bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plant water stress and gall formation (Cecidomyiidae: Asphondylia spp.) on creosote bush
Authors: WARING GWENDOLYN L. , PRICE PETER W. 
Published: March 2008

Abstract. 1. Populations of creosote bush (Larrea tridentata (DC) Coville), were studied in Arizona to determine whether associated gallformers (Cecidomyiidae: Asphondylia spp.) were more abundant on water‐stressed or nonstressed plants. Gall densities were measured along a steep elevational gradient that extended from mesic, higher elevations to lower elevations in the desert; and in the Grand Canyon where severely water‐stressed and relatively unstressed plants occurred adjacently. At the Grand Canyon site, the responses of creosote bush to water stress were also studied.2. The number and densities of Asphondylia species increased both at lower elevations and locally on water‐stressed plants in the Grand Canyon, indicating that climatic and local conditions influence gallformer abundance in the same way.3. Five of the eight Asphondylia species studied at the Grand Canyon site were more abundant on stressed plants, two species were more abundant on nonstressed plants and one species showed no preference for either plant type.4. Densities of most species on stressed plants were positively correlated with the number of meristematic terminals per branch, which were more numerous on stressed plants, due to a bushier architecture. Flower gallformers were more abundant on nonstressed plants, which produced more flowers. Gall densities did not correlate with chemistry measurements, although these parameters also varied with level of stress.5. These results suggest that gallforming species respond variably to plant stress, even within a closely‐related lineage, and that there are effects of stress on plants, including architectural changes, that may be more important to herbivores than biochemical effects emphasized by White (1984) and others.
Diel changes in forager size, activity, and load selectivity in a tropical leaf‐cutting ant, Atta cephalotes
Authors: WETTERER JAMES K. 
Published: March 2008

Abstract. 1. The leaf‐cutting ant Atta cephalotes (L.) in a Costa Rican tropical moist forest showed diel changes in foraging activity. In most colonies studied, foraging was primarily nocturnal, although in a few colonies it was primarily diurnal.2. In all colonies studied, mean forager mass was larger at night than during the day.3. At night, most foragers carried freshly cut leaf fragments, whereas during the day a large proportion carried dried fragments and other vegetable matter collected from along their trail.4. Along one trail, where foraging was primarily nocturnal, the match between ant mass and load mass was compared for laden ants at night and during the day. Laden ants at night were larger, carried relatively heavier loads, and showed a higher degree of matching between their mass and load mass than those foraging during the day.5. A comparison of load masses of ants coming down a local tree and of ants picking up marked fragments from along their trail suggested that the diel difference in load mass and in the match between ant mass and load mass were related to the greater proportion of ants carrying freshly cut leaf fragments at night. Fresh fragments weighed more due to higher water content, and the match between ant mass and load mass was greater for ants cutting fresh fragments than for ants picking up abandoned fragments from along their trail.6. Possible explanations for the diel changes in forager size and activity are discussed.
Predation of the cereal aphid Sitobion avenae by polyphagous predators on the ground
Authors: WINDER LINTON 
Published: March 2008

Abstract. 1. Polyphagous predator densities were manipulated in a wheat crop using polythene exclusion barriers.2. The rates at which aphids fell to the ground and subsequently climbed and returned to the crop canopy were measured.3. Peak aphid density was highest when polyphagous predator density was lowest.4. Similar rates of aphid fall‐off were measured in each plot, but aphid climbing rate was highest when predator densities were lowest.5. It was concluded that ground‐zone predators reduced the rate at which aphids return to the crop canopy.
Characterization of terrestrial insect communities using quantified, Malaise‐trapped Coleoptera
Authors: HUTCHESON JOHN 
Published: March 2008

