas H. Q. Powell 《Diversity & distributions》2023,29(11):1355-1370