Host-Parasitoid Interactions

Ecology ◽  
2013 ◽  
Author(s):  
Jeffrey A. Harvey
Keyword(s):  
Population Dynamics ◽  
Food Webs ◽  
20Th Century ◽  
Host Species ◽  
Trophic Levels ◽  
Diverse Group ◽  
Ecological Communities ◽  
Major Focus ◽  
Species Identity ◽  
Wide Range

Insects are a highly diverse group due to their ability to exploit a wide range of niches. Each plant is attacked by multiple herbivores and these in turn may harbor a bewildering complexity of natural enemies, particularly parasitoids, which are often quite specialized in terms of the host species identity (and stage of attack) of their hosts. Furthermore, these parasitoids have their own parasitoids that attack them, meaning that food webs including these insects may go up to five trophic levels (or even more). Due to their diversity and strong link population dynamics, parasitoids comprise important aspects of ecological communities. Because of this and their potential as biocontrol agents, host-parasitoid dynamics have been a major focus of ecological and evolutionary study since the beginning of the 20th century.

scholarly journals A Perspective on the Consequences for Insect Herbivores and Their Natural Enemies When They Share Plant Resources

ISRN Ecology ◽  
2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Patrik Kehrli ◽  
Steve D. Wratten
Keyword(s):  
Food Webs ◽  
Feeding Strategy ◽  
Multitrophic Interactions ◽  
Trophic Levels ◽  
Ecological Communities ◽  
Agricultural Pests ◽  
Plant Resources ◽  
Plant Resource ◽  
Individual Fitness ◽  
Relative Change

Thousands of insect species consume both animal and plant-derived food resources. However, little recognition is given to the fact that omnivory is a general feeding strategy common to all higher trophic levels. Species in multitrophic interactions can all directly rely on the same plant resources. Nonetheless, little is known about the effect of a change in the relative abundance of a shared plant resource on trophic dynamics. Here we describe how a relative change of resource availability can affect multitrophic interactions and we emphasise its importance. Changes in multitrophic interactions can be induced by unequal alterations of individual fitness across trophic levels, possibly leading to changes in population structure of interacting species. At least ten ecological mechanisms can be involved and these are explored here. It is concluded that shared plant resources that are differentially used over several trophic levels have the potential to modify community structure and energy flow within food webs and ecosystems in more complex ways than previously recognised. The synthesis presented here provides an understanding of this complexity and can lead to improved deployment of biodiversity when manipulating food webs to protect ecological communities or to enhance ecosystem services such as biological control of agricultural pests.

scholarly journals Multiple parasitoid species enhance top-down control, but parasitoid performance is context-dependent

2021 ◽  
Author(s):  
Melanie Thierry ◽  
Nicholas A. Pardikes ◽  
Miguel G Ximenez-Embrun ◽  
Gregoire Proudhom ◽  
Jan Hrcek
Keyword(s):  
Community Structure ◽  
Host Species ◽  
Species Interactions ◽  
Switching Behavior ◽  
Global Changes ◽  
Ecological Communities ◽  
Parasitoid Species ◽  
Species Identity ◽  
Larval Parasitoid ◽  
Species Specific

Ecological communities are composed of a multitude of interacting species, forming complex networks of interactions. Current global changes are altering community composition and we thus need to understand if the mechanisms structuring species interactions are consistent across different species compositions. However, it is challenging to explore which aspects of species interactions are primarily driven by community structure and which by species identity. Here we compared the outcome of host-parasitoid interactions across four community modules that are common in host-parasitoid communities with a laboratory experiment using a pool of three Drosophila host and three larval parasitoid species, resulting in nine different species assemblages. Our results show general patterns of community structure for host-parasitoid interactions. Multiple parasitoid species enhanced host suppression without general antagonistic effects between parasitoid species. Presence of an alternative host species had no general effects on host suppression nor on parasitoid performance, therefore showing no evidence of indirect interactions between host species nor any host switching behavior. However, effects of community structure on parasitoid performance were species-specific and dependent on the identity of co-occurring species. Consequently, our findings highlight the importance of both the structure of the community and its species composition for the outcome of interactions.