Abstract. 1. Weekly samples of Malaise trapped Coleoptera from regenerating shrubland and an adjacent mature, podocarp‐broadleaved forest, in the North Island, New Zealand, were compared over one season. Three traps were monitored in each site.2. Diversity indices did not group samples by site whereas the divisive polythetic classification analysis TWINSPAN showed that the two sites possessed clearly different communities. In the classification, site was of primary importance, with time of year, and trap position within site of secondary and tertiary importance respectively.3. Samples were compared at different taxonomic levels and using different subsets of the database. Determination of the main families, morphotyped to species or species complex, was found to be sufficient to classify most samples to the appropriate community group.4. The divisive classification procedure applied to four consecutive weekly Coleoptera samples over early summer, is suggested as a means of describing and identifying terrestrial arthropod communities characteristic of site and year of collection. This approach provides a potentially sensitive tool for monitoring terrestrial ecosystems.
Factors affecting the rate of attack by Cotesia rubecula (Hymenoptera: Braconidae)
Authors: NEALIS VINCENT G. 
Published: March 2008

Abstract. 1. The relationship between responses of the insect parasitoidCotesia rubecula (Marshall) to kairomones produced by the feeding activities of its host,Pieris rapae (L.), and patterns of parasitism were investigated under field conditions.2. Parasitoid adults aggregated in patches with the highest densities of host larvae but there was no commensurate increase in the rate of attack in these patches.3. The rate of attack was not limited by the availability of eggs.4. The rate of parasitoid attack was highest where feeding damage by the host was highest, irrespective of current host density.5. The rate of parasitoid attack was further influenced by host age distribution. Late instar larvae were less susceptible to parasitism than were early instar larvae. The rate of attack on early instar larvae occupying the same plants as late instar larvae was reduced. This reduction in rate of attack was due to limitations on parasitoid search time imposed by the increased feeding damage associated with large host larvae and by the increased time the parasitoid required to recover from an attack on these large host larvae.
Avoidance mechanisms of three Pieris butterfly species against the parasitoid wasp Apanteles glomerulus
Authors: OHSAKI NAOTA , SATO YOSHIBUMI 
Published: March 2008

Abstract. 1. Experimental studies have shown that larvae of threePieris butterflies, P.rapae L., P.melete Mènètriés and P.napi L., are attacked by a parasitoid wasp, Apanteles glomeratus L. Although P.rapae larvae are parasitized heavily in the field, P.melete and P.napi are infrequently parasitized successfully because they possess mechanisms for encapsulating parasitoid larvae and for avoiding parasitism.2. This study examines spatial and temporal variation in rates of parasitism of the three Pieris species by A.glomeratus in the field. We attempted to determine whether P.rapae possesses any means of avoiding parasitism by this wasp, and then to deduce why both P.melete and P.napi have more distinctive avoidance mechanisms than P.rapae.3. Our results indicate that in temporary habitats, which are the main habitats of P.rapae, P.rapae is able to escape A.glomeratus in time and space by colonizing new habitats before the parasitoid arrives. In permanent habitats, however, such escape is not possible. P.rapae larvae lack physiological or behavioural avoidance mechanisms of reducing parasitism rates in permanent habitats. P.melete and P.napi, in contrast, live only in permanent habitats, where the parasitic pressure is potentially high, and have evolved active avoidance mechanisms.
The effects of temperature and prey density on the development rates and growth of damselfly larvae (Odonata: Zygoptera)
Authors: PICKUP JONATHAN , THOMPSON DAVID J. 
Published: March 2008

Abstract. 1. The effects of prey density and temperature on the feeding and development rates of several late instars of the larvae of three common European damselflies (Lestes sponsa (Hansemann), Coenagrion puella (L.) and Ischnura elegans van der Linden) were investigated in a laboratory experiment.2. Functional responses were used to estimate maximum feeding rates. Maximum feeding rates were compared between species, instars and temperatures by expressing prey consumption in terms of prey biomass consumed per unit predator biomass. Lestes was capable of feeding at almost twice the rate of either Coenagrion or Ischnura.3. Higher feeding rates led to faster development rates and there was an interaction between species and temperature. With the exception of those with very low feeding rates, larvae maintained at higher temperatures, but similar feeding rates, developed faster. Under similar conditions of temperature and feeding rate, Lestes larvae developed faster than larvae of either Coenagrion or Ischnura.4. Faster development rates at similar rates of food intake were achieved at the cost of reduced size‐increases between instars.5. The differences in the responses of the three species are discussed in the light of their respective life histories, and with reference to a recent model of population regulation in damselflies.
Within‐plant distribution of a galling adelgid (Homoptera: Adelgidae): the consequences of conflicting survivorship, growth, and reproduction
Authors: FAY PHILIP A. , WHITHAM THOMAS G. 
Published: March 2008

