bluuebunny/crossref_metadata_2025 huggingface dataset:
Complex competitive interactions in four species of Lucilia blowflies
Authors: PRINKKILÁ MAIJA‐LIISA , HANSKI ILKKA
Published: March 2008

Abstract.

The effects of intraspecific and interspecific larval competition on larval survival, adult size, adult longevity and fecundity were quantified in four species of coexisting Lucilia blowflies: illustris, silvarum, sericata and caesar.

There was a general negative effect of increasing density on larval and adult survival, size and fecundity. Additionally, complex species‐specific and frequency‐dependent responses were identified, which were not expected in these biologically and morphologically closely similar species.

Lucilia illustris, the numerically dominant species in the natural community, was a superior competitor to L.silvarum at intermediate densities but an inferior competitor at high density. Such nonlinear responses may be related to differences in the life histories and larval behaviour of the species (bigger eggs and more contest‐type outcome of competition in L.silvarum).

We parameterized a model of interspecific competition on a subdivided resource in an attempt to reconcile the conflicting results on larval competitive abilities and the abundances of the species in the field. Using laboratory and field‐estimated parameter values the model predicted coexistence of L.illustris and L.silvarum and the observed numerical dominance of the former species. The average densities of flies in the field are limited to relatively low levels, apparently preventing L.silvarum (the superior competitor at high density) from dominating and excluding L. illustris.
Systematic within‐tree variation in mountain birch leaf quality for a geometrid, Epirrita autumnata
Authors: SUOMELA JANNE , KAITANIEMI PEKKA , NILSON ANNA
Published: March 2008

Abstract.

We studied within‐tree variation in leaf quality of the mountain birch, Betula pubescens ssp. tortuosa, for larvae of the autumnal moth, Epirrita autumnata.

The purpose of the study was to determine the possible occurrence of systematic differences in larval growth on short shoot leaves (i.e. leaves of the same age): among leaves facing in different compass directions, between leaves of lower and upper branches, among leaves on different positions within a branch and among leaves of different sizes within a short shoot. We also measured larval growth between short shoot and long shoot leaves (i.e. between leaves of different age).

The larvae grew best on leaves on the north side of trees and most poorly on south side leaves, the east and west sides being intermediate. Leaves from the upper branches supported larval growth better than leaves from the lower ones. The larvae grew better on the smallest leaf of each short shoot and were able to utilize it more efficiently than the two larger leaves. Short shoot leaves from the basal and middle parts of the upper branches of the trees were of better quality for the larvae than short shoot leaves from the tip part of the branches. The larval growth rate did not differ between short shoot and long shoot leaves. In general, within‐tree variation in the larval growth rate was lower than variation among different trees.

Damage to leaves can decrease leaf quality for herbivores in the same year (rapidly inducible responses) or the following year(s) (delayed inducible responses). Our results show that systematic within‐tree variation in larval growth can be as great as the effects of rapidly inducible responses and that variation among individual trees can be as great as the mean effects of delayed inducible responses.
The calling behaviour and spatial distribution of male bushcrickets (Sciarasaga quadrata) and their relationship to parasitism by acoustically orienting tachinid flies
Authors: ALLEN GEOFF R.
Published: March 2008

Abstract.

This paper examines the calling behaviour and spatial distribution of male Sciarasaga quadrata Rentz (Orthoptera: Tettigoniidae), a bushcricket that is subject to attack by an acoustically orienting parasitoid fly, Homotrixa sp. (Diptera: Tachinidae: Ormiini).

Checks on calling activity in populations of S.quadrata confirmed that calling began 2–3 h before sunset and continued well beyond midnight. Calling activity was not restricted by temperature with males calling over air temperatures of 10.6–24.2°C.

Nearest‐neighbour analyses, within the sampled areas, revealed that the spacing between calling males was random and the minimum distance between calling males was 3.74 m. Mean distances between calling males varied between 9.2 m and 23.0 m and significantly changed as male density, which peaked at 0.36 calling males per 100 m2, declined over the calling season.

Males showed no preference for any one plant species, with their distribution across bushes not significantly different to the frequency of the plants within the habitat. The perch height of calling males was on average half way up the height of a bush and was significantly influenced by the height of the bush. Perch height was not significantly influenced by proximity to calling males or by whether or not males were parasitized.

Site fidelity of males was low with only 0–10% of bushes occupied by calling males over successive nights. Males, though flightless, moved on average 6.70 m and up to 26.56 m per night.

No evidence was found for the use of aggregation in S.quadrata as a primary defence against ormiine attack. Commencing calling prior to sunset, frequent movement, and a lack of association with any particular plant species, although possibly relevant to ormiine attack, could also be explained in terms of other activities such as male‐male interactions and mating behaviour.
A test of the validity of insect food‐plant and life‐history records: Lepidoptera on heather (Calluna vulgaris)
Authors: FIELDING C. A. , COULSON J. C.
Published: March 2008

Abstract.

A comparison was made between data collected from a literature search and a field study on the species richness and larval phenology of the Lepidoptera that feed as larvae on Calluna vulgaris.

