bluuebunny/crossref_metadata_2025 huggingface dataset:
Humidity responses and water balance of riparian species of Bembidiini (Col., Carabidae)
Authors: ANDERSEN JOHAN
Published: March 2008

Abstract. 1. The humidity responses of Asaphidion pallipes (Duftschmid) and Bembidion spp. were studied at various temperatures in choice chambers.

2. Several species initially showed a hygropositive or indifferent response. Other species had a hygronegative reaction which later changed to a hygropositive one. The duration of the hygronegative reaction varied with species, age, temperature and relative humidity. B.litorale (Olivier) and B.semipunctatum (Donovan) change response when they have lost 8–9% of their initial body weight as water.

3. The survival time of species of Bembidion under dry conditions was short compared with that reported for many other carabid beetles. Newly emerged adults of B.argenteolum Ahrens that had been kept away from sand for 3 weeks had lower transpiration rates than any other species. Young adult Bembidion had lower transpiration rates than those in the breeding phase, larvae and dead adults. Transpiration rate appeared to be inversely proportional to the relative humidity whereas there was a non‐linear increase in weight loss with increasing temperature.

4. The species gain most water by drinking and/or from food.

5. There was no correlation between humidity response and transpiration rate or ability to tolerate dry conditions of the species. There was, however, a correlation between behaviour/habitat affinity and humidity response. Diurnal species, living in sandy or silty, half shady‐exposed habitats had an initial hygronegative response, whereas those which hide among gravel/stones, leaves or vegetation were indifferent or hygropositive.
Population dynamics of Mallophaga and Acari on reed buntings occupying a communal winter roost
Authors: FOWLER J. A. , WILLIAMS L. R.
Published: March 2008

Abstract. 1. Mallophaga and Acari were collected from 324 reed buntings (Emberiza schoeniclus (Linnaeus)) captured in a communal winter roost between October 1980 and March 1981.

2. Frequency distributions of one of the mallophagan species, (Philopterus docophorulus (Zlotorzycka)), of the aggregated Mallophaga, and of the aggregated Acari, conform well with a negative binomial model. The remaining three mallophagan species collected were not present in sufficient numbers to describe a frequency distribution.

3. The ratio of nymphs to adults in the mallophagan community increased significantly in the second half of the roosting period (January–March) indicating the onset of increased reproductive activity.
Patchiness, aggregation, and the coexistence of competitors for ephemeral resources
Authors: KNEIDEL KENNETH A.
Published: March 2008

Abstract. 1. A laboratory experiment was conducted to determine the outcome of competition between two species of carrion‐breeding Diptera for food at two levels of resource patchiness.

2. Adults of Fannia howardi Malloch (Muscidae) and Megaselia scalaris Loew (Phoridae) were released into a large population cage and were given access to three 2g sections of pork kidney in one treatment (low patchiness) and to twelve 0.5g sections in the other (high patchiness).

3. Increasing the patchiness of the resource resulted in reduced overlap in the distribution of the two species, and therefore less interspecific competition. However, this did not result in improved survival of the poorer competitor, F.howardi. Both species aggregated their eggs at high patchiness, and therefore suffered from increased levels of intraspecific competition.

4. The experiment shows that increasing patchiness in this way could lead to prolonged coexistence, as has been predicted in other studies.
Some aspects of overwintering in southern England of the mosquitoes Anopheles atroparvus and Culiseta annulata (Diptera: Culicidae)
Authors: RAMSDALE C. D. , WILKES T. J.
Published: March 2008

Abstract. 1. Overwintering of the mosquitoes Anopheles atroparvus van Thiel and Culiseta annulata Schrank, both of which feed on blood throughout the year, is compared.

2 The aquatic stages, males and gonoactive females of A.atroparvus disappear before winter, leaving a generation of inseminated, nulliparous, diapausing females to overwinter. Blood meals taken by diapausing females merely serve to maintain fat reserves. After re‐activation in March–April, gonoactive life expectancy appears to be rather short. Aquatic development at this season is slow and eggs laid in the spring do not significantly affect adult densities until June.

3. Aquatic stages, males and gonoactive females of C.annulata are present throughout the year. This species appears to be able to overwinter without recourse to diapause, females passing the winter in alternating, or lasting, states of cold‐induced quiescence or normal gonoactivity.
The relationship between feeding specialization and host plants to aldrin epoxidase activities of midgut homogenates in larval Lepidoptera
Authors: ROSE H. A.
Published: March 2008

Abstract. 1. Aldrin epoxidase activities of midgut homogenates in fifty‐eight species of phytophagous lepidopterous larvae, were determined.

