bluuebunny/crossref_metadata_2025_split huggingface dataset:
Population dynamics of the white pine weevil, Pissodes strobi, infesting jack pine, Pinus banksiana, in Ontario, Canada
Authors: NEALIS V. G. 
Published: March 2003

1. Eight generations of white pine weevil, Pissodes strobi (Peck) , infesting the terminal shoots of young jack pine trees, were sampled as larvae, pupae, and adults between 1988 and 1995.2. The density of adult weevils increased rapidly for the first 3 years of the study, then declined in the next 4 years. Between‐generation rates of change in density of weevils were related to mean number of weevils produced per terminal shoot of the host tree. Net increases in population density followed years in which a relatively high number of weevils emerged per terminal shoot and vice versa.3. The mean number of weevils emerging per terminal shoot was determined by survival of weevils between the end of the larval stage and the successful emergence of adult weevils.4. There was no clear relationship between survival of the post‐feeding stages of the weevil and rates of parasitism or bird predation on these same stages. There was, however, a strong negative relationship between survival of weevils within the terminal shoot and the abundance of the facultative dipteran predator Lonchaea corticis Taylor.5. The relationship among generational rates of change in populations, survival, and predation was evident irrespective of the age of the trees infested, suggesting that population dynamics of the weevil may be influenced as much by local predation pressure as by physical and biotic changes associated with growth of the young host trees.
Spatial and temporal variation in species composition of dung beetle assemblages in southern Ireland
Authors: Finn JohN. A. , Gittings ToM. , Giller PauL. S. 
Published: March 2003

Abstract. 1. This study attempts to identify the main community characteristics that contribute to variability in dung beetle assemblage composition and structure across a range of spatial and temporal scales.2. Dung beetle assemblages (Aphodius, Sphaeridium, and Geotrupes species) were monitored by dung‐baited pitfall trapping at 10‐day intervals during the seasonally active period at eleven sites in southern Ireland. Three of the sites were monitored over at least 2 years between 1991 and 1996.3. Although the species composition of the above taxonomic groups was comparable among sites and years, relative abundances of component species varied considerably. Detrended correspondence analysis ordinations indicated a similar level of variability in dung beetle assemblage structure among years, and among sites ≈1–180 km apart.4. Processes that may contribute to spatio‐temporal variability in dung beetle assemblages are discussed, and strategies for future research are suggested.
Temperature‐dependent reproduction of the spruce bark beetle Ips typographus, and analysis of the potential population growth
Authors: Wermelinger BeaT. , Seifert MarC. 
Published: March 2003

Summary1. The spruce bark beetle Ips typographus (L.) is one of the most important forest pests in Central Europe, but despite this the effects of temperature on life history and population growth are largely unknown. This study examines the effects of temperature on reproduction and intrinsic demographic statistics.2. Laboratory experiments on oviposition were carried out at six temperatures in the range 12–33 °C, using the so‐called sandwich rearing technique for bark beetles.3. A linear relationship between oviposition rates and temperatures in the range 15–25 °C was used to estimate the lower temperature threshold for oviposition as 11.4 °C. With a nonlinear model fitted to the data across the whole range of experimental temperatures, the lower and upper limiting temperatures and optimum temperature were found to be 7.9, 33.7, and 28.9 °C, respectively. A model for daily oviposition rate was fitted, which describes the pattern of oviposition over the entire oviposition period.4. The analysis of life tables, combining developmental rates, reproduction, mortality, and sex ratio, suggests maximum population growth (rm) at near 30 °C.5. After generating a first brood, spruce bark beetles often re‐emerge from the tree and produce other sister broods. The effects of temperature and number of sister broods on demography were evaluated using age‐specific life‐table analyses. It is hypothesized that sister broods play an important role in regions where I. typographus is monovoltine, but have only moderate significance where this species has more than one generation per season.
Crab spider hunting performance is temperature insensitive
Authors: Schmalhofer Victoria R. , Casey Timothy M. 
Published: March 2003

