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1.
1 The native range of the gypsy moth Lymantria dispar (L.) spans the temperate forests of Eurasia. Across this region, a clinal female flight polymorphism exists; gypsy moth females in eastern Asia are mostly capable of directed flight, those in western and southern Europe are largely incapable of flight and populations distributed across the centre of the distribution exhibit a range of intermediate flight behaviours. 2 Although information exists about the timing and duration of female flight from laboratory and wind tunnel studies, little or no quantitative data are available on average distances flown by Asian gypsy moth females prior to oviposition in the field. This information is critical for estimating risk of contamination at specific ports and transit terminals, as well as for predicting the spread of populations that might someday invade currently uninfested regions of the world. 3 In the present study, an extensive visual survey of gypsy moth egg masses was conducted during a walk through streets and paths in a 3.92 × 5.76 km area in Kanazawa, Japan. This area consisted of a matrix of urban, agricultural and forest land uses. The distribution of egg masses relative to distances from host forests was used to infer the magnitude of pre‐ovipositional female flight. 4 A total of 3172 egg masses was recorded from surveys conducted during the search of a path totalling 384 km. Within urban areas, egg masses were most abundant in the area <1 km from the edge of forest land. 5 These results suggest that most female gypsy moth flight is limited to the area within 1 km of host forests. They also suggest that shipping containers and other parcels located >1 km from forests are at a much lower risk of contamination with Asian gypsy moth egg masses. 相似文献
2.
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
3.
Mario Contarini Ksenia S. Onufrieva Kevin W. Thorpe Kenneth F. Raffa Patrick C. Tobin 《Entomologia Experimentalis et Applicata》2009,133(3):307-314
The movement of humans and goods has facilitated the arrival of non‐native insects, some of which successfully establish and cause negative consequences to the composition, services, and functioning of ecosystems. The gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae), is currently invading North American forests at variable rates, spreading by local and long‐distance movement in a process known as stratified dispersal. Newly arriving colonizers often occur considerably ahead of the population front, and a key question is the degree to which they successfully establish. Prior research has highlighted mate‐finding failures in sparse populations as a cause of an Allee effect (positive density dependence). We explored this mechanism by measuring the relationship between female mating success and background male moth densities along the gypsy moth western front in Northern Wisconsin (USA) over 2 years. The mating results were then compared with analogous previous studies in southern Wisconsin, and the southern front in West Virginia and Virginia (USA). Mate‐finding failures in low‐density populations were consistently observed to be density‐dependent across all years and locations. Mate‐finding failures in low‐density populations have important ramifications to invasive species management, particularly in predicting species invasiveness, preventing successful establishment by small founder populations, and concentrating eradication efforts where they are most likely to succeed. 相似文献
4.
Plants can defend themselves indirectly against herbivores by emitting a volatile blend upon herbivory that attracts the natural enemies of these herbivores, either predators or parasitoids. Although signal transduction in plants from herbivory to induced volatile production depends on jasmonic acid (JA) and salicylic acid (SA), the pathways downstream of JA and SA are unknown. Use of Arabidopsis provides a unique possibility to study signal transduction by use of signalling mutants, which so far has not been exploited in studies on indirect plant defence. In the present study it was demonstrated that jar1‐1 and npr1‐1 mutants are not affected in caterpillar (Pieris rapae)‐induced attraction of the parasitoid Cotesia rubecula. Both JAR1 and NPR1 (also known as NIM1) are involved in signalling downstream of JA in induced defence against pathogens such as induced systemic resistance (ISR). NPR1 is also involved in signalling downstream of SA in defence against pathogens such as systemic acquired resistance (SAR). These results demonstrate that signalling downstream of JA and SA differs between induced indirect defence against herbivores and defence against pathogens such as SAR and ISR. Furthermore, it was demonstrated that herbivore‐derived elicitors are involved in induced attraction of the parasitoid Cotesia rubecula 相似文献
5.
6.
Aude Couty Helmut Van Emden Joe N. Perry JIM Hardie John A. Pickett Lester J. Wadhams 《Physiological Entomology》2006,31(2):134-145
Abstract. The relative roles of olfaction and vision in the crepuscular host-finding process of a major lepidopteran pest of cruciferous crops, the diamondback moth Plutella xylostella are investigated in a series of laboratory and semi‐field experiments. Flying female moths use volatile plant chemical cues to locate and to promote landing on their host, even in complex mixed-crop environments in large cages. Multiple regression analysis shows that both the plant position (front, middle or back rows) and the type of plant (host plant, nonhost plant) are needed to explain the distribution of insects in such a mixed-crop situation. This strong plant position effect indicates that, when host plants are present in a mixture, foraging P. xylostella are more likely to alight on the first row of the plants. The findings are discussed with regard to current theories of host-plant location by phytophagous insects and the possible implications for integrated pest management. 相似文献
7.
