The food of the silvereye, Zosterops gouldi (Aves : Zosteropidae), in relation to its role as a vector of a granulosis virus of the potato moth, Phthorimaea operculella (Lepidoptera : Gelechiidae)

1973 ◽  
Vol 21 (4) ◽  
pp. 533 ◽  
Author(s):  
JN Matthiessen ◽  
BP Springett
Keyword(s):  
Functional Response ◽  
Western Australia ◽  
Response Curve ◽  
Larval Density ◽  
Phthorimaea Operculella ◽  
Alternative Prey ◽  
Granulosis Virus ◽  
Potential Vector ◽  
Large Numbers

The silvereye feeds in farmland in south-western Western Australia, eating mainly arthropods. Larvae of the potato moth are regularly a major summer food, and the silvereye shows a well-defined functional response to larval density. The silvereye functional response curve differs from the characteristic vertebrate sigmoid-shaped curve in that it lacks the initial positively accelerating portion. This is attributed to the occurrence of prey in many discrete habitats, combined with silvereye mobility and its sensitive response to low potato moth larval densities. The number of potato moth larvae that are eaten is reduced when a larger alternative prey is available, but the numerical proportion of larvae in the food remains unchanged. The silvereye is a potential vector of a granulosis virus of the potato moth through its regular predation on larvae of the potato moth, its large numbers, and its mobility.

Alternative Prey and Abundance Covariance Switches an Intraguild Predator’s Functional Response

2014 ◽  
Vol 27 (4) ◽  
pp. 503-513 ◽  
Author(s):  
Lucas Del Bianco Faria ◽  
Juliana Tuller ◽  
Laís Ferreira Maia ◽  
Carolina Reigada ◽  
Wesley Augusto Conde Godoy
Keyword(s):  
Functional Response ◽  
Alternative Prey

scholarly journals Towards a function-first framework to make soil microbial ecology predictive

2021 ◽  
Author(s):  
Johannes Rousk ◽  
Lettice Hicks
Keyword(s):  
Microbial Community ◽  
Environmental Factors ◽  
Microbial Communities ◽  
Functional Response ◽  
Community Composition ◽  
Ecosystem Function ◽  
Bacterial Growth ◽  
Response Curve ◽  
Ecosystem Functions ◽  
Soil Microbial

<p>Soil microbial communities perform vital ecosystem functions, such as the decomposition of organic matter to provide plant nutrition. However, despite the functional importance of soil microorganisms, attribution of ecosystem function to particular constituents of the microbial community has been impeded by a lack of information linking microbial function to community composition and structure. Here, we propose a function-first framework to predict how microbial communities influence ecosystem functions.</p><p>We first view the microbial community associated with a specific function as a whole, and describe the dependence of microbial functions on environmental factors (e.g. the intrinsic temperature dependence of bacterial growth rates). This step defines the aggregate functional response curve of the community. Second, the contribution of the whole community to ecosystem function can be predicted, by combining the functional response curve with current environmental conditions. Functional response curves can then be linked with taxonomic data in order to identify sets of “biomarker” taxa that signal how microbial communities regulate ecosystem functions. Ultimately, such indicator taxa may be used as a diagnostic tool, enabling predictions of ecosystem function from community composition.</p><p>In this presentation, we provide three examples to illustrate the proposed framework, whereby the dependence of bacterial growth on environmental factors, including temperature, pH and salinity, is defined as the functional response curve used to interlink soil bacterial community structure and function. Applying this framework will make it possible to predict ecosystem functions directly from microbial community composition.</p>

Implications of hormesis on the bioassay and hazard assessment of chemical carcinogens

1998 ◽  
Vol 17 (5) ◽  
pp. 254-258 ◽  
Author(s):  
Justin G Teeguarden ◽  
Yvonne P Dragan ◽  
Henry C Pitot
Keyword(s):  
Hazard Assessment ◽  
Dose Response ◽  
Response Curve ◽  
Dose Response Curve ◽  
Low Doses ◽  
Response Curves ◽  
Large Numbers ◽  
Carcinogenic Agents ◽  
Assessment Guidelines ◽  
Study Designs

Hormesis has been defined as a dose-response relationship which depicts improvement in some endpoint (increased metabolic rates, reduction in tumor incidence, etc.) at low doses of a toxic compound followed by a decline in the endpoint at higher doses. The existence of hormetic responses to carcinogenic agents has several implications for the bioassay and hazard assessment of carcinogens. To be capable of detecting and statistically testing for hormetic or other nonlinear dose-response functions, current study designs must be modified to include lower doses and sufficiently large numbers of animals. In addition, improved statistical methods for testing nonlinear dose-response relationships will have to be developed. Research integrating physiologically-based pharmacokinetic model descriptions of target dose with mechanistic data holds the greatest promise for improving the description of the dose-response curve at low doses. The 1996 Proposed Carcinogen Risk Assessment Guidelines encourage the use of mechanistic data to improve the descriptions of the dose-response curve at low doses, but do not distinguish between the types of nonlinear dose-response curves. Should this refined approach lead to substantial support for hormesis in carcinogenic processes, future guidelines will need to provide guidance on establishing safe doses and communicating the results to the public.