2. There were no significant differences in mean activities amongst monophagous, oligophagous and polyphagous feeders. These results question the widely held view that there is a correlation between mixed function oxidase activity and feeding specialization.

3. Aldrin epoxidase activity depended largely on the host which was consumed. Larvae with high activity invariably fed on hosts containing monoterpene compounds.

4. The proposal that mixed function oxidases provide polyphagous insects with an effective biochemical defence against diverse allelochemicals is discussed.
Development, fecundity and survival of the herbivore Lymantria dispar and the number of plant species in its diet
Authors: BARBOSA P. , MARTINAT P. , WALDVOGEL M.
Published: March 2008

ABSTRACT.

Larval gypsy moth Lymantria dispar (L.) mortality depends upon the number and type of plant species consumed as well as the sequence in which they are consumed.

When a two‐species diet is composed of a favourable and an unfavourable species, larval mortality is higher on the two‐species diet than on the diet of the favourable species alone.

When a two species diet is composed of a favourable and unfavourable coniferous species, larval mortality is higher on the single conifer species diet than on the two‐species diet.

Two‐species diets, in which one species is a conifer, produce individuals with a greater fecundity than diets of either species alone.

The influence of diets composed of two favourable species, on development, size and fecundity, depends both on the relative quality of each of the two plant species and which of the two is consumed by older instars.
Reproductive strategies of female butterflies: variation in and constraints on fecundity
Authors: BOGGS CAROL L.
Published: March 2008

ABSTRACT.

This study first examines the reproductive strategy of female Speyeria mormonia Edwards (Lepidoptera: Nymphalidae):

Egg weight and number laid per day decrease with age.

Survival and daily egg number may be affected by temperature; mean daily egg weight is not affected by temperature.

Daily egg number is not correlated with body size. In the central range of body size, egg weight is also not correlated with body size. However, exceptionally large or small females lay respectively heavier or lighter eggs than average.

A simple trade‐off between offspring size and number does not occur within females on a daily basis, or among females averaged over their lifespans.

Fat body resources are depleted at a rate independent of body size.

Females are essentially monogamous.

Age‐specific fecundity data reported here for S.mormonia are next compared with data for other Lepidoptera with different adult feeding habits and egg maturation patterns, and hence different possibilities for adult feeding to play a role in egg production. Based on these comparisons, I propose that the shape of the age‐specific fecundity curve for each species under optimal conditions is constrained by the potential importance of adult nutrients in egg production.
Is the Iberian lacewing Chrysopa regalis a semivoltine species?
Authors: CANARD M.
Published: March 2008

ABSTRACT.

Adults of the lacewing Chrysopa regalis Navás were caught in north Spain, Huesca province, Aragon.

Their progeny reared in the laboratory under short‐ and long‐day light conditions at 20°C, entered a long diapause as prepupae within the cocoon.

Transferred outdoors after spinning up, only a few (12%) became active again in the following spring, whereas the rest remained in diapause for one more year and waited for the end of the second spring to resume their morphogenetic development. Thus most of the studied strain exhibited a 2–year life cycle. This semivoltine strategy is new to chrysopid biology.

The predaceous larval phase did not exceed 3% of the total individual lifespan, though the duration of the free‐living larval instars averaged 19.9±1.1 (SD) days.

During the extended diapause, weight loss was very small, no more than 6.6% of the initial weight, 16.9±2.7 (SD) mg, at the end of diapause, and 8.8% at the time of pupal ecdysis.
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.
The effects of simulated and natural rainfall on cochineal insects (Homoptera: Dactylopiidae): colony distribution and survival on cactus cladodes
Authors: MORAN V. C. , HOFFMANN J. H.
Published: March 2008

ABSTRACT. 1. The distribution of Dactylopius opuntiae (Cockerell) colonies on Opuntia ficus‐indica (L.) Miller cladodes collected during a prolonged drought, was recorded for the proximal and distal portions of the cladodes, for the exposed and sheltered surfaces, the edges, and in relation to the proximity of the colonies to areoles at the base of the thorns.

