bluuebunny/crossref_metadata_2025_split huggingface dataset:
Refugia and habitat partitioning among midges (Diptera: Chironomidae) in rain‐pools
Authors: McLACHLAN ATHOL J. 
Published: March 2008

ABSTRACT.

Rain‐pools on granite exposures are common in tropical Africa and they are inhabited by the larvae of two midge species, Chironomus imicola Kieffer and Chironomus pulcher Wiedemann.
These pools differ from other ephemeral island habitats such as carrion, fallen fruit, sap flows, mushrooms and dung in their high degree of spatial predictability. Most pools are predictably inhabited by either C.imicola or C.pulcher. This finding is considered in the light of contemporary competition theory.
An arrangement whereby the same species repeatedly invades the same temporary habitat indicates that there is something about the habitat itself causing the discrimination. I suggest that degree of exposure to sunlight may provide a cue allowing females to discriminate between pools as oviposition sites.
Both species survive the long dry season by retreating to pools of river water left by receding rivers. Dispersal to rain‐pools by emerging adults occurs during the following season with imicola occupying rain‐pools remote from shaded rivers. Appropriately, measured against pulcher, the biology of imicola is that of a colonizing species.
The possibility is discussed that the chironomids in rock‐pools do not survive to breed. Instead, these populations may be maintained externally, for example by invasions from breeding populations in the Great Lakes of Africa, where larval densities may be too low to be detected by sampling. The evolutionary implications of such a situation are considered.
Are galling insects better protected against parasitoids than exposed feeders?: a test using tenthredinid sawflies
Authors: PRICE PETER W. , PSCHORN‐WALCHER H. 
Published: March 2008

ABSTRACT.

Data mostly from the published literature were used to assess the effect of galling on the number of parasitoid species per host species in the phylogeny of nematine sawflies from free external feeders (colonial and solitary) to leaf gallers and shoot gallers.
The strongest effects of galling were the total elimination of the species‐rich cocoon‐attacking guild of parasitoids, and eonymphal parasitoids, from the parasitoid community on shoot gallers, all of which are in the genus Euura.
All tachinid larval parasitoids were also eliminated by the galling habit.
The cumulative effects of these exclusions resulted in a decline in mean number of parasitoid species per host species from almost sixteen species on external colonial feeders to 4.0 species on shoot gallers.
General patterns in per cent parasitism by non‐tachinid and tachinid larval parasitoids, eonymphal and cocoon parasitoids, on exposed feeders to shoot gallers, showed declines in non‐tachinid attack and elimination of tachinid, eonymphal and cocoon parasitoids. But leaf gallers tended to be attacked more than exposed feeders by non‐tachinid larval parasitoids.
The galling habit had a long‐term impact by reducing the number of parasitoid species attacking nematine sawfly gallers and per cent mortality inflicted, so that natural enemies may have been important as a selective factor in the evolution of galling nematine sawflies.
Spatial and temporal patterns of predation by ants on eggs of Cactoblastis cactorum
Authors: ROBERTSON HAMISH G. 
Published: March 2008

ABSTRACT.

Predation of Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae) eggs by ants was studied for a summer and a winter generation on prickly pear Opuntia ficus‐indica (L.) Miller plants in the field.
Egg Predation between plants was spatially density‐dependent in the winter but not in the summer generation.
To test for the presence of delayed density‐dependent mortality within generations, percentage egg Predation during 5‐day periods was plotted against the number of eggs available in each period. Data points joined in a time sequence moved in an anticlockwise direction in the summer generation, suggesting a delayed density‐dependent response by the ants, whereas in the winter generation the points moved in a clockwise direction.
The degree of coincidence of the C. cactorum eggs with the peak larval production periods of the ants is suggested as the main reason for the temporal changes in egg Predation.
Interspecific competition between insect herbivores: asymmetric competition between cinnabar moth and the ragwort seed‐head fly
Authors: CRAWLEY M. J. , PATTRASUDHI R. 
Published: March 2008

ABSTRACT.

