bluuebunny/crossref_metadata_2025 huggingface dataset:
Flower constancy and learning in foraging preferences of the green‐veined white butterfly Pleris napi
Authors: GOULSON D. , CORY J. S.
Published: March 2008

Abstract.

Evolutionary pressure should select for efficient foraging strategies, within the constraints of other selective forces. We assess the mechanisms underlying flower choice in the butterfly, Pieris napi (L.), which as an adult forages for nectar. Experiments were carried out on a laboratory colony, using artificial flowers of two colours, and replicated on two successive generations.

When nectar was freely available from all flowers, equal numbers of butterflies visited each colour, but individual butterflies exhibited flower constancy, showing a strong preference for one colour or the other.

Following 3 day conditioning periods in which nectar was available from flowers of one colour only, butterflies responded by developing a preference for this colour, which persisted when both flower colours were refilled. This preference could subsequently be switched to the other flower colour following a further 3 days of conditioning. These are interpreted as adaptive (learned) responses, which would have obvious selective benefits in the field, enabling butterflies to avoid flower species which experience has shown are poor sources of nectar, and to adapt to temporal and spatial changes in nectar availability.
Gall aphids do not select optimal galling sites (Smynthurodes betae; Pemphigidae)
Authors: BURSTEIN MOSHE , WOOL DAVID
Published: March 2008

Abstract. 1. In studies of insect‐host plant interaction it is often suggested that insects preferentially colonize host plants (or sites within plants) on which their fitness is maximized (a positive covariance of preference and performance). This suggestion stems from the assumption that natural selection has driven the system toward optimal use of resources.

2. Our study of the galling aphid Smynthurodes betae Westw. demonstrates that the distribution of galls on leaves is not due to preference, and can be altered by manipulating the aphid arrival time or the shoot growth rate.

3. We found no correlation between gall density and performance (aphid clone size) at different positions along the shoot.

4. Because leaves on the growing shoot are not equally responsive to aphid stimulation, the colonizers have no choice but to settle on leaves that are at the right stage when they arrive.

5. S.betae colonizers did not discriminate between shoots of their host and a congeneric non‐host, on which their fitness is invariably zero.

6. Synchronization between galler and host plant phenologies seems to be the key to the observed distribution of galls on the tree. The data give no support to the preference‐performance hypothesis.
Long‐term dynamics of leaf miners,Eriocraniaspp., on mountain birch: alternate year fluctuations and interaction withEpirrita autumnata
Authors: BYLUND HELENA , TENOW OLLE
Published: March 2008

Abstract.

Abundance of leaf‐mining larvae of the outbreak speciesEriocraniaspp. was monitored in northern Sweden in 1955–67 and 1984–92 in a mountain birch forest rejuvenated by anEpirrita autumnataoutbreak in 1954–55.

Eriocraniamine density fluctuated in a regular biennial pattern, probably due to a semivoltine life cycle. The alternate year fluctuations had shifted phase between the two study periods.

The density fluctuated at a significantly higher mean level and with a lower amplitude in thec.10‐year‐old forest in the 1960s than in the 30‐year‐old forest in the 1980s. However, no difference was found in mine density betweenc.30‐ and >60‐year‐old stands in the 1980s.

Significant correlations between the density of mines in high‐density years and date of budburst, and between rate of change between high‐density years and the time between snow‐melt and budburst indicate effects of weather. No correlation was found between yearly average mine density and date of budburst, precipitation or temperatures in May or June.

No correlation was found between the mean densities ofEriocraniamines andE.autumnatacaterpillars in the same and the two preceding years. However, in the first (1955) and highest of three studiedE.autumnatapeaks a negative effect on population density ofEriocraniawas indicated.

A significant, negative correlation between the number ofEriocraniamines andE.autumnatacaterpillars on single branches was found in three out of eighteen years. The separation of caterpillars and mines at branch level indicates an effect of avoidance at intermediate population densities.
The effect of a foliar disease (rust) on the development of Gastrophysa viridula (Coleoptera: Chrysomelidae)
Authors: HATCHER PAUL E. , PAUL NIGEL D. , AYRES PETER G. , WHITTAKER JOHN B.
Published: March 2008

Abstract.

Gastrophysa viridula Degeer (Coleoptera: Chrysomelidae) and the pathogenic rust fungus Uromyces rumicis (Schum.) Wint. both occur on leaves of Rumex crispus L. and R.obtusifolius L. Individual stages of beetle development, and egg laying, were compared on healthy and infected leaves of each plant species in the laboratory. Oviposition choice was investigated in the field and laboratory.

Beetles reared on infected leaves of each species had greater larval mortality and slower development than those reared on healthy leaves. Although larvae feeding on infected leaves consumed up to 2.5 times more dry weight than those reared on healthy leaves, they had a lower relative growth rate and pupated at a lower weight. These changes were consistent with the reduced nutritive quality of rust‐infected Rumex leaves.

Fecundity of beetles reared on infected leaves of both species was considerably reduced. Eggs laid by beetles feeding on infected R.crispus leaves also had a reduced viability.

