bluuebunny/crossref_metadata_2025 huggingface dataset:
Sulfur assimilation in plants and weed control: Potential targets for novel herbicides and action sites of certain safeners
Authors: HIRASE KANGETSU , MOLIN WILLIAM T.
Published: August 2003

Sulfur is an indispensable element for plants. It is found in sulfur‐containing amino acids, cysteine and methionine, and in various other important biochemical components and processes. Inhibitors of sulfur assimilation, or cysteine and methionine synthesis, could be potential herbicides. In the present paper, the sulfur assimilation pathway in plants is described, followed by the introduction of several compounds (inhibitors and safeners) acting on this pathway. Uptake of inorganic sulfate through the roots is the first step of sulfur assimilation in plants. Sulfate is reduced mainly in chloroplasts to sulfide by a multistep process, and sulfide is then incorporated into cysteine. Cysteine is converted to cystathionine, homocysteine and methionine. Cysteine is incorporated into glutathione (GSH) by γ‐glutamylcysteine synthetase and GSH synthetase. Three enzymes involved in cysteine and methionine biosynthesis, cysteine synthase, cystathionine γ‐synthase and cystathionine β‐lyase, have been investigated as target sites for herbicides. Several inhibitors of these enzymes (e.g. rhizobitoxine and propargylglycine) were also phytotoxic, suggesting that the synthetic pathway of sulfur‐containing amino acids could be a new target site for herbicides. Some safeners for herbicides were found to act on the sulfur assimilation pathway and on GSH synthesis to increase GSH, which can be involved in herbicide metabolism and detoxification. Several safeners elevate GSH levels by increasing the activities of enzymes involved in sulfur assimilation and GSH synthesis. Further studies on plant sulfur metabolism may lead to the discovery of new herbicides and to the comprehensive understanding of the mode of action of safeners.
ISSR variation in a worldwide collection of velvetleaf (Abutilon theophrasti) and the genetic background of weedy strains mingled in grains imported into Japan
Authors: KUROKAWA SHUNJI , SHIMIZU NORIHIRO , UOZUMI SUNAO , YOSHIMURA YOSHINORI
Published: August 2003

Velvetleaf seeds have been found in imported grains in Japan. The plants from these seeds show a weedy growth habit, such as that seen in the noxious velvetleaf which has recently emerged in Japan and noted in our previous study. To elucidate the genetic background of the velvetleaf strains found in imported grains we evaluated the genetic variation of six strains and an additional 39 worldwide velvetleaf accessions using the intersimple sequence repeat (ISSR) polymorphism. Cluster analysis based on the ISSR polymorphism emitted two major clusters which corresponded well with classification by growth habit, that is, crop type and weed type. Five of the six strains from the imported grains formed a small cluster. All six strains united into one major cluster containing the weed type accessions, while all of the old Japanese accessions formed another major cluster containing the crop type accessions. The genetic difference between imported weedy velvetleaf and old Japanese accessions suggests that imported velvetleaves are the source of the recent outbreak of the noxious velvetleaf in Japan.
Comparison of different weed management systems and their effects on yield of coconut plantations in Sri Lanka
Authors: SENARATHNE S.H.S. , SAMARAJEEWA A.D. , PERERA K.C.P.
Published: August 2003

The influence of five different weed management systems on nut yield of coconut were evaluated to determine an economical and effective method of controlling weeds in coconut plantations in the low country, dry zone in Sri Lanka. Treatments imposed included slashing and mulching around the palms with slash (T1), slashing and removing the slash (T2), application of glyphosate (N‐(phosphonomethyl)‐glycine) alone at 1.44 kg ai ha−1 (T3), application of glyphosate alone at 2.88 kg ai ha−1 (T4) and cover cropping with Pueraria phaseoloides (T5). All treatments were applied twice a year, except for the cover cropping treatment, T5. Based on a reduction in weed biomass, treatments T3, T4 and T5 were found to be significantly effective over other treatments. Coconut yield was increased significantly (P < 0.05) in glyphosate‐applied plots at both tested rates. Control of weeds with the lower concentration of glyphosate (1.44 kg ai ha−1) resulted in a 25% increase in nut yield over the uncontrolled weed plots. At this rate, it was found to be the most effective and economical method of controlling weeds in coconut plantations. Cover cropping with Pueraria phaseoloides was effective in controlling weeds in the long‐term, but was not economical compared with the glyphosate application.
Rice yield losses by competition with weeds in rainfed paddy fields in north‐east Thailand
Authors: TOMITA SHINSUKE , MIYAGAWA SHUICHI , KONO YASUYUKI , NOICHANA CHAIRAT , INAMURA TATSUYA , NAGATA YOSHIKATSU , SRIBUTTA AKKADET , NAWATA EIJI
Published: August 2003