Removal field experiments and observational studies have been undertaken to determine whether feeding by cinnabar moth Tyria jacobaeae L. on the flower heads of ragwort Senecio jacobaea L. affects the abundance of the fly Pegohylemyia seneciella (Meade) that feeds in the flower heads as a larva.
Correlations between the population density of cinnabar moth and the population density of the fly were suggestive of habitat separation, but provided little evidence of exploitation competition.
Removal of cinnabar moth by hand from replicated plots over two years shows that, in years when ragwort flower production is consumed by cinnabar moth caterpillars, the fly may show no recruitment at all.
Fly populations persist in refugia, exploiting ragwort plants that grow in areas where there are no cinnabar moth.
Recruitment of ragwort is not seed limited, so the reduction in seed production caused by P. seneciella (maximum about 30%) has no impact on ragwort abundance, or on the abundance of cinnabar moth.
We conclude that there is strong interspecific competition between these two species, and that the competition is highly asymmetric. The cinnabar moth had a substantial effect on the recruitment of the fly in 1986, but the fly has no measurable impact on the recruitment of the moth. In six years out of seven in our long‐term study, cinnabar moth reduced flower production to levels comparable to those measured in 1986, and we infer that strong competition with the fly was likely in six years out of seven.
One reason why there are so few published examples of asymmetric interspecific competition may be simply that the experiments are thought too obvious to be worth doing. We argue that this is not a good reason for eschewing manipulative field experiments, and that few processes in ecology are at all obvious when investigated in detail.
Adaptive significance of wing dimorphism in the absence of dispersal: a comparative study of wing morphs in the waterstrider, Gerris remigis
Authors: FAIRBAIRN DAPHNE J. 
Published: March 2008

ABSTRACT.

Gerris remigis Say (Hemiptera; Gerridae) is primarily apterous, but populations with up to 33% macropters have been reported. The macropters seldom fly, and field studies have revealed no detectable differences between wing morphs in movement or survival at any time of year.
In this paper, life history traits of macropterous and apterous G. remigis are compared in an attempt to determine the mechanisms responsible for the maintenance of macroptery in this species in spite of the very low flight capacity and infrequent flight of macropters.
Development time, proportion breeding without diapause, and overwinter survival do not differ between morphs. However, pre‐diapause macropterous females have a significantly shorter pre‐oviposition period than apterous females. In contrast, post‐diapause macropters begin reproducing later than apters, and have a lower cumulative fecundity.
These results suggest that macropters may be at a selective advantage in warm habitats which favour pre‐diapause reproduction, but that apters should be favoured in the preferred, cool, lotic habitats.
However, crossing and rearing experiments indicate that wing morphology is primarily environmentally controlled in this species, and that the heritability of wing morphology is low, at best. In light of this, the relative impacts of purely phenotypic (environmental) variation, random effects, and the observed fitness differences on the maintenance of macroptery in this species are discussed.
Field experiments on a new method for determining age in tsetse flies (Diptera: Glossinidae)
Authors: LEHANE M. J. , HARGROVE J. 
Published: March 2008

ABSTRACT.

Data are presented which suggests that the accurate determination of the age of tsetse flies (Glossina morsitans morsitans Westwood and G. pallidipes Austen) in the field can be achieved by measuring the fluorescence content of the head capsule.
The way in which this can be achieved and further work which would improve the accuracy of the technique are discussed.
Euphorine phylogeny: the evolution of diversity in host‐utilization by parasitoid wasps (Hymenoptera: Braconidae)
Authors: SHAW SCOTT RICHARD 
Published: March 2008

ABSTRACT.