Abstract. 1. Adelges cooleyi (Gil.) was rarely found in the top‐most whorl of shoots in its host plant Engelmann spruce.2. The survivorship of the few Adelges fundatrices which did colonize the top whorl was at or near zero for the 3 years in which survivorship was assessed, while survivorship in the bottom whorls was at least 60%.3. In contrast, when an Adelges fundatrix did survive in the top whorl, her growth and reproductive output, and the growth of her progeny, the gallicolae, were at least double that of bottom whorl fundatrices.4. The distribution of fundatrices within spruce trees was strongly correlated (R2=0.934) with fundatrix fitness (=survivorship × fecundity × growth).5. We hypothesize that the vigorous growth of top whorl shoots promotes Adelges growth and fecundity, but the earlier growth of these shoots results in low temperature mortality of fundatrices.
Digestion rate in relation to alternative feeding in three species of polyphagous predators
Authors: LÖVEI GÁBOR L. , SOPP PAUL I. , SUNDERLAND KEITH D. 
Published: March 2008

Abstract. 1. Disappearance of different amounts of aphid ingested by three species of polyphagous predators, the carabids Bembidion lampros (Herbst) and Nebria brevicollis (F.) and the staphylinid Philonthus cognatus Stephens, was monitored by a quantitative enzyme‐linked immunosorbent assay (ELISA). The effect on the rate of inactivation of prey antigens by the ingestion of subsequent, non‐aphid food was also studied.2. Antigen inactivation was significantly more rapid in the staphyilinid than in the carabids.3. No statistically significant differences were found in the rate of antigen inactivation between beetles which consumed only aphids and those which were given a different type of food after feeding on aphids; the detection period was longer in the former groups. A higher proportion of beetles with low levels of aphid antigen were found earlier in the latter group.4. The results did not unequivocally support the prediction derived from optimal digestion theory that beetles without continuous access to food would retain an initial meal longer than beetles with unlimited access.
A functional classification for analysis of the structure of dung beetle assemblages
Authors: DOUBE BERNARD M. 
Published: March 2008

Abstract. 1. Regional scarabaeid dung beetle assemblages in southern Africa may contain over 100 species, ranging in live weight from 10 mg to 10 g. These show a wide variety of dung‐use and reproductive strategies.2. To facilitate analysis of these diverse assemblages, a system of classification analogous to guilds is proposed. Scarabaeid dung beetle species are allocated to one of seven functional groups (FGs) according to the way they use and disrupt dung. Each group therefore contains a set of species which are functional analogues of each other. This classification provides a conceptual framework within which to analyse the structure of dung beetle assemblages and the interactions between dung beetles and other dung‐breeding species such as coprophagous flies.3. There is a clear hierarchy of functional groups in their ability to compete for dung. Competitively dominant groups such as the large ball rollers (FG I) and fast‐burying tunnellers (FG III) are mostly large, aggressive beetles which rapidly remove dung from the pad. The smaller ball rollers (FG II) are also effective competitors for dung. Subordinate groups are those which bury dung slowly over many days (FG IV and V) and those which breed inside the pad (FG VII, endocoprids). Kleptocoprids (FG VI) breed in dung buried by other beetles and so are not part of the hierarchy.4. The use of this classification is illustrated by reference to three contrasting assemblages of dung beetles in a summer rainfall region of southern Africa. The potential of these beetles for biological control of dung‐breeding flies is discussed.
Insect responses to plant water deficits. II. Effect of water deficits in soybean plants on the growth and survival of Mexican bean beetle larvae
Authors: McQUATE GRANT. T. , CONNOR EDWARD F. 
Published: March 2008