Of the macrolepidopteran species that the literature predicted should be found as larvae on C.vulgaris during the field study, 55% were never recorded. The literature was used to classify these unrecorded species into species that are uncommon or confined to unsampled habitats (60%) which were less likely to be recorded, and common species (40%) that were more likely to be recorded. Various reasons are suggested for the absence of these latter species, including the possibility of inaccurate host plant records in the literature.

Of the macrolepidopteran species that were discovered during the field study, 27% were not reported by the literature as feeding on the plant. The omission by the literature of C.vulgaris from the food plant lists of these species occurred both because of the inability of the literature to list all the hosts of widely polyphagous species (40%) and because of possible inaccurate recording (60%).

The literature was found to contain inaccuracies in its descriptions of the larval phenology for 61% of the macrolepidopteran species. This resulted in marked differences between the two data sources in their estimations of seasonal changes in species richness of larval macrolepidoptera feeding on C.vulgaris.
Reproductive and subsocial behaviour in the ovoviviparous leaf beetle Gonioctena sibirica (Coleoptera: Chrysomelidae)
Authors: KUDO SHIN‐ICHI , ISHIBASHI EIJI , MAKINO SHUN'ICHI
Published: March 2008

Abstract.

In the spring, females of the leaf beetle Gonioctena sibirica deposited larvae on the ventral surface of growing young leaves situated on the apical position of shoots of the willow Salix bakko.

The parent females remained with the larvae usually on the underside of the basal part of leaves, facing toward the base of shoots. When other arthropods approached, the females temporarily moved towards these intruders, showing aggressive behaviour such as swinging the body or stamping the legs. Many females remained with their larvae until the larvae grew into the final (fourth) instar. No female produced an additional brood in the field.

Broods from which parent females were experimentally removed suffered higher mortality than those in which females were left intact. Arthropods such as spiders and ants were observed preying on the larvae. In contrast, the survivorship of broods from which females were removed and intruders were excluded with a sticky substance applied to the base of twigs was not different from that of control broods. These results demonstrate that the main mortality factor of offspring is pedestrian arthropod predators and females physically repel the predators.

Potentially alternative reproductive strategies, such as producing a large number of offspring by iteroparity and/or larger brood(s) with less or no care, seem to be inhibited in G.sibirica by larval dependence on growing young leaves which are temporally limited and by ovoviviparity which may have limited brood size.
Pupation site choice of a North American lycaenid butterfly: the benefits of entering ant nests
Authors: WAGNER DIANE
Published: March 2008

Abstract.

Larvae of the North American lycaenid butterflyHemiargus isolaReakirt tended by the antFormica perpilosaWheeler often enter nests of this ant species, and pupate in tunnels and chambers near the surface. Untended larvae and those tended by the antsDorymyrmexForel sp. (smithicomplex),Forelius foetida(Buckley), andMyrmecocystus mimicusWheeler pupate in crevices in the ground, under bark, and on leaves; but rarely inside ant nests.

The location and structure ofF.perpilosanests facilitates discovery byH.isolaprepupae. At the southeast Arizona study site,F.perpilosanests are located at the base ofH.isola'shost plant, whereas other species’nests are in open ground. Also,F.perpilosanest openings are wide, whereas those of other species may be too narrow for prepupae to enter.

Prepupae associated withF.perpilosaspent 67% less time on the ground searching for pupation sites than prepupae associated with other ant species. Pupae in artificial chambers connected toF.perpilosanests were 4–5 times less likely to disappear overnight, presumably due to predation, than those not connected to nests.

Formica perpilosaants tend pupae inside nests. However, in the laboratory experiments tended pupae did not lose more weight prior to eclosion than untended ones, suggesting that chemicals or sounds produced by pupae as ant attractants are inexpensive, or are produced whether or not ants are present.

Newly‐eclosed butterflies exited nests unmolested by ants in the field, but were attacked if confined with ants for several minutes after eclosion in the laboratory.
Effect of mating frequency and brood cell infestation rate on the reproductive success of the honeybee parasite Varroa jacobsoni
Authors: DONZÉ GÉRARD , HERRMANN MIRIAM , BACHOFEN BORIS , GUERIN PAT RICK M.
Published: March 2008

Abstract.

The reproductve biology of Varroa jacobsoni, whose females infest honeybee brood, was studied in natural and transparent artificial brood cells. These investigations were made under the headings of maturation behaviour and fertilization, and the influence of infestation rate of brood cells on the number of mated females produced per infesting Varroa.

Mating of Varroa daughters, observed in the transparent brood cells with time‐lapse video, occurs just after ecdysis and as soon as they arrive on the faecal accumulation prepared by the mother. Such females are remated for as long as no other freshly moulted daughter arrives on the faecal accumulation.

The number of spermatozoa stocked in the spermatheca increases with remating, a strong indication for sperm mixing in this species when brood cells contain more than one Varroa foundress.

The number of daughters per infesting mother decreases at higher rates of infestation per cell, but the proportion of such daughters with a mate rises sharply due to the higher probability of finding a male within multi‐infested cells. The number of mated daughters per mother is maximal in cells with two foundress Varroa females.

The frequency distributions of infesting mites in drone cells are aggregated, and approximate to negative binomial distributions.