2. Most of the colonies were found on the more sheltered parts of the cladodes and a disproportionately large number of the colonies on exposed surfaces had settled below the areoles.

3. Individuals in colonies on the exposed surfaces were all protected by a relatively hard, compacted wax cover and were thus less vulnerable to simulated rainfall than those on sheltered surfaces. Thorns provided some protection from simulated rainfall for individuals in colonies on exposed surfaces, but not for individuals on sheltered surfaces.

4. Natural rainfall greatly reduced the numbers of colonies, but did not significantly change the distribution of the colonies on the cactus cladodes.

5. Rainfall does not explain the observed distribution of D. opuntiae colonies on the cladodes, but does explain the poor performance of cochineal insects as biological control agents of prickly pear cacti in high rainfall areas.
The evolutionary dynamics of batesian and muellerian mimicry: similarities and differences
Authors: TURNER JOHN R. G.
Published: March 2008

ABSTRACT. 1. The continuous spectrum of palatability can be divided without difficulty into two halves: the distasteful forms in one half tend to become models and muellerian mimics, the palatable forms in the other half to become batesian mimics.

2. Most of the traditionally recognized differences between batesian and muellerian mimicry are valid and useful: negative versus positive frequency‐dependence, detriment versus benefit to the model, convergent evolution versus advergent evolution. None the less in both kinds, mimicry usually evolves by means of a major mutation whose effects are later modified. ‘Supergenes’ tend to be discovered more in batesian mimics than in muellerian mimics. This results from a complex interaction between natural selection on the one hand, and the origin of clusters of genes of related function through tandem duplication on the other.

3. Adaptation is not simply the creation of the best of all possible worlds: what natural selection can do is limited by what is possible for the gene.
Tenebrionid beetles in the shortgrass prairie: daily and seasonal patterns of activity and temperature
Authors: WHICKER APRIL D. , TRACY C. RICHARD
Published: March 2008

ABSTRACT. 1. Patterns of daily and seasonal activity for seven species of tenebrionid beetles, genus Eleodes, were investigated in the shortgrass prairie of northeastern Colorado. The relationship between time of activity, body temperatures, and rates of water loss of the beetles was examined in the field and in laboratory experiments.

2. Common species were active from April until the end of October; however, asynchronous peaks of abundance occurred.

3. Beetles were diurnally active with peaks of daily activity occurring 2–4 h after sunrise and before sunset. Less than a 2 h shift in mean time of activity occurred between seasons.

4. Within species, body temperatures measured in the field closely corresponded to temperatures selected in an experimental thermal gradient; hence, species seemed to prefer particular body temperatures and were most active during times when those temperatures could be achieved. Body temperatures measured in the field approximated ambient temperatures measured in the vicinity of the beetle.

5. Significant differences among several species were found for times of daily activity and corresponding body temperatures.

6. Ability to resist water loss by evaporation was not correlated with daily or seasonal activity patterns.
Changes in egg colour, egg weight and oviposition rate with the number of eggs laid by wild females of the small heath butterfly, Coenonympha pamphilus
Authors: WICKMAN PER‐OLOF , KARLSSON BENGT
Published: March 2008

ABSTRACT. 1. The colour of eggs laid by individual Coenonympha pamphilus (L.) (Lep., Satyridae) females changed over their lifespan. The first laid eggs were green, but after having laid about 100 eggs, females laid only yellow eggs.

2. By following females in the field, or by capturing wild females, and noting the colour of their eggs, it was established that younger females showed higher oviposition rates and laid heavier eggs than older females.

3. Hence, wild C.pamphilus females are unable to sustain a constant egg production by extracting amino acids or any other nutrients from nectar. We hypothesize that this is a general phenomenon in nectar feeding butterflies.

4. The egg colour did not seem to match the colour of the substrate on which the female chose to deposit the egg.
Host plant relations in the planthopper genus Ribautodelphax (Homoptera, Delphacidae)
Authors: Den BIEMAN C. F. M.
Published: March 2008

ABSTRACT. 1. Host plant relations of closely related species and pseudogamous triploid forms of the planthopper genus Ribautodelphax were studied.

2. From field data and experimental results it is concluded that eleven European Ribautodelphax species and undescribed taxa are monophagous or oligophagous on different grass species. Only two Ribautodelphax species are found on the same grass species in the field.