Abstract. 1. We examined the effect of water deficits in soybean, Glycine max [L.] Merr., on the growth and survival of Mexican bean beetle larvae, Epilachna varivestis Mulsant (Coleoptera: Coccinellidae).2. Larvae were reared under growth chamber, glasshouse, and field conditions on foliage from plants that were either well‐watered or subjected to water deficits.3. Larval survival, growth rate and pupal weight were reduced, and development time was increased when larvae were reared on foliage from plants subjected to water deficits. These results are contrary to White's (1974) hypothesis that water deficits in plants cause increased growth and survival of herbivorous insects.4. Changes in foliage chemistry caused by water deficits, possibly in the concentration of free amino acids, are the most likely causes of the observed effects on growth rate and development time. However, under glasshouse and field conditions, physical changes in foliage and/or the foliage's environment that accompany water deficits are also important.
Bruchid egg mortality on Acacia farnesiana caused by ants and abiotic factors
Authors: TRAVESET ANNA 
Published: March 2008

Abstract. 1. This study investigated the effect of arboreal ants on the bruchid beetles that prey upon the seeds of Acacia farnesiana (L.) Willd., a common shrub in the savannas of Santa Rosa National Park, in northwestern Costa Rica.2. Experiments demonstrated that ants removed an average of about 50% of unhatched bruchid eggs that had been laid on the pods of this leguminous plant. Ants also removed shells of hatched eggs.3. In addition to the mortality caused by ant predation, about 30% of the eggs disappeared before hatching, presumably due to the combined effects of temperature and wind.4. The orientation of the branch on which a pod was located did not affect the proportion of eggs lost from that pod.
Competition, resource partitioning and coexistence of an endoparasitoid Encarsia perniciosi and an ectoparasitoid Aphytis melinus of the California red scale
Authors: YU D. S. , LUCK R. F. , MURDOCH W. W. 
Published: March 2008

Abstract. 1. Laboratory experiments and field studies were conducted to explain the coexistence of an endoparasitoid, Encarsia perniciosi Tower, and an ectoparasitoid, Aphytis melinus DeBach, both of which were introduced into California to control the California red scale, Aonidiella aurantii (Mask.).2. Encarsia parasitized all scale stages but it preferred first and second instar scales. This is in contrast to Aphytis melinus, in which previous studies have shown that it parasitizes second and third instar females and second instar males but prefers third instar female scales. Encarsia developed most rapidly when it parasitized an early second instar and slowest when it parasitized the mature female scale. However, on early second instar scales it was about 80% as fecund as a wasp that emerged from a mature female scale.3. Second instar scales parasitized by Encarsia were accepted by Aphytis as readily as unparasitized scales.4. Encarsia did not distinguish between unparasitized hosts and those previously parasitized by Aphytis.5. Encarsia always outcompeted by Aphytis when both species parasitize the same host.6. Encarsia prefers scale on stems whereas Aphytis prefers those on leaves and fruits. This, too, may be a result of interspecific competition with Aphytis.7. The partitioning of the scale resource by the two species explains why they coexist in coastal southern California but it does not explain why Encarsia disappeared from citrus groves in the inland valleys coincident with the introduction of Aphytis melinus into southern California.
Field manipulation of populations of individual staphylinid species in cereals and their impact on aphid populations
Authors: DENNIS PETER , WRATTEN STEPHEN D. 
Published: March 2008

Abstract.

Four species of staphylinids were caged separately on wheat and their effect on the population development of the grain aphid, Sitobion avenae (F.), was investigated over two seasons.
A novel field cage design was used to exclude all but the staphylinid species under investigation.
Predator effects were compared with total‐exclusion cages in which all predators and parasitoids were kept out.
During a high‐density phase of aphid population development only Philonthus cognutus (Stephens) significantly influenced aphid population numbers.
At low aphid densities, Tachyporus obtusus (L.), T.chrysomelinus (L.) and P.cognatus reduced aphid population levels.
The experiments showed that Tachyporus spp. can reduce the numbers of cereal aphids prior to the exponential phase of aphid population increase and that P.cognatus causes some reduction at both the stages of aphid population growth investigated.
Brood sex ratios of the solitary parasitoid wasp,Coccophagus atratus
Authors: DONALDSON J. S. , WALTER G. H. 
Published: March 2008