We postulate from the above that the observed non‐random infestation by Varroa in drone brood augments the mite's mean reproductive success through the production of a higher number of mated daughters than the corresponding Poisson distributions would.
Host‐searching and mating in an outbreeding parasitoid wasp
Authors: GUERTIN D.S. , ODE P.J. , STRAND M.R. , ANTOLIN M.F.
Published: March 2008

Abstract.

Female parasitoid wasps (Hymenoptera) must search for hosts to reproduce, but only require mates if their broods are to contain female progeny. In outbreeding species, females locate mates after dispersal from the emergence site. Unmated females may therefore face a trade‐off between searching for hosts and searching for mates, if hosts and mates are spatially separated.

In the outbreeding parasitoid Bracon hebetor Say (Hymenoptera: Braconidae), males and females are spatially segregated in the field. Females are found primarily below the surface of stored corn where they search for hosts, whereas males are found on or above the surface.

Wasps placed in laboratory observation chambers designed to mimic B.hebetor's stored corn habitat distributed themselves in a manner consistent with field observations. Males remained on the surface of the grain, whereas females moved below the surface to attack hosts.

In the laboratory, female distribution was influenced by their mating status, the presence of males or hosts, and female age. Virgin females were more reluctant to move into the corn than were mated females, younger females foraged deeper than older females, and all females moved deeper into the com when males were present.

10% of all females did not mate even when males were present in the chambers, a percentage consistent with previous observations from the field. If B.hebetor faces a trade‐off between host‐searching and mate‐searching, the trade‐off seems to be part of 'split sex ratio strategies', with some females remaining constrained to producing only male offspring.
Adaptive trade‐offs of leaf folding in Dichomeris caterpillars on goldenrods
Authors: LOEFFLER CAROL C.
Published: March 2008

Abstract.

Leaf folding is a common behaviour among caterpillars that has many potential benefits such as creation of a favourable microclimate and protection from predation or dislodgment.

One cost of leaf folding which has not previously been quantified is the reduction in growth rate that might result from the energetic expenditures of producing silk and applying it to fold leaves.

On caged goldenrods in field and forest habitats, early‐instar Dichomeris leuconotella (Busck) caterpillars that were repeatedly forced to spin new leaf refuges (either folds or webs of silk) actually had higher growth rates than caterpillars left undisturbed.

This surprising result apparently reflected the fact that disturbed caterpillars chose relatively young green leaves for new refuges, whereas undisturbed caterpillars tended to remain in their webs or folds on ageing leaves.

In a glasshouse experiment using plants that underwent little senescence, growth rates were unaffected by the amout of refuge‐making effort, indicating that the costs of such effort were either negligible or easily compensated for by these caterpillars.

On glasshouse plants, caterpillars periodically forced to change refuges had higher disappearance rates than those left undisturbed, despite the absence of predators. Wandering or falling from plants is evidently a major hazard of frequent refuge changes.

Thus, early‐instar Dichomeris caterpillars face a trade‐off in which risks of predation or loss of contact with the host favour the observed low rate of refuge changes, but in which growth rates could actually be improved with more refuge changes.
The usefulness of destructive host feeding parasitoids in classical biological control: theory and observation conflict
Authors: JERVIS MARK A. , HAWKINS BRADFORD A. , KIDD NEIL A.C.
Published: March 2008

Abstract.

We examine the conventional wisdom among biological control practitioners that destructive host feeding is a desirable attribute in parasitoids employed for classical biological control, using both the predictions of population dynamics theory and historical data on biological control introductions of Hymenoptera against Homoptera.

Population dynamics theory predicts that destructive host feeders, compared with other parasitoids, are (a) either just as likely or more likely to become established, and (b) unable to depress host equilibria as strongly.

Analyses of the B IOC AT database suggest that among parasitoids of Homoptera destructive host feeders are superior to other parasitoids with respect to both establishment rate and success rate.

We present likely explanations for the disparity between the predictions of population dynamics theory and the results of database analysis. A partial explanation for the mismatch between theory and observation with respect to the degree of pest suppression may be that females of destructive host feeding parasitoids rely less upon hosts as a food source when alternative foods such as honeydew and nectar are plentiful.

We conclude that, despite the predictions of population dynamics theory, destructive host feeders are probably better biological control agents than other parasitoids, and certainly no worse, but that it would imprudent to use destructive host feeding as the sole, or even primary, selection criterion when seeking agents for classical biological control.
Consequences of adult size for survival and reproductive performance in a herbivorous ladybird beetle
Authors: OHGUSHI TAKAYUKI
Published: March 2008

Abstract.

A univoltine herbivorous ladybird beetle Epilachna niponica (Coleoptera: Coccinellidae) shows a large variation in adult size within a population.

Large adults had higher survival from emergence to the reproductive season, and the size‐dependent adult survival was most apparent during hibernation. On the other hand, adult survival during pre‐hibernation contributed little to size‐dependent overall survival.

Neither reproductive lifespan nor lifetime fecundity were a function of adult size, though large females produced larger size of egg batches.

