bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parasitoid–host relationships when host size varies: the case of Pseudacteon flies and Solenopsis fire ants
Authors: Morrison Lloyd W. , Gilbert Lawrence E. 
Published: March 2003

Abstract.1. Phorid flies in the genus Pseudacteon are parasitoids of ants. Variation in host size preferences of four South American and two North American Pseudacteon species on monogyne and polygyne forms of their host Solenopsis species [S. invicta Buren and S. geminata (F.), respectively] was documented.2. Monogyne Solenopsis workers were, on average, significantly larger than polygyne workers, and the average size monogyne worker attacked was significantly larger than the average size polygyne worker attacked in four of the six Pseudacteon species.3. Three South American Pseudacteon species attacked larger than average size workers, whereas one attacked smaller than average size workers, in both monogyne and polygyne forms. Both North American Pseudacteon species attacked larger than average size polygyne workers and smaller than average size monogyne workers.4. Three Pseudacteon species were reared from eggs to adults in infected ants in the laboratory. The size of the emergent phorid fly was related positively to the size of the host worker ant, with females emerging from larger hosts. Similar patterns were documented for both monogyne and polygyne forms.5. The mean size of worker host from which phorids emerged did not differ significantly between the monogyne and polygyne forms in the subsample of phorids reared to adults.6. The observed patterns elucidate factors that may cause variation in Pseudacteon sex ratios, and have implications for biological control efforts of pest Solenopsis species.
Differences between understorey and canopy in herbivore community composition and leaf quality for two oak species in Missouri
Authors: Corff Josiane LE. , Marquis Robert J. 
Published: March 2003

Summary1. From July 1994 to September 1995, at six censuses, the herbivore community associated with understorey (< 2.5 m height) and canopy (15–20 m) leaves of Quercus alba and Q. velutina was sampled in south‐eastern Missouri, U.S.A.2. Across all censuses, herbivore densities were not significantly different between canopy and understorey for Q. alba and Q. velutina, except in August 1994 when herbivore densities were 60% higher in the canopy on Q. alba. Little significant spatial variation in herbivore densities or community composition was found during the study years.3. The herbivore community was diverse, consisting of 138 species of leaf‐chewing insects. Species richness was significantly greater (by 5–20%) in the understorey than in the canopy for both tree species, and the relative abundance of the main families, different feeding guilds, and most common species differed significantly between understorey and canopy.4. To determine the extent to which leaf quality explained the observed patterns, percentage nitrogen and protein binding capacity were measured in canopy and understorey leaves of Q. alba and Q. velutina. Per cent nitrogen was higher in canopy leaves for Q. velutina while protein binding capacity was higher in canopy leaves for Q. alba.5. These results suggest that the herbivore community associated with these two species of Quercus comprises species that appear to respond individually to environmental and biological conditions encountered in the understorey and the canopy.
Colour‐coded sampling: the pan trap colour preferences of oligolectic and nonoligolectic bees associated with a vernal pool plant
Authors: Leong JoaN. M. , Thorp Robbin W. 
Published: March 2003

Summary1. Pan traps or water traps have been used widely to sample agricultural insect pests, but no formal studies have assessed the utility of these traps as sampling devices for bees.2. Coloured pan traps, used as flower models, can efficiently and selectively sample an oligolectic bee, Andrena (Hesperandrena) limnanthis, and other bees associated with white‐flowered Limnanthes douglasii rosea.3. Females and males of A. limnanthis unexpectedly exhibit different colour preferences. Females are strongly attracted to white and blue traps, but discriminate against yellow traps. Males prefer white traps over blue and yellow traps. Consequently, blue traps are selective for females only, while white traps are selective for both sexes.4. Non‐A. limnanthis bees were caught in significantly greater numbers in yellow than in blue or white traps. These bees included generalists, as well as specialists that are oligolectic on mostly yellow‐flowered species.5. Colour of traps had a significant effect on the numbers of A. limnanthis females and males, and non‐A. limnanthis bees caught in traps. These results indicate that quantitative sampling of bees by pan trap methods can be highly sensitive to trap colour.
Interaction between the solitary bee Chelostoma florisomne and its nest parasite Sapyga clavicornis − empty cells reduce the impact of parasites
Authors: Münster‐Swendsen Mikael , Calabuig Isabel 
Published: March 2003