Salinisation and prospects for biodiversity in rivers and wetlands of south-west Western Australia

2003 ◽  
Vol 51 (6) ◽  
pp. 673 ◽  
Author(s):  
S. A. Halse ◽  
J. K. Ruprecht ◽  
A. M. Pinder
Keyword(s):  
Western Australia ◽  
Aquatic Ecosystems ◽  
Saline Water ◽  
Biological Communities ◽  
Invertebrate Species ◽  
South West ◽  
Large Numbers ◽  
High Concentrations ◽  
Water Volumes ◽  
Western Australian

Saline water was common in south-west Western Australian aquatic systems prior to land-clearing because most streams and wetlands were ephemeral and evapo-concentrated as they dried, and there were high concentrations of stored salt in groundwater and soil profiles. Nevertheless, a 1998 review of salinity trends in rivers of south-west Western Australia showed that 20-fold increases in salinity concentrations had occurred since clearing in the medium-rainfall zone (300–700 mm). More recent data confirm these trends and show that elevated salinities have already caused substantial changes to the biological communities of aquatic ecosystems. Further substantial changes will occur, despite the flora and fauna of the south-west being comparatively well adapted to the presence of salinity in the landscape. Up to one-third of wetland and river invertebrate species, large numbers of plants and a substantial proportion of the waterbird fauna will disappear from the wheatbelt, a region that has high biodiversity value and endemism. Increased salinities are not the only threat associated with salinisation: increased water volumes, longer periods of inundation and more widespread acidity are also likely to be detrimental to the biota.

Selection for increased resistance to a granulosis virus in the potato moth, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae)

1983 ◽  
Vol 73 (1) ◽  
pp. 1-9 ◽  
Author(s):  
D. T. Briese ◽  
H. A. Mende
Keyword(s):  
Resistance Gene ◽  
Laboratory Strain ◽  
Fold Increase ◽  
Phthorimaea Operculella ◽  
Field Conditions ◽  
Granulosis Virus ◽  
Selection For

AbstractSerial exposure of a susceptible laboratory strain of Phthorimaea operculella (Zell.) recently obtained from the field to granulosis virus over six generations produced a 140-fold increase in LD50. The evidence suggests that this was due to a change in frequency of a resistance gene within the population. An attempt to select for even greater resistance in an already highly resistant laboratory strain resulted in only a small increase, due mainly to reduced variability in response of the population. The implications of resistance to viral insecticides developing under field conditions are discussed.

Large-scale field testing of a granulosis virus for the control of the potato Moth (Phthorimaea Operculella (Zell.) (Lep., Gelechiidae))

1971 ◽  
Vol 61 (2) ◽  
pp. 223-233 ◽  
Author(s):  
E. M. Reed ◽  
B. P. Springett
Keyword(s):  
Large Scale ◽  
Residual Effect ◽  
Field Testing ◽  
Phthorimaea Operculella ◽  
Virus Spread ◽  
Infection Rates ◽  
Granulosis Virus ◽  
Larval Body ◽  
Scale Field ◽  
Large Scale Field

A granulosis virus was tested on a field scale at Manjimup and Pemberton in Western Australia for control of its host, the potato moth Phthorimaea operculella (Zell.). The virus was produced on laboratory-reared larvae, and applied as a suspension of pulverised larvae (6 275 in 111 gal/ha) to second-crop (December-planted) potatoes. There were untreated and insecticide-treated (DDT, dieldrin, methyl-demeton) fields for comparison. The effectiveness of the treatments was assessed on numbers of larval mines and tuber damage. Virus infection rates of 100% were achieved, with a residual effect of 12 weeks. Variation in larval body weight indicated that initial dosages and those due to recycled virus were excessive, but were optimum after two months. Virus applications were as effective in preventing damage as insecticide treatments. Virus spread to untreated crops some miles distant was attributed to movements of personnel, farm materials or birds.

Viewing soil systems from the top-down can make microbial ecology predictive for ecosystem functions

2020 ◽  
Author(s):  
Johannes Rousk ◽  
Lettice Hicks
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Microbial Communities ◽  
Functional Response ◽  
Community Composition ◽  
Ecosystem Function ◽  
Response Curve ◽  
Ecosystem Processes ◽  
Ecosystem Functions ◽  
Top Down

<p>Understanding the role of ecological communities in maintaining multiple ecosystem processes is a central challenge in ecology. Soil microbial communities perform vital ecosystem functions, such as the decomposition of organic matter to provide plant nutrition. However, despite the functional importance of soil microorganisms, attribution of ecosystem function to particular constituents of the microbial community has been impeded by a lack of information linking microbial processes to community structure.</p><p>Here, we propose a new conceptual framework to determine how microbial communities influence ecosystem processes, by applying a “top-down” approach. Looking from the “top”, we first view the microbial community associated with a specific function as a whole, and describe the dependence of microbial community processes on environmental factors (e.g. the intrinsic temperature dependence of bacterial growth rates), allowing us to define the aggregate functional response curve of the community. We then demonstrate that the whole community contribution to ecosystem function can be predicted, by parameterising the functional response curve with current environmental conditions. In a final step, we show how this functional information can be linked to the taxonomic community composition (amplicon assessments of microbial community composition) in order to identify “biomarker” taxa that capture microbial communities’ regulation of ecosystem processes and the susceptibility of microbial community structure and function to environmental change. Ultimately, these biomarkers may be used as a diagnostic tool, enabling predictions of ecosystem function from community composition information combined with environmental metadata.</p>

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