8.
The extrafloral nectaries of many plants promote ant defense against insect herbivores. We examined the influence of extrafloral nectaries on the levels of parasitism of a generalist insect herbivore, the gypsy moth (Lymantria dispar L.). Larvae and pupae of the moth were collected from trees with and without extrafloral nectaries growing in the same forests in South Korea and reared to evaluate parasitism. More parasitism occurred on plants with extrafloral nectaries in seven of the nine season-long collections at the six sites and in four out of five collecting periods. Parasitism was higher on the four main genera of plants with extrafloral nectaries than on any of five main genera of plants without extrafloral nectaries. There was no difference in parasitoid richness; nine species occurred in each group, eight of which were the same. There was a positive and almost significant correlation between the abundance of plants with extrafloral nectaries and the parasitism of gypsy moth at the sites. Extrafloral nectaries may reduce herbivory by inducing more parasitism of the insect herbivores that attack plants bearing the glands. 相似文献
9.
Abstract. 1. Non-Mendelian maternal effects, the effects of maternal phenotype or environment on offspring phenotype, have been documented in numerous taxa. By affecting offspring vital rates (birth, death, and movement), maternal effects have the potential to influence population dynamics. However, relatively few studies have directly linked maternal phenotype or environment to offspring vital rates. Additionally, even fewer studies have compared the magnitude of across-generation effects (i.e. maternal effects) to within-generation effects.
2. Because of their telescoping generations, aphids can be strongly influenced by maternal effects. The effects of maternal density and maternal host-plant species on offspring survival, fecundity, and alate formation were investigated experimentally in Aphis nerii , the milkweed–oleander aphid.
3. Additionally, the relative strength of maternal effects were compared with those operating within a generation. Therefore, in another set of experiments, the effects of current density and host-plant species (within-generation effects) on aphid vital rates were examined.
4. While maternal effects were present, within-generation effects were much stronger and more strongly influenced aphid vital rates. Within a generation, aphids exhibited density-dependent survival, fecundity, and alate formation and these effects varied among host-plant species.
5. These results indicate that while maternal effects have the potential to affect population dynamics, this potential is not always met. Additionally, the current environment, not the environment of previous generations, more strongly impacts population dynamics. 相似文献
2. Because of their telescoping generations, aphids can be strongly influenced by maternal effects. The effects of maternal density and maternal host-plant species on offspring survival, fecundity, and alate formation were investigated experimentally in Aphis nerii , the milkweed–oleander aphid.
3. Additionally, the relative strength of maternal effects were compared with those operating within a generation. Therefore, in another set of experiments, the effects of current density and host-plant species (within-generation effects) on aphid vital rates were examined.
4. While maternal effects were present, within-generation effects were much stronger and more strongly influenced aphid vital rates. Within a generation, aphids exhibited density-dependent survival, fecundity, and alate formation and these effects varied among host-plant species.
5. These results indicate that while maternal effects have the potential to affect population dynamics, this potential is not always met. Additionally, the current environment, not the environment of previous generations, more strongly impacts population dynamics. 相似文献
10.
Kiggundu A Goulet MC Goulet C Dubuc JF Rivard D Benchabane M Pépin G van der Vyver C Kunert K Michaud D 《The Plant journal : for cell and molecular biology》2006,48(3):403-413
Cysteine proteinase inhibitors of the cystatin superfamily have several important functions in plants, including the inhibition of exogenous cysteine proteinases during herbivory or infection. Here we used a maximum-likelihood approach to assess whether plant cystatins, like other proteins implicated in host-pest interactions, have been subject to positive selection during the course of their evolution. Several amino acid sites were identified as being positively selected in cystatins from either Poaceae (monocots) and Solanaceae (dicots). These hypervariable sites were located at strategic positions on the protein: on each side of the conserved glycine residues in the N-terminal trunk, within the first and second inhibitory loops entering the active site of target enzymes, and surrounding the larfav motif, a sequence of unknown function conserved among plant cystatins. Supporting the assumption that positively selected, hypervariable sites are indicative of amino acid sites implicated in functional diversity, mutants of the 8th cystatin unit of tomato multicystatin including alternative residues at positively selected sites in the N-terminal trunk exhibited highly variable affinities for the cysteine proteases papain, cathepsin B and cathepsin H. Overall, these observations support the hypothesis that plant cystatins have been under selective pressure to evolve in response to predatory challenges by herbivorous enemies. They also indicate the potential of site-directed mutagenesis at positively selected sites for the generation of cystatins with improved binding properties. 相似文献
11.
