bluuebunny/crossref_metadata_2025 huggingface dataset:
Interactions between a hunting spider and a web‐builder: consequences of intraguild predation and cannibalism for prey suppression
Authors: Denno Robert F. , Mitter Margaret S. , Langellotto Gail A. , Gratton Claudio , Finke Deborah L.
Published: September 2004

Abstract. 1. Antagonistic interactions among invertebrate predators such as intraguild predation and cannibalism have the potential to dampen top‐down impacts on shared prey at lower trophic levels. Two abundant spider predators, the large wolf spiderPardosa littoralisand the small sheet‐web builderGrammonota trivitattaco‐occur on the salt marshes of eastern North America where they both attack planthoppers (Prokelisiaspp.), the dominant herbivores on the marsh. Experiments both in the laboratory and field were used to assess the incidence of intraguild predation and cannibalism in these spiders and elucidate how such antagonistic interactions influence planthopper suppression.

2. Functional response experiments showed that with an increase in planthopper prey density,Grammonotacaptured more prey but not a higher proportion of that offered.Pardosaexhibited the same response whenGrammonotawere offered as intraguild prey. Both functional responses were type I over the range of prey densities offered.

3. Grammonotais moderately cannibalistic, and the presence of planthopper prey reduced the incidence of cannibalism.

4. Factorial experiments in the laboratory showed thatPardosabut notGrammonotareduced planthopper prey populations when prey density was low. By contrast, at high prey densities, bothPardosaandGrammonotahad significant adverse effects on planthopper populations. Moreover, there was an interactive effect such thatGrammonotareduced planthopper populations relatively more whenPardosawas absent than when it was present.

5. There was direct evidence for the intraguild predation ofGrammonotabyPardosasuch that fewerGrammonotasurvived in the presence ofPardosathan when it was absent. This result occurred whether planthopper prey were abundant or not.

6. Field releases ofGrammonotain open plots resulted in significant but small decreases in the density of planthopper prey, both nymphs and adults.

7. Enhancing densities ofPardosain open plots resulted inGrammonotasuppression. The intraguild predation ofGrammonotaat this enhancedPardosadensity, however, did not precludePardosafrom significantly reducing planthopper populations.

8. Although there was evidence thatGrammonotareduced planthopper populations and that the intraguild predation ofGrammonotabyPardosaoccurred, the strength of these interactions was relatively weak given the low consumption rate of planthoppers byGrammonota(< 3 day–1) andGrammonotabyPardosa(≈ 2 day−1). Thus, weak asymmetric intraguild predation among spiders on the marsh likely dampens but does not eliminate the ability ofPardosato exert significant top‐down control on planthopper populations.
Population dynamics and occurrence of Spodoptera frugiperda host strains in southern Florida
Authors: Meagher Robert L. , Nagoshi Rod N.
Published: September 2004

Abstract.  1. The development of an area‐wide management programme for the migratory pest fall armyworm [Spodoptera frugiperda (J. E. Smith)] requires knowledge of its preferred habitats throughout the year and a detailed description of seasonal changes in population numbers.

2. Molecular markers were used to determine the host strain (corn or rice) of male moths captured in sex pheromone‐baited traps placed in different habitats in the overwintering areas of southern Florida.

3. The results indicated that rice strain moths were found in all traps and that this strain was the primary population observed in naturalised pasture and wetlands in southern Florida. In comparison, larger populations of both strains and a higher proportion of corn strain moths were observed in areas associated with golf courses, agriculture, or urban development. Corn strain adults were most prevalent during the spring and early summer.

4. These results represent the first geographical survey of fall armyworm host strain distribution in Florida and indicate that corn strain moths are limited in their habitat choice while rice strain moths have a substantially broader range. The localisation of the corn strain population to discrete areas at specific times of the year provides an opportunity to reduce or delay its northward migration.
Population responses of a conifer‐dwelling aphid to seasonal changes in its host
Authors: Day Keith R. , Armour Hazel , Docherty M.
Published: September 2004

Abstract.  1. Current evidence suggests that seasonal changes in spruce needle sap nutrients have a decisive influence on green spruce aphid (Elatobium abietinum) population density, but the mechanisms of population change, the roles of development rate, fertility and mortality, and the existence of density‐dependent processes, are not clearly understood.

2. Experimental studies of aphid populations were conducted in controlled environments to estimate seasonal patterns in aphid mean relative growth rate, prenatal development, fertility, and mortality. Studies were also made of the effect of aphid crowding on vital rates.

3. Independent of the degree of aphid crowding, seasonal changes in the amino acid concentration of needle sap were tracked by aphid growth rate, fertility (and adult size), but not by rates of aphid mortality. The most pronounced change in vital rates, and the one most likely to drive seasonal population change, was in fertility. Prenatal development time actually became shorter in periods when nutrients were scarce, but the resulting adult aphids were smaller and less fertile than during periods of improved nutrition.