Summary1. Nesting behaviour and interactions between the bee Chelostoma florisomne (L.) (Megachilidae) and its nest parasite Sapyga clavicornis (L.) (Sapygidae) were studied through continual observations of individuals and dissections of bee nests. Protection of bee offspring is based on (1) the bee’s discovery and removal of parasite eggs deposited prior to the construction of a cell closure, (2) minimising the time when fully provisioned cells might be parasitised successfully, and (3) the construction of empty cells in front of brood cells.2. An empty cell was found in front of 64.4% of all brood cells and, if the outermost brood cell in a nest was excluded, in front of 74.3% of inner brood cells. A vestibule closure is most often constructed in front of the outermost brood cell.3. Following oviposition, the bee made only five flights, which together lasted 6–13 min, to construct a cell closure. A cell closure does not prevent the nest parasite from oviposition inside the brood cell, however, and parasite eggs deposited through the cell closure are not detected and removed by the bee. Only an additional cell closure, i.e. the formation of an empty cell, may protect a brood cell when the bee is not in the nest. The nest parasite often oviposited through the additional cell closure but its offspring were then trapped in the empty cell and starved to death.4. Only 5.4% of the inner brood cells that were protected by an empty cell were parasitised, compared with 28.9% of those without an anterior, empty cell; 27.4% of the empty cells contained dead parasite offspring (eggs and larvae). Thus, the empty cells provided significant protection and, combined with additional means of protection of brood cells, led to a low degree of parasitism. More than 77% of the wasp offspring died at an early stage due to intraspecific interference competition within brood cells and as result of the wasps’ oviposition into empty cells.
Winter foraging patterns and voluntary hypothermia in the social caterpillar Eucheira socialis
Authors: Fitzgerald Terrence D. , Underwood Dessie L. A. 
Published: March 2003

Summary1. Analysis of 28 years of weather data for the Sierra Madre Occidentals of Mexico showed that while flight, mating, and oviposition of the social caterpillar Eucheira socialis (Lepidoptera: Pieridae) occurred in the warmest and wettest months, much of the caterpillar’s feeding and growth occurred in the winter when nocturnal temperatures often fell below 0 °C.2. Although daytime temperatures at the study site in midwinter were markedly warmer than overnight temperatures, colonies remained sequestered in their bolsas by day. Caterpillars initiated activity shortly after the onset of darkness and foraged overnight at temperatures as low as − 2 °C. The remarkably low chill‐coma temperature recorded for this species has been reported previously only for a sub‐Antarctic caterpillar.3. Temperature measurements on sunny days showed the interiors of bolsas to be thermally heterogeneous, with an average differential of 12 °C between the warmest and coolest regions of the structure. Although caterpillars clustered within the bolsas had body temperatures significantly greater than ambient, they exhibited voluntary hypothermia by day, seeking out and resting in the coolest pockets of the bolsas.4. Voluntary hypothermia may influence growth rate adaptively and prevent acclimatisation to daytime temperatures that would have a negative effect on the caterpillar’s ability to locomote at low overnight temperatures.
The distribution and decline of a widespread butterflyLycaena phlaeasin a pastoral landscape
Authors: León‐Cortés Jorge L. , Cowley Matthew J. R. , Thomas Chris D. 
Published: March 2003