scholarly journals Environmental variability uncovers disruptive effects of species' interactions on population dynamics

2015 ◽  
Vol 282 (1812) ◽  
pp. 20151126 ◽  
Author(s):  
Sara Gudmundson ◽  
Anna Eklöf ◽  
Uno Wennergren
Keyword(s):  
Population Dynamics ◽  
White Noise ◽  
Food Webs ◽  
Species Interactions ◽  
Environmental Variability ◽  
Single Species ◽  
Ecological Communities ◽  
Species Response ◽  
To Come ◽  
Isolated Species

How species respond to changes in environmental variability has been shown for single species, but the question remains whether these results are transferable to species when incorporated in ecological communities. Here, we address this issue by analysing the same species exposed to a range of environmental variabilities when (i) isolated or (ii) embedded in a food web. We find that all species in food webs exposed to temporally uncorrelated environments (white noise) show the same type of dynamics as isolated species, whereas species in food webs exposed to positively autocorrelated environments (red noise) can respond completely differently compared with isolated species. This is owing to species following their equilibrium densities in a positively autocorrelated environment that in turn enables species–species interactions to come into play. Our results give new insights into species' response to environmental variation. They especially highlight the importance of considering both species' interactions and environmental autocorrelation when studying population dynamics in a fluctuating environment.

Relationship between morphometrics and trophic levels in deep-sea fishes

2020 ◽  
Vol 637 ◽  
pp. 225-235 ◽  
Author(s):  
MA Ladds ◽  
MH Pinkerton ◽  
E Jones ◽  
LM Durante ◽  
MR Dunn
Keyword(s):  
Stable Isotopes ◽  
Trophic Level ◽  
Deep Sea ◽  
Strong Relationship ◽  
Ecosystem Model ◽  
Trophic Levels ◽  
Fish Size ◽  
Wide Range ◽  
Gape Size ◽  
Morphological Variables

Marine food webs are structured, in part, by predator gape size. Species found in deep-sea environments may have evolved such that they can consume prey of a wide range of sizes, to maximise resource intake in a low-productivity ecosystem. Estimates of gape size are central to some types of ecosystem model that determine which prey are available to predators, but cannot always be measured directly. Deep-sea species are hypothesized to have larger gape sizes than shallower-water species relative to their body size and, because of pronounced adaptive foraging behaviour, show only a weak relationship between gape size and trophic level. Here we present new data describing selective morphological measurements and gape sizes of 134 osteichthyan and chondrichthyan species from the deep sea (200-1300 m) off New Zealand. We describe how gape size (height, width and area) varied with factors including fish size, taxonomy (class and order within a class) and trophic level estimated from stable isotopes. For deep-sea species, there was a strong relationship between gape size and fish size, better predicted by body mass than total length, which varied by taxonomic group. Results show that predictions of gape size can be made from commonly measured morphological variables. No relationship between gape size and trophic level was found, likely a reflection of using trophic level estimates from stable isotopes as opposed to the commonly used estimates from FishBase. These results support the hypothesis that deep-sea fish are generalists within their environment, including suspected scavenging, even at the highest trophic levels.

Evaluation and Avoidance of False Alarm by Controlling Rhine Water with Continuously Working Biotests

1994 ◽  
Vol 29 (3) ◽  
pp. 207-209 ◽  
Author(s):  
H. Puzicha
Keyword(s):  
Warning System ◽  
Point Sources ◽  
Trophic Levels ◽  
River Rhine ◽  
Wide Range ◽  
River Test ◽  
Continuous Working ◽  
Range Of Variation ◽  
Contaminant Load ◽  
Rhine Water

