bluuebunny/crossref_metadata_2025_split huggingface dataset:
The distribution of a typhlocybine leafhopper, Ribautiana ulmi (Homoptera: Cicadellidae) on a specimen wych elm tree
Authors: CLARIDGE D.W. 
Published: March 2008

ABSTRACT.

Higher numbers of feeding and resting Ribautiana ulmi (L.) were found on the more highly illuminated areas of the canopy of a wych elm tree, Ulmus glabra Huds. cv. Camperdownii.
Higher numbers were also found on the basal leaves of each branch when compared with the distal leaves, and on exposed areas of individual leaves when compared with the shaded areas which they overlapped.
Leaf thickness, tannin concentrations and leaf toughness were greater, and water content lower, in leaves from exposed areas of the canopy than from shaded ones.
R.ulmi feeds selectively on the contents of the palisade mesophyll cells, and therefore was assumed to ingest the highest available levels of tannins.
The use of chemical composition as a population marker in insects: a study of the Brimstone butterfly
Authors: DEMPSTER J. P. , LAKHANI K. H. , COWARD P. A. 
Published: March 2008

ABSTRACT.

The elemental composition of 249 adult Brimstone butterflies (Gonepteryx rhamni L.) was studied by wavelength dispersive X‐ray fluorescence spectrometry, to determine whether site/population‐specific differences could be detected. The chemical elements studied were K, Ca, Fe, Cu, Zn, Ti, P, CI and S.
Marked differences were found in the chemical composition of the two sexes, and between individuals caught on different sites and in different years and seasons.
Multivariate analyses of the data using principal component analysis and canonical variate analysis showed a clear separation of the butterflies by sex, and within each sex, by seasons. Of the elements studied, the main discriminating ones for this butterfly were K, Ca, P, Zn, CI and S.
Whilst differences in chemical composition appear to result from variations in the composition of soil and food‐plants in different localities, any site/population‐specific differences are soon masked by the passage of time, as adults age and feed. This makes the technique of limited value in the study of dispersal in this species.
Clutch size in a leaf‐mining fly (Pegomya nigritarsis: Anthomyiidae)
Authors: GODFRAY H. C. J. 
Published: March 2008

ABSTRACT.

Pegomya nigritarsis Zetterstedt is a gregarious leaf‐mining fly attacking Rumex sp. The larvae from one clutch of eggs all inhabit the same mine.
Egg‐batch size varies between host plants and is correlated with leaf size.
On Rumex obtusifolius L. larval survival as a function of clutch size was measured in the field. This measure was incorporated in an optimal clutch size model and a clutch size prediction obtained.
The predicted optimal clutch size, three, is that most frequently found in the field.
Territoriality and fighting in a colonial thrips, Hoplothrips pedicularius, and sexual dimorphism in Thysanoptera
Authors: CRESPI BERNARD J. 
Published: March 2008

ABSTRACT.

Hoplothrips pedicularius (Haliday) (Thysanoptera: Phlaeothripidae), a tubuliferan thrips in which males possess greatly enlarged forelegs, lives in colonies on Stereum fungus.
Females oviposit onto communal egg masses, and males fight by grasping and stabbing with their forelegs in territorial defence of oviposition areas. Prolonged escalated fights occur between males who are of similar size.
Larger males usually win fights and become dominant at the oviposition area. Dominant males secure 80% of matings, and mate most frequently during oviposition periods, with an ovipositing female.
Smaller, subordinate males avoid fights and attempt to 'sneak’copulations. However, they occasionally challenge the dominant male. Challenges tend to follow copulations by the subordinate male and occur more frequently between males who are of similar size.
Subordinate males who eventually leave the oviposition area are larger than those who remain, have frequently challenged the dominant male, and have more frequently been stabbed.
Sexual dimorphism in thrips is associated with gregariousness, claustral habitats, female‐biased sex ratios, and male winglessness. In thrips genera in which males exhibit foreleg armature, males are larger relative to females. The ecological circumstances promoting sexual dimorphism and male fighting in spatially‐structured populations are discussed.
Hierarchical structure in kairomone preference of the predatory miteAmblyseius potentillae:dietary component indispensable for diapause induction affects prey location behaviour
Authors: DICKE MARCEL , GROENEVELD ADRIE 
Published: March 2008

