bluuebunny/crossref_metadata_2025_split huggingface dataset:
Holly leaf‐miners on two continents: what makes an outbreak species?
Authors: Eber Sabine , Smith Hugh P. , Didham Raphael K. , Cornell Howard V. 
Published: March 2003

Summary1. Some herbivore species periodically undergo damaging, high‐density outbreak phases followed by less damaging low‐density phases. Others maintain steady, low to moderate density levels that do little damage to their hosts.2. Two closely related holly leaf‐miner species were compared that share many ecological traits and have very similar life cycles, but only one of which exhibits outbreaks. Phytomyza ilicicola in the eastern U.S.A. varied widely in mortality and infestation levels, reaching local densities of over 10 mines per leaf. In contrast, Phytomyza ilicis in the U.K. showed low infestation and high mortality at all sites. Using data from the literature and from field studies, the factors responsible for these contrasting dynamics were sought.3. Phytomyza ilicicola oviposits into the leaf lamina, and experiences weak larval competition only at high densities. Phytomyza ilicis oviposits into the leaf midrib, which leads to high mortality of young larvae before mine formation. Multiply mined leaves were therefore very common in P. ilicicola but rare in P. ilicis.4. Differences in the parasitoid complexes of the two systems accounted for further differences in survival to adulthood. The main (larval) parasitoid, which was found to impose high, density‐dependent mortality on P. ilicis, is missing on P. ilicicola. It is replaced by an egg–pupal parasitoid, which varies in its impact at differe∼t sites. Multiple emergence of adults from multiply mined leaves is therefore widespread in P. ilicicola but does not occur in P. ilicis.5. The differences in oviposition behaviour and in the parasitoid complexes are likely to allow P. ilicicola to outbreak when habitat conditions are favourable, while P. ilicis is always tightly regulated.
Assessment of the relative impact of different natural enemies on population dynamics of the grain aphid Sitobion avenae in the field
Authors: Plantegenest M. , Pierre J. S. , Dedryver C. A. , Kindlmann P. 
Published: March 2003

Summary1. A detailed population dynamics model was devised to provide a tool for integrated pest management against the cereal aphid Sitobion avenae on winter wheat.2. This model allowed investigation of the relative impact of different natural enemies on aphid population dynamics.3. The output of the model was compared with a set of data collected in the western part of France from 1976 to 1986.4. Fungal diseases accounted for 75% of the reduction in peak aphid density and were the key factor acting on aphid dynamics in this region.5. This study highlights the importance of detailed population dynamics modelling of keystone species, like aphids, for elucidation of the relations between the keystone species and other species associated in the ecosystem.
Effects of larval competition on survival and growth in Mediterranean fruit flies
Authors: Dukas Reuven , Prokopy Ronald J. , Duan Jian Jun 
Published: March 2003

Summary1. Larval success was compared when one, two, or three egg clutches were laid in kumquat fruits (≈ 10 ml in volume) either successively on the same day or at the rate of one clutch per day.2. Increased clutch density was associated with a significant decrease in larval survival rate and non‐significant decreases in larval growth rate and pupal mass.3. Larval and pupal parameters showed significantly larger variance when clutches were laid on successive days than on the same day, suggesting a competitive advantage for older larvae over younger larvae.4. The results suggest that, in small fruit, reduced fitness due to larval competition may act against possible fitness benefits due to social facilitation among adult females, hence reducing the likelihood of non‐linear population dynamics caused by processes such as the Allee effect.
Influence of atmospheric carbon dioxide enrichment on induced response and growth compensation after herbivore damage in Lotus corniculatus
Authors: Bazin Alain , Goverde Marcel , Erhardt Andreas , Shykoff Jacqui A. 
Published: March 2003