The beetle developed consistently poorer on healthy R.crispus than on healthy R.obtusifolius throughout its life‐cycle. Differences in larval performance were greater between host species than between infected and healthy leaves.

Oviposition was similar on infected and healthy R.crispus in both the laboratory and field. However, adults consumed less, and laid fewer eggs on infected than on healthy R.obtusifolius. The pattern of egg laying on different aged leaves was affected by rust infection: a greater proportion of eggs was laid on the older, infected leaves, than on the equivalent aged leaves on the healthy plants. Few larvae survived from eggs laid on rusted leaves in the field.
Spittlebug indicators of nitrogen‐fixing plants
Authors: THOMPSON VINTON
Published: March 2008

Abstract.

Spittlebugs (Homoptera: Cercopoidea) are preferentially associated with nitrogen‐fixing angiosperms. Generally, the Aphrophoridae associate with legumes, the Clastopteridae with actinorhizal plants, and the Cercopidae with associative nitrogen‐fixing grasses. This is the first reported insect—host association specific to nitrogen‐fixing plants.

It is probable that spittlebugs are attracted to nitrogen‐fixing plants because these hosts provide a relatively rich, reliable source of organic nitrogen compounds for xylem‐sucking insects.

Many spittlebugs live on plants that do not fix nitrogen, and ecological, mechanical or chemical factors may bar some spittlebugs from otherwise suitable nitrogen‐fixing plants.

Among nitrogen‐fixing hosts, spittlebugs appear to prefer plants that transport fixed nitrogen as amino acids and amides to plants that transport fixed nitrogen as ureides.
Adult movements between populations in the specialist butterflyProclossiana eunomia(Lepidoptera, Nymphalidae)
Authors: BAGUETTE MICHEL , NÈVE GABRIEL
Published: March 2008

Abstract.

The structure of local populations of a monophagous butterfly, the bog fritillaryProclossiana eunomia, was studied in a complex of suitable habitat patches separated by spruce plantations or fertilized pasture.

An unexpected high level of adult movements between habitat patches was detected by a mark—release—recapture technique. Local populations were connected by adult movements across unsuitable habitats, leading to a meta‐population structure.

This evidence of the metapopulation structure of a specialist butterfly challenges the supposed relationship between habitat specialization and closed, isolated populations.

Males and females ofP.eunomiaexhibited different spatial behaviours; females were more likely to emigrate and dispersed further than males. These differences in spatial behaviour are related to the mating system.
Performance of Symydobius americanus (Homoptera: Aphididae) on paper birch grazed by caterpillars
Authors: MARTIN MARC‐ANDRÉ , CAPPUCCINO NAOMI , DUCHARME DOMINIC
Published: March 2008

Abstract.

The potential for host plant‐mediated interactions between leaf‐chewers and the aphid Symydobius americanus on paper birch (Betula papyrifera) was investigated experimentally.

Datana ministra and Malacosoma disstria caterpillars were caged on randomly chosen, undamaged branches until they had eaten 30–50% of the leaf area. Control branches received cages but no larvae.

Alates of S.americanus were than caged on the experimental and control branches to assess the effect of chewing damage on colony performance.

Chewing damage had no detectable effect on initiation of alate reproduction, development time, mortality of nymphs or colony growth rate.
The feeding behaviour of Carterocephalus palaemon (Lepidoptera: Hesperiidae) caterpillars: does it avoid host defences or maximize nutrient intake?
Authors: RAVENSCROFT N. O. M.
Published: March 2008

Abstract.

The larvae of the chequered skipper butterfly Carterocephalus palaemon notch the blades of purple moor‐grass Molinia caerulea before feeding.

The nutrient concentrations above and below these notches were measured and the nutrient concentrations of undamaged blades of the host plant.

Nutrient concentrations above the notches remained similar to undamaged blades for a short period, whilst concentrations below declined, especially nitrogen, calcium and magnesium.

The feeding behaviour of C.palaemon larvae is discussed in relation to declining levels of nutrients in the food plant over the larval season and to other possible reasons for this behaviour, such as avoidance of host defences initiated in response to attack.
Host‐plant effects on Parasyrphus melanderi (Diptera: Syrphidae) feeding on a willow leaf beetle Chrysomela aeneicollis (Coleoptera: Chrysomelidae)
Authors: RANK NATHAN E. , SMILEY JOHN T.
Published: March 2008

Abstract.

Generalist predators are repelled by chrysomelid (Chrysomela spp., Phratora vitellinue L.) larval defensive secretions that are obtained from salicin in their host plants. But little is known about the effect of these secretions on specialist predators.

In this study, we describe the feeding behaviour of a fly, Parasyrphus melanderi Curran (Diptera: Syrphidae), which feeds on Chrysomela aeneicollis Schaeffer (Coleoptera: Chrysomelidae). Parasyrphus melanderi lays its eggs on C.aeneicollis egg clutches, and its larvae consume C.aeneicollis eggs and larvae.