Summary1. Ecological specialists are often regarded as most likely to be threatened by anthropogenic habitat changes but few relevant data are available on changes in the status of widespread species.2. Grid square distribution maps have been used widely to measure rates of decline and target conservation resources but it is known that coarse grain mapping is not appropriate to identify declines in widespread species that initially contain numerous local populations per grid cell. Changes in the status of widespread species need to be quantified.3. Present‐day habitat associations, determined from over 2000 transect counts, combined with data on historical and present‐day habitat distributions, reveal that the area of occupancy and population‐level rate of decline of the Small Copper butterflyLycaena phlaeasis likely to have been of the order of 92 and 89% respectively, in 35 km2of North Wales. Similar data on the species' major host plantsRumex acetosaandR. acetosellaindicate possible declines in area occupied of 48 and 91%. If a 1‐km2grid was applied to the landscape, and ifL. phlaeas,R. acetosa, andR. acetosellahad occupied all 1‐km2cells in the study area in 1901 (non‐limestone cells forR. acetosellaonly), their declines would only have been recorded as 15, 9, and 35% respectively.4. Many declining ecological specialists are threatened with extinction because of their initial rarity. At a population level, however, they may or may not be declining faster than less specialised species. The results presented here illustrate that some widespread species may have declined as much as many of Britain's rarities.
Contrasting patch choice behaviour by immature ambush predators, a spider (Misumena vatia) and an insect (Phymata americana)
Authors: Kevan Peter G. , Greco Carlos F. 
Published: March 2003

Summary1. Spiderlings of the crab spider Misumena vatia and nymphs of the ambush bug Phymata americana normally ambush prey in flowers, as do the adults. The immatures of M. vatia are more mobile, by ballooning, than the ambulatory but largely sedentary adult female spiders, but the apterous immatures of P. americana are less mobile than the alate adults. The aim of the work reported here was to investigate how immatures, as compared with adults, select sites from which to ambush their prey.2. Individual immatures of both species were released in experimental arenas with variously manipulated natural stems: normal, with and without leaves, and with and without flowers of three species of plants.3. The spiderlings and nymphs showed discriminatory behaviour but not in accordance with optimal foraging in either case. The spiderlings chose more leafy stems than any other kind of stem. For the nymphs, the importance of leaves was less marked, food apparently being more important than shelter.4. Neither of the predators discriminated among flowering stems of Solidago canadensis, Daucus carota, and Cirsium arvense.5. In other experiments, in which flowered and deflowered stems were located in two separated groups in the arena and the individual was released in a bare area between the two groups, the spiderlings chose either group as predicted by chance but the nymphs showed a slight preference for the flowered sector. Nevertheless, once in either of the groups, the predators showed similar behaviour in choosing leafy stems more often than other stems.6. Nymphs of P. americana are much more selective than adults but spiderlings of M. vatia are less selective than adult females. These results appear to accord with the time and energy costs of changing hunting sites, walking being slower than flying or ballooning.7. The results indicate the need to include other parameters, such as enemy‐free space and time spent in not being able to forage, in the analysis of foraging behaviour.
The role of nutrition, crowding and interspecific interactions in the development of winged aphids
Authors: Müller Christine B. , Williams Iain S. , Hardie Jim 
Published: March 2003

Summary1. Winged morph production in aphids is a phenotypic trait that has traditionally been seen as a response to unfavourable environmental conditions. The evidence to support this theory is reviewed and the ecological and evolutionary significance of the findings is discussed.2. The common assertion of poor host‐plant nutritional quality leading to increased production of winged morphs does not always apply, particularly when the host‐plant quality is exceptionally poor. The available data are skewed heavily towards Myzus persicae, and for this species the dynamical change in plant quality appears to be important with respect to wing induction.3. Crowding may be a less influential stimulus for wing induction as study methods approach natural conditions experienced by aphids on their host plant.4. The growing evidence that interactions with other organisms can induce the production of winged morphs by aphid colonies is reviewed. In the case of natural enemies, such a response by an aphid colony may be regarded as induced defence. Wing induction may also act as a means of transmission for a virus or fungal pathogen.
Increased reproduction by pea aphids in the presence of secondary parasitoids
Authors: Van Veen F. J. F. , Rajkumar A. , Müller C. B. , Godfray H. C. J. 
Published: March 2003