New data on the phylogeny of the braconid subfamily Euphorinae supports the hypothesis that parasitism of adult insects by Euphorinae originated during parasitism of Chrysomelidae, a group whose larvae are ecologically coincident with adults.
Evolution of the habit of attacking the adult stage opened a new adaptive zone; subsequently the Euphorinae have diversified on to a phylogenetically greater variety of hosts than any other braconid subfamily.
Parasitism of eumastacid grasshoppers evolved from beetle parasitism in the tribe Perilitini.
The tribe Euphorini shows the greatest diversity of hosts utilized. Most attack Heteroptera; however, Chrysopopthorus diversified on to adult Chrysopidae, Euphoriella on to Psocoptera, and Cryptoxilos on to Scolytidae.
Parasitism of bark beetles (Scolytidae) has evolved independently in three genera: Cosmophorus, Cryptoxilos and Ropalophorus. This is the most specialized form of beetle parasitism by euphorines, since it involves direct parasitism of concealed hosts.
Parasitism of adult hymenopterans by the tribe Syntretini may be related to attacking hosts while they are foraging at flowers.
The pattern of diversification in the Euphorinae indicates several adaptive radiations within host orders, as well as a history of major host‐shifts between phylogenetically distantly‐related host groups: Coleoptera to Orthoptera; Coleoptera to Hymenoptera; Coleoptera to Heteroptera; Heteroptera to Neuroptera, Psocoptera, and back to Coleoptera. Both the‘host taxonomy’and‘host habitat’hypotheses of host‐shifting are supported. Host‐shifts have involved hosts occurring in the same micro‐habitat and usually having similar feeding habits. This is consistent with current theory of host‐location by means of host‐produced kairomones and visual cues.
Habitat quality and reproductive investment in aphids
Authors: WALTERS K. F. A. , BROUGH C. , DIXON A. F. G. 
Published: March 2008

ABSTRACT.

Genetically identical vetch aphids, Megoura viciae (Buckton), showed a weak but significant positive relationship between reproductive investment (number of ovarioles) and weight, here used as an indicator of habitat quality.
Apterae reared on poor quality plants showed the same range in numbers (twelve to twenty‐two) but on average fewer ovarioles than those reared on high quality plants.
The variability in ovariole number was determined prior to birth.
Under constant conditions the age of a mother does not affect the range of ovariole numbers or the proportion of her offspring in each ovariole class.
Apterae reared on poor quality host plants gave birth to proportionately fewer offspring with a high ovariole number than apterae reared on high quality plants.
Winged individuals gave birth to proportionately more offspring with a high number of ovarioles than apterae.
The control and ecological significance of the intramorph variation in reproductive tactics shown by many species of aphids is discussed in the light of these results.
The distribution of risk and density‐dependent mortality in the galls of Eurosta solidaginis, the goldenrod gall fly
Authors: WALTON ROD 
Published: March 2008

ABSTRACT.

This paper explores the net effect of a suite of mortality factors on a sedentary prey, the larvae of the goldenrod gall fly, Eurosta solidaginis Fitch (Diptera: Tephritidae).
Mortality is caused by unknown factors early in larval development, two species of parasitoid wasp (Hymenoptera: Eurytomidae), an inquiline beetle larva (Coleoptera: Mordellidae), and during the winter months downy woodpeckers Picoides pubescens (L.).
Distribution of mortality among galls relative to prey (gall) distribution was measured and discussed with respect to the distribution of relative risk of predation.
Galls are by and large contagiously distributed among quadrats, and mortality is distributed in a comparable pattern to that of galls.
The pattern of mortality on Eurosta larvae is neither density‐dependent nor aggregated independently of gall distribution. Persistence in the system is probably a result of a combination of other factors such as adult mortality and early larval death which may have intergenerational density‐dependent effects, and the linkage of locally unstable sub‐populations via migration.
Bionomics of Aphis chloris Koch (Hemiptera: Aphididae) for biological control of St John's wort in Australia
Authors: CSIRO D. T. BRIESE 
Published: March 2008

ABSTRACT.