Chrysomela aeneicollis hatching rates were significantly lower (20%) on clutches with fly eggs than on clutches without them (40%). Half of the clutches with one fly egg had survival rates below 5%, and when two fly eggs were present (four clutches), the entire clutch was consumed.

In nature, P.melanderi eggs were 3 times more abundant on a salicylaterich willow species S.orestera Schneider, than on the medium‐salicylate S.geyeriana Anderss. (1.8 v 0.6 eggs per clutch). On 18% of the S.orestera clones, all the beetle clutches contained fly eggs. In laboratory‐choice tests, P.melanderi larvae fed equally rapidly on C.aeneicollis larvae that were chemically defended (feeding on S.orestera) as on larvae that produced no secretion (feeding on the salicylate‐poor S.lutea Nutt.). This predator does not appear to be deterred by C.aeneicollis's defensive secretion. We discuss the implications of specialist predators on determining host suitability to herbivorous insects.
Oviposition substrate affects adult mortality, independent of reproduction, in the seed beetle Callosobruchus maculatus
Authors: FOX CHARLES W. , TATAR MARC
Published: March 2008

Abstract.

Seed beetles (Coleoptera: Bruchidae) are commonly used to study the influence of reproduction on life‐span and senescence. To study the physiological trade‐off between reproduction and mortality, many experiments rely on manipulating access to oviposition substrates to manipulate the reproductive rate of females.

The presence of host seeds, independent of reproduction, results in increased mortality of female Cullosobruchus muculutus. This influence on mortality varies between two host seed species, suggesting a role of either allelochemicals or energetic costs associated with behaviour on hosts.

The influence of host seeds on survivorship, independent of reproduction, confounds the interpretation of cost‐of‐reproduction studies with seed beetles. This complication must thus be considered in the design and interpretation of life‐history studies of seed beetles and other insects.
The effects of host plant phenology on the demography and population dynamics of the leaf‐mining moth, Cameraria hamadryadella (Lepidoptera: Gracillariidae)
Authors: CONNOR EDWARD F. , ADAMS‐MANSON ROBERT H. , CARR TIMOTHY G. , BECK MICHAEL W.
Published: March 2008

Abstract.

We examined the effects of variation in the timing of spring leaf production and autumn leaf fall on the survival, mortality and abundance of Cameraria hamadryadella on Quercus alba and Q.macrocarpa.

We monitored and manipulated the timing of foliation on field and potted Q.alba trees and observed the abundance of C.hamadryadella on those trees. We also monitored and manipulated the timing of leaf fall on Q.alba and Q.macrocarpa trees in the field and observed its effects on survival, mortality and abundance of C.hamadryadella.

Variation in the timing of spring leaf production has no effect on C. hamudryadella abundance. However, a warm winter and spring in 1991 led to accelerated development and the imposition of a facultative third generation in one out of ten years of observation.

In 1989, leaves fell relatively early and leaf fall in the autumn accounted for more than 50% of the mortality of C.hamudryadella. in 1990 and 1991 leaves fell relatively late and leaf fall induced mortality was substantially reduced and overwinter survival was markedly increased.

The abundance of C.hamadryadella remained constant in the spring and summer of 1990 following the previous autumn's relatively early leaf fall, but increased by 10‐fold in the spring of 1991 following the relatively late leaf fall of autumn 1990. The abundance of C.hamadryadella also increased 4‐fold between the summer of 1991 and the spring of 1992 after another autumn of relatively late leaf fall. We attribute these increases in abundance in part to reduced mortality because of later leaf fall.

Variation in the timing of autumn leaf fall may be responsible for initiating outbreaks of C.hamadryadella.
Optimum body size in aphids
Authors: DIXON A.F.G. , KINDLMANN P.
Published: March 2008

Abstract.

Smallness in British plant‐sucking bugs is associated with feeding on the contents of individual plant cells, especially phloem.

The sizes of species of aphids living in similar habitats and the rates of water loss from those that have and lack a filter chamber do not support the contention that small size in aphids is a means of maximizing the loss of water by cuticular transpiration.

An optimum energy partitioning model, previously developed for aphids, was used to predict the interspecifie relation between adult weight and birth weight that would maximize the population growth rate, rm. Using the observed rm/IRGR ratio (0.8–0.9) and that the gonads are smaller than the soma at birth the predicted relation between the logarithm of the adult weight and the logarithm of the birth weight is linear and has a slope of 1.

The relation between the logarithm of the adult weight and the logarithm of the birth weight for eighteen species of aphids is linear and has a slope of 1.

Birth size differs between species of aphids and in each species is assumed to be the minimum size necessary for feeding. Accepting this constraint then the optimum adult size for maximizing rm is approximately 15 times the birth size.
Host range expansion by British moths onto introduced conifers
Authors: FRASER SIMON M. , LAWTON JOHN H.
Published: March 2008

Abstract.

Over 2% of British angiosperm‐feeding moths (Lepidoptera) have been recorded feeding on conifers introduced to Britain, and may be undergoing host range expansion.