ABSTRACT.The phytoseiid predatorAmblyseius potentillae(Garman) responded to volatile kairomones emitted from leaves infested by the two‐spotted spider mite (Tetranychus urticaeKoch), the apple rust mite (Aculus schlechtendali(Nalepa)) or the thripsFrankliniella pallida(Uzel), only when the predators had been reared on a carotenoid‐free diet. In contrastA.potentillaeresponded to the European red spider mite (Panonychus ulmi(Koch)) both when the predators had been reared on a carotenoid‐containing and a carotenoid‐free diet.Carotenoid‐deficient predators did not respond to odour emitted from a host plant that was infested by larvae of the fruit‐tree leaf roller (Adoxophyes orana(F.v.R)), a carotenoid‐containing phytophage, that cannot be preyed upon byA.potentillae.Carotenoids are indispensable for diapause induction inA.potentillae.Hence, carotenoid‐deficient predators can increase their fitness by feeding from a carotenoid source. This may explain the response of carotenoid‐deficient predators to the kairomones of the two‐spotted spider mite,F.pallidaand the apple rust mite (all containing ingestible carotenoids). As the fruit‐tree leaf roller cannot serve as prey and thus as a carotenoid source, it makes sense that the predators lacking carotenoids do not respond to the kairomone of this phytophagous insect.Two‐choice experiments in a Y‐tube olfactometer showed that the kairomone preference ofA.potentillaehas a hierarchical structure: the kairomone of the European red spider mite is the most preferred one, followed by that of apple rust mite, whereas the kairomone of the two‐spotted spider mite is the least preferred of these three.
Latitudinal gradients in ichneumonid species‐richness in Australia
Authors: GAULD IAN D. 
Published: March 2008

ABSTRACT.

New data from Australia support previous suggestions that the Ichneumonidae as a whole is not more species‐rich in the tropics than the group is in temperate regions.
Part of the overall lack of increase in tropical species‐richness results from an absence of large groups whose sawfly hosts are not present.
In comparison with temperate faunas, a larger proportion of tropical ichneumonids are generalists, exploit pupae/prepupae, or have long ovipositors, corroborating predictions made by hypotheses advanced to explain the anomalous tropical diversity of ichneumonids.
Two large groups of pupal/prepupal parasitoids (Pimplinae and Mesostenini) are more speciose in equatorial areas.
Diurnal lepidopterous larval parasitoids, and specialist lepidopterous pupal/prepupal parasitoids are scarcer in the tropics than one might expect, but nocturnal lepidopterous larval parasitoids show an increased species‐richness in the tropics. It is suggested that this may be a result of a larger proportion of the suitable host larvae being nocturnally active.
Honey bee orientation behaviour and the influence of flower distribution on foraging movements
Authors: GINSBERG HOWARD 
Published: March 2008

ABSTRACT.

Directional movement by foraging honey bees (Apis mellifera L.) was studied on several flower arrays. The most frequent move among equidistant flower stalks was straight ahead from stalk to stalk with frequencies decreasing for increasing turn angles. Turns to the left were about equal in frequency to turns to the right.
Bees maintained directionality when moving from flower stalks that had been rotated 90° counterclockwise while the bee was on the stalk (no difference between moves from rotated stalks and unrotated controls). Thus, directionality is maintained by the bee and is not an artefact of flower distribution.
Bees also maintained directionality when the entire array was rotated around the flower stalk the bee was on. Thus, bees use an external cue to orientate in a given direction rather than fixing on an inflorescence within the flower array.
Bees foraging on very different flower arrays differed in patterns of directionality and in distances flown between flower stalks. Therefore, even though bees maintain directionality using external cues, flower distribution can nevertheless influence flight patterns.
Cold hardiness and overwintering of the grain aphid Sitobion avenae
Authors: KNIGHT J. D. , BALE J. S. 
Published: March 2008

ABSTRACT.