3. Differential host plant relations indicate that four recently discovered taxa are probably true species.

4. Ribautodelphax species show a more restricted host plant range in choice experiments compared with breeding tests.

5. Choice experiments indicate no differences in host plant preference between males and females of two Ribautodelphax species.

6. No differences are found in host plant relations between bisexual species and associated pseudogamous triploid forms.
Arthropod faunal similarity of Bornean rain forest trees
Authors: STORK N. E.
Published: March 2008

ABSTRACT. 1. Arthropod samples, collected by insecticide fogging ten Bornean lowland rain forest trees, were sorted to species and used to study some of the determinants of faunal similarity of these trees.

2. Similarity indices were calculated between pairs of trees for guilds of beetles, beetle families and for different orders and other families of insects.

3. Multiple regression analyses of five independent variables of the trees (taxonomic similarity, distance apart, vertical canopy overlap, similarity in tree height, epiphytic load) were carried out against these similarity indices.

4. In eight of the eighteen insect groups analysed, taxonomic similarity of the trees is the most important variable affecting their species composition, accounting for a maximum of 29.4% of the variation.

5. For the Homoptera, Gryllidae, Anthicidae, Chrysomeloidea and scavengers, distance between the trees and the similarity of the trees’epiphyte load have a greater effect on their faunal similarities than taxonomic similarity of the trees.

6. The maximum variation accounted for by variables with significant T ratios was 38.6% in the Anthicidae. In four groups, the Formicidae, Heteroptera, Galerucinae and Corylophidae, none of the variables was significant.

7. These data may support the view that for many insect groups there is less host‐specificity in the tropics than in temperate regions.
Carrion fly community dynamics: patchiness, seasonality and coexistence
Authors: HANSKI ILKKA
Published: March 2008

ABSTRACT. 1. An outdoor cage experiment was conducted to test the theory that localized interactions facilitate coexistence of species breeding in ephemeral habitats. The same amount of larval resource (50 g of liver) but divided into one, two, four, eight or sixteen pieces was placed into each of fifteen cages once a week from June to September for 4 years.

2. The cage populations were initially mixtures of thirteen species but after 4 years only Lucilia illustris (Meig.), Sarcophaga scoparia Pand. and S.aratrix Pand. remained. Lucilia illustris, by far the most abundant species in the field, predominated in every cage.

3. Sarcophaga went extinct in most cages, but they survived in five cages in which the larval resource was much divided, in agreement with the theoretical prediction.

4. Lucilia silvarum (Meig.) emerged about a week later than L.illustris in early summer; this phenological difference gave rise to a competitive asymmetry between the two species. This difference appears to explain why L.silvarum went extinct in the cages in 3 years, and it may explain why L.silvarum has consistently been less abundant than L.illustris in the natural community.

5. Other differences in phenology, voltinism and rate of development in the flies are described, and such differences are suggested to facilitate regional coexistence of many species in seasonal environments.
Behaviour of late‐instar gypsy moth larvae in high and low density populations
Authors: LANCE D. R. , ELKINTON J. S. , SCHWALBE C. P.
Published: March 2008

ABSTRACT. 1. Using scaffolding and night‐vision equipment, we observed fifth and sixth instars of the gypsy moth, Lymantria dispar (L.), on Quercus velutina Lam. in the field.

2. In low‐density populations, larvae fed at night and spent the day resting in sheltered sites away from the canopy. In high‐density populations, larvae remained in the canopy throughout the day and night, and the amount of feeding during daylight hours increased with population density.

3. Larvae at all population densities used a similar sequence of behaviours and sampled a number of leaves when selecting feeding sites, but larvae in high‐density populations switched feeding sites more frequently and fed continuously for shorter periods.

4. Larvae seldom interfered with each other's feeding in any of the populations.

5. When fifth instars were collected from the field and held for 24 h in an electronic feeding monitor, they maintained feeding rhythms that were characteristic of their source populations. Larvae spent more time crawling and less time feeding when offered foliage from high‐density rather than low‐density populations.
The effects of gregarine parasites on longevity, weight loss, fecundity and developmental time in the field crickets Gryllus veletis and G.pennsylvanicus
Authors: ZUK MARLENE
Published: March 2008

ABSTRACT. 1. Gregarines, debilitating gut parasites, significantly reduced longevity and increased weight loss in the field cricket Gryllus pennsylvanicus Burmeiser when adults were kept on suboptimal diets, but in G.pennsylvanicus and G.veletis (Alexander and Bigelow) fed ad libitum, weight change, longevity, and fecundity were not significantly different in infected and control individuals.