We compared some of the life‐history traits and ecological characteristics of fifty such species, originally exploiting angiosperms and now recorded feeding on conifers, with those of 400 non‐shifting angiosperm‐feeding moths, to identify those factors linked with host shifting.

Shifting species attack a wider range of angiosperms than non‐shifting species, their original hosts tend to be woody tress and shrubs, and they hatch from the egg earlier in the year.

Comparisons with the random control samples suggest that larval feeding habit and overwintering stage are also important (species with less intimate relations with the host plant, and those overwintering as eggs are more likely to shift); these trends persisted when the taxonomic distribution of the shift species was controlled for, though were no longer significant.

Moth species in habitats and on host plant families which are associated with conifer afforestation in upland Britain are more likely to shift, suggesting that ecological opportunity is an important factor in host range expansion.
Herbivorous insect species in the tree canopy of a relict South African forest
Authors: MORAN V.C. , HOFFMANN J. H. , IMPSON F. A. C. , JENKINS J.F.G.
Published: March 2008

Abstract.

The herbivorous insects on twelve species of evergreen broadleafed trees were repeatedly sampled over a period of 11 months in a small relict forest on the east coast of South Africa. This extraordinarily speciose forest patch has an unusually high proportion of endemic tree species, some of which are extremely rare.

The insect herbivore fauna (number of species) seems to be markedly depauperate compared to that reported on native, broadleafed trees from other parts of the world. Some possible reasons for this are discussed.

The total number of herbivorous insect species on each tree species was strongly correlated with the local relative abundance of the host plant species.

There was no relationship between the total number of insect herbivore species on each tree species and the relative taxonomic isolation of the trees. The proportion of seemingly unique (= specialist) herbivorous insect species (i.e. those that occurred on one tree species only) was greatest on taxonomically isolated trees.

A fundamental deficiency in the interpretation of the data in this study, and of many other similar studies that report on the number of insect species on plants, is discussed, namely the lack of clarity on the closeness of the association between individual insect herbivore species and their respective host plants.
Relation between temporal persistence of host plants and wing length in leafhoppers (Hemiptera: Auchenorrhyncha)
Authors: NOVOTNý VOJTĚCH
Published: March 2008

Abstract.

Wing form frequencies in 255 populations of 101 species of leafhoppers (Auchenorrhyncha) in temporary and permanent habitats were documented.

The proportion of brachypterous specimens in the leafhopper assemblages on ruderal host plants in temporary habitats (median 2%, range 0–8%) was significantly lower than that on permanent host plants in undisturbed habitats (median 22%, range 0–94%).

Leafhopper species typical of temporary habitats were either monomorphic, macropterous, or wing‐dimorphic with macropterous forms prevailing in both sexes.

Among the eighty‐nine species recorded in permanent habitats, forty‐five species were wing dimorphic. In forty‐one dimorphic species, a brachypterous form prevailed. This prevalence was found for both sexes in thirty‐one species, for only females in nine species and for only males in one species.

The prevalence of brachypters in males, but not in females, found in Anoscopus flavostriatus, is probably the first such documented case in Auchenorrhyncha.

The hypothesis is proposed that in temporary habitats, density‐dependent production of macropters in wing dimorphic species is an adaptation to frequent habitat deterioration caused by factors independent of the density of the species.

The predominance of brachypters in permanent habitats indicates that a density‐dependent decrease in fitness usually does not offset the potential decrease in fitness connected with macroptery and dispersal. Because of this inability of leafhopper populations to decrease significantly the quality of their resources, a high population density cannot be used as a predictor of future quality of these resources, which is information essential for efficient dispersal behaviour.
Parasitism and predation as agents of mortality of winter moth populations in neglected apple orchards in Nova Scotia
Authors: PEARSALL I.A. , WALDE S.J.
Published: March 2008

Abstract.

This study compared the roles of pupal mortality and parasitism in winter moth (Operophtera brumata) population dynamics in Nova Scotian apple orchards and assessed the importance of beetles as pupal predators.

The component of pupal mortality termed predation accounted for greater stage‐specific mortality of winter moth than parasitism by Cyzenis albicans in four neglected orchards.

Parasitism by Cyzenis albicans was not spatially density‐dependent in any orchard, whereas the predation component of pupal mortality was spatially density‐dependent in the two orchards most densely populated by winter moth.

Field experiments indicated that over 60% of pupal predation may be attributed to beetles, and that about 46% of pupal predation occurred within 4 weeks after pupal drop.

Mortality of introduced populations of winter moth in Nova Scotia resembles that of native populations in England where density‐dependent predation regulates the winter moth population and reduces the parasitoid population to minimal levels. The situation in Nova Scotia appears to have changed appreciably since the establishment of parasitoids into the system in the 1950s.
Effects of scale on detecting interactions between Coleophora and Eriocrania leaf‐miners
Authors: VALLADARES G. R. , HARTLEY S. E.
Published: March 2008

Abstract.

The possibility of interactions between leaf‐miners in the genus Eriocrania and Coleophora serratella L. on birch (Betula pendula Ehrh. and B.pubescens Roth.) was studied via: (i) co‐occurrence patterns on random samples of leaves; (ii) palatability of Eriocraniidae‐mined leaves to C.serratella, in laboratory and field preference tests.