Size of adult beetles was significantly reduced by leaf damage to plants on which they grew up on larval stage. Since leaf herbivory increases through the season, late emerged adults that were subjected to food deterioration during the larval period were smaller than early‐emerged individuals.
Larval development of two parasitic flies (Conopidae) in the common host Bombus pascuorum
Authors: SCHMID‐HEMPEL REGULA , SCHMID‐HEMPEL PAUL
Published: March 2008

Abstract.

Whenever parasitism by more than one female occurs, larvae of parasitoids not only have to resist host defence but also face competition with other (unrelated) larvae. Competition is particularly important in solitary parasitoids where only one larva is able to complete its development. Such a situation is found in Conopidae (Diptera) parasitizing adult bumble bees where larvae of two species of conopid flies, Sicus ferrugineus L. and Physocephala rufipes F. often compete within the common host Bombus pascuorum Scopoli. This study analysed the larval development of the two species and asks how competition among larvae may be regulated.

Parasitized workers of B.pascuorum were caught in the field and kept according to different experimental schedules in the laboratory. This provided stage‐structured data for the temporal course of development of the parasitic larvae. For the analysis, a simulation model was constructed that estimated the duration of all parasitic stages (Manly, 1990, first method). In both species the egg stage was found to be approximately 2 days, first instar 3 days, second instar 4 days, and third instar 3 days. The total development time is an estimated 10.8 days from oviposition in S.ferrugineus and 11.4 days in P.rufipes. S.ferrugineus develops faster in the beginning, probably because of its larger egg size, whereas P.rufipes pupates at larger size. First‐instar larvae of both species possess strong, pointed mandibles.

The success of conopid larvae seems only marginally affected by host defence, for a single larva per host almost always completes development. Under competition, however, mortality rate increases substantially, and most larvae die in their first instar. Moreover, they show signs of melanization. The estimates for developmental times and the patterns found in this study suggest that conopid larvae seem capable of physical attacks, particularly during the first instar, when elimination of competitors is most common, and that S.ferrugineus has a time advantage because of its faster early development. Because most studies have previously been carried out with hymenopteran parasitoids, this study provides new information about the other large group of parasitoid insects, the Diptera, and demonstrates convergent patterns.
Alien herbivores and native parasitoids: rapid developments and structure of the parasitoid and inquiline complex in an invading gall waspAndricus quercuscalicis(Hymenoptera: Cynipidae)
Authors: SCHÖNROGGE K. , STONE G.N. , CRAWLEY M.J.
Published: March 2008

Abstract.

Rapid and substantial changes have occurred in the parasitoid and inquiline community associated with the agamic gallsof Andricus quercuscalicissince it invaded Britain in the late 1950s. The number of parasitoid and inquiline species has risen from one to thirteen over a 15‐year period. Although the number of species has been relatively consistent over the last 8 years, the species composition has changed considerably and in a highly characteristic way during this period.

The parasitoid complex can be divided into two broadly distinct sets of parasitoid species; one set attacks only the gall former whereas the other set concentrates on the inquilines living in the wall of the gall.

The most dramatic change, however, is in the abundance of inquilines which were reported to be virtually absent in earlier studies on this community in Britain. Over a period of only 5 years, between 1988 and 1993, inquiline attack rose from less than 0.01 to an average of 0.26 inquilines per gall. The intensity of inquiline attack is geographically heterogenous, with high inquiline numbers restricted to south‐east England. Because of the relatively high specificity of the parasitoids, high inquiline abundance is positively correlated with parasitoid species richness in knopper galls.

Parasitism rates, particularly on the gall former, were generally low (<10%). Over the last 5 years, however, seven parasitoid species have been consistently recorded and the mortality caused by these species has increased continuously. The species composition of the community associated with this alien gall wasp in Britain has quickly converged to the community known from its native range in continental Europe. Parasitoid species known to attack the galls ofA.quercuscalisison the continent have been recorded from it in Britain for the first time mainly in areas where inquilines have recently become abundant.

Since rates of parasitism of the gall former are still low, parasitoids are unlikely to play a major role in the population dynamics of this invading gall wasp at present, but the rapidly increasing inquiline and parasitoid attack could be a source of increased mortality for native cynipid species which are the alternative hosts of those parasitoid species.
Duration and benefits of biparental brood care in the dung beetle Onthophagus vacca (Coleoptera: Scarabaeidae)
Authors: SOWIG PETER
Published: March 2008

Abstract.

Single males, single females or pairs of dung beetles, Onthophagus vacca, were released on artificial small (100 g) or large (1000 g) dung pats in the laboratory. Emigrating beetles were trapped at 12 h intervals, and the number and size of the brood chambers were recorded after each replicate.

Emigration of males was delayed if females were present in the same dung pats, whereas emigration times of females were independent of the presence or absence of males.

A residency of 60 h proved to be a threshold value. Females emigrating before this time did not breed, whereas those emigrating later had built at least two brood chambers.

Females paired with males built more brood chambers than single females.

The reproductive success of pairs was not influenced by the size of the dung pats.
The effects of crop microclimate and associated physiological constraints on the seasonal and diurnal distribution patterns of raspberry beetle (Byturus tomentosus) on the host plant Rubus idaeus
Authors: WILLMER P.G. , HUGHES J.P. , WOODFORD J.A.T. , GORDON S.C.
Published: March 2008

Abstract.