Summary1. The influence of the presence of secondary parasitoids on aphid reproduction was tested in a field experiment.2. Single pea aphids Acyrthosiphon pisum in clip cages on potted bean plants were exposed to a collection of secondary parasitoids enclosed within a small perforated bag. The aphids were exposed to volatile chemicals released by the secondary parasitoids but there was no physical contact.3. The production of nymphs was recorded over an 11‐day period. Aphids produced significantly more offspring in the presence of secondary parasitoids than in the absence of secondary parasitoids (36.9 vs. 31.2).4. This is the second reported occurrence of this phenomenon, and the reasons for its occurrence and its consequences for aphid population and community ecology are discussed.
Influence of chorion ingestion on the performance of Ascia monuste and its association with cannibalism
Authors: Barros‐Bellanda Helen C. H. , Zucoloto Fernando S. 
Published: March 2003

Summary1. In some lepidopterans, the newly hatched caterpillars feed on chorion (animal protein) as their first food. This is also a frequent behaviour of newly hatched caterpillars of Ascia monuste.2. According to some parameters tested (time for pupation, number of adults, male imago weight, and fifth‐instar ingestion), chorion ingestion by first‐instar larvae affects adult performance positively. The ingestion of ultraviolet‐sterilised chorion provided the same positive effect on performance. It is thus suggested that young caterpillars may be benefiting from chorion nutritionally, and that chorion ingestion is a chain of events that leads to positive effects on insect performance.3. Cannibalism in A. monuste was observed in newly hatched caterpillars and is related to the chorion ingestion behaviour. A condition for this to occur was the interval of time of hatching, which means that, if a group of caterpillars hatches very much before another group, once the caterpillars have ingested the chorion of their own eggs, there is a tendency for them to ingest the chorion of other eggs (including unhatched eggs) and, consequently, practice cannibalism.4. Ascia monuste immatures are considered to be herbivorous, however it is important to know that they eat animal tissue (chorion and conspecific eggs).
Apparent competition between two species of aphid via the fungal pathogen Erynia neoaphidis and its interaction with the aphid parasitoid Aphidius ervi
Authors: Pope T. , Croxson E. , Pell J. K. , Godfray H. C. J. , Müller C. B. 
Published: March 2003

Abstract 1. Motivated by a community study on aphids and their fungal pathogens, three hypotheses were tested experimentally to investigate the influence of the fungal pathogen, Erynia neoaphidis Remaudière and Hennebert, on aphid population and community ecology.2. Field experiments were performed in 2 years to test whether two susceptible aphid species on different host plants might interact through the shared fungal pathogen. No strong pathogen‐mediated indirect interactions (apparent competition) between populations of pea aphid Acyrthosiphon pisum Harris and nettle aphid Microlophium carnosum Buckton were detected.3. In the first of the field experiments, pea aphids exposed to the fungus showed a weak tendency to produce more winged dispersal morphs than control populations not exposed to the fungus. In a laboratory test, however, no support was found for the hypothesis that the presence of volatiles from fungus‐infected cadavers promotes production of winged offspring.4. The response of the pea aphid parasitoid Aphidius ervi Halliday to colonies containing hosts infected 1 and 3 days previously was assessed. Wasps initiated fewer attacks on 1‐day‐old infected colonies than on healthy colonies, with the numbers on 3‐day‐old fungus‐infected colonies intermediate.
Immunoreactive osteocalcin forms in conditioned media from human osteoblast culture and in sera from healthy adult control subjects and patients with bone pathologies
Authors: Diaz Diego  , Nacher  , Rapado  , Serrano  , Bosch  , Aubia  , De La Piedra  
Published: March 2003