Alison F. Moldenke Ralph E. Berry Jeffrey C. Miller James G. Wernz 《Entomologia Experimentalis et Applicata》1997,84(2):157-163
We examined toxicity of acephate to third-instar gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae), under different conditions of administration method, availability of food to larvae during bioassay, host plant, and activity of detoxifying enzymes. Larvae that had been fed field-collected foliage of white alder (Alnus rhombifolia Nutt.) were less susceptible 48 h after treatment with topically applied acephate if they were allowed to continue feeding on foliage during the bioassay period (LD50= 60.6 μg/g larva ) than if they were not (LD50= 13.5 μg/g larva ). All surviving larvae were replaced on their original food plant after the 48-h bioassay; of these, 14.4% of the larvae not fed during treatment died before pupation, compared with 1.3% of the larvae fed alder during treatment. The LD50 obtained for topically treated larvae reared and treated on Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, (51.1 μg/g larva) was comparable to that obtained for larvae fed alder (60.0 μg/g larva) throughout treatment. Larvae treated orally with acephate, however, were slightly more susceptible when reared on Douglas-fir (LC50, 20.3 ppm ) than when reared on alder (LC50, 27.0 ppm ). Post-treatment mortality in orally treated larvae was 10.3% in those fed alder and 9.5% in those fed Douglas-fir. Higher cytochrome P-450 activities in larvae reared on Douglas-fir apparently did not enhance tolerance to acephate. Both sexes of orally treated larvae took significantly longer to pupate than did controls on both foliage types, as did topically treated males fed Douglas-fir. Pupal weight generally was slightly, but not always significantly, higher in treated than untreated larvae under all dietary and treatment regimes. 相似文献
12.
1. There are myriad ways in which pollinators and herbivores can interact via the evolutionary and behavioural responses of their host plants.
2. Given that both herbivores and pollinators consume and are dependent upon plant-derived nutrients and secondary metabolites, and utilize plant signals, plant chemistry should be one of the major factors mediating these interactions.
3. Here we build upon a conceptual framework for understanding plant-mediated interactions of pollinators and herbivores. We focus on plant chemistry, in particular plant volatiles and aim to unify hypotheses for plant defence and pollination. We make predictions for the evolutionary outcomes of these interactions by hypothesizing that conflicting selection pressures from herbivores and pollinators arise from the constraints imposed by plant chemistry.
4. We further hypothesize that plants could avoid conflicts between pollinator attraction and herbivore defence through tissue-specific regulation of pollinator reward chemistry, as well as herbivore-induced changes in flower chemistry and morphology.
5. Finally, we test aspects of our predictions in a case study using a wild tomato species, Solanum peruvianum , to illustrate the diversity of tissue-specific and herbivore-induced differences in plant chemistry that could influence herbivore and pollinator behaviour, and plant fitness. 相似文献
2. Given that both herbivores and pollinators consume and are dependent upon plant-derived nutrients and secondary metabolites, and utilize plant signals, plant chemistry should be one of the major factors mediating these interactions.
3. Here we build upon a conceptual framework for understanding plant-mediated interactions of pollinators and herbivores. We focus on plant chemistry, in particular plant volatiles and aim to unify hypotheses for plant defence and pollination. We make predictions for the evolutionary outcomes of these interactions by hypothesizing that conflicting selection pressures from herbivores and pollinators arise from the constraints imposed by plant chemistry.
4. We further hypothesize that plants could avoid conflicts between pollinator attraction and herbivore defence through tissue-specific regulation of pollinator reward chemistry, as well as herbivore-induced changes in flower chemistry and morphology.
5. Finally, we test aspects of our predictions in a case study using a wild tomato species, Solanum peruvianum , to illustrate the diversity of tissue-specific and herbivore-induced differences in plant chemistry that could influence herbivore and pollinator behaviour, and plant fitness. 相似文献
13.