4. Density dependence of vital rates was only observed during mid‐summer when nutrients were least available. Mortality, growth rate, and prenatal development were the most strongly density‐dependent processes. In contrast, there was no evidence that fertility rates were likely to respond to crowding.

5. There were no important differences between populations reared on small, potted spruce trees and those on plantation trees aged 25 years. This gives confidence that demographic data from a variety of field and laboratory sources could be used to compile data appropriate for population models.
The importance of specialist natural enemies for Chrysomela lapponica in pioneering a new host plant
Authors: Gross Jürgen , Fatouros Nina E. , Neuvonen Seppo , Hilker Monika
Published: September 2004

Abstract.  1. The Salicaceae have been suggested as ancestral host plants of Chrysomela species (Coleoptera: Chrysomelidae). In Chrysomela lapponica, some populations are specialised on salicaceous plants, but others have switched to birch. This study aimed to elucidate the significance of natural enemies as possible selective forces for the host plant shift of C. lapponica from willow to birch.

2. Two C. lapponica populations were studied, one specialised on willow Salix borealis in Finland, and another one specialised on birch Betula pubescens in the Czech Republic. Abundances of predators and parasitoids on birches and willows were recorded at both population sites. Furthermore, field and laboratory experiments were conducted.

3. Field data do not support the hypothesis that generalist predators affected the host shift from willow to birch in C. lapponica.

4. Parasitism of C. lapponica (pre)pupae by a specialised phorid fly was significantly stronger in specimens living on willow than in birch‐living ones.

5. The predatory syrphid Parasyrphus nigritarsis specialised on Chrysomelinae was only detected on willows. The syrphid preferred to orient towards substrates treated with defensive larval secretion or faeces of the willow‐specialised C. lapponica specimens compared with the birch‐specialised ones.

6. The data suggest that specialised parasitoids and predators might have been driving forces for C. lapponica to leave willows and to pioneer birches as sites with a lowered risk of predation and parasitism. This hypothesis is discussed with respect to results of earlier studies on the impact of bottom‐up effects by the plant.
Age and experience influence patch assessment for oviposition by an insect predator
Authors: Frechette Bruno , Dixon Anthony F. G. , Alauzet Claude , Hemptinne Jean‐Louis
Published: September 2004

Abstract.  1. Dynamic models of optimal foraging predict that an animal's decision to accept or reject a patch depends not only on the environment and patch quality, but also on its internal state. Previous experiments have shown that the two‐spot ladybird beetle, Adalia bipunctata (L.), is reluctant to lay eggs in a patch of prey contaminated by the oviposition‐deterring pheromone produced by conspecific larvae.

2. An experiment was conducted to test whether the internal state of an A. bipunctata female affects its oviposition response to oviposition‐deterring pheromone. Firstly, the oviposition response to oviposition‐deterring pheromone of young and old females was compared. Secondly, the oviposition response to oviposition‐deterring pheromone of females previously exposed continuously to oviposition‐deterring pheromone was compared with that of females of the same age but with no previous experience of oviposition‐deterring pheromone.

3. Old females and females with previous experience of oviposition‐deterring pheromone were less reluctant to lay eggs in the presence of oviposition‐deterring pheromone than young and naive females. These results are consistent with the predictions of optimal foraging theory.
Intra‐ and interspecific aggregation of north temperate dung beetles on standardised and natural dung pads: the influence of spatial scale
Authors: Hutton Stephen A. , Giller Paul S.
Published: September 2004

Abstract.  1. The spatial distribution of north temperate dung beetles (Aphodius, Sphaeridium, and Margarinotus) was investigated at three spatial scales (scale a between all pads – large spatial scale, small patch size; scale b between block – large spatial scale, large patch size; scale c within block – small spatial scale, small patch size) in the field using standardised and naturally dropped dung pads that varied in size and volume.

2. Results indicated that all the major colonising species of dung beetle expressed strong intraspecific aggregation, while interspecific aggregation, though present, was of a lesser magnitude.

3. In both controlled and natural dung treatments, intra‐ and interspecific aggregation decreased with increasing patch size (from pad to block) and also decreased with decreasing spatial scale (from whole plot to within‐block scale).

4. The data also suggested that intraspecific aggregation was more important than interspecific aggregation in the distribution of adult dung beetles in natural and standardised dung pads and hence has the potential to facilitate coexistence.

5. Intra‐ and interspecific aggregation was greater in the natural dung compared with that of the standardised dung, and the effect of pad size partly explains this phenomenon.

6. The within‐patch spatial distribution of dung beetles observed in the natural and standardised dung was possibly mediated through within‐patch differences between the two treatments. Six confounding factors could explain this difference and these factors are discussed in relation to resource utilisation by north temperate dung beetles.
Intraspecific variation in the strength of density dependence in aphid populations
Authors: Agrawal Anurag A. , Underwood Nora , Stinchcombe John R.
Published: September 2004

Abstract.  1. Experimental evidence is presented for positive, negative, and no density dependence from 32 independent density manipulations of milkweed aphids (Aphis nerii) in laboratory and field experiments. This substantial variation in intraspecific density dependence is associated with temperature and host‐plant species.