Abstract.Female eggs ofCoccophagus atratusare deposited within the haemolymph of coccoid scale insects. Male eggs are deposited on to late larval and prepupal stages of parasitoids of scale insects, including conspecifics.When presented with either one host type or a combination of both host types, femaleC.atratusdeposit all their available eggs, assigning the appropriate sex egg to each host encountered. Brood sizes are not adjusted for different combinations of hosts.Behavioural observations show that females do not move away from patches of hosts until all their eggs are laid, regardless of the host type.Brood sex ratios varied with changes in the relative availability of hosts for males and hosts for females. When both host‐types were present in equal numbers, male biased sex ratios resulted (mean ±SEM =0.71 ± 0.009) and when 70% of hosts provided were suitable for female eggs, mostly female‐biased sex ratios resulted (mean ± SEM = 0.37±0.01).Our results do not fit predictions based on the assumption that a sex ratio of 0.5 should be expected inC.atratus. Observed sex ratios indicate that the unusual life histories of these parasitoids need to be taken into account in explanations of their sex ratios.
Brood guarding in a bethylid wasp
Authors: HARDY IAN C. W. , BLACKBURN TIM M. 
Published: March 2008

Abstract.

Atypical of the parasitoid Hymenoptera, female Goniozus nephantidis Muesebeck remain with offspring until they pupate. This behaviour will only have evolved if the consequent reduction in fecundity is outweighed by fitness returns.
G.nephantidis competes for hosts with conspecific and non‐conspecific parasitoids. The effectiveness of G.nephantidis at deterring superparasitism and multiparasitism is tested. Brood survivorships were compared when G.nephantidis and Bracon hebetor Say intrude on hosts with the mother present and absent and with offspring at different developmental stages.
Laying by the intruder reduced brood survivorship. Guarding reduced oviposition on unparasitized hosts by intruding females, and prevented superparasitism of hosts with egg broods. Hosts with larval broods were rarely superparasitized. Multiparasitism was common except on hosts with guarded larval broods, but even here survivorship was reduced.
Competitive asymmetries determined the outcome of contests for possession of host resources.
The costs of remaining seem at least partially offset by the prevention of oviposition by competing parasitoids.
Parasitization by Edovum puttleri (Hymenoptera: Eulophidae) in relation to host density in the field
Authors: RUBERSON JOHN R. , TAUBER MAURICE J. , TAUBER CATHERINE A. , GOLLANDS BRIAN 
Published: March 2008

Abstract.

The relationship between parasitization by Edovum puttleri Grissell and density of eggs of the Colorado potato beetle, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae), was studied on two spatial scales (eggs mass and 6 m2 cage).
For both scales, rates of parasitism were generally inversely related to host density for periods ranging from 2 to 8 days after parasitoid release. Thereafter, parasitism became independent of host density.
The initial inverse‐density relationship and subsequent shift to density independence may result from several factors: (1) ambient temperatures, (2) the parasitoid's limited egg production, (3) differential times of exposure of egg masses to parasitoids, and/or (4) the parasitoid's patterns of host feeding and oviposition.
Although overall levels of parasitism were relatively low, total mortality of L.decemlineata eggs (including nonviable and cannibalized eggs, and those killed by parasitoid feeding) in parasitized egg masses was consistently high (˜70–90%).
Estimating death rates from transect counts
Authors: ZONNEVELD COR 
Published: March 2008

Abstract.

The time course of abundance of adult insects emerging in discrete generations is modelled, assuming the absence of net migration and a constant death rate. The time till emergence is assumed to be logistically distributed.
The qualitative features of the model depend on one dimensionless parameter only, namely the product of the death rate and a dispersion measure for the symmetric emergence distribution.
The model is fitted to data on the abundance of five butterfly species. The tit is excellent; moreover, the estimated death rates are well within the range given in the literature (mostly 0.1–0.2 day‐1). Death rates are generally obtained by mark‐recapture methods. The present model gives the opportunity to evaluate some assumptions of these methods.