The occurrence of raspberry beetles (Byturus tomentosus) on the host plant Rubus idaeus is extremely variable between seasons, between days and within days, with occupancy of the available raspberry flowers (the feeding and oviposition sites) varying from 0 to 60%.

This variation could not be explained by plant chemistry or food quality (leaf nitrogen, carbon or water levels, or floral nectar reward); however, beetle distributions were in part attributable to microclimatic constraints acting via the insects’physiological constraints.

Initial ascent into raspberry canes from soil emergence sites was limited by the three‐fold higher water loss rates from recently eclosed young adult beetles as compared with mature beetles. Young adults reduced their hygric stress by remaining in the humid microclimate of tightly furled primocane leaftips.

Mature beetles spread upwards over the plant, but showed a preference for insolated sites (tops of canes, east or west facing according to time of day). In such sites their body temperatures could rise above the threshold for flight (requiring a Tb of 15°C in laboratory studies). Flight activity was therefore common only in the early afternoon of warm days. Later in the day, beetles moved down and sometimes off the plants, starting to return at around dawn.

Thus physiological constraints, even on adult beetles (relatively well‐protected insect stadia), can be important components in predicting insect movements and locations on a host plant; they are likely to be even more crucial to less highly sclerotized plant‐feeding adult insects and many larval herbivorous pests.
Prey selection and baculovirus dissemination by carabid predators of Lepidoptera
Authors: VASCONCELOS SIMÃO D. , WILLIAMS TREVOR , HAILS ROSEMARY S. , CORY JENNIFER S.
Published: March 2008

Abstract.

The interaction between coleopteran predators and baculovirus‐infected larvae was studied in the laboratory and the field in order to assess the potential role of predators in the dissemination of a nucleopolyhedrovirus (NPV).

Preference tests using three carabid species, Harpalus rufipes De Geer, Pterostichus melanarius Illiger and Agonum dorsale Pont, showed no evidence of discrimination between healthy and diseased larvae of the cabbage moth Mamestra brassicae L. (Lepidoptera: Noctuidae) as prey items.

Virus infectivity was maintained after passage through the predator's gut. NPV mortality ranged from 97% to 20% when test larvae were exposed to faeces collected immediately after and 15 days post‐infected meal respectively.

The potential for transfer of inoculum in the environment was estimated in the laboratory by soil bioassay. Carabids continuously passed infective virus to the soil for at least 15 days after feeding on infected larvae.

Field experiments showed that carabids which had previously fed on diseased larvae transferred sufficient virus to the soil to cause low levels of mortality in larval populations of the cabbage moth at different instars.
Competition and resistance to starvation in larvae of container‐inhabiting Aedes mosquitoes
Authors: BARRERA ROBERTO
Published: March 2008

Abstract. 1. Hypotheses about declining populations of container‐inhabiting Aedes mosquitoes following the invasion by additional species were tested.

2. The larval competition hypothesis was studied experimentally in pure and mixed cultures of Aedes aegypti (L.), A.albopictus (Skuse) and A.triseriatus (Say). The experiments used decomposing leaf litter in the laboratory, as opposed to most previous research which used non‐natural food.

3. Resistance to starvation is introduced as a new measure of larval performance and competitiveness. The hypothesis is that more successful larvae store larger energy reserves and resist the lack of food longer.

4. Contrary to previous research showing better performance of A.aegypti in mixed cultures, A.albopictus developed faster and had greater survival when natural food was used.

5. Resistance to starvation was greater in the better performing species (i.e. A.aegypti with non‐natural food and A.albopictus with leaf litter). Oxygen consumption by starved larvae was similar in the three container species, and in the ground‐water mosquito, A.taeniorhynchus (Wied.), whose resistance to starvation was comparatively very low.
Insect invasion sequences: systematic or stochastic?
Authors: HODGE SIMON , ARTHUR WALLACE
Published: March 2008

Abstract. 1. This study examined the invasion sequence of Drosophila species arriving at decomposing strawberries.

2. It was found that the age of fruit affected the likelihood of Drosophila arrival, flies preferring relatively fresh fruit. However, there were no repeatable trends in invasion sequence of Drosophila species, different species responding in a similar manner to changes in fruit age.

3. Although no systematic trends in invasion sequence were observed, species tended to be temporally separated due to stochastic differences in their arrival at the fruit.

4. It is suggested that stochastic, as well as repeatable, temporal separation of species can have an important influence on subsequent community development.
Searching behaviour and mate recognition by males of the two‐spot ladybird beetle, Adalia bipunctata
Authors: HEMPTINNE J‐L. , DIXON A. F. G. , LOGNAY G.
Published: March 2008

Abstract. 1. Adult males of the two‐spot ladybird beetle, Adalia bipunctata, did not show a functional response to increase in aphid abundance and consumed markedly fewer aphids than do the females.

2. At high densities of prey, females spent more time in area‐restricted search than when prey was scarce. Males were always less active than females and they did not respond to an increase in prey abundance by a change in searching behaviour.

3. After a brief encounter with a female, a male showed area‐restricted searching behaviour. This behaviour occurred in response to encountering a female's elytra and in particular to a chloroform‐soluble component (sex pheromone) present on or in the elytra.