2. It is reported that as population growth rate increases, density dependence becomes more strongly negative, suggesting that the monotonic definition of density dependence used in many common population models is appropriate for these aphids, and that population growth rate and carrying capacity are not directly proportional.

3. For populations that conform to these assumptions, population growth rate may be widely applicable as a predictor of the strength of density dependence.
Phorid fly parasitoids of invasive fire ants indirectly improve the competitive ability of a native ant
Authors: Mehdiabadi Natasha J. , Kawazoe Elizabeth A. , Gilbert Lawrence E.
Published: September 2004

Abstract.  1. The red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), is an invasive species of south‐eastern U.S.A. Since its introduction from South America approximately 70 years ago, this pest has devastated natural biodiversity.

2. Due to such ecological costs, Pseudacteon phorid fly parasitoids (Diptera: Phoridae) from South America are being introduced into the U.S.A. as a potential biological control agent. Here, the indirect effects of these specialised parasitoids on an interspecific native ant competitor, Forelius mccooki (Hymenoptera: Formicidae), are evaluated.

3. Over the course of a 50‐day laboratory experiment, the results show that the native ant improved aspects of exploitative, but not interference, competition when S. invicta‐attacking flies were present compared with when they were absent.

4. Forelius mccooki colonies from the phorid treatment had approximately twice as many foragers at food baits relative to controls; however, there was no significant difference in interference aspects of competition or native ant colony growth between the two treatments.

5. These results suggest that the S. invicta‐specialised parasitoids help shift the competitive balance more in favour of F. mccooki than if these flies were not present; however, this competitive advantage does not translate into increased colony growth after 50 days. These laboratory findings are interpreted with regard to the more complex interactions in the field.
Species diversity and structure of phytophagous beetle assemblages along a latitudinal gradient: predicting the potential impacts of climate change
Authors: Andrew Nigel R. , Hughes Lesley
Published: September 2004

Abstract.  1. Assemblages of phytophagous beetles on Acacia were examined along a 1150 km latitudinal gradient in eastern Australia to investigate the potential effects of climate change on insect communities. The latitudinal gradient was used as a surrogate for differences in temperature. Several possible confounding variables were held constant by selecting comparable sites and emphasising a single host‐plant species.

2. Total species richness increased towards the tropics, but there were no significant differences among latitudes for average species density, species richness, Fisher's α, or average Chao‐1 index.

3. Beetles sampled along the gradient were classified into four climate change response groups, depending on their latitudinal range and apparent host specificity: cosmopolitan species, generalist feeders, climate generalists, and specialists. These four groups might respond differently to shifting climate zones. Cosmopolitan species (22% of community, found at more than one latitude and on more than one host plant) may be resilient to climate change. Generalist feeders (16%, found only at one latitude but found on more than one Acacia species) may well feed on several species but will have to move with their climatic envelope. Climate generalists (6%, found only on Acacia falcata but found at more than one latitude) may be constrained by the host species' ability to either cope with the changing climate or move with it. Finally, specialists (55%, found only on A. falcata and at only one latitude) may be forced to move poleward concurrently with their host species, or go extinct.

4. The analyses indicate that community structure may be fairly resilient to temperature change. The displacement or local extinction of species, especially the species that are found at only one latitude and on only one host plant, however, may lead to significant changes in community composition.
Winged leaf‐cutting ants on nuptial flights used as transport by Attacobius spiders for dispersal
Authors: Ichinose K. , Rinaldi I. , Forti L. C.
Published: September 2004

Abstract.  1. Sexuals of a leaf‐cutting ant, Atta bisphaerica Forel, left their nest for nuptial flights in October to December.

2. When leaving a nest, 53 of the 479 winged sexuals (or alates) observed (11.1%) carried up to three inquiline spiders of Attacobius luederwaldti.

3. Spiders exclusively selected winged sexuals, not workers, and preferred females, indicating their expectation of the stronger flight ability of females. Neither these sexuals nor workers that appeared out of the nest on flight days attempted to remove or attack spiders on the body of alates.

4. New qucens landing from their nuptial flight did not carry spiders, indicating that the spiders had left the ants in the sky to be dispersed by wind.

5. No spiders were found in more than 100 incipient nests, which were estimated to be 2–3 months old. This suggests that the spiders jumped off the alate during mid‐flight and dispersed on the wind to inhabit larger nests.
Shifting average body size during regeneration after pollution – a case study using ground beetle assemblages
Authors: Braun Sascha D. , Jones T. Hefin , Perner Jörg
Published: September 2004

Abstract. 1. Pitfall data, collected periodically between 1980 and 1996, were used to analyse the spatial and temporal body size pattern of ground beetle assemblages (Carabidae) in a former polluted grassland.

2. Two hypotheses were tested: (i) Siemannet al.'sefficiency–specialisation hypothesisthat predicts that during succession (or regeneration) processes the mean body sizes of consumer assemblages decrease and (ii) Blakeet al.'s hypothesis that predicts that smaller body sizes are found with increasing level of disturbance.