Abstract 1. Plant growth and chemical defence compounds in four Lotus corniculatus genotypes exposed to factorial combinations of ambient and elevated carbon dioxide, and herbivory by caterpillars of Polyommatus icarus were measured to test the predictions of the carbon/nutrient balance hypothesis.2. Shoot and root biomass, allocation to shoots versus roots, and carbon‐based defence compounds were greater under elevated carbon dioxide. Pupal weight of P. icarus was greater and development time shorter under elevated carbon dioxide.3. Herbivory decreased shoot growth relative to root growth and production of nitrogen‐based defence (cyanide). Young leaves contained more defence compounds than old leaves, and this response depended on carbon dioxide and herbivory treatments (significant interactions).4. Genotype‐specific responses of plants to carbon dioxide and herbivory were found for the production of cyanide. Furthermore, maternal butterfly‐specific responses of caterpillars to carbon dioxide were found for development time. This suggests the existence of genetic variation for important defence and life‐history traits in plants and herbivores in response to rising carbon dioxide levels.
Host utilisation by moth and larval survival of pine processionary caterpillar Thaumetopoea pityocampa in relation to food quality in three Pinus species
Authors: Hódar José A. , Zamora Regino , Castro Jorge 
Published: March 2003

Abstract 1. The work reported here analysed host utilisation by the pine processionary moth Thaumetopoea pityocampa (Lepidoptera: Thaumetopoeidae), the relationship between moth oviposition patterns and larval performance, the chemical characteristics of the plant in relation to the performance of different larval instars, and the role of these factors in the outbreak capacity of the species. In order to do this, a combination of field and laboratory techniques was used to study three pine species differing in nutritional characteristics.2. Moths oviposited in the three pine species analysed, although cluster pine received a lower number of batches. Late‐instar larvae were able to feed on all three pine species, however first‐instar larvae developed on Scots and black pine but died on cluster pine. Consequently, oviposition in cluster pine can be considered an oviposition mistake, and indicates that moths are rather unselective when ovipositing on different pine species.3. Chemical analysis of needles suggested that the quantity of nitrogen was the main factor responsible for the difference in survival of larvae.4. The oviposition pattern of the moth and the larval susceptibility to food quality in Thaumetopoea pityocampa agree with the theory that unselective oviposition of the moth is a precondition for eruptive dynamics in phytophagous insects.5. The success of the larvae depends mainly on the probability of the moth finding a suitable host. This probability is determined strongly by the changes of structure and coverage in Mediterranean pine woodlands, due to human management.
Density‐mediated responses of bark beetles to host allelochemicals: a link between individual behaviour and population dynamics
Authors: Wallin Kimberly F. , Raffa Kenneth F. 
Published: March 2003

Abstract 1. Bark beetles (Coleoptera: Scolytidae) accept or reject host conifers based partly on concentrations of phloem monoterpenes. They colonise trees in aggregations, in response to pheromones that attract flying beetles to trees undergoing colonisation. A series of entry and gallery construction assays was conducted to determine whether responses by individual beetles to monoterpenes are altered by pheromones and/or the presence of other beetles.2. Entry into the amended media byIps piniand the length of time until entry were not influenced by the presence of aggregation pheromones.3. Entry into amended media was influenced by the presence of other beetles on the surface of, or constructing galleries in, the substrate. The effects of alpha‐pinene and limonene on host entry behaviour were mediated by the density of beetles on the surface of the assay arena, and by the density of beetles constructing galleries within the medium.4. The percentage of beetles entering medium amended with higher concentrations of monoterpenes increased with increased density of beetles on the surface of the assay arena, until a threshold density of three or four beetles per assay arena, after which entrance rate declined.5. The presence of other beetles constructing galleries elicited more rapid entry by the test beetles.6. Gallery lengths were generally higher in the presence of aggregation pheromones.7. Gallery lengths increased with increased density of beetles within the assay arena.8. These results suggest a link between the density of bark beetles and responses of individuals. This linkage may partially explain behavioural changes observed during population eruptions.
Conspicuous colouration attracts prey to a stationary predator
Authors: Hauber Mark E. 
Published: March 2003