Economic growth in recent years has induced a labor shortage for agriculture in north‐east Thailand. Labor‐saving techniques, such as the replacement of transplanting with direct seeding, have become widespread. Direct seeding methods have advantages over transplanting regarding labor savings and reductions in production risks, but may cause weed problems. Therefore, rice yield reduction by competition with weeds becomes a potential problem in this region. In the present research, the extent of weed competition in rice production from the viewpoint of resource level and disturbance intensity was studied. A large number of paddy fields from a wide range of climatic, topographical, soil and hydrological conditions were analyzed. The survey was conducted every 3 weeks, and data on paddy cultivation, weeds and water conditions were recorded. Average yield of direct seeded rice was significantly lower than that of transplanted rice. The yield decreased with resource decreases in both direct seeded (DSF) and transplanted paddy fields (TF). Although the yield was not different under resource‐rich conditions, the yield of direct seeded rice was lower than that of transplanted rice under resource‐medium and ‐poor conditions. Competition intensity was not different among resource levels or between DSF and TF. Competition intensity in all fields was between 0.02 and 0.09 on average, indicating 2–9% yield losses caused by competition with weeds regardless of resource level and disturbance intensity. This suggests that low yield of direct seeded rice under resource‐medium and ‐poor conditions was not mainly caused by competition with weeds, whereas yield losses by weeds were observed in all field types. However, from an economical viewpoint, weeding should be applied only to limited parts of this region with stable and relatively high rice yields.
Evaluation of the suppression ability of rice (Oryza sativa) on Monochoria vaginalis by measuring photosynthetic photon flux density below rice canopy
Authors: KOARAI AKIRA , MORITA HIROHIKO
Published: August 2003

Field experiments involving eight cultivars were conducted in 1998 and 16 cultivars in 1999 to study the ability of rice (Oryza sativa L.) to suppress Monochoria vaginalis (Burm. f ) Kunth through light competition. Dry weights of M. vaginalis shoots in early season culture exceeded those in normal season culture of any rice cultivars. The relative photosynthetic photon flux density (R‐PPFD), which was calculated as the ratio of the photosynthetic photon flux density (PPFD) below the rice canopy to that measured above the rice canopy, varied according to rice cultivar. A strong linear correlation was observed between the mean R‐PPFD at 29–35 days after transplanting (DAT) (r2 = 0.80; p < 0.01 in 1998; r2 = 0.63, p < 0.001; and r2 = 0.93, p < 0.001 in 1999), or 36–42 DAT (r2 = 0.66, p < 0.05 in 1998; r2 = 0.72, p < 0.001; and r2 = 0.97, p < 0.001 in 1999), and the dry weight of M. vaginalis shoots at approximately 60 DAT. Data from the three experiments could be pooled into one regression line because intercepts and regression coefficients were not significantly different. The r2 values of the combined regression were highest when R‐PPFD was expressed as the mean of measurements taken during 14 days (from 29 to 42 DAT; r2 = 0.81, p < 0.001). The shortest period for measuring mean R‐PPFD in order to obtain a meaningful relationship with M. vaginalis shoot dry weight was 7 days (from 29 to 35 DAT; r2 = 0.78, p < 0.001). For that same period, relationships between M. vaginalis shoot dry weight at 60 DAT and rice tiller number or leaf area index (LAI) at ground level were weak. However, there were negative relationships between M. vaginalis shoot dry weights at 60 DAT and rice LAI measured 20 cm above the ground, plant heights or rice shoot dry weight, but these coefficients of determination were smaller than those calculated by R‐PPFD for the same period. Thus, the ability of rice to suppress M. vaginalis can be evaluated more accurately by measuring mean R‐PPFD below the rice canopy for 7 days (from 29 to 35 DAT) than by measuring rice LAI, plant height and shoot dry weight.
Involuntary stretching during yawning in patients with pyramidal tract lesions: further evidence for the existence of an independent emotional motor system
Authors: Töpper R. , Mull M. , Nacimiento W.
Published: August 2003

A variety of associated movements have been described in patients with pyramidal tract lesions. We report three patients in whom involuntary stretching of an otherwise plegic arm could be observed during yawning. These patients had radiologically verified lesions at different levels of the pyramidal tract. As yawning and stretching are an automatic behavioural pattern in animals, it is likely that stretches during yawning in man are also an automatic motor pattern, usually inhibited in the presence of an intact corticospinal tract. The physiological function of yawning is unclear at present. Yawning might be the somatomotor manifestation of a particular emotional state characterized by boredom and fatigue. Our observation that movements of an otherwise plegic arm occur in patients with pyramidal tract lesions supports therefore the concept of an emotional motor system which has an independent input to motoneurones in the brain stem and the spinal cord.
Cognitive performance following endarterectomy in asymptomatic severe carotid stenosis
Authors: Aharon‐Peretz J. , Tomer R. , Gabrieli I. , Aharonov D. , Nitecki S. , Hoffman A.
Published: August 2003

Cognition and the effects of carotid endarterectomy (CEA) were evaluated in 22 non‐demented subjects with vascular risk factors (VRF) and asymptomatic severe carotid artery stenosis (ASCAS), 14 volunteers with VRF but without stenosis, and 24 healthy controls (HC) without VRF. Non‐demented subjects with VRF, with or without carotid stenosis scored inferior to HC. It is concluded that carotid stenosis is not a primary cause of cognitive deterioration and CEA does not improve cognition in patients with ASCAS.
Multiple sclerosis: a study of chemokine receptors and regulatory T cells in relation to MRI variables
Authors: Putheti P. , Morris M. , Stawiarz L. , Teleshova N. , Kivisäkk P. , Pashenkov M. , Kouwenhoven M. , Wiberg M. K. , Bronge L. , Huang Y.‐M. , Söderström M. , Hillert J. , Link H.
Published: August 2003