3. Biovolume was considered as a determinant of ground beetle body size. This was analysed by using a digital–optical volume measurement. The mean error associated with the idealisation of the ground beetle body shape as an ellipsoid was determined as 10.24 ± 2.5%.

4. A significant decrease in average ground beetle body size was recorded in moving from the pollution (1980) to the post‐pollution (1996) period. The mechanisms linked with ecological succession after factory closure (1990) were discussed as the main causal factor sustaining Siemannet al.'s hypothesis.

5. The analyses of the mean body size during the transition period from the pollution to the post‐pollution period demonstrate that Blakeet al.'s hypothesis was also partly supported, and may overlay the effects driven by succession.

6. It is therefore concluded that both hypotheses may be used to explain not only the change in body size from a highly polluted to a less polluted area, but also the relationship between habitat structure and predatory ground beetles.
Alcohol and pancreatitis mortality at the population level: experiences from 14 western countries
Authors: Ramstedt Mats
Published: September 2004

Aims  To test if there is relationship between alcohol consumption and pancreatitis mortality at the population level.

Data and methods  Annual pancreatitis death rates for 1950–95 were converted into age‐adjusted mortality rates per 100 000 inhabitants. Per capita alcohol consumption was measured by alcohol sales. The relationship was estimated with time‐series analysis on data from 14 western countries. Several models were tested with different assumptions about risk function and lag structure.

Results  According to the assumed most appropriate model, a positive relationship was found in each country, and statistical significance was reached in all countries except from Finland, Italy and Canada. The magnitude of the association was fairly consistent across countries, with the alcohol effect parameters ranging between 0.05 and 0.14. However, Sweden and Norway deviated from this pattern with estimates between 0.30 and 0.40.

Conclusions  Pancreatitis joins a wide range of causes of death where the mortality rate is influenced by per capita alcohol consumption, and more so in northern Europe. It is suggested that pancreatitis mortality is an important indicator of alcohol‐related harm, not least because a large amount of morbidity is likely to be connected to the mortality rate.
Alcohol impairment of behavior in men and women
Authors: Fillmore Mark T. , Weafer Jessica
Published: September 2004

Aims  Studies have shown that alcohol impairs the ability to inhibit behavioral responses in humans and some evidence suggests that men might display greater impairment than women. The present study compared men and women in the degree to which a moderate dose of alcohol impaired their inhibitory control at comparable blood alcohol concentrations.

Design  Twelve male and 12 female adult social drinkers received a moderate dose of alcohol (0.65 g/kg) and a placebo in a counterbalanced order and performed a cued go/no‐go task that measured the ability to inhibit and execute behavioral responses.

Findings  When the behavioral response was pre‐potent (i.e. instigated), men displayed greater impairment of inhibitory control under alcohol than women. Men also reported greater levels of subjective stimulation from alcohol compared with women, who reported more sedation from the drug.

Conclusions  A gender difference in alcohol impairment of inhibitory control could account for observations that disinhibited and aggressive behaviors under alcohol are more pronounced in men than in women.
Early adolescent cannabis exposure and positive and negative dimensions of psychosis
Authors: Stefanis N. C. , Delespaul P. , Henquet C. , Bakoula C. , Stefanis C. N. , Van Os J.
Published: September 2004

Aims  To investigate the effect of exposure to cannabis early in adolescence on subclinical positive and negative symptoms of psychosis.

Design  Cross‐sectional survey in the context of an ongoing cohort study.

Setting  Government‐supported general population cohort study.

Participants  A total of 3500 representative 19‐year olds in Greece.

Measurements  Subjects filled in the 40‐item Community Assessment of Psychic Experiences, measuring subclinical positive (paranoia, hallucinations, grandiosity, first‐rank symptoms) and negative psychosis dimensions and depression. Drug use was also reported on.

Findings  Use of cannabis was associated positively with both positive and negative dimensions of psychosis, independent of each other, and of depression. An association between cannabis and depression disappeared after adjustment for the negative psychosis dimensions. First use of cannabis below age 16 years was associated with a much stronger effect than first use after age 15 years, independent of life‐time frequency of use. The association between cannabis and psychosis was not influenced by the distress associated with the experiences, indicating that self‐medication may be an unlikely explanation for the entire association between cannabis and psychosis.

Conclusions  These results add credence to the hypothesis that cannabis contributes to the population level of expression of psychosis. In particular, exposure early in adolescence may increase the risk for the subclinical positive and negative dimensions of psychosis, but not for depression.
Urbanization and hospital admission rates for alcohol and drug abuse: a follow‐up study of 4.5 million women and men in Sweden
Authors: Sundquist Kristina , Frank Gölin
Published: September 2004

Aims  This study analyses whether the level of urbanization is associated with hospital admissions for alcohol and drug abuse, after adjustment for individual demographic and socio‐economic characteristics.

Design  Follow‐up study from 31 December 1996 to 31 December 1999.

Setting  Sweden.