4. Males needed to encounter a female in order to respond to her presence, which indicated the pheromone is a contact pheromone.

5. The searching behaviour of males appeared to be mainly directed towards locating females; that of females towards locating aphids. This difference between the sexes should be taken into account when quantifying the predatory response of ladybirds to aphid abundance in the field.
Components of male fitness in relation to body size in Epirrita autumnata (Lepidoptera, Geometridae)
Authors: TAMMARU TOOMAS , RUOHOMÄKI KAI , SAIKKONEN KARI
Published: March 2008

Abstract. 1. The effect of body size on different components of male fitness was studied for Epirrita autumnata, a geometrid known for its eruptive population dynamics. Body size is the main determinant of female fecundity in this species.

2. Longevity of males was found to have a weak negative correlation with body size at low temperatures. No significant correlation was found at higher temperatures.

3. We found no correlation between male size and female fecundity or egg size which is consistent with the small size of spermatophores in this species.

4. Small and large males were equally successful when allowed to compete for females in laboratory conditions.

5. In one or two field collections, males found mating were larger than males found singly. Large males also had an advantage in finding of virgin females, offered experimentally. No size‐assortative mating was recorded.

6. We conclude that size‐dependent mate location ability is the factor accounting for most of the variance in male fitness in E.autumnata. The dependence of fitness on body size may well be equally strong in males and females.
Mechanisms of regulatory T‐cell suppression – a diverse arsenal for a moving target
Authors: Sojka Dorothy K. , Huang Yu‐Hui , Fowell Deborah J.
Published: March 2008

Naturally‐occurring regulatory T cells (Tregs) are emerging as key regulators of immune responses to self‐tissues and infectious agents. Insight has been gained into the cell types and the cellular events that are regulated by Tregs. Indeed, Tregs have been implicated in the control of initial activation events, proliferation, differentiation and effector function. However, the mechanisms by which Tregs disable their cellular targets are not well understood. Here we review recent advances in the identification of distinct mechanisms of Treg action and of signals that enable cellular targets to escape regulation. Roles for inhibitory cytokines, cytotoxic molecules, modulators of cAMP and cytokine competition have all been demonstrated. The growing number of inhibitory mechanisms ascribed to Tregs suggests that Tregs take a multi‐pronged approach to immune regulation. It is likely that the relative importance of each inhibitory mechanism is context dependent and modulated by the inflammatory milieu and the magnitude of the immune response. In addition, the target cell may be differentially susceptible or resistant to distinct Treg mechanisms depending on their activation or functional status at the time of the Treg encounter. Understanding when and where each suppressive tool is most effective will help to fine tune therapeutic strategies to promote or constrain specific arms of Treg suppression.
Apoptosis‐induced inhibition of CD1d‐mediated antigen presentation: different roles for caspases and signal transduction pathways
Authors: Khan Masood A. , Sriram Venkataraman , Renukaradhya Gourapura J. , Du Wenjun , Gervay‐Hague Jacquelyn , Brutkiewicz Randy R.
Published: March 2008

The stimulation of programmed cell death can either enhance or inhibit antigen presentation by classic major histocompatibility complex molecules. In the current study, we report that the induction of apoptosis by topoisomerase I inhibition or elevation of intracellular ceramide levels substantially impairs CD1d‐mediated antigen presentation. In the former case, such a reduction occurred via the regulation of both the p38 mitogen‐activated protein kinases and protein kinase C δ signal transduction pathways as well as the caspase cascade, whereas the latter was p38‐(but not caspase)‐dependent. Confocal microscopic analysis showed an altered intracellular distribution of CD1d following the inhibition topoisomerase I or by an increase in intracellular ceramide levels, that was prevented by p38 and caspase inhibitors. Thus, the induction of apoptosis in antigen presenting cells severely compromises CD1d‐mediated antigen presentation by multiple mechanisms.
The malaria vector mosquito Anopheles gambiae expresses a suite of larval‐specific defensin genes
Authors: Meredith J. M. , Hurd H. , Lehane M. J. , Eggleston P.
Published: March 2008

cDNAs of Anopheles gambiae Defensin 2 (AgDef2), Defensin 3 (AgDef3) and Defensin 4 (AgDef4), identified in the genome sequence, have been characterized and their expression profiles investigated. In contrast to both typical defensins and insect antimicrobial peptides generally, the newly identified defensins were not upregulated with acute‐phase kinetics following immune challenge in insects or cell culture. However, mRNA abundance of AgDef2, AgDef3 and AgDef4 increased significantly during the larval stages. Promoter analysis of all three genes failed to identify putative immune response elements previously identified in other mosquito defensin genes. As previous studies failed to identify these larval‐specific defensins, it seems likely that further antimicrobial peptide genes with nontypical expression profiles will be identified as more genome sequences become available.
Identification of aphid salivary proteins: a proteomic investigation of Myzus persicae
Authors: Harmel N. , Létocart E. , Cherqui A. , Giordanengo P. , Mazzucchelli G. , Guillonneau F. , De Pauw E. , Haubruge E. , Francis F.
Published: March 2008