2. Adults harbouring gregarines at eclosion took significantly longer to develop from the second and third instars than did uninfected adults.

3. Longevity of nymphs kept in the laboratory without food was decreased in infected individuals compared with uninfected ones, but not significantly so.

4. The evolutionary and ecological implications of nonlethal parasites are discussed.
Effects of maternal age and adult diet on egg weight in the butterfly Euphydryas editha
Authors: MOORE RICHARD A. , SINGER MICHAEL C.
Published: March 2008

ABSTRACT. 1. Euphydryas editha (Boisduval) (Nymphalidae) butterflies exhibited no consistent pattern of change in egg weight over their lifetimes. This was the case for captive butterflies fed diets containing sugars and amino acids, for butterflies fed diets containing only sugar, and for those left completely at liberty in their natural habitats between ovipositions.

2. Two aspects of these results conflict with the findings of a previous study on the same subspecies. First, the previous study found that egg weight decreased with increasing maternal age. Second, this decrease was mitigated by addition of amino acids to the adult diet.

3. We accept the findings of these previous workers that egg weight decreased with maternal age under their laboratory conditions. The discrepancy between their data and ours is likely to stem from the more natural conditions under which our insects were kept. Our own data from captive insects are not distinguishable from our field data.

4. These results suggest that declines of egg weight with maternal age found in studies of other insects may also result from the artificial nature of laboratory conditions. We question whether such declines are general.

5. We suggest that the second discrepancy between the two sets of work (effects of amino acids) stems from a design problem in the previous study.
Improved insect performance from host‐plant defoliation: winter moth on oak and apple
Authors: ROLAND JENS , MYERS JUDITH H.
Published: March 2008

ABSTRACT. 1. We test the hypothesis that defoliation has short‐term and long‐term negative effects on performance of winter moth Operophtera brumata L. on two species of food plants: Garry oak (Quercus garryana Dougl.) and apple (Malus domesticus L.).

2. Pupal weight (and hence potential fecundity of females) decreased with increased defoliation in the current year on both tree species.

3. Pupal weight increased, however, with increased level of defoliation in the previous year.

4. Increased weight of pupae from larvae which had fed on previously defoliated trees may buffer population decline by increasing fecundity of moths in the next generation.
Nesting behaviour of a subsocial African ball‐roller Kheper platynotus (Coleoptera, Scarabaeidae)
Authors: SATO H. , IMAMORI M.
Published: March 2008

ABSTRACT. 1. The nesting behaviour of Kheper platynotus (Bates) was observed in the Tsavo West National Park, east Kenya.

2. The construction of the brood ball seemed to be initiated by the female; thereafter, the male joined in. After its construction, the ball was rolled and buried by the male, whilst the female rode on the ball and occasionally helped the male.

3. After burying the ball, the male came out on the ground, leaving the female under‐ground. The female coated the ball with soil and her excrement, and let it ferment for about 2 weeks. Thereafter, the female converted the ball into one to four free‐standing brood pears, and laid one egg in each pear. The number of pears produced depended on the size of ball. Even after oviposition, the female remained in the nest to care for the brood.

4. Oocytes matured a little before being laid. Excess oocytes were gradually assimilated during brood care.

5. Females seemed most likely to breed in two or more successive rainy seasons.

6. Although male‐male aggression was observed, size assortative mating was not observed.
Lek behaviour of Drosophila cnecopleura in Hawaii
Authors: SHELLY TODD E.
Published: March 2008

ABSTRACT.

Male spacing, aggression, and female visitation are described for a lek of Drosophila cnecopleura Hardy within a Hawaiian rainforest. The lek was located at a single tree of Pisonia umbellifera, and the males present defended individual leaves as mating territories. Observations were made in October 1986 and April 1987.

Approximately twice as many males were present at the lek in October than in April. At both times, males generally perched on the lowest leaves in the lek. Individuals did not remain on particular leaves for long periods of time but frequently moved among different territories.

Males engaged in two types of aggressive encounters, face‐offs and chases, and in all encounters the resident displaced the intruder.

Females were sighted at the lek 0.69 times/h in October and 0.23 times/h in April. Most of the leaves visited by females were among the lowest in the lek.