Participants  The entire Swedish population aged 25–64 yeras, in total 4.5 million women and men.

Measurements  Hospital admission rates for alcohol abuse (12 812 events) and drug abuse (6459 events). Level of urbanization was defined by population density and divided into quintiles. Cox proportional hazard models were used to analyse the data.

Findings  The results showed an apparent gradient for both women and men; with increasing level of urbanization the hospital admission rates for alcohol abuse and drug abuse increased sharply. After adjustment for age, marital status, education and immigrant status, the hazard ratios for hospital admission for alcohol abuse were 1.76 [confidence interval (CI) = 1.58–1.96] for women and 1.71 (CI = 1.60–1.82) for men in the most densely populated areas (quintile 5). For drug abuse the corresponding hazard ratios were 1.89 (CI = 1.67–2.15) for women and 2.38 (CI = 2.12–2.67) for men.

Conclusions  A high level of urbanization was associated with increased hospital admission rates for alcohol abuse and drug abuse. The level of urbanization should be considered in the distribution of resources for prevention and treatment of alcohol and drug abuse.
Prevalence of personality disorder in alcohol and drug services and associated comorbidity
Authors: Bowden‐Jones Owen , Iqbal Muhammad Z. , Tyrer Peter , Seivewright Nicholas , Cooper Sylvia , Judd Ali , Weaver Tim ,   the COSMIC study team
Published: September 2004

Aims  To compare the prevalence of personality disorder in alcohol and drug populations with special attention to its impact on psychopathology and service characteristics.

Design  Cross‐sectional survey.

Setting  Three alcohol and four drug services in four urban UK centres.

Participants  Two hundred and sixteen drug and 64 alcohol service patients randomly sampled from current treatment populations.

Measurements  A treatment population census recorded demographic and diagnostic data. Patient interviews assessed the presence, cluster type and severity of personality disorder using the Quick Personality Assessment Schedule (PAS‐Q). Other psychopathology was measured using the Comprehensive Psychopathological Rating Scale (CPRS). A case‐note audit recorded psychotic psychopathology using the OPCRIT schedule and data regarding social morbidity.

Findings  The overall prevalence of personality disorder was 37% in the drug service sample and 53% in the alcohol service sample. The distribution of severity and clusters differed markedly between the two samples. There was a significant association between the severity of personality disorder and psychopathology in both samples. Levels of morbidity associated with clusters B and C were similar. Clinical diagnosis of personality disorder showed high specificity but low sensitivity when compared to PAS‐Q.

Conclusions  In both alcohol and drug service populations, personality disorder is associated with significantly increased rates of psychopathology and social morbidity that worsens with increasing severity of the disorder. Despite this, personality disorder is poorly identified by clinical staff. The PAS‐Q may be useful as a clinical assessment tool in the substance misuse population for the early identification and management of patients with personality disorder.
The burden of alcohol misuse on emergency in‐patient hospital admissions among residents from a health board region in Ireland
Authors: O'Farrell A. , Allwright S. , Downey J. , Bedford D. , Howell F.
Published: September 2004

Aims  To identify in‐patient emergency admissions to acute hospitals of residents from a health board region in the Republic of Ireland with an acute alcohol intoxication diagnosis; to profile the admissions and to assess whether the increase in alcohol consumption in Ireland has been mirrored by an increase in alcohol related emergency admissions over the same time period.

Design  A retrospective review of hospital admissions using Hospital In‐Patient Enquiry (HIPE) data and alcohol consumption trends using data from the Central Statistics Office (CSO).

Setting  Acute hospitals in the Republic of Ireland.

Participants  All residents from a health board region admitted with a recorded alcohol intoxication emergency admission to non‐private acute hospitals in Ireland.

Measurements  All in‐patient emergency admissions for which an acute alcohol intoxication diagnosis (ICD Codes 303.0 and 305.0) was recorded of residents from one health board region were extracted from the HIPE system for years 1997–2001 inclusive. Pearson's χ2 test was used to compare proportions in groups of categorical data and χ2 test for trend was used to identify linear trends. Age standardized rates were calculated for each year and trend analysis carried out. Demographic data on the patients were also extracted from the database.

Findings  There were 3289 acute alcohol intoxication admissions to acute hospitals of residents from the study region recorded for years 1997–2001 inclusive. There were 777 acute alcohol intoxication admissions in 2001 compared to 432 admissions in 1997, an increase of 80%. Age standardized rates showed a significant increasing linear trend (P < 0.001). Over half the admissions occurred on weekends. The average length of stay was 2.7 days (95% CI 2.5–2.8) with just under a quarter (24.3%) of these admissions being discharged on the same day. The majority of these patients were male (71.5%), 40.9% were under 30 years old and over half (59.4%) were single.