A parthenogenic strain of Aphis chloris Koch, imported into Australia for the biological control of St John's wort Hypericum perforatum L. was found, under laboratory conditions, to develop over a temperature range of 8.5–33°C.
Optimal performance, as measured by fecundity, survival and rm occurred in the range 20–30°C, and at temperatures above 26°C A.chloris performed better than the majority of aphids for which comparable data was available.
Under crowded conditions A.chloris produced smaller apterae, a high proportion of alatae, and a low number of oviparae, but no males. Sexually‐reproducing forms could not be induced under conditions of short photoperiod or low temperatures in the absence of crowding.
Apterae were larger and more fecund when fed on older flowering stems of the host‐plant, than when fed on new rosette growth.
The high potential rate of increase, ability to disperse, and good performance of A.chloris at high temperatures and on the phenological stage of the host‐plant present over summer, suggest that it could contribute to the biological control of St John's wort in Australia, especially during the warmer part of the year when the principal existing control agents (Chrysolina spp.) are inactive.
Coexistence of pseudogamous and sexual planthoppers of the genus Ribautodelphax (Homoptera, Delphacidae)
Authors: den BIEMAN C. F. M. 
Published: March 2008

ABSTRACT.

The occurrence of pseudogamous triploid females in populations of the diploid species Ribautodelphax pungens (Ribaut) was studied throughout Europe.
Considerable differences in triploid frequencies were found between populations but no regular geographic pattern was discerned.
Within populations triploid frequencies proved to be stable from generation to generation.
The twofold reproductive advantage of the pseudogamous triploid females is counterbalanced by active mate discrimination by diploid males against the pseudogamous triploid females in populations with high triploid frequencies.
Sexual diploid and pseudogamous triploid females showed no differences in phenology.
Differential winter mortality was found between diploid and triploid larvae.
The intrinsic rates of increase of insects of different sizes
Authors: GASTON K. J. 
Published: March 2008

ABSTRACT.

A negative relationship between intrinsic rate of increase, r, and body size has only clearly been shown using data for species drawn from a number of phyla and covering several orders of magnitude in size. Analyses for more closely related species are equivocal.
Data for ninety‐one species of insects, from nine orders, were used to examine the correlation between intrinsic rate of increase and size.
Intrinsic rate of increase was negatively correlated with both length and weight across orders, but no relationship could be shown within orders.
Generation times were positively related to body size, but there was no relationship between net reproductive rate (RQ) and size.
These results support the hypothesis that documented relationships between species size and colonization success in insects could be a consequence of the scaling of intrinsic rate of increase with size.
Body temperature regulation in desert robber flies (Diptera: Asilidae)
Authors: MORGAN KENNETH R. , SHELLY TODD E. 
Published: March 2008

ABSTRACT.

We investigated effective thermal environments and behavioural and physiological mechanisms for thermoregulation in two sympatric desert robber flies, Promachus giganteus (Hine) and Efferia texana (Banks). Although similar in body shape and colour, P. giganteus are 4–8 times heavier than E. texana.
During midday, operative temperatures near the ground were substantially higher for P. giganteus (56–73°C) than for E. texana (54–63°C). Correspondingly, P. giganteus generally perched at greater heights above the ground than did E. texana.
Both species maintained thoracic temperatures between 40 and 45°C during most of the day. However, differences between thoracic and abdominal temperatures for individual flies were significantly lower in P. giganteus than in E. texana.
In the laboratory, P. giganteus regulated thoracic temperature by pumping haemolymph into the abdomen. This ability may have accounted for the smaller differences observed between thoracic and abdominal temperatures in P. giganteus and may have allowed this species to search for food and mates during midday when E. texana sought shade.
Endophyte fungus confers resistance to ryegrass: Argentine stem weevil larval studies
Authors: PRESTIDGE R. A. , GALLAGHER R. T. 
Published: March 2008

ABSTRACT.

Conferred insect resistance arises from a mutualistic relationship between claviciptaceous endophytic fungi and various grasses. A number of secondary compounds are responsible for the insect resistance. This paper describes studies of the relationship between the endophytic fungus Acremonium lolii Latch, Christensen & Samuels and the Argentine stem weevil Listronotus bonariensis (Kuschel) (Curculionidae); in particular, the effects on larval feeding behaviour, growth and survival.
Larvae are stem borers. Tunnel length and distance bored into the basal sheath zone of ryegrass was reduced when the plants were infected by A. lolii.
Lolitrem B, a potent mammalian neurotoxin, levels were highest in A. lolii infected grasses and ranged from 2.61 to 7.08 μg/g dry wt, the higher value being recorded in summer.
Lolitrem B extracted from A. lolii‐infected perennial ryegrass reduced larval growth rates and survival.
Lolitrem B acted via the insect stomach rather than by absorption through the integument.
The potential role of endophytic fungi in plants is discussed briefly in relation to herbivory.
Honey supplementation and its developmental consequences: evidence for food limitation in a paper wasp, Polistes metricus
Authors: ROSSI A. M. , HUNT J. H. 
Published: March 2008

ABSTRACT.