The role of insect saliva in the first contact between an insect and a plant is crucial during feeding. Some elicitors, particularly in insect regurgitants, have been identified as inducing plant defence reactions. Here, we focused on the salivary proteome of the green peach aphid, Myzus persicae. Proteins were either directly in‐solution digested or were separated by 2D SDS‐PAGE before trypsin digestion. Resulting peptides were then identified by mass spectrometry coupled with database investigations. A homemade database was constituted of expressed sequence tags from the pea aphid Acyrtosiphon pisum and M. persicae. The databases were used to identify proteins related to M. persicae with a nonsequenced genome. This procedure enabled us to discover glucose oxidase, glucose dehydrogenase, NADH dehydrogenase, α‐glucosidase and α‐amylase in M. persicae saliva. The presence of these enzymes is discussed in terms of plant–aphid interactions.
Role of haemagglutinins in adhesion of Erwinia carotovora to potato tissue
Authors: Wallace Anne , Pérombelon M.C.M.
Published: March 2008

The adhesion of two strains each of Erwinia carotovora subsp. carotovora and Erwinia carotovora subsp. atroseptica to potato tuber discs, leaflets and tuber cell cultures was examined and found to occur independently of the presence of either mannose‐sensitive (MSHA) or mannose‐resistant (MRHA) haemagglutinins. Adhesion was generally greater when bacteria were grown in nutrient broth than on phosphate‐buffered agar. The specific MSHA inhibitor α‐methyl mannoside reduced the adhesion of two strains to tuber discs and leaflets and the specific MRHA inhibitor, asialofetuin inhibited strains only on leaflets. A reduction in adhesion of a MSHA‐producing strain by α‐methyl mannoside was observed by scanning electron microscopy which found that adhesion was localized at intercellular junctions.
Toxin production by Fusarium culmorum IMI 309344 and F. graminearum NRRL 5883 on grain substrates
Authors: O'Neill Kathleen , Damoglou A.P. , Patterson Margaret F.
Published: March 2008

The production of deoxynivalenol, acetyl deoxynivalenol and zearalenone by Fusarium culmorum and F. graminearum on autoclave‐sterilized grain (maize, rice, wheat and barley) was investigated. Fusarium culmorum produced significantly greater levels of toxins than F. graminearum. The four substrates examined differed in their ability to support toxin production. Toxin production on maize and rice was significantly greater than toxin production on barley or wheat.
In vitro assay for testing the toxicity of Bacillus thuringiensis subsp. israelensis delta endotoxin using blood agarose plates
Authors: Ingle S.S. , Rao K.K. , Chhatpar H.S.
Published: March 2008

An in vitro assay system that used erythrocytes was developed to assess the toxicity of delta endotoxin of Bacillus thuringiensis subsp. israelensis (Bti), a mosquito larvicidal agent. This endotoxin was activated at high alkaline pH without causing alkaline injury to the erythrocytes. The assay is carried out on blood agarose plates, prepared in MOPS‐buffered saline (0·01 mol 1‐1), pH 7·0. The threshold dose for toxicity of Bti HD‐567 was 8 ng protein and that of Bti H‐14 and IPS‐82 standard were 6 ng and 4 ng protein respectively. The assay is rapid, sensitive, quantitative and applicable to different Bti formulations to assess the toxicity of the products. Only the activated toxin is detected by this method and has good correlation with insect bioassay. The percentage toxicity dose of different Bti preparations agrees well with percentages of LC50 values when the second instar larvae of Aedes aegypti were tested.
PhoE porin of Escherichia coli and phosphate reversal of acid damage and killing and of acid induction of the CadA gene product
Authors: Rowbury R.J. , Goodson Margaret
Published: March 2008

The lethal effects of inorganic acid on phoE+Escherichia coli strains, grown at neutral pH0, were enhanced by chloramphenicol, apparently because some organisms acquire acid tolerance (habituate) during challenge and chloramphenicol stops this. Phosphate (and/or polyphosphate) present during challenge prevented killing and damage by acid to outer membranes, DNA and cellular enzymes but did not prevent acid pH0 enhancing novobiocin activity. To reverse acid effects, phosphate must interact with or cross the outer membrane but need not enter the cytoplasm; it is probable that it competes with H+ (or protonated anions) for passage through the PhoE pore. Phosphate also prevented induction of β‐galactosidase in a strain with the cadA promoter fused to lacZ. Four unc mutants showed essentially normal acid sensitivity and habituation; the same was true for strains with lesions in fur, oxyR, katF, phoP, cadA and hycB. In contrast, deletion of rpoH led to slightly increased acid sensitivity for cells grown at pH0 7·0, although habituation was relatively normal.
Iron requirement and siderophore production in Bradyrhizobium strains isolated from Acacia mangium
Authors: Lesueur D. , Diem H.G. , Meyer J.M.
Published: March 2008