Magnetic resonance imaging (MRI) remains the most valuable tool for monitoring disease activity and progression in patients with multiple sclerosis (MS), a chronic demyelinating disease of the central nervous system (CNS) with presumably autoimmune etiology. Chemokine receptors have been implicated in MS as key molecules directing inflammatory cells into the CNS. Regulatory (CD4+CD25+) T cells (Tr cells) are important in suppressing autoimmunity, and their absolute or functional deficit could be expected in MS. In the present study, venous blood was obtained from MS patients concurrent with MRI examination of the brain, and expression of chemokine receptors CCR1, CCR2, CCR5, CXCR3 and CXCR4 by CD4 T cells and monocytes, proportions of Tr cells, as well as expression of CD45RO, CD95, CTLA‐4, HLA‐DR and interleukin (IL)‐10 by Tr cells and non‐Tr (CD25−) CD4 T cells was analyzed by flow cytometry. Surface expression of CXCR3 by CD4 T cells was downregulated in the group of patients with high lesion load (LL) on T2‐weighted images and gadolinium (Gd)‐enhancing lesions on T1‐weighted images, compared to the group with high LL and no Gd‐enhancing lesions, and to the group with low LL, suggesting internalization of CXCR3 due to the release of its chemokine ligand (IP‐10/CXCL10) from active MS lesions. Proportions of Tr cells amongst all CD4 T cells, and expression of IL‐10 by Tr cells were increased in the patients with high LL and Gd‐enhancing lesions. These results suggest that there is correlation between MRI parameters, chemokine receptor expression and the status of circulating Tr cells in MS, but further studies need to discriminate between pathogenetically relevant and bystander phenomena.
Incidence of first‐ever ischemic and hemorrhagic stroke in a well‐defined community of southern Italy, 1993–1995
Authors: Intiso D. , Stampatore P. , Zarrelli M. M. , Guerra G. L. , Arpaia G. , Simone P. , Tonali P. , Beghi E.
Published: August 2003

Most epidemiological surveys in the Italian population, have concentrated on areas of northern and central Italy. The incidence of the first‐ever ischemic and hemorrhagic strokes in a well‐defined population of the province of Foggia, a rural area of southern Italy, over a 3‐year period has been investigated, to compare the occurrence of stroke by type in this and other areas.

A retrospective study in a local health district (USL FG3) in the province of Foggia was conducted and all cases of first‐ever cerebral infarction (CI) and intracerebral hemorrhage (ICH) in the local population (41 269) from January 1, 1993 to December 31, 1995 have been investigated. Case ascertainment was performed by a chart review in the two local hospitals and examination of death certificates. General practitioners were also asked to report on non‐hospitalized cases suffering a stroke during the study period. Patients with recurrent stroke, unclassifiable stroke, transient ischemic attacks and subarachnoid hemorrhage were excluded. Risk factors for stroke and 30‐day mortality were investigated. The rates were standardized to the Italian population (57 138 489, 1991 census).

During the 3‐year study period, 202 patients had a first‐ever ischemic or hemorrhagic stroke (66 in 1993, 69 in 1994 and 67 in 1995). Of these, 174 (86.1%) had cerebral ischemia, accounting for 57, 60 and 57 cases in the three index years. The overall crude annual incidence of CI and ICH was 1.60, 1.67 and 1.62 of 1000 for 1993, 1994 and 1995, respectively. The corresponding standardized incidences rates were 2.0, 2.10 and 2.06 of 1000. The rate was 0.11 in patients <55 years of age, and 1.97, 7.01, 13.52, and 25.34 at ages 55–64, 65–74, 75–84, and 85+ years for the entire period; the 30‐day mortality was 27.2, 21.7, and 15% for 1993, 1994, and 1995, respectively. Hypertension (45.9%), diabetes (26.4%) and atrial fibrillation (16.6%) were the most common risk factors.

The incidence of CI and ICH was similar to that of most other Italian studies. It was constant during the 3‐year period, and mostly involved older people.
Facial premature ageing as a side‐effect following bone marrow transplantation
Authors: Selvaag Edgar , Jacobsen Niels , Thomsen Kristian
Published: August 2003

Two female patients developed an acute graft versus host reaction with generalized erythema and subsequent desquamation after allogeneic bone marrow transplantation. Later, over a period of months both developed chronic graft versus host reactions with involvement of liver and lungs. Shortly after the diagnosis of the chronic graft versus host disease both patients developed severe elastosis of the facial skin.

 The pathogenetic linkage of the clinical picture, which resembles photodamage to graft versus host disease and autoimmunity is discussed.
Actinic superficial folliculitis
Authors: Jaeger C , Hartschuh W , Jappe U
Published: August 2003

Actinic superficial folliculitis was first described in 1985, and since then only three reports have been published. Clinically and histopathologically this disease is very particular and has been suggested to be considered as an entity.