Conclusions  This study shows that alcohol intoxication accounted for a substantial number of emergency in‐patient admissions to acute hospitals in one health board region in Ireland and that the age standardized recorded acute alcohol related emergency admission rate increased significantly over the 5‐year period, 1997–2001. This increase mirrored the national increase in alcohol consumption over the same time period.
Risk of injury from acute alcohol consumption and the influence of confounders
Authors: Watt Kerrianne , Purdie David M. , Roche Anne M. , McClure Roderick J.
Published: September 2004

Aim  To quantify the relationship between acute alcohol consumption and risk of injury, in the context of other potential confounding factors (i.e. usual alcohol intake, risk‐taking behaviour and substance use—defined as prescription/over‐the‐counter medication or illicit substances), using three separate measures of alcohol consumption.

Design  A hospital‐based, case–control study.

Setting  The accident and emergency department at a large metropolitan teaching hospital in Queensland, Australia.

Participants  Four hundred and eighty‐eight cases were matched to 488 population controls on gender, age group, neighbourhood, day and time of injury.

Measurements  Risk factor and injury information was obtained by questionnaire and medical record review.

Results  After controlling for demographic and situational variables (i.e. activity, location and companions at time of injury), consuming any alcohol in the 6 hours prior to time of injury significantly increased risk of injury [odds ratio (OR) = 2.13, 95% confidence interval (CI): 1.3–3.9]. Drinking at levels above low‐risk guidelines for short‐term health (i.e. drinking > 40 g alcohol per occasion if female, and drinking > 60 g alcohol if male) increased injury risk by a factor of almost 2.5 (OR = 2.41; 95% CI = 1.1–5.2). Finally, drinking beer (OR = 1.86; 95% CI = 0.9–3.9), spirits (OR = 3.05; 95% CI = 1.1–8.2) or a combination of beverages (OR = 3.16; 95% CI = 1.1–8.8) increased risk of injury. When usual alcohol consumption patterns were adjusted for, substantial increases in the alcohol–injury odds ratios were observed for all measures of alcohol. When risk‐taking behaviour and substance use were considered, changes in the effect of alcohol on injury risk were observed, for all measures of alcohol. These data support the hypotheses that some confounding exists in the alcohol–injury relationship due to usual drinking patterns, risk‐taking and substance use.

Conclusions  In this study, acute alcohol consumption significantly increased the risk of injury, even when situational and other risk factors were considered. However, the relationship between alcohol and injury appears confounded by usual drinking patterns, risk‐taking behaviour and substance use. Therefore, these variables should be considered in any analysis of the alcohol–injury relationship, and also considered when developing public health strategies to reduce alcohol‐related injury. Further research is required to elucidate the nature of this relationship, and to identify the effect of risk‐taking and substance use on different types of injuries (e.g. mechanism of injury; body region injured) and injury severity. The stability of the models and the consistency of the findings across all measures of alcohol used support claims for the validity of the observed effects.
Five‐year alcohol and drug treatment outcomes of older adults versus middle‐aged and younger adults in a managed care program
Authors: Satre Derek D. , Mertens Jennifer R. , Areán Patricia A. , Weisner Constance
Published: September 2004

Aims  This study compared 5‐year treatment outcomes of older adults to those of middle‐aged and younger adults in a large managed care chemical dependency program. We examined age group differences in individual, treatment and extra‐treatment factors, which may influence long‐term outcome.

Design  Seventy‐seven per cent of original study participants completed a telephone interview 5 years after out‐patient chemical dependency treatment at Kaiser Permanente. This sample (N = 925) included 65 patients aged 55–77, 296 patients aged 40–54 and 564 patients aged 18–39 (age at baseline).

Measurements  Measures at follow‐up included alcohol and drug use, Addiction Severity Index (ASI), Alcoholics Anonymous Affiliation Scale, social resource and self‐reported health questions. Mortality data were obtained from contact with family members of patients as well as automated health plan records.

Findings  Older adults were less likely to be drug‐dependent at baseline than younger and middle‐aged adults, and had longer retention in treatment than younger adults. At 5 years, older adults were less likely than younger adults to have close family or friends who encouraged alcohol or drug use. Fifty‐two per cent of older adults reported total abstinence from alcohol and drugs in the previous 30 days versus 40% of younger adults. Older women had higher 30‐day abstinence than older men or younger women. Among participants dependent only on alcohol, there were no significant age differences in 30‐day abstinence. In logistic regression analysis, age group was not significant. Variables associated with greater age that independently predicted 30‐day abstinence in the logistic regression model included longer retention in treatment and having no close family or friends who encouraged alcohol or drug use at 5 years; female gender was also significant.

Conclusions  Results indicate that older adults have favorable long‐term outcome following treatment relative to younger adults, but these differences may be accounted for by variables associated with age such as type of substance dependence, treatment retention, social networks and gender. Age differences in these characteristics inform intervention strategies to support long‐term recovery of older adults and provide direction for investigation of how age affects outcome.
The Marijuana Check‐up: reaching users who are ambivalent about change
Authors: Stephens Robert S. , Roffman Roger A. , Fearer Stephanie A. , Williams Carl , Picciano Joseph F. , Burke Randy S.
Published: September 2004

Aims  A brief intervention called the Marijuana Check‐up (MCU) was designed to attract adult marijuana users who were experiencing adverse consequences, but who were ambivalent about change and would be unlikely to seek treatment. Our objective was to determine whether the MCU would reach the target population.