Herbivore-damaged plants emit volatile organic compounds that attract natural enemies of the herbivores. This form of indirect plant defence occurs aboveground as well as belowground, but it remains unclear how simultaneous feeding by different herbivores attacking leaves and roots may affect the production of the respective defence signals. We employed a setup that combines trapping of volatile organic signals and simultaneous measurements of the attractiveness of these signals to above and belowground natural enemies. Young maize plants were infested with either the foliar herbivore Spodoptera littoralis , the root herbivore Diabrotica virgifera virgifera , or with both these important pest insects. The parasitic wasp Cotesia marginiventris and the entomopathogenic nematode Heterorhabditis megidis were strongly attracted if their respective host was feeding on a plant, but this attraction was significantly reduced if both herbivores were on a plant. The emission of the principal root attractant was indeed reduced due to double infestation, but this was not evident for the leaf volatiles. The parasitoid showed an ability to learn the differences in odour emissions and increased its response to the odour of a doubly infested plant after experiencing this odour during an encounter with hosts. This first study to measure effects of belowground herbivory on aboveground tritrophic signalling and vice-versa reemphasizes the important role of plants in bridging interactions between spatially distinct components of the ecosystem. 相似文献
14.
1. The plant phenological age hypothesis predicts that phytophagous insects should prefer and perform better on phenologically young plants than on old plants because plant nutritional quality decreases with plant phenological age. This hypothesis was tested under field and laboratory conditions with the grass miner Chromatomyia milii on the free‐growth species Holcus lanatus. 2. The field experiment was conducted at four sample sites in Belgium where nutritional quality of H. lanatus leaves and performance of C. milii were monitored throughout the growth season. Foliar nutritional quality was highest early in the season due to high levels of proteins and soluble carbohydrates and low levels of lignin. Offspring performance (pupal size) decreased with plant phenological age, due at least partially to the decreasing foliar nutritional quality. 3. In the laboratory experiment, preference and performance of C. milii were determined on three different age classes of H. lanatus. Multiple‐choice experiments demonstrated that oviposition preference did not differ among age classes. Offspring survival decreased with plant phenological age, while pupal size did not differ among age classes. The relationship between foliar nutritional quality and plant phenological age was equivocal and did not correspond to the predictions of the plant phenological age hypothesis. 4. The results of the field experiment were consistent with the idea that the phenological age hypothesis holds in free‐growth species. The laboratory experiment gave only little support to the plant phenological age hypothesis. Possible causes for the differences between field and laboratory experiments are discussed. 相似文献
15.
Anurag A. Agrawal Arne Janssen Jan Bruin Maarten A. Posthumus & Maurice W. Sabelis 《Ecology letters》2002,5(3):377-385
Plants produce defences that act directly on herbivores and indirectly via the attraction of natural enemies of herbivores. We examined the pleiotropic effects of direct chemical defence production on indirect defence employing near‐isogenic varieties of cucumber plants (Cucumis sativus) that differ qualitatively in the production of terpenoid cucurbitacins, the most bitter compounds known. In release–recapture experiments conducted in greenhouse common gardens, blind predatory mites were attracted to plants infested by herbivorous mites. Infested sweet plants (lacking cucurbitacins), however, attracted 37% more predatory mites than infested bitter plants (that produce constitutive and inducible cucurbitacins). Analysis of the headspace of plants revealed that production of cucurbitacins was genetically correlated with large increases in the qualitative and quantitative spectrum of volatile compounds produced by plants, including induced production of (E )‐β‐ocimene (3E )‐4,8‐dimethyl‐1,3,7‐nonatriene, (E,E)‐α‐farnesene, and methyl salicylate, all known to be attractants of predators. Nevertheless, plants that produced cucurbitacins were less attractive to predatory mites than plants that lacked cucurbitacins and predators were also half as fecund on these bitter plants. Thus, we provide novel evidence for an ecological trade‐off between direct and indirect plant defence. This cost of defence is mediated by the effects of cucurbitacins on predator fecundity and potentially by the production of volatile compounds that may be repellent to predators. 相似文献
16.
In a field experiment with 30 locally occurring old‐field plant species grown in a common garden, we found that non‐native plants suffer levels of attack (leaf herbivory) equal to or greater than levels suffered by congeneric native plants. This phylogenetically controlled analysis is in striking contrast to the recent findings from surveys of exotic organisms, and suggests that even if ‘enemy release’ does accompany the invasion process, this may not be an important mechanism of invasion, particularly for plants with close relatives in the recipient flora. 相似文献
17.
Anurag A. Agrawal 《Entomologia Experimentalis et Applicata》2005,115(1):97-105
This paper reviews current progress and makes recommendations for future studies of induced plant responses to herbivory in three research areas: the role of induction in structuring herbivore communities, costs associated with the expression of induced responses, and theory and data on the macro‐evolution of induced responses. It is argued that although mechanistic approaches will be important for progress, it is also critical to maintain a holistic approach, including a consideration of field environments, multi‐species interactions, and patterns over ecological and evolutionary time. 相似文献
18.
Abstract. 1. On two dates, foliar characteristics of pin oak, Quercus palustris , infested with stem galls caused by the horned oak gall, Callirhytis cornigera , were investigated, and the consequences for subsequent herbivory assessed.