We report on a 30‐year‐old man who presented with an extensive superficial follicular pustulosis on his back, shoulders and upper chest after exposure to intense heat and subsequent sweating on a sunny day. The pustules arose within 24–36 h afterwards. Histology and immunohistochemistry revealed subcorneal pustules, suppurative folliculitis and an infiltrate consisting of T cells, macrophages and neutrophils around the hair follicle, sebaceous glands and small vessels. To the best of our knowledge this is the fourth report on actinic superficial folliculitis and the first on which a characterization of the inflammatory infiltrate has been performed. Because of the impressive, unique symptoms and the characteristic histology we agree with those who have suggested that actinic superficial folliculitis is a new entity.
The emigration of Germany's Jewish dermatologists in the period of National Socialism
Authors: Eppinger S , Meurer M , Scholz A
Published: August 2003

In the context of our investigation, we found information on 432 (76%) of the 569 Jewish dermatologists in Germany. There is evidence that 57 (10%) of the Jewish dermatologists were murdered in concentration camps, 61 (10.7%) died a natural death, 13 (2%) committed suicide, and 25 (4%) survived the Third Reich in Germany. After 1933, 276 (49%) Jewish dermatologists were able to leave Germany; the United States of America was the main destination and 107 (or 41%) emigrated there. A total of 34 (13%) Jewish dermatologists emigrated from Germany to Palestine and 16 to Latin America. Regarding emigration to other European countries, 20 of the Jewish dermatologists from Germany went to Great Britain (including Walter Freudenthal, 1893–1952, and Ernst Sklarz, 1894–1975), and 24 emigrated to other European countries, such as France (Rudolf Mayer, 1895–1962), Sweden (Carl Lennhoff, 1883–1963), and the Netherlands (Otto Schlein, 1895–1944).
Diversity of Mitochondrial DNA Lineages in South Siberia
Authors: Derenko M. V. , Grzybowski T. , Malyarchuk B. A. , Dambueva I. K. , Denisova G. A. , Czarny J. , Dorzhu C. M. , Kakpakov V. T. , Miścicka‐Śliwka D. , Woźniak M. , Zakharov I. A.
Published: August 2003

To investigate the origin and evolution of aboriginal populations of South Siberia, a comprehensive mitochondrial DNA (mtDNA) analysis (HVR1 sequencing combined with RFLP typing) of 480 individuals, representing seven Altaic‐speaking populations (Altaians, Khakassians, Buryats, Sojots, Tuvinians, Todjins and Tofalars), was performed. Additionally, HVR2 sequence information was obtained for 110 Altaians, providing, in particular, some novel details of the East Asian mtDNA phylogeny. The total sample revealed 81% East Asian (M*, M7, M8, M9, M10, C, D, G, Z, A, B, F, N9a, Y) and 17% West Eurasian (H, U, J, T, I, N1a, X) matrilineal genetic contribution, but with regional differences within South Siberia. The highest influx of West Eurasian mtDNAs was observed in populations from the East Sayan and Altai regions (from 12.5% to 34.5%), whereas in populations from the Baikal region this contribution was markedly lower (less than 10%). The considerable substructure within South Siberian haplogroups B, F, and G, together with the high degree of haplogroup C and D diversity revealed there, allows us to conclude that South Siberians carry the genetic imprint of early‐colonization phase of Eurasia. Statistical analyses revealed that South Siberian populations contain high levels of mtDNA diversity and high heterogeneity of mtDNA sequences among populations (Fst = 5.05%) that might be due to geography but not due to language and anthropological features.
Mapping Expert Knowledge: Redesigning the Monarch Butterfly Biosphere Reserve
Authors: Bojórquez‐Tapia Luis A. , Brower Lincoln P. , Castilleja Guillermo , Sánchez‐Colón Salvador , Hernández Mariano , Calvert William , Díaz Salomón , Gómez‐Priego Paola , Alcantar Georgina , Melgarejo Erika Daniela , Solares María José , Gutiérrez Liliana , Del Lourdes Juárez María
Published: August 2003

Abstract: Expert consultation has been used to fill the information gaps that hamper conservation planning and nature reserve design. The use of expert knowledge in conservation planning is difficult, however, because it is subjective, biased, and value‐laden. Decision theory provides a systematic and comprehensive means for addressing experts' subjective—and sometimes contradictory—judgments in the design of nature reserves. Thus, the experts can separate the objective criteria from the subjective components of decision making that place value on those criteria. When linked to a geographic information system ( GIS ), these techniques foster consensus among experts by allowing the exploration of alternative designs in an iterative way. We used such a decision‐analysis approach to redesign the Monarch Butterfly Biosphere Reserve ( MBBR ) in central Mexico. We examined three reserve scenarios to identify the optimal overwintering habitats considering ( 1 ) an area equivalent to the previously defined boundaries of the core zone of the MBBR ( 4500 ha ); ( 2 ) an area equivalent to the previously defined boundaries of the whole MBBR ( 16,000 ha ); and ( 3 ) the maximum possible extent for a new core zone. This last scenario produced an area of 21,727 ha. These results were transferred to the GIS to create the respective nominal maps that were presented to the environmental authorities, who selected the third scenario for the core zone of the new MBBR. Our results allowed us to locate the prime overwintering habitats precisely and to delimit a core area for the reserve that would minimize the inclusion of forest stands valuable to local loggers.
Occurrence of Moths in Boreal Forest Corridors
Authors: Mönkkönen Mikko , Mutanen Marko
Published: August 2003