Cold hardiness as measured by supercooling ability in the active stages of the grain aphid Sitobion avenae (F.) decreased progressively with maturation.
Aphids showed no acclimation response when maintained at low temperatures.
Starvation did not improve supercooling ability.
In a single exposure, surface moisture caused inoculation above the inherent supercooling point in a small proportion of a population.
Field populations show a seasonal change in supercooling ability, which is at a maximum in summer and a minimum in late winter.
It is concluded that the act of feeding on healthy plant tissue may confer extensive supercooling ability.
Multiple oviposition by Apoderus balteatus (Coleoptera, Attelabidae) is associated with larger leaves
Authors: SAKURAI KAZUHIKO 
Published: March 2008

ABSTRACT.

The female weevil of Apoderus balteatus Roelofs cuts the leaf near its base in order to make a leaf‐roll‘cradle', in which one, two or three eggs are laid. Cuts are always located about 5 mm from the leaf base, independent of leaf size.
Larger leaves are made into larger cradles.
Weevils tend to lay more eggs in large cradles.
Eggs are laid through different holes and separated by leaf layers in the cradle. Cannibalism by larvae will be prevented by this isolated oviposition.
Multiple oviposition of this weevil allows larger leaves to be used by multiple larvae. It facilitates more efficient use of larger leaves and economizes on female effort in cradle formation.
The effect of weather on the life cycle of the speckled wood butterfly Pararge aegeria
Authors: SHREEVE T. G. 
Published: March 2008

ABSTRACT.

Pararge aegeria (L.) is a very unusual butterfly of Britain, having a long period of adult activity, from April to October, without discrete flight periods. In central Britain it overwinters in two stages: pupae and third instar larvae, both being the progeny of late summer adults. Other larval stages die at the onset of cold winter weather. The overwintering stages give rise to the first adult generation in spring, split into two parts.
Different temperature regimes affect development rates in larvae and pupae differently. Late larval development is more rapid than that of pupae at low temperatures, thus in cool spring weather the overlap of the two parts of the first generation is greater than in warm spring weather.
Adults emerge continuously throughout the summer because larval development rates are variable. When summer is warm there is a partial third generation but when cool only two.
The timing of the end of the flight period is consistent with the hypothesis that both temperature and photoperiod are important in determining whether individuals enter diapause or develop directly. In warm summers larvae develop beyond a sensitive stage before critical daylength is reached and develop directly, but in cool summers individuals enter diapause because they are at the sensitive stage when critical daylength is reached.
It is suggested that variable development rates can facilitate parasite escape in autumn and increase the probability of adult success when weather is unpredictable, and this strategy is maintained because these benefits are greater than the cost of winter mortality of larvae.
The costs of reduced feeding due to predator avoidance: potential effects on growth and fitness in Ischnura elegans larvae (Odonata: Zygoptera)
Authors: HEADS PHILIP A. 
Published: March 2008

ABSTRACT.

This paper investigates the behaviour, in the laboratory, of a forager simultaneously confronted with the conflicting needs to feed and to avoid predators. The foragers were larvae of the damselfly Ischnura elegans Van der Linden, feeding on Daphnia magna Strauss. The predators were adult females of Notonecta glauca L.
Patch choice by Ischnura larvae was significantly modified by the presence of predators. Larvae moved to feed in patches of high prey density when predators were absent but preferred dense cover, even though virtually no prey were available, when predators were present. This behaviour was not altered by hunger, up to 12 days without food. In other words, Ischnura larvae were risk averse in their foraging behaviour.
In experiments with abundant prey available, the feeding rates of Ischnura larvae confined to a single patch were also significantly reduced by the presence of hydrodynamically and chemically detectable predators. Predators detectable only by vision had little effect.
Calculations made from published data show that reduced larval feeding rates can lead to slower growth and development and prolonged instar durations in Ischnura elegans larvae. This may have important consequences for larval survival and adult reproductive fitness.
Load size selection by foraging leaf‐cutter ants (Atta cephalotes)
Authors: RUDOLPH SERI G. , LOUDON CATHERINE 
Published: March 2008