In the field, C.serratella and Eriocrania spp. fed on common leaves less frequently than expected by chance. This result is consistent with, and could be explained by, the avoidance of mined leaves shown by C.serratella in most of the feeding trials.

Avoidance was not observed at the between‐tree level, i.e. the number of leaves mined by each type of insect was unrelated. However, when tree species was taken into account, an inverse distribution was observed: mine abundance was higher for Eriocrania spp. on B.pubescens, whereas for C.serratella it was higher on B.pendula.

B.pubescens leaves mined by Eriocrania spp. had consistently higher phenolic contents and were better at precipitating proteins than unmined leaves. These induced chemical changes could explain the reduced preference shown by C.serrate1la for Eriocrania mined leaves.

We speculate about the evolution of adult host‐plant selection shown by these insects in response to potential larval interactions.
On the relationship between food, reproduction and survival of two carabid beetles: Calathus melanocephalus and Pterostichus versicolor
Authors: VAN DIJK TH. S.
Published: March 2008

Abstract.

The relative influences of temperature and availability of food on reproduction, survival and growth of all developmental stages of two carabid beetle species are discussed with special reference to the suggested relationship between availability of food, size of egg production and survival of adults from one breeding season to the next.

Temperature as well as food supply influence the length of larval growth and adult body size. Beetles grown at low temperatures and low amounts of food are smaller than those grown at higher temperature and with more food.

The number of eggs laid per female was correlated with the amount of food gathered. There was no inverse relationship (trade‐off) between reproductive output and survival in the field until the next breeding season.

In 1980 no significant relationship was found between winter mortality and the amounts of food gathered by beetles in the period after reproduction and before winter diapause. However, in 1981 in C. melanocephalus a lower number of starved beetles survived the winter than the fed ones and‘field’beetles.

Only in the first part of the feeding activity period in autumn can enough food be gathered by C.melunocephalus for successful hibernation. In the second part of this period there is not enough food to build up the fat reserves needed to survive the winter.

Difference in population fluctuations of both species are discussed in relation to their life histories.
Reproductive seasonality in tropical satyrine butterflies: strategies for the dry season
Authors: BRABY M. F.
Published: March 2008

Abstract.

In tropical savanna environments rainfall is often very seasonal, so that much of the year is characterized by a long and unpredictable dry season. Because the timing and availability of rain exerts a major influence on plant growth and production, many species during the dry period exhibit dramatic reduction in leaf quality. Accordingly, and kind of behaviour shown by phytophagous insects that synchronizes larval feeding with food availability will be adaptive.

The reproductive status of three Mycalesis butterflies was monitored over a 2‐year period (1989–90) in north‐eastern Queensland, Australia, at a lowland site (Cardwell, 18°16's, 146°02′E) which experiences a pronounced dry season. Females of these species and of five other satyrines (Ypthima, Hypocysta spp.) were also examined less intensively during the dry season in areas throughout northern and central Queensland, north of the tropic of Capricorn.

These relatively sedentary butterflies exhibit three different strategies for dealing with the unpredictable dry period and associated deterioration of larval food plants (grass). First, five species appear to breed continuously, though for most reproductive activity (mature egg number) declines markedly in the late dry season. Two of these (Hypocysta irius, H.metirius) are restricted to less seasonal and more favourable (wetter) areas but the three others (Ypthima arctous, H.adiante, H.pseudirius) occur widely in the relatively dry savanna, where they may specialize on grass in moister microenvironments. Second, two species (M.terminus, M.sirius) live in predictably moist habitats which are buffered from climatic extremes; they breed for much of the season but reproductive activity declines as the dry season progresses and may cease late in the season. Third, one species (M.perseus) is more opportunistic, breeding for only a limited interval during the favourable (wet) periods; during the long dry season adults contract to moist refugia and remain in reproductive diapause.

Spending the late dry season as an adult, either in diapause or with mature eggs, may improve the capacity to utilize new growth of grasses at the start of the favourable season, thereby enhancing population growth during good times. It may also provide additional flexibility to counter the temporal uncertainty of the dry season.

The strategy of residing in more equitable habitats or specializing on predictable foods may be the most restrictive in terms of distribution.
The effect of season and group size on survivorship and larval growth in Plagiodera versicolora
Authors: CROWE MARY L.
Published: March 2008

Abstract.

The larvae of the multivoltine imported willow leaf beetle, Plagiodera versicolora (Laicharting), are found in larval aggregations during the first half of the larval stage. An experimental study was conducted to test for seasonal (brood) and group size effects on larval fitness. For each of the three broods, egg group sizes of1, 4, 8, 16, 24 and 32 were established in the field and monitored for the first 6 days post‐hatching.

There was no effect of group size on larval weight, but there was a significant effect of group size on survival. Individuals from group size 16 had the highest survival, which coincides with the mean natural cluster size of 15.3 eggs.

There were no significant interactions between brood and group size.