Effluents from point sources (industries, communities) and diffuse inputs introduce pollutants into the water of the river Rhine and cause a basic contaminant load. The aim is to establish a biological warning system to detect increased toxicity in addition to the already existing chemical-physical monitoring system. To cover a wide range of biocides, continuous working biotests at different trophic levels (bacteria, algae, mussels, water fleas, fishes) have been developed and proved. These are checked out for sensitivity against toxicants, reaction time, validity of data and practical handling under field conditions at the river. Test-specific appropriate methods are found to differentiate between the normal range of variation and true alarm signals.

scholarly journals Elevated temperature and browning increase dietary methylmercury, but decrease essential fatty acids at the base of lake food webs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pianpian Wu ◽  
Martin J. Kainz ◽  
Fernando Valdés ◽  
Siwen Zheng ◽  
Katharina Winter ◽  
...  
Keyword(s):  
Climate Change ◽  
Fatty Acids ◽  
Organic Matter ◽  
Food Webs ◽  
Essential Fatty Acids ◽  
Trophic Levels ◽  
Climate Change Scenarios ◽  
Essential Nutrients ◽  
Aquatic Food Webs ◽  
Aquatic Food

AbstractClimate change scenarios predict increases in temperature and organic matter supply from land to water, which affect trophic transfer of nutrients and contaminants in aquatic food webs. How essential nutrients, such as polyunsaturated fatty acids (PUFA), and potentially toxic contaminants, such as methylmercury (MeHg), at the base of aquatic food webs will be affected under climate change scenarios, remains unclear. The objective of this outdoor mesocosm study was to examine how increased water temperature and terrestrially-derived dissolved organic matter supply (tDOM; i.e., lake browning), and the interaction of both, will influence MeHg and PUFA in organisms at the base of food webs (i.e. seston; the most edible plankton size for zooplankton) in subalpine lake ecosystems. The interaction of higher temperature and tDOM increased the burden of MeHg in seston (< 40 μm) and larger sized plankton (microplankton; 40–200 μm), while the MeHg content per unit biomass remained stable. However, PUFA decreased in seston, but increased in microplankton, consisting mainly of filamentous algae, which are less readily bioavailable to zooplankton. We revealed elevated dietary exposure to MeHg, yet decreased supply of dietary PUFA to aquatic consumers with increasing temperature and tDOM supply. This experimental study provides evidence that the overall food quality at the base of aquatic food webs deteriorates during ongoing climate change scenarios by increasing the supply of toxic MeHg and lowering the dietary access to essential nutrients of consumers at higher trophic levels.

Effects of Host Species Identity and Diet on the Biodiversity of the Microbiota in Puerto Rican Bats

2021 ◽  
Author(s):  
Steven J. Presley ◽  
Joerg Graf ◽  
Ahmad F. Hassan ◽  
Anna R. Sjodin ◽  
Michael R. Willig
Keyword(s):  
Puerto Rican ◽  
Host Species ◽  
Species Identity

scholarly journals Morphometric and Molecular Analyses of Ostertagia leptospicularis Assadov, 1953 from Ruminants: Species Diversity or Host Influence?

Animals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 182
Author(s):  
Anna Wyrobisz-Papiewska ◽  
Jerzy Kowal ◽  
Elżbieta Łopieńska-Biernat ◽  
Paweł Nosal ◽  
Iwona Polak ◽  
...  
Keyword(s):  
Host Species ◽  
Roe Deer ◽  
Bos Taurus ◽  
Capreolus Capreolus ◽  
Nematode Species ◽  
Molecular Techniques ◽  
Systematic Classification ◽  
Morphological Variations ◽  
Wide Range ◽  
Induced Changes

Ostertagia leptospicularis Assadov, 1953 was formally described in roe deer Capreolus capreolus and has been reported in a wide range of ruminants, including other Cervidae, as well as Bovidae. Nematode specimens derived from various host species exhibit morphological similarity; however, some differences can be observed. It is unclear if this is due to the differential reaction of one nematode species in different host species (i.e., host-induced changes) or because of distinct nematode species in these hosts (i.e., species complex). This paper focuses on specimens resembling O. leptospicularis f. leptospicularis and its closely related species (Ostertagia ostertagi f. ostertagi) collected from various hosts. Morphometric and molecular techniques were applied to assess host-induced changes in nematode morphology and to clarify its systematic classification. There was an overall effect of host species on measurements of nematodes resembling O. leptospicularis (both males and females), but the distinctiveness of the specimens from cattle Bos taurus were highlighted. The results obtained may suggest that the specimens of O. leptospicularis from cattle in Germany and cervids in central Europe belong to different strains. Furthermore, nematodes from the cervid strain appear to circulate within particular host species, which can be seen in the stated morphological variations.