ABSTRACT.Velocity of load‐carryingAtta cephalotes(L.) foragers increases with increasing ant size and decreasing load size.Foragers are selective in the sizes of loads they carry, but heavier loads would apparently increase their rate of leaf transport to the nest (mg of leaf m s−1).Even for very thin leaves, leaf diameter is not correlated with ant body size despite the method of cutting (rotating around a fixed point on the leaf edge).When cutting leaves of different densities, load mass is more closely matched to ant size than is load surface area. This implies that ants choose loads based on mass rather than surface area, and thus the several possible disadvantages associated with carrying loads of large surface area (e.g. increased disturbance by wind or rain) are unlikely explanations of why ants do not select larger loads.The relationship beween forager size and load size is made more complex by further selectivity at the level of colony recruitment: larger ants recruit to higher‐density (thicker) leaf types.Gross leaf transport rate is not maximized by foragingA.cephalotes, but net rate of energy intake cannot be assumed to follow the same pattern. If costs/time (not measured) are constant with changing load size, then the net rate of energy intake is not maximized. An alternative hypothesis is that costs/time increase with larger loads, thereby decreasing net rate of gain for larger loads.
Vertical community structure and resource utilization in neotropical forest cockroaches
Authors: SCHAL COBY , BELL WILLIAM J. 
Published: March 2008

ABSTRACT.

Patterns of vertical habitat use of ten species of cockroaches are examined. Three assemblages of cockroaches are recognized on the basis of morphology, foraging behaviour, foraging heights, and overlaps and breadths of vertical distributions.
Three apterous and brachypterous species occur near the ground and comprise one assemblage. They feed mainly on material in the leaf‐litter.
Species that perch higher either migrate into the leaf‐litter on a diel basis and feed on both leaf‐litter and epiphyllic materials, or some are strictly arboreal and forage on algae, liverworts, lichens, spores, pollen and trichomes on the surfaces of leaves.
Trophic and behavioural correlations with perch height are described and the functions of perching are examined.
We conclude that studies of interactions among species are confounded by our lack of understanding of stage‐ and sex‐specific interactions of coexisting species. A simplistic ‘species’approach to such interactions is inadequate because it does not recognize intraspecific variation.
Population density, phenotype and mortality in the grasshopper Chorthippus brunneus
Authors: WALL RICHARD , BEGON MICHAEL 
Published: March 2008

ABSTRACT.

The patterns of mortality in laboratory populations of the grasshopper Chorthippus brunneus Thunberg are examined at a range of densities and at different stages of nymphal development with particular reference to the phenotypes of nymphs that die or survive.
Total mortality during nymphal development rises from density‐independence at the lowest densities to approximately compensating density‐dependence at the highest densities.
The greatest proportion of total mortality occurs in the first two instars. The stage broadly covering the second instar is the ‘key‐stage’ determining adult density. The mortality during these stages is largely density‐independent. There is relatively little mortality during stages broadly covering the final instar, but it is density‐dependent and also plays a significant part in determining final adult density.
As the mortality becomes more density‐dependent, either with density itself or with cohort age, the smallest individuals become increasingly disproportionately prone to mortality.
Males, which are smaller, are more susceptible to mortality than females, but their susceptibility relative to their size is less than that of females.
Maternal behaviour of a webspinner (Order Embiidina)
Authors: EDGERLY JANICE S. 
Published: March 2008

ABSTRACT. 1. This first detailed behavioural field study of any species within the order Embiidina (=Embioptera) examines the function of parental care in the webspinner Clothoda urichi (Saussure) (Clothodidae).2. Time budgets of nymphs and females in different stages of reproduction differ significantly due, in part, to maternal behaviours.3. Nymphs, non‐reproductive adult females and females with nymphs are active only at night when they feed and spin silk. In contrast, females with eggs guard their eggs both day and night, rarely feeding during the 6‐week period prior to hatch.4. Females physically repel egg parasites. In addition, females construct a substantial egg mass covering, of substrate materials and silk, which hinders parasites.
Flight threshold, wing muscle histolysis, and alary polymorphism: correlated traits for dispersal tendency in the Gerridae
Authors: FAIRBAIRN D. , DESRANLEAU L. 
Published: March 2008