Summary1. Laboratory and field experiments showed that the hunting performance of two flower‐dwelling crab spiders, Misumenops asperatus and Misumenoides formosipes, was thermally insensitive over a broad range of temperatures normally experienced by these spiders.2. In the laboratory, HP, a behavioural metric of spider hunting performance, was similar for spiders of a given species over an ≈ 30 °C temperature range.3. Spiders in the field captured predominantly hymenopterans and dipterans, and field hunting performance, measured as the number of prey captured per spider per day, also proved to be unaffected by temperature.4. These findings counter the general rule that physiological/ecological performance in terrestrial arthropods is temperature dependent.5. Freedom from temperature constraints on the capacity of crab spiders to capture prey may be due to the use of venom and/or to muscle physiological adaptations for anaerobic metabolism.6. Wide thermal performance breadth increases the spectrum of prey available to M. asperatus and M. formosipes by allowing spiders to hunt prey active during cooler periods of the day as well as those active during warmer periods.7. Wide thermal performance breadth also benefits M. asperatus and M. formosipes due to adult phenology; both species experience a seasonal temperature shift during the adult phase.
Metal content in insects associated with ultramafic and non‐ultramafic sites in the Scottish Highlands
Authors: Davison Gemma , Lambie Claire L. , James Wendy M. , Skene Marion E. , Skene Keith R. 
Published: March 2003

Summary1. Concentrations of magnesium, manganese, chromium, and cadmium were measured in Coleoptera, Diptera, Hemiptera, and Hymenoptera captured at ultramafic and non‐ultramafic sites in the Highlands of Scotland.2. The Hemiptera showed the greatest concentration differences between the ultramafic and non‐ultramafic sites in manganese, magnesium, and chromium, with greatly increased levels in ultramafic sites.3. The Coleoptera and Hymenoptera had lower levels of manganese, magnesium, and chromium at the ultramafic site than at the non‐ultramafic sites. The Diptera had increased levels of manganese and magnesium at the ultramafic site, but showed no difference in chromium levels from any site.4. Cadmium occurred at lower levels in all insect orders at the ultramafic site.
Inter‐strain competition and dispersal in aphids: evidence from a greenhouse study
Authors: Rochat Jacques , Vanlerberghe‐Masutti Flavie , Chavigny Pascal , Boll Roger , Lapchin Laurent 
Published: March 2003

Summary1. Crops are often colonised by aphids having different life‐history traits, and the aphids and their offspring compete for the shared resource. The intraspecific competition and dispersal characteristics of two strains (A and B) of the cotton aphid Aphis gossypii on cucumber were examined in a greenhouse study. Strain A normally feeds on cucumber, whereas strain B originated from melon but develops on cucumber. Both strains reproduce exclusively via parthenogenesis and can be discriminated using molecular markers.2. The strains were released at the same time on different plants in a greenhouse. Total density and their dispersion within and between plants were recorded through time, and the frequency of each strain was assessed using DNA fingerprinting. The Lotka–Volterra competition model was used to test for inter‐strain competition and to estimate its intensity.3. Strain A had the highest rate of increase and carrying capacity, and became the most frequent strain, nearly displacing strain B. Strain B was the most common only on the plants it infested first. The competition was unbalanced as strain B was affected strongly by strain A, but strain A was only affected minimally by strain B. This asymmetrical relationship for strain B was not due only to competition for the shared resource.4. Such competition may in part explain the reduction of genetic polymorphism observed by others in the field where colonising strains coming from different hosts compete and some are eliminated. Polymorphism in A. gossypii populations in nature is thought to be maintained by heterogeneous patches of hosts differentially favourable for different clones.
Does a single meal affect female reproductive output in the sexually cannibalistic praying mantid Iris oratoria?
Authors: Maxwell Michael R. 
Published: March 2003