Abstract:We studied the utility of riparian corridors in boreal forest landscapes as habitats and dispersal routes for forest‐associated noctuid and geometrid moths in northern Finland. We collected moths with baited traps to investigate their occurrence and abundance in four habitat types—forest interior, forest edge, forested corridors, and clearcuts—along riparian zones. This was done with a sampling design in which the four habitat types were nested within four riparian systems. Corridors were strips of forest 30–70 m wide surrounded by clearcuts and sapling stands. Trap sites in forest interior were more than 100 m away from the nearest forest edge within large ( >50 ha ) patches of mature ( timber volume> 100 m 3/ha ), spruce‐dominated forests. Forest ‐ edge trap sites were in the same forest patches within 25 m from the nearest clearcut edge, and clearcut trap sites were in recent ( <10 ‐year‐old ) clearcuts>50 m away from the nearest mature forest. A total of 6485 specimens, representing 57 moth species, were captured during the 6‐week trapping period in late June–August 1999. The number of species and total number of individuals did not differ among the forested habitats ( interior, edge, corridor ) but were significantly lower in clearcuts. A consistent pattern across the nine species we examined in more detail was the low number of individuals captured in clearcuts. In general their abundance in corridors was equal to that observed in forest interiors and edges. Two species tended to occur in corridors in higher numbers than in forest‐interior habitats. Our results suggest that corridors in boreal forest landscapes serve as breeding habitats or dispersal routes for the moths and may direct the movements of these forest‐associated species. Results from studies showing positive effects of corridors on dispersal or population persistence should not, however, be used to justify more habitat destruction.
Response of Vegetation and Breeding Birds to the Removal of Cattle on the San Pedro River, Arizona (U.S.A.)
Authors: Krueper David , Bart Jonathan , Rich Terrell D.
Published: August 2003

Abstract:In late 1987 cattle were removed from the San Pedro Riparian National Conservation Area ( NCA ) in southeastern Arizona ( U.S.A. ). We monitored vegetation density and abundance of birds during the breeding season during 1986–1990 in riparian, mesquite grassland, and Chihuahuan desert‐scrub communities in the NCA. The density of herbaceous vegetation increased four‐ to six‐fold in riparian and mesquite grassland communities. Little change occurred in herbaceous vegetation in desert scrub, or in the density of shrubs or trees in any of the communities. Of 61 bird species for which sufficient data were collected, mean detections per kilometer increased for 42 species, 26 significantly, and decreased for 19 species, 8 significantly. The number of individuals of all avian species detected on surveys increased each year from 103/kilometer in 1986 to 221/kilometer in 1991, an average annual increase of 23% ( p< 0.001 ). The largest increases occurred in riparian species, open‐cup nesters, Neotropical migrants, and insectivores. Species of the Chihuahuan desert‐scrub, in which vegetation changed the least, showed the smallest increases. Only a few of the species showed increasing regional trends for the same period, as demonstrated by the North American Breeding Bird Survey; thus, increases on the San Pedro Riparian NCA were likely caused by the change in local conditions, not by regional effects. Our results suggest that removing cattle from riparian areas in the southwestern United States can have profound benefits for breeding birds.
Impacts of Landscape Change on Wolf Restoration Success: Planning a Reintroduction Program Based on Static and Dynamic Spatial Models
Authors: Carroll Carlos , Phillips Michael K. , Schumaker Nathan H. , Smith Douglas W.
Published: August 2003

Abstract:Mammalian carnivores are increasingly the focus of reintroduction attempts in areas from which they have been extirpated by historic persecution. We used static and dynamic spatial models to evaluate whether a proposed wolf reintroduction to the southern Rocky Mountain region ( U.S.A ) would advance recovery by increasing species distribution beyond what might be expected through natural range expansion. We used multiple logistic regression to develop a resource‐selection function relating wolf distribution in the Greater Yellowstone region with regional‐scale habitat variables. We also used a spatially explicit population model to predict wolf distribution and viability at several potential reintroduction sites within the region under current conditions and under two contrasting predictions of future landscape change. Areas of the southern Rocky Mountains with resource‐selection‐function values similar to those of currently inhabited areas in Yellowstone could potentially support>1000 wolves, 40% within protected areas and 47% on unprotected public lands. The dynamic model predicted similar distribution under current conditions but suggested that development trends over 25 years may result in the loss of one of four potential regional subpopulations and increased isolation of the remaining areas. The reduction in carrying capacity due to landscape change ranged from 49% to 66%, depending on assumptions about road development on public lands. Although much of the wolf population occurs outside core protected areas, these areas remain the key to the persistence of subpopulations. Although the dynamic model's sensitivity to dispersal parameters made it difficult to predict the probability of natural recolonization from distant sources, it suggested that an active reintroduction to two sites within the region may be necessary to ensure low extinction probability. Social carnivores such as the wolf, which often require larger territories than solitary species of similar size, may be more vulnerable to environmental stochasticity and landscape fragmentation than their vagility and fecundity would suggest.
Effects of elevated CO2 and temperature on development and consumption rates of Octotoma championi and O. scabripennis feeding on Lantana camara
Authors: Johns Caitlin V. , Beaumont Linda J. , Hughes Lesley
Published: August 2003

We carried out a factorial experiment to explore the effect of doubled CO2 concentration and a 3 °C temperature increase on the development of a complete generation of the beetles Octotoma championi Baly and O. scabripennis Guérin‐Méneville (Coleoptera: Chrysomelidae). These species are biological control agents of Lantana camara L. (Verbenaceae), with a leaf‐mining larval phase and free‐living, leaf‐chewing adults.