Fourteen Bradyrhizobium strains isolated from nitrogen‐fixing Acacia mangium trees which originated from different geographical areas were analysed for their iron requirement and siderophore production. All strains were affected by starvation but responded differently to it. The increase in bacterial cell yield in response to iron supplementation, as well as the strain's sensitivity towards the synthetic iron‐chelator 2,2‐dipyridyl, suggested a discrimination of these strains into two groups. Four strains in one group, including a reference strain, produced siderophore(s) when grown under starvation. Other strains belonging to the second group were characterized by a lower iron requirement, a higher sensitivity to 2,2‐dipyridyl, and did not apparently demonstrate any siderophore production. Two of the siderophore‐producer strains, as well as a Rhizobium reference strain, excreted citrate, which was under iron regulation. Citrate was shown to facilitate iron incorporation in strains of either group.
A Note: Serological study of four pathovars of Pseudomonas syringae: Ps. syr. aptata, Ps. syr. tabaci, Ps. syr. mors‐prunorum and Ps. syr. phaseolicola
Authors: Guillorit Christiane , Samson Régine
Published: March 2008

The antigenic reactions of 35 strains of four pathovars of Pseudomonas syringae (Ps. syr. aptata, Ps. syr. tabaci, Ps. syr. mors‐prunorum and Ps. syr. phaseolicola) were studied by double diffusion and indirect immunofluorescent staining, and anti‐whole‐cell and anti‐LPS‐extract sera. It had already been shown that the precipitating lines in Ouchterlony double‐diffusion tests, due to bacterial LPS, were suitable for the distinction of O‐serogroups. The investigation of serological cross‐reactions between the 35 strains and 20 antisera revealed that three pathovars were serologically homogeneous: Ps. syr. aptata, Ps. syr. tabaci and Ps. syr. phaseolicola. They could fit into three O‐serogroups formerly described: namely APTPIS, TAB and PHA. The O‐serogroups APTPIS and TAB showed some common antigens. The 10 strains of Ps. syr. mors‐prunorum studied were distributed into two O‐serogroups (eight strains belonging to the O‐serogroup MOP1, one strain to MOP2, and the last strain failed to react with any of the serogroups).
Serious games for higher education: a framework for reducing design complexity
Authors: Westera W. , Nadolski R.J. , Hummel H.G.K. , Wopereis I.G.J.H.
Published: March 2008

Abstract  Serious games open up many new opportunities for complex skills learning in higher education. The inherent complexity of such games, though, requires large efforts for their development. This paper presents a framework for serious game design, which aims to reduce the design complexity at conceptual, technical and practical levels. The approach focuses on a relevant subset of serious games labelled as scenario‐based games. At the conceptual level, it identifies the basic elements that make up the static game configuration; it also describes the game dynamics, i.e. the state changes of the various game components in the course of time. At the technical level, it presents a basic system architecture, which comprises various building tools. Various building tools will be explained and illustrated with technical implementations that are part of the Emergo toolkit for scenario‐based game development. At the practical level, a set of design principles are presented for controlling and reducing game design complexity. The principles cover the topics of game structure, feedback and game representation, respectively. Practical application of the framework and the associated toolkit is briefly reported and evaluated.
The role of Candida albicans FAR1 in regulation of pheromone‐mediated mating, gene expression and cell cycle arrest
Authors: Côte Pierre , Whiteway Malcolm
Published: March 2008

Candida albicans cells homozygous for the MTLa locus respond to α‐mating pheromone by activating gene expression and triggering morphological changes, and the cells undergo a pheromone‐mediated cell cycle arrest that can be influenced by nutritional conditions. Disruption of C. albicans ORF19.7105, which is the predicted homologue of the yeast FAR1 gene, blocks pheromone‐mediated morphological changes, prevents pheromone‐mediated cell cycle arrest, greatly compromises mating and also blocks pheromone‐triggered gene induction. C. albicans ORF19.7105 is not pheromone inducible, but overexpression of this gene from the actin promoter greatly enhances pheromone‐mediated cell cycle arrest, leading to clear halos in growth inhibition assays on a variety of solid media. Transcriptional profiling of the ORF19.7105‐overexpressing strain has established an enhanced responsiveness of pheromone‐induced genes. Thus the C. albicans FAR1 gene is a dosage‐dependent regulator of the pheromone response, and is critically required for all aspects of mating process of this pathogenic fungus.
Biochemical and Immunochemical Investigations on the Light‐Harvesting System of the Cryptophyte Rhodomonas sp.: Evidence for a Photosystem I Specific Antenna
Authors: Bathke L. , Rhiel E. , Krumbein W. E. , Marquardt J.
Published: March 2008

Abstract: Thylakoid membranes of the cryptophyte Rhodomonas sp. were solubilized with the mild detergent dodecyl‐β‐maltoside and subjected to sucrose density gradient centrifugation. The resulting gradients showed six pigment‐bearing bands which were characterized further by means of absorption and fluorescence emission (77K) spectroscopy, polyacrylamide gel electrophoresis and Western immunoblotting. Two of the bands showed characteristics of light‐harvesting complexes, other bands could be attributed to photosystem II and photosystem I. Up to 10 different light‐harvesting proteins could be identified, some of which are specific for photosystem I, others for photosystem II. The polypeptides of the light‐harvesting complex of photosystem II show a higher chlorophyll c/a ratio than the antenna proteins of photosystem I. As in vascular plants, they represent the bulk of the membrane‐intrinsic light‐harvesting proteins.