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M. Boots 《Oecologia》2000,124(2):172-175
The effects of resource limitation on the transmission of a pathogen were explored. Resource limitation was achieved by replacing
part of the host’s diet with an indigestible bulking agent. Populations of the pyrallid moth, Plodia interpunctella, raised on high- and low-quality food regimes were exposed to a granulosis virus. Moths subjected to a lower food quality
were more likely to become infected, despite the fact that in previous studies, individuals showed no increased susceptibility
when exposed individually to the virus. This effect is suggested to be due to a higher exposure to the pathogen due to a faster
feeding rate and longer developmental period. The implications of resource levels to the population dynamics of host-pathogen
interactions are discussed.
Received: 8 July 1999 / Accepted: 14 February 2000 相似文献
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Jessica Kansman Vamsi Nalam Punya Nachappa Deborah Finke 《Ecological Entomology》2020,45(6):1437-1444
- The effects of drought-induced changes in plant quality on aphid performance and population growth is well-studied. The response of aphid behaviour to plant water limitation has received less attention. Water limitation may affect host-plant colonization by altering the attractiveness of plants. Additionally, plant water limitation may inhibit feeding site establishment and phloem ingestion.
- Our goal was to examine bird cherry-oat aphid (Rhopalosiphum padi L.) host selection and feeding behaviour under water limitation. We assessed aphid response to well-watered, mildly-stressed, and highly-stressed wheat (Triticum aestivum L.) by evaluating (i) host-plant selection through two-choice assays, (ii) feeding behaviour using the electrical penetration graph technique, and (iii) phloem ingestion by quantifying honeydew production.
- Aphids were less likely to select highly stressed plants than a mildly stressed or well-watered alternative. Aphids did not distinguish between mildly stressed and well-watered plants. Aphid feeding behaviours, including duration of phloem ingestion, were not affected by water availability. However, honeydew production was reduced under both levels of water limitation. These results suggest that the volume of phloem ingested by aphids per unit time declined on stressed plants. The combination of lower colonization and diminished access to food on stressed plants may lead to a reduction in aphid abundance, independent of the direct effects of nutrition on individual aphid performance.
- This study highlights the potential contribution of herbivore behaviour to documented changes in aphid abundance on stressed plants and underscores the important role of plant water stress intensity in mediating plant-herbivore interactions.
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Yu Peng Xiao‐li Shao Grant C. Hose Feng‐xiang Liu Jian Chen 《Agricultural and Forest Entomology》2010,12(4):343-351
- 1 Mixtures of organophosphorus and pyrethroid insecticides are widely used to combat resistance in agricultural pests, although few studies have been conducted on the effects of pesticide mixtures on beneficial nontarget organisms.
- 2 In the present study, we exposed adult females (F0) of Hylyphantes graminicola (Araneae: Linyphiidae) to fenvalerate, dimethoate and their commercially available 1 : 1 mixture (by mass). We investigated the acute toxicity of these pesticides to the exposed adults, as well as sublethal effects on reproduction and acetylcholinesterase and carboxylesterase activity. We also studied the effects of parental exposure on the size, development and enzyme activity of unexposed offspring.
- 3 All three formulations were acutely toxic to H. graminicola, with synergism between dimethoate and fenvalerate leading to greater toxicity in the 1 : 1 mixture than for the two insecticides alone. The sublethal effects of direct pesticide exposure were a reduction in acetylcholinesterase and carboxylesterase activity and a reduction in the number of egg sacs produced by exposed spiders relative to the control spiders. The unexposed offspring of the fenvalerate and mixture exposed spiders were smaller and took longer to mature than the control spiders. Offspring of all exposed spiders also had significantly reduced carboxylesterase activity relative to control spiders.
- 4 We concluded that the effects of parental exposure on the offspring were likely to increase their susceptibility to future pesticide exposures, and reduce the capacity of this spider to serve as a pest control agent.
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GRAHAM N. STONE 《Ecological Entomology》1994,19(2):177-189
Abstract.
- 1 Patterns of activity at a large nesting aggregation and at foraging sites are described for females of the solitary bee Anthophora plumipes (Pallas). Changes in the quality and quantity of the resource collected by females provisioning cells are related to variation in female body mass and microclimate.
- 2 Activity at the nest site demonstrated relationships with aspects of the thermal environment experienced by A.plumipes. Measures of temperature showing significant relationships differed for females in different stages in the nesting cycle exhibiting characteristically different behaviour patterns.