Plants grown at elevated CO2 had enhanced above‐ground biomass, thicker leaves, reduced nitrogen concentration, and increased C:N ratios. Under the high temperature treatment, plants grown at ambient CO2 suffered wilting and premature leaf loss, despite daily watering; this effect was ameliorated at elevated CO2. The wilting of plants in the ambient CO2/high temperature treatment reduced the emergence success of the beetles, particularly O. championi. Development time was accelerated by approximately 10–13 days at the higher temperature, but was not affected by CO2. Neither CO2 nor temperature affected adult beetle weight. Consumption rates of free‐living beetles were not affected by either CO2 or temperature. By contrast, in the short‐term trials using excised foliage, beetles given no choice between ambient and elevated CO2‐grown foliage, consumed more from ambient plants. When beetles were offered a choice between foliage grown at the two CO2 levels, O. championi did not display a significant preference but O. scabripennis consumed more ambient CO2‐grown foliage when feeding at the lower temperature.

This study indicates that under future conditions of higher temperatures, amelioration of water stress in host plants growing in elevated CO2 may benefit some endophagous insects by reducing premature leaf loss. Under some circumstances, this benefit may outweigh the deleterious effects of lower leaf nitrogen. Our results also indicate that foliage consumption under elevated CO2 by mobile, adult insects on whole plants may not be significantly increased, as was previously indicated by short‐term experiments using excised foliage.
Comparative population genetic structures of the fruit fly Urophora cardui and its primary parasitoid Eurytoma robusta
Authors: Johannesen Jes , Seitz Alfred
Published: August 2003

The interaction between two species may depend on geographic scale and this in turn can affect co‐evolution among them. The present study comparatively examines population genetic structures of the tephritid gall fly Urophora cardui and its primary ectoparasitoid Eurytoma robusta for inference of relative dispersal patterns and host‐parasitoid specificity. Genetic differentiation patterns indicated two levels of hierarchical structure in both species: locally similar distance‐dependencies but globally differences. Locally, both species showed isolation by distance and a high correlation between host and parasitoid FST for the same population‐pairs was found. At the local level, E. robusta populations were most structured. These findings suggest that locally E. robusta is tracking behind its host, U. cardui, and that colonisation of new patches by both species underlie a stepping‐stone dispersal process. The investigation as a whole showed that U. cardui populations were hierarchically structured across a genetic‐geographical cline. There was no sign of a comparable cline in E. robusta where populations globally became independent of one another and of the host. The different degree of hierarchical genetic structure of the two species suggests that dispersal processes or interactions differ relative to geographical scale and population history.
Evidence for host race formation in the leaf beetle Galerucella lineola
Authors: Ikonen Arsi , Sipura Mika , Miettinen Sari , Tahvanainen Jorma
Published: August 2003

We examined preference and performance of four Finnish Galerucella lineola F. populations on alder and willow. In standardized two‐choice laboratory feeding trials with alder and willow, only two naturally alder‐associated G. lineola populations accepted alder. Two conspecific willow‐associated populations preferred willow. These preferences seem to be unstable, however, because they can be modified by the beetles’ experience. Thus, there probably is not a complete host preference‐based isolation of alder‐ and willow‐associated G. lineola beetles in nature. In performance experiments, larvae of all four populations survived better on willow than on alder. This may indicate that willows are the ancestral hosts for G. lineola. Nevertheless, larvae of the two alder‐associated G. lineola populations survived better on alder than larvae of the two willow‐associated populations. On the other hand, larvae of the two willow‐associated populations survived better on willow than larvae of the two alder‐associated populations. This performance trade‐off suggests that G. lineola encounters different selective pressures on alders and willows. On both of them, selection probably disfavours those G. lineola genotypes that are the most successful and abundant on alternative hosts. This may reduce the effects of gene flow that is likely to occur as a consequence of incomplete host preference‐based isolation of alder‐ and willow‐associated G. lineola populations. Data from pupal weights support the idea that alder‐ and willow‐associated G. lineola populations may be genetically differentiated. Pupae of the two alder‐associated populations were heavier than those of the willow‐associated populations irrespective of whether larvae had fed on alder or on willow. Overall, our results indicate host race formation in G. lineola. This process may be enforced by the variable abundance of alders and willows in local communities.
Dietary specialization and infochemical use in carnivorous arthropods: testing a concept
Authors: Steidle Johannes L. M. , Van Loon Joop J. A.
Published: August 2003

For the location of hosts and prey, insect carnivores (i.e., parasitoids or predators) often use infochemical cues that may originate from the host/prey itself but also from the food of the host/prey, a food plant, or another feeding substrate. These cues can be either specific for certain host/prey complexes or generally present in various complexes, and the reaction of the carnivores to these cues is either innate or learned. According to the concept on dietary specialization and infochemical use in natural enemies, the origin and specificity of the infochemical cues used and the innateness of the behavioural response are dependent on the degree of dietary specialization of the carnivore and its host/prey species. This concept has been widely adopted and has been frequently cited since its publication. Only few studies, however, have been explicitly designed to test predictions of the concept. Thus, more than 10 years after publication and despite of its broad acceptance, the general validity of the concept is still unclear. Using data from about 140 research papers on 95 species of parasitoids and predators, the present literature study comparatively scrutinises predictions from the concept.