Summary1. One explanation of the evolution of sexual cannibalism, the female’s consumption of a male during or following courtship or copulation, is that this behaviour increases the female’s fitness. This study tests the assumption that a single meal increases female reproductive output significantly in the sexually cannibalistic praying mantid Iris oratoria L.2. In 38 mating trials, seven of the females cannibalised the males. In order to augment the number of females that fed, an additional nine females were each fed one cricket nymph at the end of the mating trial.3. Three measures of female reproductive output – the occurrence of oviposition, the mass of the first ootheca, and the number of eggs in the first ootheca – increased significantly with female feeding condition, which was a reflection of food consumed before the mating trial. Females that copulated later in the season tended to lay lighter oothecae.4. The females’ consumption of a meal during the mating trial, either a conspecific male or a cricket, did not influence any measure of reproductive output significantly, although possible effects upon subsequent oothecae cannot be ruled out.5. If, as the present study suggests, a single meal provides a negligible or delayed benefit to female reproductive output, the evolution of sexual cannibalism might lie in alternative explanations, which include possible fitness benefits to cannibalistic females in the nymphal stage or possible paternity benefits to the cannibalised males.
Parasitoid and inquiline attack in the galls of four alien, cynipid gall wasps: host switches and the effect on parasitoid sex ratios
Authors: Schönrogge K. , Walker P. , Crawley M. J. 
Published: March 2003

Summary1. Four alien cynipid gall wasps of the genus Andricus are established and still spreading in the British Isles. The order, according to the northerliness of their distribution boundary, is: A. corruptrix→A. quercuscalicis→A. lignicola→A. kollari. All four aliens have a sexual generation in spring on Quercus cerris (introduced to Britain) and an agamic generation in autumn on native oak species.2. For 2 years 1994 and 1995, galls of both generations of the four alien species were sampled at eight sites from the south of England to the north of Scotland to determine the parasitoid and inquiline species that attack the new galls. The spring generations of the invading species shared a parasitoid complex of four pteromalid species. Five species of inquilines and 11 species of parasitoids emerged from the autumn galls.3. Two colonisation events were recorded for A. lignicola and A. corruptrix. On both occasions, the spring generations were found first at the new sites, indicating that the agamic generation provides the colonisers for these invading species. After colonisation, the galls of both species were attacked by parasitoids in their first season.4. In spring, the invading species were among the most abundant cynipids at all eight sites. By sampling the whole local community of cynipid galls, it was found that the parasitoid species attacking the spring galls of the invaders seemed to have shifted their attack to the new hosts.5. The secondary sex ratios of the parasitoid species emerging from the sexual galls of A. quercuscalicis (the smallest of the four) showed a strong and significant male bias at all sites and in both years. Parasitoid emergence from the galls of the sexual generations of the other three species (all about equal in size) was between 60 and 70% male, and variable among sites and between years.
Mating frequency, genetic structure, and sex ratio in the intermorphic female producing ant speciesMyrmecina nipponica
Authors: Murakami T. , Wang L. , Higashi S. 
Published: March 2003

Summary1.Myrmecina nipponicahas two types of colonies: a queen colony type, in which the reproductive females are queens and new colonies are made by independent founding, and an intermorphic female colony type, in which reproductive females belong to a wingless intermediate morphology between queen and worker, and where colonies multiply through colonial budding.2. The mating frequencies of reproductive females in both types indicate monoandry. The relatedness among nestmates in both types was almost 0.75, however relatedness between mother and daughter in intermorphic female colonies was slightly higher than that of queen colonies.3. The sex ratio (corrected investment female ratio) was 0.70 at the population level, suggesting that the sex ratio is controlled by workers in this species, however the ratio differed greatly between the two types of colonies. Queen colonies (n = 37) had a female‐biased sex ratio of 0.77 while intermorphic female colonies (n = 33) had a ratio of 0.56.4. Each reproductive intermorphic female was accompanied by an average of 2.9 workers (including virgin intermorphic females) in the colonial budding, and when the investment to those workers was added to the female investment, the sex ratio reached 0.81.5. The frequency distribution of sex ratio was bimodal, with many colonies producing exclusively males or females, however mean estimated relatedness within colonies was almost 0.75. These data are inconsistent with the genetic variation hypothesis, which is one of the predominant hypotheses accounting for the between‐colony variation in sex ratio.
Diversity patterns of eucalypt canopy arthropods in eastern and western Australia
Authors: Majer J. D. , Recher H. F. , Ganesh S. 
Published: March 2003