The effect of larval weight on adult fitness was determined in the laboratory and the field. Larval weight was correlated with egg production in the laboratory but not in the field.
Genetic differentiation as a result of adaptation to the phenologies of individual host trees in the galling aphid Kaltenbachiella japonica
Authors: KOMATSU TADASHI , AKIMOTO S.
Published: March 2008

Abstract.

The adaptation of the non‐migratory galling aphid Kaltenbachiella japonica (Matsumura) to the budburst phenologies of individual host trees (Ulmus davidiana var. japonica Nakai) was investigated. There was a large variation in budburst time between individual host trees. We tested a hypothesis that aphid populations on respective host trees are genetically differentiated through adaptation to the budburst phenologies of host trees.

There was significant correlation between the budburst time of eight host trees in two successive years.

Tree‐associated populations differed significantly in egg‐hatching time, and the mean hatching time was significantly correlated with the mean budburst time of respective host trees.

Mating was made between male and female sexuales of the same clone (i.e. self‐mating) to obtain selfed eggs. Hatching patterns of selfed eggs showed that there was a substantial amount of genetic variance in hatching time between clones (galls). Nested ANOVA demonstrated that the between‐tree component contributed more to the phenotypic variance than the within‐tree or within‐gall components.

Reciprocal crosses between males and females of different clones furthermore demonstrated significant differences in hatching time between cross combinations, but no significant differences between the two reciprocals within combinations. This result suggests that there are no maternal effects for the timing of egg hatch and that the differences between selfed lines are attributable to genetic variance.

The fine‐scale adaptation hypothesis was supported by egg‐hatching experiments, which further suggest that budburst phenology varying between individual trees is acting as intense selective pressure on the egg‐hatching time of associated insects.
Population biology of swift (Apus apus) ectoparasites in relation to host reproductive success
Authors: LEE PATRICIA L. M. , CLAYTON DALE H.
Published: March 2008

Abstract.

We censused ectoparasite populations of adult and nestling swifts over the course of the host's breeding season. Nearly all of the birds were infested with chewing lice and two‐thirds of the nests were infested with louse flies. Feather mites were observed but not quantified.

Lice and louse flies both showed aggregated distributions among hosts. Louse eggs, hatched lice and adult louse flies had negative binomial distributions, whereas the aggregated distribution of louse fly pupae was not adequately described by negative binomial or Poisson models.

Transmission of lice from parents to offspring was documented. A comparison of the age structure of lice on parents and offspring indicated that most transmission was by nymphal lice.

Host reproductive success and survival appeared to be independent of the number of lice or louse flies. Neither parasite correlated with the number, body mass, or date of fledging of young birds, nor with the overwinter survival of adults. We caution, however, that experimental manipulations of parasite load are required for a definitive test of the impact of ectoparasites on evolutionary fitness components.
Larval age differences and competition between Drosophila aldrichi and D.buzzatii
Authors: KREBS ROBERT A. , BARKER J. S. F.
Published: March 2008

Abstract.

Competitive interactions among larvae of Drosophila species using the same habitat will usually involve individuals varying in age and size. Older, larger larvae might be expected to outcompete younger, smaller larvae.

Newly hatched laryae of Drosophila aldrichi and D.buzzatii were placed on induced cactus necroses (simulating the natural habitat), either simultaneously, or with a 1 or 2 day difference in the time at which individuals of the other species were added.

Evidence for competitive differences with larval age were found. In both species, body weight was significantly higher for those larvae added first than for later addition larvae, and a longer time to complete development was required for those larvae added 2 days later. However, pre‐adult viability of D.aldrichi was significantly higher for larvae started 1 or 2 days after larvae of D.buzzatii. For D.buzzatii, viability was lowest for larvae started simultaneously with D.aldrichi, but not different between those started either before or after D.aldrichi.

Considering all three traits, no clear advantage for the early addition larvae was observed.
Coexistence of competing species of seaweed flies: the role of temperature
Authors: PHILLIPS DAVID S. , LEGGETT MARGARET , WILCOCKSON RAY , DAY THOMAS H. , ARTHUR WALLACE
Published: March 2008

Abstract.

Competition is shown to be occurring within and between the congenersCoelopa frigidaandC.pilipes;it is noted that the two species frequently coexist despite ongoing competition.

Observations on natural wrack‐beds indicate that there is a marked difference in the distributions of the larvae:C.frigidalarvae aggregate in cooler parts of the bed,C.pilipesin warmer parts. This difference in microdistribution reflects a broader‐scale difference in the geographical distributions of the species ‐C.pilipesbeing the more southerly of the two.

The larval distributions are shown to be caused primarily by the behaviour of the larvae themselves ‐ not by choices made by ovipositing females, nor (at least to any great extent) by differential survival.

The different micro‐distributions within beds constitute a form of niche difference which will cause competitive abilities to be frequency‐dependent and hence have a stabilizing effect. It is possible that this effect may be supplemented by others; and, in particular, effects operating at the level of the‘linear meta‐population’may be worthy of further investigation both inCoelopaand in other coastal species.
Clumped distribution patterns in goldenrod aphids: genetic and ecological mechanisms
Authors: PILSON DIANA , RAUSHER MARK D.
Published: March 2008

Abstract.