 In accordance with the concept, learning to react to infochemicals and the use of general host and host plant cues was more often found in generalists than in specialists. In addition, more specialists were using specific infochemicals than generalists. In contrast to the concept, however, there was no significant difference between specialists and generalists in the proportion of carnivore species that use infochemicals during foraging and also extreme generalists are using infochemical cues for foraging. Likewise, an innate reaction to infochemicals was found in both specialists and generalists. Several reasons why infochemical use, including an innate reaction to infochemicals, is adaptive in generalist carnivores are discussed . We conclude that the concept has been a useful paradigm in advancing the chemical ecology of arthropod carnivores, but needs to be modified: the use of infochemicals is expected in all arthropod carnivores, regardless of dietary specialization.
Effects of herbicide‐tolerant transgenic oilseed rape genotypes on honey bees and other pollinating insects under field condtions
Authors: Pierre J. , Marsault D. , Genecque E. , Renard M. , Champolivier J. , Pham‐Delègue M.H.
Published: August 2003

Field experiments were carried out to compare the diversity and density of pollinators foraging on two winter oilseed rape varieties, ‘Falcon’ and ‘Artus’, and their respective transgenic counterparts ‘Falcon pat’ and ‘Artus LL’, which are tolerant to glufosinate, a non‐specific herbicide. The number of insects per 1000 available flowers was counted for the four main pollinators: honeybees, bumblebees, solitary bees, and Diptera. Additionally, on ‘Falcon’/‘Falcon pat’ the foraging behaviour of the main pollinating insects, i.e., honeybees and bumblebees, was observed (number of flowers visited per min, foraging postures, intervariety flights). A pleiotropic effect could affect nectar and pollen production, therefore we measured nectar volume, nectar sugar concentration, and composition for the four plant genotypes, and on ‘Falcon’ and ‘Falcon pat’ pollen production was also estimated. The diversity and density of the foraging insect population observed on the transgenic genotypes were similar to that on the non‐transgenic controls. Moreover, the foraging behaviour strategy was similar on ‘Falcon’ and ‘Falcon pat’, and honeybees flew indifferently across these two genotypes. No difference was found in nectar and pollen between the genotypes. Thus, we may assume that the insects do not discriminate between conventional and transgenic oilseed rape specifically resistant to glufosinate. A case‐by‐case approach is recommended for other genetic modifications to plants potentially visited by bees.
Possible roles of esterase, glutathione S‐transferase, and superoxide dismutase activities in understanding aphid–cereal interactions
Authors: Ni Xinzhi , Quisenberry Sharron S.
Published: August 2003

Activities of the detoxification enzymes esterase, glutathione S‐transferase, and of superoxide dismutase in aphids and aphid‐infested cereal leaves were assayed using polyacrylamide gel electrophoresis and a spectrophotometer to elucidate the enzymatic mechanisms of aphid resistance in cereal plants. A chlorosis‐eliciting Russian wheat aphid, Diuraphis noxia (Mordvilko), and non‐chlorosis‐eliciting bird cherry‐oat aphid, Rhopalosiphum padi (L.), and four cereals were used in this study. The four cereal genotypes were ‘Arapahoe’ (susceptible) and ‘Halt’ (resistant) wheat (Triticum aestivum L.), ‘Morex’ (susceptible) barley (Hordeum vulgare L.), and ‘Border’ (resistant) oat (Avena sativa L.). Esterase isozymes differed between the two aphid species, although glutathione S‐transferase and superoxide dismutase did not. Esterase, glutathione S‐transferase, and superoxide dismutase activities in either aphid species were not affected by the level of resistance of a cereal to D. noxia. The assays of cereal leaf samples showed that D. noxia feeding elicited an increase in esterase activity in all four cereal genotypes, although R. padi feeding did not. The increase of esterase activity in cereals, however, was not correlated to aphid resistance in the cereals. The time‐series assays of aphid‐infested cereal leaves showed that D. noxia‐infested Morex barley had a significant increase in esterase activity on all sampling dates (3, 6, and 9 days) in comparison with either uninfested or R. padi‐infested barley. No difference in glutathione S‐transferase activity was detected among either aphid infestations or sampling dates. The electrophoretic assays, however, revealed that aphid feeding elicited a significant increase in superoxide dismutase activity, which served as the control of glutathione S‐transferase activity assays. The increase in esterase and superoxide dismutase activities suggested that D. noxia feeding imposes not only toxic, but also oxidative stresses on the cereals. The ramification of using these enzyme activity data to understand the etiology of D. noxia‐elicited chlorosis is discussed.
Effects of plot vegetation diversity and spatial scale on Coccinella septempunctata movement in the absence of prey
Authors: Banks J. E. , Yasenak C. L.
Published: August 2003

The influence that vegetation diversity and the spatial scale of that diversity exert on insect behavior has increasingly been explored in the ecological literature, but relatively few experiments have explicitly incorporated both factors in experimental treatments. We conducted a field study designed to explore the effect of both of these factors on insect movement behavior in a broccoli agroecosystem. We caught and released seven‐spotted ladybird beetles (Coccinella septempunctata L.) in plots containing different degrees of vegetation diversity at two different spatial scales in which prey had been removed. Beetle movement was recorded at timed intervals, and move lengths and turning angles were used to generate discrete path maps for each beetle. Observed mean beetle net squared displacements were compared with predicted net squared displacements, and 95% confidence intervals were generated using a bootstrap method described by Turchin (1998) [Quantitative Analysis of Movement: Measuring and Modeling Population Redistribution in Animals and Plants. Sinauer Associates Inc., Sunderland, MA.]. Predicted net squared displacements underestimated beetle movement in smaller plots with both low and higher vegetation diversity for the first five move lengths, whereas no significant difference between observed and predicted net squared displacement for beetles in larger plots of either level of vegetation diversity were detected. These findings highlight the need for a better understanding of how natural enemies are influenced by vegetation diversity and the spatial scale of that vegetation in agroecosystems. The implications of these results for biological control are discussed.
Oviposition preference and larval performance of monarch butterflies (Danaus plexippus) on two invasive swallow‐wort species
Authors: DiTommaso Antonio , Losey John E.
Published: August 2003