Polistes metricus Say (Hymenoptera: Vespidae, Polistinae) field colonies were supplemented with dilute honey during the pre‐emergence and early post‐emergence phases of colony development.
Supplementation did not increase number of nest cells constructed or rates of loss to predation or foundress disappearance compared with controls.
Colonies receiving honey supplementation produced first offspring earlier in the season than control colonies. The difference is due to a shorter time span between founding and first emergence.
Foundresses of supplemented and control colonies did not differ in wing length or per cent body fat.
Offspring of both supplemented and control colonies had shorter wing lengths than did foundresses of supplemented colonies. Offspring of control colonies had shorter wing lengths than did foundresses of control colonies but not foundresses of supplemented colonies.
The per cent body fat of offspring from control colonies was lower than that of all foundresses and of offspring from supplemented colonies.
The per cent body fat of offspring from supplemented colonies was higher than that of all foundresses.
Distribution and abundance of the intertidal saltmarsh beetle, Bledius spectabilis
Authors: WYATT T. D. , FOSTER W. A. 
Published: March 2008

ABSTRACT.

The burrowing intertidal beetle Bledius spectabilis Kraatz (Coleoptera: Staphylinidae) occurs on all but the very youngest marshes on Scolt Head Island, Norfolk, U.K., and may reach densities of up to 4000 m−2 (combined adult and larval densities).
The beetles are restricted to a narrow band about 1m wide along the edges of creeks draining the low marsh areas of the island, and the vertical range is restricted to a zone between 0.8 and 1.55m above Ordnance Datum. The majority of the aggregations and the highest densities are between 1.2 and 1.3m O.D., that is between about 24 and 40cm below MHWN (mean high water at neap tides).
Poor drainage, in particular the presence of long‐standing pools of water over the soil surface, is important in restricting the beetles to well‐drained edge regions.
Transplant experiments suggest that displacement by saltmarsh vegetation, in particular Halimione portulacoides (L.) Aell., sets the upper limit of the beetles’distribution.
The zonation of B.spectablis fits well into the general scheme that has been proposed for the zonation of marine animals from rocky shores.
The beetles produce large (3–6 mm diameter), rapidly draining, abundant (up to 9% of soil volume) and persistent burrows. We suggest that these beetle aggregations may play an important role in the development of the saltmarsh.
Differences between the 7‐spot and 2‐spot ladybird beetles (Coccinellidae) in their toxic effects on a bird predator
Authors: MARPLES NICOLA M. , BRAKEFIELD PAUL M. , COWIE RICHARD J. 
Published: March 2008

Abstract. 1. Experiments with nestling blue tits Parus caeruleus L. examined the effects of feeding them 7‐spot ladybird Coccinella septempunctata (L.), 2‐spot ladybird Adalia bipunctata (L.) or controls Tenebrio sp.2. A feeding rate of 51/3 7‐spot ladybirds per day ‘killed’ nestlings within 2 days. Three of six nestlings fed at half this rate survived 4 days. In contrast, all experimental birds survived sixty‐four 2‐spot ladybirds fed over 4 days (equivalent by weight to the high 7‐spot diet).3. Nestlings fed 7‐spot ladybirds also grew more slowly than birds fed 2‐spot ladybirds. The latter birds showed no difference in weight gain from the controls although they begged more strongly for food.4. Cadavers of birds fed 7‐spot ladybirds showed evidence of severe liver damage.5. The results indicate a substantial difference between the ladybird species in their toxicity to nestling blue tits. They support the hypothesis that 2‐spot ladybirds are largely‐edible, polymorphic Batesian mimics of well‐protected, monomorphic species such as the 7‐spot ladybird.