2. Second-instar caterpillars of the gypsy moth, Lymantria dispar , preferred foliage from ungalled trees.
3. Ungalled trees broke bud earlier than their galled counterparts.
4. Galled trees produced denser leaves with higher nitrogen and tannin concentrations, but foliar carbohydrates did not differ among galled and ungalled trees.
5. Concentrations of foliar carbohydrates in both galled and ungalled trees increased uniformly between the two assay dates. Nitrogen concentrations were greater in leaves from galled trees, and decreased uniformly in galled and ungalled trees over time. Foliar tannins were also greater in foliage from galled trees early in the season; however, foliar tannins declined seasonally in galled tissue so that by the second assay date there was no difference in tannin concentrations between galled and ungalled foliage.
6. In spite of differences in foliar characteristics, performance of older, fourth instar gypsy moth caterpillars did not differ between galled and ungalled trees. 相似文献
2. Second-instar caterpillars of the gypsy moth, Lymantria dispar , preferred foliage from ungalled trees.
3. Ungalled trees broke bud earlier than their galled counterparts.
4. Galled trees produced denser leaves with higher nitrogen and tannin concentrations, but foliar carbohydrates did not differ among galled and ungalled trees.
5. Concentrations of foliar carbohydrates in both galled and ungalled trees increased uniformly between the two assay dates. Nitrogen concentrations were greater in leaves from galled trees, and decreased uniformly in galled and ungalled trees over time. Foliar tannins were also greater in foliage from galled trees early in the season; however, foliar tannins declined seasonally in galled tissue so that by the second assay date there was no difference in tannin concentrations between galled and ungalled foliage.
6. In spite of differences in foliar characteristics, performance of older, fourth instar gypsy moth caterpillars did not differ between galled and ungalled trees. 相似文献
19.
- 1 Plant patch shape may affect the abundance of herbivorous insects. Patches of the same size but longer or irregular have a higher perimeter/area relationship (P/A) than square or regular ones, which may determine the immigration, emigration and abundance of individuals in the patch.
- 2 Only specialist species should be affected by plant patch shape. Those species that are more abundant in smaller patches should be more abundant in patches with higher P/A, whereas those that are more abundant in larger patches should be more abundant in patches with lower P/A.
- 3 We studied the density of eggs, larvae and pupae of Pieris brassicae, Plutella xylostella and Trichoplusia ni in square (low P/A) and I‐shaped (high P/A) patches of 144 plants of Brassica oleracea. We also estimated their immigration to these patches, and the final plant weight.
- 4 Plant patch shape affected the abundance, but not the distribution, of the two specialist species. Whereas P. brassicae was denser in I‐shaped patches, P. xylostella was more abundant in square patches. The generalist T. ni was not affected by patch shape. Immigration of P. brassicae was higher in I‐shaped patches, but immigration of P. xylostella and T. ni was not affected by patch shape. Plants were heavier in the centre of square patches.
- 5 Our results suggest that plant patch shape affects the density of herbivorous insects and should be considered independently from other plant patch variables when studying the population dynamics of these organisms.
20.
Abstract. Beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), caterpillars are destructive crop pests responsible for considerable annual economic losses. These generalist herbivores are challenged with a diversity of dietary choices that can impact their survival, development and fecundity. In the present study, dietary choices of S. exigua caterpillars, based on the protein to digestible carbohydrate (P : C) ratio of the food, and the impact of nutritionally unbalanced foods on caterpillar performance are assessed. In choice experiments, individual third-instar caterpillars are offered simultaneously a P-biased and a C-biased food until pupation. Caterpillars feed nonrandomly and select a slightly P-biased diet (22P : 20C). In no-choice experiments, second instar caterpillars are reared until pupation on diets ranging in P : C ratio from extremely P- to extremely C-biased. High mortality and delayed development are observed on the C-rich, P-poor diets, highlighting the potential deleterious effects of excess carbohydrates and the importance of protein for growth and development. Diet-dependent differences in pupal weight or pupal lipid reserves are not observed. This contrasts with closely-related Spodoptera species where pupal mass and lipid stores increase on C-rich, P-poor diets. On the extremely P-biased diet, performance is similar to that of individuals reared on the self-selected diet, suggesting that these caterpillars may efficiently be deaminating excess amino acids to generate carbon skeletons, which are shunted into lipid biosynthesis. Spodoptera exigua caterpillars exhibit flexible and efficient pre-ingestive nutrient intake regulation and post-ingestive utilization, allowing these generalist feeders to cope with the heterogeneous diets they may encounter. 相似文献