The potential of two invasive herbaceous vinesVincetoxicum nigrum(L.) Moench andVincetoxicum rossicum(Kleopow) Barbar. (Asclepiadaceae) to reduce monarch butterfly (Danaus plexippusL.) (Lepidoptera: Nymphalidae, Danainae) populations was investigated by evaluating oviposition selection in adult monarch butterflies and larval feeding preference in choice tests comparing the native host plant of monarch butterflies,Asclepias syriacaL. (Asclepiadaceae) and the two non‐indigenousVincetoxicumspecies. In both choice and no‐choice tests, no eggs were oviposited on either of the twoVincetoxicumspecies whereas over 66 eggs per female were oviposited onA. syriacaplants. All first instar larvae allowed to feed onA. syriacafor 48 h survived while a significantly lower proportion survived onV. rossicum(44%) andV. nigrum(14%). Mean weight of larvae that did survive on theVincetoxicumspecies was significantly lower than the mean weight of larvae that fed onA. syriaca. The mean weight of surviving larvae, however, did not differ between the twoVincetoxicumspecies. The mean proportion of leaves consumed by larvae feeding onA. syriacawas significantly greater than the mean proportion of leaves consumed by larvae feeding on eitherVincetoxicumspecies. Findings from this research indicate thatV. rossicumandV. nigrumare not viable hosts of monarch butterflies and are likely to pose little direct threat to their populations as oviposition sinks. The ability of these highly aggressive plants, however, to out‐compete and displace the native host of monarchs,A. syriaca, may pose a more serious threat. The potential of monarch populations to adapt to the twoVincetoxicumspecies as host plants over the long‐term is discussed.
Defense mechanisms and coping strategies in conjugal relationships: An integration
Authors: Bouchard Geneviève , Thériault Vicky J.
Published: August 2003

Coping strategies and defence mechanisms are used to describe people's responses to stressful situations. The concept of coping strategies comes from the social psychological tradition, whereas the concept of defence mechanisms comes from the psychoanalytic tradition. According to the traditional view, the two concepts are very different. However, recently, a growing number of researchers suggested that coping strategies and defence mechanisms are more interrelated than what was assumed previously. This study was aimed at documenting the relationship between both concepts in the context of predicting adjustment in a specific situation, marital relationships, one of the most well‐suited situations to investigate people's responses to stressful situations. The sample consisted of 157 couples. Each partner completed the Ways of Coping Questionnaire, the Defense Style Questionnaire, and the Dyadic Adjustment Scale. Two theoretical models, the independence model and the effectiveness model, accounting for the relationship between coping strategies and defence mechanisms were first tested, using confirmatory factor analyses. According to the independence hypothesis, one latent dimension should measure defence mechanisms and the other latent dimension should measure coping strategies. According to the effectiveness hypothesis, coping strategies and defence mechanisms could vary along two dimensions: adaptive and maladaptive ways of dealing with marital difficulties. Results revealed that the effectiveness hypothesis was a better representation of the relationship between the two concepts than the independence hypothesis. The unique contribution of defence mechanisms and coping strategies to the prediction of marital adjustment was next examined using multiple regression analyses. Again, results were generally congruent with the effectiveness hypothesis. Positive and negative relationships with marital adjustment were observed for both concepts. In addition, coping strategies did not result in more positive outcomes on marital adjustment than defence mechanisms. It seems that coping strategies and defence mechanisms have both their specificity and their shared characteristics.
Children’s ability to attribute different interpretations of ambiguous drawings to a naive vs. a biased observer
Authors: Barquero Beatriz , Robinson Elizabeth J. , Thomas Glyn V.
Published: August 2003

In two experiments we investigated 5- to 7-year-olds’ ability to attribute to a naive or a biased observer an interpretation of ambiguous drawings (restricted views of a nondescript part of a depicted object) corresponding to that observer’s mental state: ignorance for the naive observer and expectation for the biased observer. In Experiment 1, in which the expectation was only based on the observer’s prior viewing experience, children mostly failed to infer a proper interpretation for both a biased and a naive observer; instead, they ascribed to this character an interpretation corresponding to the real identity of the target picture. In Experiment 2, in which the expectation was additionally based on a more stable characteristic of the observer, a high percentage of children succeeded in generating for the biased observer an interpretation according to that expectation. For the naive observer, children’s answers seemed to be at random. In addition, we used a replication of Gopnik and Astington’s “book” task (1988), obtaining different results. We conclude that children aged 5 to 7 years have a rudimentary understanding of the interpretive nature of external representations. Hence their varying performance on interpretive theory of mind tasks, depending on the details of the task or the context in which it is presented.