Abstract1. Conspicuous body colouration is counter‐intuitive in stationary predators because sit‐and‐wait tactics frequently rely on concealed traps to capture prey. Consequently, bright colours and contrasting patterns should be rare in predators using traps as they may alert potential prey. Yet, some orb‐weaving spiders are brightly coloured and contrastingly patterned. How can conspicuousness of trap‐building sit‐and‐wait predators be favoured by natural selection?2. Observations of spiny spidersGasteracantha fornicatain north‐eastern Australia showed that the size of spiders relative to their orb webs correlated positively with relative prey numbers already captured in their webs. A possible explanation is that the relatively larger appearance of the yellow–black striped dorsal surface of this spider attracts more visually oriented prey items. Prey attracted to webs may get trapped, thereby increasing the spiders' foraging success.3. To test this hypothesis for the function of conspicuous body colouration, a field experiment was conducted that documented the prey capture rates of spiny spiders after manipulating or sham‐manipulating their appearance.4. As predicted, spiders that were dyed black on their striped dorsal surface caught relatively fewer prey items than did control spiders. Thus, conspicuous dorsal body colouration may be adaptive in spiny spiders because it increases foraging success and, presumably, survival rates and reproductive outputs. Overall, these data support thecolour‐as‐prey‐attractanthypothesis in a stationary, trap‐building predator.
A comparative study of larval cannibalism in three species of ladybird
Authors: Michaud J. P. 
Published: March 2003

Abstract.1. Cannibalism was studied under laboratory conditions in three species of Coccinellidae (Coleoptera):Cycloneda sanguinea,Olla v‐nigrum, andHarmonia axyridis. Larval cannibalism varied among species,C. sanguinea >H. axyridis ≥ O. v‐nigrum.2. Larvae of all species cannibalised more in response to reduced food availability (14 h starvation daily) than in response to reduced food quality (dryEphestiaeggs).3. Larvae ofH. axyridiscannibalised siblings at lower rates than non‐siblings, but larvae ofC. sanguineaandO. v‐nigrumdid not. Rates of cannibalism increased significantly with increasing size disparity among larvae of all three species.4. Cannibalism inC. sanguineaandH. axyridis, but not inO. v‐nigrum, increased with larval density, suggesting that not all attacks on conspecifics are driven by hunger.5. Costs, not benefits, were the predominant effects of exclusively and partially cannibalistic diets. A diet of conspecific eggs yielded survival equivalent to theEphestiaegg diet forH. axyridisandO. v‐nigrum, but developmental time was extended and adults were smaller. Larvae ofC. sanguineahad superior survival and faster development on conspecific eggs than on theEphestiaegg diet. OnlyH. axyridislarvae survived as well on diets comprised exclusively or partially of conspecific larvae as onEphestiaeggs, although they developed more slowly.
Flight activity of adult stoneflies in relation to weather
Authors: Briers Robert A. , Cariss Helen M. , Gee John H. R. 
Published: March 2003

Abstract. 1. Dispersal of adult aquatic insects between streams may have important consequences for local and regional population dynamics, but little is known about how dispersal is affected by weather conditions.2. The influence of meteorological variables on flight activity of adult stoneflies (Plecoptera: Leuctridae, Nemouridae, and Chloroperlidae) was investigated using Malaise traps adjacent to three upland streams in the Plynlimon area of mid Wales, U.K.3. Numbers of adult stoneflies captured weekly in the traps were related positively to air temperature and related negatively to wind speed. Meteorological conditions during daylight showed stronger relationships with flight activity than did conditions at night.4. There was inter‐site variation in the strength of weather effects on stonefly flight. Wind speed was significant at only one site, which had higher average wind speed than the other sites.5. Annual variation in weather conditions during adult flight periods may result in varying extent of dispersal between sites, influencing community dynamics over a wide area.
Skewed sex ratios and multiple founding in galls of the oak apple gall waspBiorhiza pallida
Authors: Atkinson Rachel J. , Brown Gordon S. , Stone Graham N. 
Published: March 2003