- 3 Larger females emerged from nest tunnels earlier in the morning and provisioned cells at lower ambient temperatures than smaller individuals. Body size therefore predicts reproductive success at low ambient temperatures.
- 4 Pollen and nectar loads carried by females increased with ambient temperature. Because only one cell is completed per day and the size of offspring is determined by the quality and quantity of resource provided by the mother, the body size of individuals emerging in the following season will depend on interactions between climate and body size, in addition to any heritable component.
- 5 Variation in activity levels at foraging sites is attributed not only to thermal considerations, but also to variation in the quality of rewards available at different floral sources.
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Systematic within-tree variation in mountain birch leaf quality for a geometrid, Epirrita autumnata 总被引：1，自引：0，他引：1
Abstract.
- 1 We studied within-tree variation in leaf quality of the mountain birch, Betula pubescens ssp. tortuosa, for larvae of the autumnal moth, Epirrita autumnata.
- 2 The purpose of the study was to determine the possible occurrence of systematic differences in larval growth on short shoot leaves (i.e. leaves of the same age): among leaves facing in different compass directions, between leaves of lower and upper branches, among leaves on different positions within a branch and among leaves of different sizes within a short shoot. We also measured larval growth between short shoot and long shoot leaves (i.e. between leaves of different age).
- 3 The larvae grew best on leaves on the north side of trees and most poorly on south side leaves, the east and west sides being intermediate. Leaves from the upper branches supported larval growth better than leaves from the lower ones. The larvae grew better on the smallest leaf of each short shoot and were able to utilize it more efficiently than the two larger leaves. Short shoot leaves from the basal and middle parts of the upper branches of the trees were of better quality for the larvae than short shoot leaves from the tip part of the branches. The larval growth rate did not differ between short shoot and long shoot leaves. In general, within-tree variation in the larval growth rate was lower than variation among different trees.
- 4 Damage to leaves can decrease leaf quality for herbivores in the same year (rapidly inducible responses) or the following year(s) (delayed inducible responses). Our results show that systematic within-tree variation in larval growth can be as great as the effects of rapidly inducible responses and that variation among individual trees can be as great as the mean effects of delayed inducible responses.
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Manipulating resource availability to assess the strength and effects of resource limitation on an animal population is relatively straightforward, and thus, common in the scientific literature. Resource quality, however, is rarely manipulated, as this requires a priori knowledge of a relationship between some measurable variation in the resource and individual preference and/or fitness. Recent research on nest‐site selection was used to inform the design of custom‐built nest‐boxes for an endangered hollow‐nester, the Gouldian finch (Erythrura gouldiae). By provisioning breeding populations with these ‘high quality’ artificial nest sites over 3 years, we experimentally investigated the strength and effects of nest‐site limitation in this species. Breeding pairs using nest‐boxes initiated nesting earlier, produced larger clutches and fledged more offspring per season than those in natural hollows. Total and mean reproductive output also increased in nest‐box provisioned sites over the duration of the study. All of these effects were predominantly driven by pairs initiating clutches earlier, potentially because of the reduced intra‐ and interspecific competition for nest sites at optimal breeding times. Our findings suggest that reproduction in wild Gouldian finch populations may be limited by the availability of high quality nest sites in the landscape, and that nest‐boxes could be used as a tool for enhancing reproduction in recovering populations. Furthermore, we conclude that resource quality is equally, if not more important than quantity when supplementing resource‐limited habitats. 相似文献
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Javier Snchez‐Hernndez Anders G. Finstad Jo Vegar Arnekleiv Gaute Kjrstad Per‐Arne Amundsen 《Freshwater Biology》2021,66(1):44-61
- Ecological opportunity (i.e. the diversity of available resources) has a pivotal role in shaping niche variation and trophic specialisation of animals. However, ecological opportunity can be described with regard to both diversity and abundance of resources. The degree to which these two components contribute to niche variation remains unexplored.
- To address this, we used an extensive dataset on fish diet and benthic invertebrate diversity and density from 73 sampling events in three Norwegian rivers in order to explore realised trophic niches and the response of dietary niche variation along gradients of resource diversity (potential trophic niches), resource density (as a proxy of resource abundance) and fish density (as a proxy of inter‐ and intra‐specific competition) in a freshwater top predator (the brown trout, Salmo trutta L.).