The aphids Uroleucon tissoti and U.nigrotuberculatum both exhibit significantly aggregated distribution patterns across clumps of their common host plant Solidago altissima, the tall goldenrod. However, U.nigrotuberculatum is significantly more aggregated than is U.tissoti. We tested the hypothesis that goldenrod genotype‐by‐U.tissoti genotype interactions for aphid performance characters could partially account for this difference.

Only one of the characters we measured showed a significant genotype‐bygenotype interaction; therefore it is unlikely that such interactions affect the distribution of U.tissoti across goldenrod stems.

In addition, we found that three environmental variables (genetic variation for resistance to herbivory, host plant morphology, and local host density) affect the degree of aggregation found in both U.tissoti and U.nigrotuberculatum populations.
Distribution of male yellow dungflies around ovipasition sites: the effect of body size
Authors: SIGURJÓNSDÓTTIR HREFNA , SNORRASON SIGURðUR S.
Published: March 2008

Abstract.

Spatial and temporal variation in body size of yellow dungflies, Scatophaga stercoraria, gathering on and around cow droppings was studied in an Icelandic population in order to elucidate the effect of male and female size on male mating tactics.

Males copulating on droppings were on average larger than males copulating in the grass, but of similar size to males guarding ovipositing females. Males searching on droppings were smaller than males copulating or guarding females on droppings but larger than males copulating in the grass. No such differences were found in female size.

Resource‐holding power of males (RHP, i.e. male: female size ratio) differed between the three mating groups and was highest for males on the droppings. Size and RHP clearly affect the tactics of copulating males. Males with low RHP tend to copulate in the grass in spite of the cost of longer copulation duration. We argue that this is caused by risk of takeovers from large searching males.

There was no change in male size with the age of individual droppings. Contrary to what might be expected, large searching males are not predominantly found at fresh droppings when the probability of catching unpaired females is highest. We suggest instead that good prospects in taking females over from other males must make the strategy to search for females on older droppings profitable.

RHP did not change with age of dropping in the three mating groups. The size of ovipositing females increased with age of dropping, probably reflecting longer copulation and egg‐laying times of large females.

We found an overall positive relationship between sizes of male and female partners. This correlation was highly significant for copulating pairs in the grass. This is probably a consequence of males with low RHP copulating in the grass and fights in which larger males take over females from smaller males. A weaker, but significant, correlation was found amongst ovipositing pairs. This must be due to take‐over effects. No size correlation was found for pairs copulating on droppings.
Effect of leaf litter and density on fitness and population performance of the hole mosquito Aedes triseriatus
Authors: LÉONARD PASCALE M. , JULIANO STEVEN A.
Published: March 2008

Abstract.

We tested the effects of food, in the form of leaf litter, and density on population growth and fitness correlates of the tree hole mosquito Aedes triseriatus. Our field experiment used a 2 x 2 randomized block design, with three holes as blocks. In cages within three holes, we manipulated densities of Aedes triseriatus larvae, and presence of leaf litter. Our laboratory experiment used a 2 x 3 factorial design in which we also manipulated densities of larvae and availability of leaf litter within similar cages (inside, outside, or absent). For both experiments we determined effects on survival, days to and mass at eclosion of both sexes, and a composite index of population performance λ′, that estimates finite rate of increase.

In the field experiment, we found significant and large effects of leaf litter and of density on the performance of A. triseriatus. The effect of density did not depend on leaf litter availability. We documented significant variation among tree holes for most correlates of fitness. Often, the effects of treatments varied significantly depending on the tree hole tested.

In the laboratory experiment we found significant effects of density and litter, and that direct browsing on leaf litter is necessary for the effect of litter on performance of A. triseriatus. In the laboratory, the negative effect of increased density was dependent on leaf litter availability.

Our results demonstrate that leaf litter has important effects on population performance of tree hole mosquitoes in natural tree holes. Direct browsing on the surface of leaf litter is the most likely mechanism by which litter enhances population growth. The impact of litter on populations varies among tree holes.
Intraspecific variation in host plant quality: the aphid Cinara cupressi on the Mexican cypress, Cupressus lusitanica
Authors: MEMMOTT J. , DAY R. K. , GODFRAY H. C. J.
Published: March 2008

Abstract.

In Kenya, the aphid Cinara cupressi (Buckton) has an aggregated distribution across individuals of its host plant, the Mexican cypress, Cupressus lusitanica (Mill).

There are significant differences in host plant quality: C.cupressi nymphs transplanted onto cypress trees with low aphid infestations are significantly less likely to establish than aphids transplanted onto trees with high aphid infestations.

Given that some transplanted nymphs establish, the previous level of infestation does not influence aphid survival.