Theory in closer contact with industrial life: American institutional economists on competition theory and policy

2021 ◽  
pp. 1-18
Author(s):  
Matthew T. Panhans ◽  
Reinhard Schumacher
Keyword(s):  
20Th Century ◽  
Competition Policy ◽  
Self Regulation ◽  
Consumer Welfare ◽  
Antitrust Enforcement ◽  
Mainstream Economic ◽  
Competition Theory ◽  
One Stage ◽  
Wide Range ◽  
Experimental Attitude

Abstract This paper investigates the views on competition theory and policy of the American institutional economists during the first half of the 20th century. These perspectives contrasted with those of contemporary neoclassical and later mainstream economic approaches. We identify three distinct dimensions to an institutionalist perspective on competition. First, institutionalist approaches focused on describing industry details, so as to bring theory into closer contact with reality. Second, institutionalists emphasized that while competition was sometimes beneficial, it could also be disruptive. Third, institutionalists had a broad view of the objectives of competition policy that extended beyond effects on consumer welfare. Consequently, institutionalists advocated for a wide range of policies to enhance competition, including industrial self-regulation, broad stakeholder representation within corporations, and direct governmental regulations. Their experimental attitude implied that policy would always be evolving, and antitrust enforcement might be only one stage in the development toward a regime of industrial regulation.

Revision of Coronostrongylus (Nematoda : Strongyloidea) parasitic in the stomachs of macropodid marsupials

2002 ◽  
Vol 16 (6) ◽  
pp. 893 ◽  
Author(s):  
I. Beveridge
Keyword(s):  
Papua New Guinea ◽  
Host Species ◽  
Related Species ◽  
New Guinea ◽  
Nematode Species ◽  
Closely Related Species ◽  
Nematode Genus ◽  
Eastern Australia ◽  
Wide Range ◽  
Species Occurrences

The monotypic nematode genus Coronostrongylus Johnston & Mawson, 1939 from the stomachs of macropodid marsupials was reviewed and was found to consist of a least seven closely related species. Coronostrongylus coronatus Johnston & Mawson, 1939 is found most commonly in Macropus rufogriseus, but occurs occasionally in M. dorsalis, M. parryi and Petrogale inornata. Coronostrongylus johnsoni, sp. nov. is most commonly found in M. dorsalis, but occurs also in M. rufogriseus, M. parma, Thylogale stigmatica, Petrogale godmani and P. brachyotis. Coronostrongylus barkeri, sp. nov. is most prevalent in Onychogalea unguifera, but occurs also in M. rufus, M. robustus and P. brachyotis. Coronostrongylus closei, sp. nov. is restricted to Petrogale persephone. Coronostrongylus sharmani, sp. nov. occurs only in rock wallabies from eastern Australia: P.�coenensis, P. godmani and P. mareeba; C. spratti, sp. nov. occurs in P. inornata and P. assimilis. Coronostrongylus spearei, sp. nov. is restricted to Papua New Guinea where it is found in Dorcopsulus vanhearni, Dorcopsis hageni and D. muelleri. Although all of the nematode species occur in one principal host species or a series of closely related host species, occurrences in geographically disjunct areas and in phylogenetically distant hosts are features of C. coronatus, C. barkeri, sp. nov. and C. johnsoni, sp. nov. The occurrence of seven closely related nematode species found in a wide range of macropodid host species is more readily accounted for by a hypothesis involving multiple colonisations of hosts than by the hypothesis of co-speciation.

Sign in / Sign up

Export Citation Format

Share Document