Abstract.1. The gall waspBiorhiza pallida(Hymenoptera: Cynipidae) reproduces by cyclical parthenogenesis. The adults of the sexual generation develop within galls (oak apples) that contain many larval cells.2.Folliot [(1964) Annales Des Sciences Naturelles: Zoologie, 12, 407–564]found asexual generation females to be of three reproductive types. Androphores produce only sons, gynophores produce only daughters, and gynandrophores produce both sons and daughters. In nature, most oak apples give rise to either only males or only females but a proportion produces both sexes. These mixed‐sex galls could result either from eggs laid by one or more gynandrophores or from eggs laid by androphores and gynophores developing within a single gall (multiple founding).3. Here the frequency of mixed‐ and single‐sex galls was quantified, and morphological and genetic analyses were carried out on the adults emerging from 10 galls to determine the frequency of multiple founding inB. pallida.4. Seventy‐five per cent of 627 galls yielded only one sex. The majority of the remaining 25% had a highly skewed sex ratio. Low genetic variation inB. pallidalimited the application of allozyme‐based genetic techniques, however seven of the 10 galls analysed in detail, including mixed‐sex galls, appeared to have been multiply founded. Contributions by the different foundresses in multiply founded galls were highly skewed.5. The significance of multiple founding is discussed in the light of possible adaptive scenarios (reduction of parasitoid‐induced mortality, avoidance of local stochastic extinction and inbreeding) and possible competition for oviposition sites.
Absence of association between a common mutation in the methylenetetrahydrofolate reductase gene and the risk of coronary artery disease
Authors: Reinhardt  , Sigusch  , Vogt  , Farker  , Müller  , Hoffmann  
Published: March 2003

BackgroundElevated total plasma homocysteine levels are associated with an increased risk of coronary artery disease. Plasma homocysteine levels are influenced by nutritional and hereditary factors. A point mutation (cytosin to thymidine substitution; C677→T) in the gene encoding methylenetetrahydrofolate reductase (MTHFR), has been reported to render the enzyme thermolabile and has been associated with elevations in homocysteine levels in homozygous carriers (TT genotype).MethodsTo examine the hypothesis that the T allele (coding for the thermolabile defect of MTHFR) influences the risk of coronary artery disease, we genotyped 340 patients with coronary artery disease and 105 control subjects in whom coronary artery disease was excluded by coronary angiography. Furthermore, we studied the genotype frequency in 104 age‐ and sex‐matched healthy persons as a control group without signs of atherosclerotic disease.ResultsAllele frequencies for C (wild‐type allele) and T allele (mutant allele) were 0.68 and 0.32 respectively in the healthy control subjects, 0.66 and 0.34 respectively in patients with angiographically excluded coronary artery disease and 0.69 and 0.31 respectively in coronary artery disease patients (P = NS). The allele frequencies of the total study population were 0.68 and 0.32.ConclusionOur data show that homozygosity for the C677→T mutation in this European population is not associated with increased risk of coronary artery disease. This finding suggests that the C677→T mutation of the MTHFR gene does not represent a marker for increased cardiovascular risk.
In vitro effects of growth hormone (GH) and insulin‐like growth factor I and II (IGF‐I and ‐II) on chromosome fragility and p53 protein expression in human lymphocytes
Authors: Cianfarani  , Tedeschi  , Germani  , Prete  , Rossi  , Vernole  , Caporossi  , Boscherini  
Published: March 2003

BackgroundWe have reported previously that growth hormone (GH) therapy increases cell radiosensitivity; in this study we tested whether GH itself or IGFs induce chromosome aberrations and investigated the expression of p53 protein in response to DNA damage.MethodsHuman peripheral blood lymphocytes were incubated with GH (100 and 1000 μg L−1), insulin‐like growth factor I (IGF‐I; 150 and 1000 μg L−1) and IGF‐II (600 and 1200 μg L−1) for 24 h. The radiomimetic agent bleomycin (BLM; 5 μg mL−1) was added in the last 3 h. Cytogenetic analysis was performed by assessing the percentages of damaged cells (%DC) and chromosome aberrations (%CA). The expression of p53 was investigated by flow cytometric assay using the monoclonal antibody DO‐7, and expressed as percentage positive cells and mean fluorescence intensity.ResultsBLM significantly increased both percentage DC and percentage CA and p53 expression (P < 0.01). The %DC was unaffected by the tested peptides. IGF‐I (150 μg L−1) increased spontaneous percentage CA (P < 0.01). All peptides further increased the BLM‐induced chromosome breakage: GH 100 and 1000 μg L−1 by 30% and 73% respectively, IGF‐I 150 and 1000 μg L−1 by 41% and 96% respectively and IGF‐II 600 and 1200 μg L−1 by 89% and 45% respectively. The spontaneous and BLM‐induced expression of p53 was unaffected by GH, whereas it was significantly increased by IGFs (P < 0.001).ConclusionsThese results indicate that the DNA‐damaging effect of BLM is amplified by GH and, more markedly, IGF‐I and ‐II. IGF‐I and ‐II also stimulate p53 protein expression that, taking part in DNA repair, may counteract the IGF action on genome stability.
Cellular and molecular characteristics of inflammation in chronic bronchitis
Authors: Sun  , Stacey  , Vittori  , Marini  , Bellini  , Kleimberg  , Mattoli  
Published: March 2003