Design  Comparisons were made between those who enrolled in the MCU versus those who were screened but failed to follow through with enrollment on demographic, drug use and stage of change variables. Comparisons were also made between participants in the MCU and participants in a concurrently offered treatment project that targeted marijuana users who wanted to quit.

Setting  The study took place at the University of Washington in Seattle.

Participants  Participants were adult marijuana users who telephoned and expressed interest in the MCU (n = 587).

Measurement  Study variables included stage of change, frequency and duration of drug use, DSM‐IV cannabis dependence and abuse diagnoses and negative consequences of marijuana use assessed via interviews and questionnaires.

Findings  Callers to the MCU were near‐daily marijuana users, two‐thirds of whom were in the pre‐contemplation or contemplation stage of change. Participants who enrolled in the MCU reported fewer problems related to marijuana use and less readiness to make changes compared to those enrolled in the treatment study, despite similar levels of drug use.

Conclusions  The MCU attracted and enrolled near‐daily users of marijuana who experienced negative consequences but were ambivalent about making changes. The MCU potentially has a role in the continuum of care for substance abuse problems.
The psychological determinants of low‐rate daily smoking
Authors: Etter Jean‐François
Published: September 2004

Aims  To compare low‐rate daily smokers (one to five cigarettes/day) with other daily smokers, using the Transtheoretical Model of Change as a framework.

Design  Mail survey with a follow‐up after 7 months.

Setting  A randomly selected population sample in French‐speaking Switzerland, in 1998.

Participants  A total of 2338 daily smokers aged 25 + years, including 95 smokers of one to five cigarettes/day, 324 smokers of six to 10 cigarettes/day, 399 smokers of 11–15 cigarettes/day and 1520 smokers of 16 + cigarettes/day, and 1765 people (75% of 2338) at 7‐month follow‐up.

Findings  Compared with smokers of 16 + cigarettes/day, low‐rate smokers of one to five cigarettes/day included more women (67% versus 46%, P < 0.001), were 4 years younger (P < 0.001), were less motivated to quit smoking (62% versus 37% in the ‘precontemplation’ stage of change, P < 0.001), thought that quitting would be easier (−3.4 points on a 0–10 scale, P < 0.001) and were less bothered by the risk of smoking. Low‐rate smokers were taking control more actively over their smoking, e.g. they more often stayed away from places where people smoked, sat in the no‐smoking sections in public places and tried to delay as much as they could their first cigarette of the day. Only 45% of low‐rate smokers were still in the same category 7 months later.

Conclusions  For many smokers, low‐rate smoking may result from a conscious effort to limit their cigarette consumption. Being a low‐rate smoker was a temporary condition for most people. Low‐rate smokers should be considered as a specific, although heterogeneous group.
Per capita alcohol consumption and all‐cause mortality in Canada, 1950–98
Authors: Norström Thor
Published: September 2004

Aims  To estimate the relationship between per capita alcohol consumption and male all‐cause mortality in Canada.

Data and method  The outcome measure comprised annual data on male all‐cause mortality for the period 1950–98. Alcohol sales (in litres 100% alcohol) were used as proxy for per capita consumption. The data were analysed using the Box–Jenkins technique. Two models were estimated, one including only female mortality as control, the other in addition cigarette sales.

Results  The first model yielded a significant alcohol effect that implied a 2.9%[standadrd error (SE) = 0.6%] increase in mortality given a 1‐litre increase in consumption. This estimate coincides with that obtained for northern Europe in previous research. When cigarette sales were included in the model the alcohol effect was still statistically significant but markedly reduced, to 1.7% (SE = 0.6%).

Conclusions  Total mortality is a classic indicator of the general health status of the population. Its relationship with per capita consumption of alcohol supports the view that total consumption is a concern for public health.
Non‐fatal cocaine overdose among injecting and non‐injecting cocaine users in Sydney, Australia
Authors: Kaye Sharlene , Darke Shane
Published: September 2004

Aim  To investigate the frequency of non‐fatal cocaine overdose, and responses to overdoses, among injecting and non‐injecting cocaine users.

Design  Cross‐sectional study.

Setting  Sydney, Australia.

Participants  Two hundred current cocaine users.

Measurements  Structured interview.

Findings  Thirteen per cent of the sample had overdosed on cocaine, 7% in the preceding 12 months. Cocaine injectors were more likely to have overdosed, both ever (17 ∨ 6%) and in the preceding 12 months (9 ∨ 3%). The most common symptoms of overdose were palpitations (68%), intense sweating (44%) and seizures (40%). The use of other drugs in combination with cocaine prior to the most recent overdose was prevalent (64%), most commonly opioids (40%), alcohol (24%) and cannabis (24%). Those who had overdosed were more likely to be female, had longer cocaine use careers, had used more cocaine in the preceding month and preceding 6 months, had higher levels of cocaine dependence and more extensive polydrug use. Twenty‐four per cent had witnessed a cocaine overdose, 13% in the preceding 12 months. Injectors were more likely to have witnessed overdoses, both ever (35% ∨ 8%) and in the preceding 12 months (20% ∨ 3%).