ABSTRACT. 1. This paper tests the hypothesis that selection for dispersal ability within a species influences not only the occurrence and extent of wing reduction but also the tendency or ability of the macropterous individuals to fly.2. Flight thresholds of four species of waterstriders (Hemiptera; Gerridae) were assessed using a tethered flight technique. The species tested varied from monomorphic macropterous (Limnoporus dissortis Drake and Harris), through seasonally polymorphic (Gerris comatus Drake and Hottes and G. buenoi Kirkaldy), to primarily apterous (G.remigis Say).3. Condition of the indirect, mesothoracic flight muscles, and presence or absence of mature or developing eggs (for females) were determined by dissection of all individuals immediately following flight testing. Only individuals with normal muscles were included in the analysis of flight thresholds.4. Comparisons among species revealed that average flight threshold and extent of flight muscle histolysis were negatively associated with the proportion of macropterous individuals. Wing reduction was also associated with significant seasonal variation in flight threshold, particularly among females.5. These results support our initial hypothesis, and further indicate that, within the Gerridae, dispersal tendency depends not only on the proportion of macropters but also on the dispersal capability of the macropterous individuals.
How much pollen can thrips destroy?
Authors: KIRK WILLIAM D. J. 
Published: March 2008

ABSTRACT. 1. A laboratory technique for measuring the number of pollen grains consumed by thrips is described.2. Thrips imaginis Bagnall and Thrips obscuratus (Crawford) (Thripidae) were studied particularly on pollen of the kiwifruit Actinidia deliciosa (A. Chevalier) Liang & Ferguson in New Zealand, and Echium plantagineum L. in Australia.3. Mean daily feeding rates (in grains per thrips per day) ranged from 29 to 843, with an individual rate as high as 1626 for T.imaginis larvae II on E. plantagineum.4. The time taken to feed on a single grain was proportional to grain volume, and decreased with temperature.5. Daily feeding rates were significantly different between pollens, and were higher for smaller grains. The total volume of pollen contents consumed and the total time spent ingesting this volume per thrips per day may be constant with respect to pollen species.6. Daily feeding rates were equivalent to 0.2–0.7% of the average total pollen production of a flower per thrips per day.7. Extrapolation of the daily feeding rates suggests that pollen damage by thrips could sometimes be reducing crop yield or plant fitness.
The effects of simulated rainfall on cochineal insects (Homoptera: Dactylopiidae): colony composition and survival on cactus cladodes
Authors: MORAN V. C. , HOFFMANN J. H. , BASSON N. C. J. 
Published: March 2008

ABSTRACT. 1. A rainfall simulator is described that was used to investigate the effects of rainfall on the cochineal insect Dactylopius opuntiae (Cockerell). This species occurs in discrete colonies that are protected by a copious covering of opaque‘woolly’wax, and is the most important biological control agent of the prickly pear cactus, Opuntia ficus‐indica (L.) Miller, in South Africa.2. We record the composition of cochineal colonies (stage and number of individuals) in relation to colony size to allow accurate predictions of colony composition from size measurements of the intact, wax‐covered colonies before their exposure to rainfall.3. Even short exposures (15 min) to simulated rainfall (delivered at a rate of about 50 mm/h) resulted in wax erosion, and the effect was most marked in small, recently established colonies. Coverings of compacted wax protected the mature colonies from erosion.4. The number of colonies that were washed off the plant was a function of colony size and the duration of exposure to simulated rainfall. Most of the small, recently established colonies were washed from the plants after 120 min. All of the large, mature colonies, albeit badly mutilated and containing far fewer individuals, remained on the plants even after 240 min exposure.5. Survival of individuals, in colonies of all sizes, was less than about 40% after short bouts of rainfall (30 min). First‐ and second‐instar individuals accounted for most of the observed mortalities, and mortality of all stages increased with increasing rainfall duration.6. These observations provide a partial explanation for the poor performance of D. opuntiae as a biological control agent of cacti in higher‐rainfall areas.