MethodsTo examine the inflammatory process in chronic bronchitis, we evaluated the cell and cytokine profile in bronchoalveolar lavage fluid from 12 chronic bronchitis patients who smoked, six chronic bronchitis patients who did not smoke, 10 subjects control subjects without pulmonary diseases who smoked and eight control subjects who did not smoke.ResultsChronic bronchitis patients who smoked had increased numbers of macrophages, neutrophils, eosinophils, mast cells and activated CD8+ T lymphocytes and predominantly expressed interleukin‐8, tumour necrosis factor alpha and interleukin‐2 genes and proteins. The number of macrophages and neutrophils and the expression of interleukin 8 were also increased in control subjects who smoked compared with healthy subjects who did not smoke. Chronic bronchitis patients who did not smoke had increased numbers of eosinophils, mast cells and activated CD4+ T lymphocytes and predominantly expressed interleukin‐5 and granulocyte–macrophage colony‐stimulating factor genes and proteins.ConclusionThus, the cellular and molecular characteristics of the inflammatory process in chronic bronchitis patients who smoke and do not smoke are different, suggesting a different pathogenesis of the disease.
New type of the internalization‐defective low‐density lipoprotein receptor owing to two‐nucleotide deletion (2199delCA or 2201delCA) in Japanese patients with familial hypercholesterolaemia
Authors: Tashiro  , Endo  , Bujo  , Shinomiya  , Morisaki  , Saito  
Published: March 2003

BackgroundIn mutations of the low‐density lipoprotein (LDL) receptor gene, the defect of internalization is caused by a mutation in the cytoplasmic domain of the receptor linked with exons 17 and 18, and the O‐linked sugar domain linked with exon 15 has been speculated not to affect the function of the receptor. Here, we describe a novel mutation of the O‐linked sugar domain of the LDL receptor gene, designated familial hypercholesterolaemia (FH)‐Mishima with Japanese pedigree, which resembles but still differs from classical defective internalization cases.MethodsLDL metabolism was examined in cultured skin fibroblasts from patients. Immunoprecipitation and immunohistochemical techniques were applied for the detection of the receptor protein size and distribution. Screening of the mutant exon(s) of the LDL receptor gene was performed using the polymerase chain reaction–single‐strand conformation polymorphism technique (PCR–SSCP), and sequencing of the mutated alleles was carried out using the dideoxy chain termination method.ResultsLDL‐binding activity at 4°C in skin fibroblasts from patients was similar to normal, but that at 37°C with the ligand decreased time dependently and was lost at 6 h, resulting in the defect of internalization and degradation of LDL. The receptor protein on the cell surface was detected at 4°C by IgG‐C7, an anti‐LDL receptor antibody, but was not detected after incubation with LDL at 37°C. The size of the receptor was 112 kD as determined by immunoprecipitation analysis. A deletion of two nucleotides in exon 15 was detected in the DNA sequence of the LDL receptor gene. The deletion results in a shift of the reading frame after Thr‐713 of the mutant and makes a stop codon at amino acid 759.ConclusionDeletion of the two nucleotides caused novel amino acid sequences after the O‐linked sugar domain, which has the ability of sorting on the cell membrane at 4°C, but not at 37°C in vivo, resulting in the complete cessation of activity of the LDL receptor.