Conclusions  Experience of, and exposure to, overdose were not rare events. Cocaine users need to be aware of the possibility and nature of overdose, and that cocaine overdose can occur irrespective of method of use. There is a need to emphasise the potential danger of combining cocaine with other drugs.
Assessing researcher impacts from a long‐term sampling program of wetland communities in the Everglades National Park, Florida, U.S.A.
Authors: Wolski Lawrence F. , Trexler Joel C. , Nelson Eric B. , Philippi Thomas , Perry Sue A.
Published: September 2004

1. Long‐term monitoring requires repeated visits to a study site, greatly increasing the potential for cumulative visitation effects. For ecological studies in general, and for monitoring in particular, data must be evaluated for confounding artefacts from researcher presence. We compared aquatic communities at long‐term sampling plots (nine sites, each with three plots, studied continuously from 6 to 22 years) in the Everglades National Park to previously unsampled reference plots adjacent to them to assess the effects of researcher visitation on the flora and fauna.

2. We identified two criteria that are sensitive to local habitat heterogeneity for assessment of visitation impacts. First, the long‐term plots must differ from adjacent reference plots by a magnitude that exceeded variation among plots separated by equal or greater distance (i.e. the difference is greater than expected by scaling of community change proportional with distance); and second, multiple reference plots must consistently differ in direction (e.g. greater abundance or less abundance) from adjacent long‐term plots. We also tested for increased heterogeneity among samples from long‐term plots compared with those not previously visited.

3. We found no evidence of researcher effects on fish or macroinvertebrates, and only weak evidence for alteration of emergent plants and periphyton floating mats. Our failure to document visitor impacts may result from either low visitation rate or the dynamic nature of the wetlands studied.
Acoustic observations of zooplankton in lakes using a Doppler current profiler
Authors: Lorke Andreas , McGinnis Daniel F. , Spaak Piet , Wüest Alfred
Published: September 2004

1. In this paper we test the usefulness of acoustic backscatter measurements from a 614 kHz Acoustic Doppler Current Profiler (ADCP) for the qualitative and quantitative characterisation of zooplankton distributions in lakes. ADCP‐based backscatter estimates were compared with frequent net hauls obtained during a calibration experiment in which the acoustic backscatter was strongly dominated by vertical migrating Chaoborus flavicans larvae.

2. The correlation between backscatter estimates and the C. flavicans concentration was very good. Vertical swimming speed of larvae, measured directly by the ADCP, was up to a maximum of 5 mm s−1 and agreed very well with the observed vertical movement of the backscatter contour lines. Although the strong backscatter from C. flavicans overwhelmed the signal from the remaining zooplankton, a good correlation between backscatter strength and the total remaining zooplankton concentration, dominated by Cyclops spp., was found for the depth and time intervals where no C. flavicans were present.

3. In addition to the calibration experiment, longer‐term ADCP measurements from different lakes revealed a strong temporal correlation between the onset of the up‐ and downward migration of zooplankton and the local sunset and sunrise.

4. We conclude that ADCPs can be used to monitor plankton distributions both temporally and spatially. It also seems possible to estimate plankton densities after appropriate calibration.
Effects of Macrobrachium hainanense predation on benthic community functioning in tropical Asian streams
Authors: Mantel Sukhmani K. , Dudgeon David
Published: September 2004

1. Macrobrachium hainanense is a large predatory palaemonid shrimp, present at high densities in pools of low‐order forested streams in Hong Kong. The present study investigated the impacts of M. hainanense on benthic community structure and functions in pools of two streams: Tai Po Kau Forest Stream and Tai Shing Stream.

2. Repeated whole‐pool experiments involving shrimp density manipulations (removal, control and addition) were conducted in both streams between October 2000 and April 2002, and included a wet (May to September) and two dry (October to April) seasons. The three objectives of the study were to determine the effects of M. hainanense predation on benthic macroinvertebrate abundance and species richness, rates of leaf litter breakdown because of effects on detritivores, and periphyton standing stocks by way of an effect on herbivores.

3. Wet season results showed consistent reductions in benthos densities and species richness following heavy rainfall, irrespective of shrimp manipulation. These results suggested that spate‐induced disturbances might override biotic effects and play a dominant role in structuring benthic communities in stream pools in Hong Kong.

4. No significant, reproducible effects on any of the response variables measured in either stream were found during the dry season. Litter breakdown was reduced in the absence of shrimps during one experiment only, suggesting it might be a type I error. These results signified no effect of shrimp removal on benthic communities, or on the functional processes of litter breakdown, or on periphyton accumulation. The large scale of the experimental units (8–40 m2), refuge availability, and the presence of benthic predatory fishes that cropped excess prey made available by removal of M. hainanense, may have contributed to the lack of any effect, despite the abundance of the predatory shrimps.