Summary1. As part of a larger study on canopy arthropods and birds, a 1‐year chemical knockdown study was carried out in one Western Australian forest, where jarrah Eucalyptus marginata and marri E. (Corymbia) calophylla were sampled, and one eastern Australian (New South Wales) forest, where narrow‐leaved ironbark E. crebra and grey box E. moluccana were sampled.2. Ten trees of each species were sampled during each of the four seasons and the arthropods were sorted to morphospecies level. This paper documents the foliage‐associated component of arboreal arthropod communities and compares arthropod species richness within orders and families, between tree species, and between the two forest types.3. Hymenoptera, Coleoptera, Diptera, and Araneae were the richest in species. Nine hundred and seventy‐six species in 173 families were found in the eastern Australian forest, while 687 species in 176 families were found in the western Australian forest. Only 53% of families were common to both forests, but almost half the families recorded were represented by fewer than five species. Species overlap between tree species in each region was 40–53%.4. Analysis using nonparametric bootstrapping procedures showed that sampling of foliage was comprehensive and that only 4–9% more species would be expected with more intensive sampling of the canopy. Absolute richness, as well as differences between tree species and regions, therefore appear to be real and not the result of sampling errors. As a consequence, arthropod species richness in Australian eucalypt forests is shown to be substantially greater than previous estimates.
Host‐specificity constrains evolutionary host change in the psyllid Prosopidopsylla flava
Authors: Van Klinken Rieks Dekker 
Published: March 2003

Summary1. At the higher taxonomic levels Psylloidea have largely co‐evolved with their host plants, and the colonisations of new plant lineages have been relatively few. The mechanisms that have constrained the evolution of host relationships throughout the history of this superfamily are not understood. The host relationships of Prosopidopsylla flava were studied in order to identify possible genetic or ecological constraints to macroevolutionary change in host range, using methodology developed for the host specificity testing of potential biological control agents.2. The five Prosopis taxa (Leguminosae) tested appeared to be indistinguishable as hosts. Adult feeding required for survival, and for the initiation and continuation of egg production, was specific to Prosopis species. Oviposition occurred on 57 of the 58 non‐Prosopis plant species tested within the Leguminosae and Rosaceae, and was highest on plant species that belonged to the same subfamily. Eggs were inserted into plant tissue by their peduncle but hatched independently of host species. Complete development was restricted to Prosopis, although some early nymphal development was observed on species within the same subfamily as Prosopis (Mimosoideae).3. Multiple phylogenetic constraints restrict host selection and utilisation by P. flava to Prosopis species, implying a long association between insect and host. Specificity of adult feeding was of special significance, being required for survival, oogenesis, and probably indirectly determining the oviposition host. This supports the hypothesis that genetically set limits in particular aspects of life history are responsible for the inability of some psyllids to readily colonise new plant lineages, rather than stabilising selection.
Local versus regional species richness in tropical insects: one lowland site compared with the island of New Guinea
Authors: Novotny Vojtech , Missa Olivier 
Published: March 2003