- Linear models indicated that individual and population niche variation increased with increasing ecological opportunity in terms of prey diversity. However, no simple cause‐and‐effect associations between niche indices and prey abundance were found. Our multiple regression analyses indicated that the abundance of certain resources (e.g. Chironomidae) can interact with prey diversity to determine individual and population realised trophic niches. Niche variation (within‐individual component and inter‐individual diet variation) decreased with increasing inter‐ and intra‐specific competition.
- This study extends prevailing trophic ecology theory by identifying diversity, rather than density, of available prey resources as a primary driver of niche variation in fish of temperate riverine systems with no extensive resource limitation. The study also shows that ecological opportunity may mask the direction of the effect (compression or expansion) of competition on niche variation when food resources are diverse.
- Our study provides novel empirical insight to the driving forces behind niche variation and reveals that diversity, rather than density, of available prey resources may be a primary driver of niche variation in freshwater fish. Our study supports the view that a broader potential trophic niche promotes broader realised trophic niche variation by individuals, which leads to individual niche diversification by opening access to alternatives resources, resulting in a concomitant rise in the realised trophic niche width of the population.
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Ryleigh V. Gelles Thomas S. Davis Kevin J. Barrett 《Agricultural and Forest Entomology》2023,25(3):435-448
- Managed low-severity surface fires are frequently implemented in efforts to restore disturbance processes to forests of North America; although the effects of managed fire on forest structure are well-studied, few studies investigate whether these disturbances cascade to impact pollinator communities.
- We analysed bee-habitat relationships in fire-treated (1- and 3-years post-treatment) and non-treated ponderosa pine stands in Colorado to test wild bee population responses.
- Observed bee richness and α-diversity were highest in stands 1-year post-fire and had more Anthophora, Bombus, Osmia and Lasioglossum spp. in comparison to 3-year post-fire and non-treated stands. Bee functional groups were responsive to treatments, with more below-ground nesting taxa present in stands 3 years post-fire.
- Floral richness was the highest mid-growing season (June, July) and within 1-year post-fire stands.
- A model analysing the effects of foraging and nesting habitat variation on bee assemblages indicated positive association between floral richness and bee α-diversity, but negative relationships with stand basal area. Nesting habitat was not associated with variation in bee assemblages.
- We conclude that managed fire has positive short-term effects on bee biodiversity that are likely mediated by floral richness. However, these effects were not detectable by 3 years post-treatment in the southern Rocky Mountain region.
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Teiji Sota 《Population Ecology》1984,26(2):389-400
The reproductive patterns of two different age classes of Leptocarabus kumagaii adults, i.e. young beetles which were in the first year of adult stage and old ones which survived for more than two years, were studied in the field. The numbers of eggs laid were compared between young and old females and the effects of food quality and quantity were studied on egg production and maintenance in the laboratory.
- Both of the young and old beetles reproduced in the field population. The number of eggs laid did not significantly differ between the two.
- The number of eggs laid by female increased with an increase in the amount of miced beef eaten. Plant materials were ineffective for egg production but sufficient for the survival of both male and female beetles.
- The two life historical aspects, i.e. repeated reproduction and polyphagy were discussed in relation to environmental fluctuation and limitation of food resources.
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Jos M. Conde‐Porcuna 《Freshwater Biology》2000,44(3):423-430
- 1 In the laboratory, the growth and reproduction of Anuraeopsis fissa were measured when fed on Scenedesmus species grown in nutrient‐sufficient, nitrogen‐limited and phosphorus‐limited media and in the presence or absence of one adult Daphnia longispina per vial.
- 2 Poor food quality may reduce the effect of competition on rotifers. Competition from Daphnia was stronger with nutrient sufficient algae than with nutrient limited algae. P‐limitation significantly reduced Anuraeopsis population growth rate and fecundity. The effect of nutrient limitation on Anuraeopsis was stronger than that of competition with Daphnia. The Anuraeopsis population declined with P‐limited food in both the presence and absence of Daphnia.
- 3 Exploitative competition by Daphnia on Anuraeopsis was stronger in the nutrient‐sufficient treatment than in the N‐limited one. Density, fecundity and population growth rate of Anuraeopsis were negatively affected by Daphnia in the nutrient‐sufficient treatment, while only fecundity was reduced by Daphnia in the N‐limited treatment. Consequently, in the N‐limited treatment, mortality should be lower in the presence of Daphnia. This result could suggest that Anuraeopsis lives longer when short of nitrogen.
- 4 Nutrient limitation may affect to the competitive interactions between zooplankton species. P‐limitation decreased the quality of algae as food for Anuraeopsis while N‐limitation decreased the susceptibility of this rotifer species to exploitative competition by Daphnia.