14 research outputs found
PROGRAMMED EFFECTS OF SURFACE WATER PRICE LEVELS ON U.S. AGRICULTURAL WATER USE AND PRODUCTION PATTERNS: COMMENT
Resource /Energy Economics and Policy,
Antagonistic interactions between an invasive alien and a native coccinellid species may promote coexistence
1. Despite the capacity of invasive alien species to alter ecosystems, the mechanisms underlying their impact remain only partly understood. Invasive alien predators, for example, can significantly disrupt recipient communities by consuming prey species or acting as an intraguild predator (IGP).
2. Behavioural interactions are key components of interspecific competition between predators,yet these are often overlooked invasion processes. Here, we show how behavioural, nonlethal IGP interactions might facilitate the establishment success of an invading alien species.
3. We experimentally assessed changes in feeding behaviour (prey preference and consumption rate) of native UK coccinellid species (Adalia bipunctata and Coccinella septempunctata),whose populations are, respectively, declining and stable, when exposed to the invasive intraguild predator, Harmonia axyridis. Using a population dynamics model parameterized with these experimental data, we predicted how intraguild predation, accommodating interspecific behavioural interactions, might impact the abundance of the native and invasive alien species
over time.
4. When competing for the same aphid resource, the feeding rate of A. bipunctata significantly increased compared to the feeding in isolation, while the feeding rate of H. axyridis significantly decreased. This suggests that despite significant declines in the UK, A. bipunctata
is a superior competitor to the intraguild predator H. axyridis. In contrast, the behaviour of non-declining C. septempunctata was unaltered by the presence of H. axyridis.
5. Our experimental data show the differential behavioural plasticity of competing native and invasive alien predators, but do not explain A. bipunctata declines observed in the UK. Using behavioural plasticity as a parameter in a population dynamic model for A. bipunctata and H. axyridis, coexistence is predicted between the native and invasive alien following an initial period of decline in the native species. We demonstrate how empirical and theoretical techniques can be combined to understand better the processes and consequences of alien species
invasions for native biodiversity
Is council tax valuation band a predictor of mortality?
BACKGROUND: All current UK indices of socio-economic status have inherent problems, especially those used to govern resource allocation to the health sphere. The search for improved markers continues: this study proposes and tests the possibility that Council Tax Valuation Band (CTVB) might match requirements. PRESENTATION OF THE HYPOTHESIS: To determine if there is an association between CTVB of final residence and mortality risk using the death registers of a UK general practice. TESTING THE HYPOTHESIS: Standardised death rates and odds ratios (ORs) for groups defined by CTVB of dwelling (A – H) were calculated using one in four denominator samples from the practice lists. Analyses were repeated three times – between number of deaths and CTVB of residence of deceased 1992 – 1994 inclusive, 1995 – 1997 inc., 1998 – 2000 inc. In 856 deaths there were consistent and significant differences in death rates between CTVBs: above average for bands A and B residents; below average for other band residents. There were significantly higher ORs for A, B residents who were female and who died prematurely (before average group life expectancy). IMPLICATIONS OF THE HYPOTHESIS: CTVB of final residence appears to be a proxy marker of mortality risk and could be a valuable indicator of health needs resource at household level. It is worthy of further exploration
Evaluating Flood Prevention in Upstream Watersheds with an Areal Point Sample -- Interim Report, Washita River Basin, Oklahoma
Excerpts from the Preface: A laboratory-type study of the economic effects of the installed upstream watershed program is being conducted by the Economic Research Service at the Department of Agricultural Economics, Oklahoma State University, at Stillwater. This continuing appraisal is part of a larger program of investigations of watershed protection and flood prevention being carried out through an agreement between the Economic Research Service and the Soil Conservation Service. This interim report describes progress achieved to January 1, 1967, toward evaluating the major economic benefits of flood prevention in small watersheds. The report is limited to data collected in 1964-65. No definitive conclusions are drawn because (1) data for only 2 years have been collected and analyzed, and (2) the results reported herein are limited in geographic scope to 11 watersheds in the central portion of the Washita Basin. The major purpose of this report is to acquaint interested persons with the methodology and procedures in use and the kind of analysis to be performed. Similar techniques could be used for estimating flood damages and the major economic effects of resource development projects in other areas. This interim report discusses the use of an areal point sampling technique in estimating the major economic effects of flood prevention in small, upstream watersheds. Data obtained from the areal point sample are also used to develop crop damage factors for use in future watershed planning
Oklahoma Agricultural Experiment Station, Bulletin no. 718, April 1975: Economics of constructing and operating sewer systems in small Oklahoma communities
The Oklahoma Agricultural Experiment Station periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311
Oklahoma Agricultural Experiment Station, Bulletin no. 716, August 1974: Economics and growth of rural water systems in Oklahoma
The Oklahoma Agricultural Experiment Station periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311
Intraguild predation involving Harmonia axyridis: a review of current knowledge and future perspectives.
As an effective generalist predator of aphids and other hemipteran pests H. axyridis has been a successful biological control agent. However, the very functional traits that have contributed to its success in this regard also implicate it as an intraguild predator that poses a significant risk not only to the diversity of other natural enemies of Hemiptera (and their associated ecosystem services), but to biodiversity more widely. In this paper we will specifically review the existing data on intraguild predation involving H. axyridis, and consider the strength and symmetry of such interactions both within its native guild and within exotic guilds where it has established as an invasive alien. We will use these studies to interpret the observed population declines in predator diversity in the field, predict species at risk in regions not yet invaded and consider implications for resulting ecosystem services. We will also indicate gaps in our knowledge that require further study in order to identify opportunities for mitigation
Identifying change over time in small area socio-economic deprivation
The measurement of area level deprivation is the subject of a wide and ongoing debate regarding the appropriateness of the geographical scale of analysis, the input indicator variables and the method used to combine them into a single figure index. Whilst differences exist, there are strong correlations between schemes. Many policy-related and academic studies use deprivation scores calculated cross-sectionally to identify areas in need of regeneration and to explain variations in health outcomes. It would be useful then to identify whether small areas have changed their level of deprivation over time and thereby be able to: monitor the effect of industry closure; assess the impact of area-based planning initiatives; or determine whether a change in the level of deprivation leads to a change in health. However, the changing relationship with an outcome cannot be judged if the ‘before’ and ‘after’ situations are based on deprivation measures which use different, often time-point specific variables, methods and geographies. Here, for the whole of the UK, inputs to the Townsend index obtained from the 1991 and 2001 Censuses have been harmonised in terms of variable detail and with the 1991 data converted to the 2001 Census ward geography. Deprivation has been calculated so that the 1991 scores are directly comparable with those for 2001. Change over time can be then identified. Measured in this way, deprivation is generally shown to have eased due to downward trends in levels of lack of access to a car, non-home ownership, household overcrowding but most particularly, to reductions in levels of unemployment. Despite these trends, not all locations became less deprived with gradients of deprivation largely persisting within the UK’s constituent countries and in different area types. For England, Wales and Scotland, the calculation of Townsend scores can readily be backdated to incorporate data from the 1971 and 1981 Censuses to create a 1971–2001 set of comparable deprivation scores. The approach can also be applied to the Carstairs index. Due to differences in data availability prior to 1991, incorporating small areas in Northern Ireland would be challenging