BackgroundThe aim of this work was to study the immunoreactive forms of bone Gla protein (BGP) present in conditioned media of human osteoblast cultures (BGP released from osteoblast) and in the sera of healthy adult control subjects and patients with bone pathologies (chronic renal failure on haemodialysis, Paget's disease of bone and post‐menopausal osteoporosis).MethodsThe technical procedure used was a combination of high‐performance liquid chromatography (HPLC) and different BGP assays with several specificities to analyse BGP levels in the different HPLC fractions. Aliquots of conditioned media or sera were purified through a Sephadex G‐50m column and by HPLC (C4 reverse‐phase column) in a 25–40% acetonitrile gradient. Two‐minute fractions were collected and divided into three aliquots in order to determine osteocalcin content using three different assays: (a) ELSA–OST–NAT IRMA, which only detects intact osteocalcin; (b) ELSA–OSTEO IRMA, which detects intact osteocalcin and N‐terminal fragments; and (c) OSCA Test RIA, which detects intact osteocalcin, C‐terminal and other fragments.ResultsWe found different immunoreactive forms of osteocalcin in the culture medium of human osteoblasts and in sera from control subjects and patients for the bone pathologies studied. We did not find great qualitative differences between the immunoreactive osteocalcin profile found in the culture medium from human osteoblasts and the sera from healthy control subjects. However, the different bone pathologies show different characteristic patterns of immunoreactive forms of osteocalcin.ConclusionsAn interesting finding has been the detection, both in sera and in osteoblast culture media, of several immunoreactive forms of intact osteocalcin that eluted from HPLC at different acetonitrile percentages, and therefore correspond to different molecular forms.
Plasma homocysteine concentration related to diet, endothelial function and mononuclear cell gene expression among male hyperlipidaemic smokers
Authors: Brude I. R. , Finstad H. S. , Seljeflot I. , Drevon C. A. , Solvoll K. , Sandstad B. , Hjermann I. , Arnesen H. , Nenseter M. S. 
Published: March 2003

BackgroundElevated plasma concentration of homocysteine is an independent risk factor for development of cardiovascular diseases.Materials and methodsWe evaluated potential links between homocysteine and atherothrombogenesis by relating the plasma concentration of homocysteine to (i) dietary antioxidants and omega‐3 fatty acids (and determined influence of intervention with antioxidants or omega‐3 fatty acids); (ii) markers of endothelial cell function; and (iii) peripheral blood mononuclear cell mRNA levels.ResultsWe observed an inverse relationship between the plasma homocysteine concentration and dietary intake of vegetables, vitamin C and β‐carotene and between homocysteine and the serum concentration of folate, vitamin B12 and omega‐3 fatty acids. Intervention with antioxidants or omega‐3 fatty acids did not affect plasma homocysteine concentration. The plasma levels of cysteinylglycine and vitamin B12 correlated positively with circulating E‐selectin and VCAM‐1, respectively, whereas folate in serum and blood correlated negatively with P‐selectin. A negative correlation was found between the concentrations of homocysteine and von Willebrand factor. Negative and positive correlations were found between plasma homocysteine and the mononuclear cell mRNA levels of peroxisome proliferator activated receptor δ (PPARδ) and c‐myc respectively. A negative correlation was also found between plasma homocysteine and mononuclear cell mRNA levels of the proteoglycan serglycin. Homocysteine was not correlated with serum activity of glutathione peroxidase or with the mRNA level of glutathione peroxidase in mononuclear cells.ConclusionThe plasma homocysteine level was negatively correlated with dietary intake of vegetables, including vitamins C and E, and serum omega‐3 fatty acids, whereas supplementation with antioxidants or omega‐3 fatty acids did not affect plasma homocysteine concentration. Homocysteine was not associated with circulating adhesion molecules or increased procoagulant activity, but homocysteine may alter mononuclear cell gene expression. Cysteine showed no significant correlation with these parameters.