Evidence for local adaptation to individual plants was not found: nymphs transplanted to the trees from which their parents were collected neither established more readily nor showed lower mortality than those transplanted to other trees with similar levels of infestation. Therefore the variation in host plant quality has not led to the development of local adaptation to particular host plants.
Coastal insect herbivore communities are affected more by local environmental conditions than by plant genotype
Authors: STILING PETER , ROSSI ANTHONY M.
Published: March 2008

Abstract.

We compared the effects of plant genotype and local environment on population densities of a community of coastal insect herbivores in west‐central Florida. Reciprocal transplants of four genotypes of three species of coastal plants, Borrichia frutescens, Iva frutescens and Limbricata, were made in July 1992 between a series of off‐shore islands.

For each plant species, phytophagous insects with a wide range of feeding modes including gall‐makers, stem borers, leaf miners and sap suckers were affected more by local environment than by plant genotype. Whereas host genotype had a significant effect on the population densities of gall‐makers on B.frutescens in the spring of 1993, no significant effect on the denrities of any other insect species was found and the effect on the gall‐makers on Borrichia disappeared in the summer, 1 year after the transplants had been made. In our study, local environment had by far the greatest effect on insect population densities among islands. This is an unusual result because in other studies over 80% of the insect species examined have been affected by plant genotype (Karban, 1992). This result is consistent with that reported by Stiling (1994), who censused populations of two phytophagous insects on reciprocal transplantr ot Borrichia in north Florida.

Local environment also had an effect on insect population densities within islands. This result contrasts with similar studies performed in north Florida (Stiling, 1994), where population densities did not differ within areas, and underlies how some biotic processes may change with in the same community even over relatively small changes in species range.
Distribution and spacing of Drosophila mycetophaga flies on bracket fungi used as mating arenas
Authors: ASPI JOUNI , HOFFMANN ARY A.
Published: March 2008

Abstract.

To understand the nature of male aggregations in Drosophila mycetophaga, data were collected on male and female distribution and male spacing on bracket fungi used as mating arenas in cool rainforests of south‐eastern Australia.

Both males and females appeared to be aggregated among bracket fungi that were used as mating arenas. Females were associated with large male aggregations. The probability of a fungus being occupied increased with its area. However, a multiple Poisson regression analysis suggested that fungus area did not affect female distribution when male number was controlled.

The presence of female breeding and feeding resources did not determine where aggregations were formed, because there were aggregations on fungi without resources, and fungi with resources were not used more often than those without them.

D.mycetophaga males did not select and defend territories within bracket fungi, and did not determine female access to areas. However, males were more evenly spaced than expected on the basis of a random distribution, suggesting that males kept apart from each other.

The distribution of the different sexes and male spacing pattern supports the interpretation that D.mycetophaga has a lek mating system.
Sexually transmitted disease in a promiscuous insect,Adalia bipunctata
Authors: HURST GREGORY D. D. , SHARPE ROSIE G. , BROOMFIELD ANGELA H. , WALKER LINDA E. , MAJERUS TAMSIN M. O. , ZAKHAROV ILIA A. , MAJERUS MICHAEL E. N.
Published: March 2008

Abstract.

Sexually transmitted diseases (STDs) have rarely been reported in insects and other invertebrates. The majority of those reported involve organisms where sexual transmission is augmented by either vertical (i.e. inherited) transmission, or horizontal transmission, independent of host sexual activity.

We here demonstrate the existence of an STD in the coccinellid beetleAdalia bipunctata. This species bears a parasitic mite of the genusCoccipolipus. We show that, like many other podapolipid mites, this mite is transmitted between host individuals at a high rate during copulation. It also appears to be transmitted at a low rate between non‐copulating individuals.

We show that infected femaleA.bipunctataproduced eggs at a reduced rate, and that the eggs produced by infected females have highly decreased viability. However, no effect of infection upon host longevity was observed.

The results are discussed in relation to the incidences of sexually transmitted disease in invertebrates in general, the causes of disease symptoms, and the importance of this disease in the evolution ofA.bipunctata.
Do trees in urban or ornamental plantings receive more damage by insects than trees in natural forests?
Authors: NUCKOLS MICHAEL S. , CONNOR EDWARD F.
Published: March 2008

Abstract.

To determine if trees in urban or ornamental plantings are more susceptible to attack and receive more damage to foliage by herbivores than trees in natural forests, we compared the amount of leaf damage caused by several guilds of insects feeding on seven species of native, broadleaf trees in two geographic locations.

Total leaf damage did not differ significantly between urban or ornamental and natural forests, although trees in natural forests tended to have slightly higher levels of leaf damage.

Damage caused by chewing insects was consistently higher on trees in natural forests than in urban or ornamental plantings. All other feeding guilds showed no consistent pattern in levels of damage between the two habitats.

Total damage levels were highest on canopy trees and lowest on understorey trees.

These results are inconsistent with the view that trees in urban or ornamental settings are more susceptible to insect attack than trees in natural forests.

The lower level of foliar damage caused by chewing insects on trees in urban or ornamental plantings may arise because of low rates of dispersal by insects into urban environments, higher levels of plant resistance to insect attack in urban or ornamental plantings, or lower survival rates of herbivorous insects in urban environments.