Summary1. The overlap in species composition of Cercopoidea (Aphrophoridae, Cercopidae, and Machaerotidae), Flatidae, and Ricaniidae between two data sets, an almost exhaustive census from 13 Ficus species and a sample from diverse vegetation in the same area, led to the estimate for local species richness of 111 (SE 11.5) species (45 species of Cercopoidea, 36 species of Flatidae, and 30 species of Ricaniidae) at a lowland rainforest site in New Guinea.2. Samples restricted to 13 species of Ficus contained 66 species, i.e. 59% of the estimated local species richness. This high proportion probably results from the high proportion of polyphagous and tourist (transient) species in the Cercopoidea, Flatidae, and Ricaniidae.3. The two largest museum collections of New Guinean insects contained 327 species of Cercopoidea from New Guinea, including 23 of the 34 species collected in the field samples. This overlap led to the estimate of 483 (SE 97.2) species of Cercopoidea present in New Guinea.4. The species found in the field samples were also 2.6 times more likely to be found in the museum collection than other species. This sampling bias can be due to a positive correlation between species local abundance and geographic distribution and/or similar patterns of species abundance at different sites.5. The estimate of species richness of Cercopoidea in New Guinea increased to 1222 species when corrected for this sampling bias. Thus, only 4% of the New Guinean species were present locally, in the study area. Such high beta diversity is probably a consequence of the exceptional habitat and vegetation diversity in New Guinea, as well as its complex geological history.
Habitat segregation based on soil texture and body size in the seed‐harvester ants Pogonomyrmex rugosus and P. barbatus
Authors: Johnson Robert A. 
Published: March 2003

Summary1. The seed‐harvester ants Pogonomyrmex rugosus and P. barbatus are ecologically equivalent sister species that have broadly overlapping distributions in the south‐western U.S.A.; however the two species are only sympatric in localised contact zones.2. Soil regimes at 25–50 cm below the surface were quantified across contact zones to assess abiotic habitat factors related to distribution pattern. Physiological parameters related to foundress survival were also measured in order to test for a correlation between these parameters and distribution pattern.3. The two species segregated among microhabitats based on soil texture; P. barbatus occurred alone in soils with a higher clay content and/or higher moisture retention. In areas of sympatry, soil texture was similar for both species but was intermediate to that in areas where the two species occurred allopatrically. The pattern of microhabitat segregation was similar across three sites that encompassed a broad range of soil regimes.4. The only measure of foundress survival correlated with microhabitat differences was an ≈ 8% greater dry mass for alate females of P. rugosus. This resulted in their surviving significantly longer than did alate females of P. barbatus under desiccating conditions.5. This microdistribution pattern may be caused indirectly by soil texture affecting plant species distribution and hence the seeds available to ants. A companion laboratory experiment demonstrated, however, that soils could also cause this distribution pattern of both ant species directly via effects on foundress wet mass.
Activity and satiation state in Pterostichus melanarius: an experiment in different agricultural habitats
Authors: Fournier Elisabeth , Loreau Michel 
Published: March 2003

Summary1. A capture–recapture experiment was conducted to examine the effects of satiation state on the activity and foraging efficiency of the carabid beetle Pterostichus melanarius Ill., in four different habitats (a hedge, a transition zone between the hedge and the adjacent wheat crop, the margin of the wheat crop, and the centre of the wheat crop) in an agricultural ecosystem in France.2. Prey biomass and density decreased from the centre of the hedge to the crop margin and to the centre of the crop, where prey density was low but prey biomass was moderate. Starved and satiated beetles were released in circular enclosures and recaptured using pitfall traps for 6 days.3. Immediately after release, starved P. melanarius were significantly more active than satiated beetles, but this difference disappeared after the first day. At each recapture date, starved individuals had gained weight whereas satiated individuals had lost weight. The analysis of activity and weight variation at the end of the first day indicated that the centre of the crop seemed to be the most favourable habitat for starved individuals to find food rapidly, whereas the behaviour of satiated individuals was identical in all habitats.4. This experiment shows that habitat use of P. melanarius is flexible. The results are discussed in the context of the classical view of foraging behaviour in carabid beetles. The activity and foraging efficiency in P. melanarius in different habitats can be explained as the result of the interaction between individual satiation state, prey availability in the habitat, and particular preferences of the species.