bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reproductive allocation and reproductive ecology of seven species of Diptera
Authors: Bonduriansky Russell , Brooks Ronald J. 
Published: March 2003

Summary1. Variation in resource allocation to egg size and number was investigated in seven sympatric species of Piophilidae that oviposit on carcasses or discarded cervid antlers: Liopiophila varipes (Meigen), Prochyliza xanthostoma Walker, Protopiophila latipes (Meigen), Protopiophila litigata Bonduriansky, Stearibia nigriceps (Meigen), and two unidentified species of Parapiophila McAlpine.2. Following optimal reproductive allocation theory, relatively larger, fewer eggs were expected in (1) species that oviposit on antlers, where larvae probably experience lower risk of predation and greater competition than larvae in carcasses, and (2) species with aggressive males and male‐biased sex ratios on the oviposition substrate, where risk of injury during oviposition may have favoured females laying fewer eggs.3. Variation in reproductive allocation strategies could not be explained by known differences in larval or adult environment, but congeneric species clustered by reproductive allocation patterns. The Parapiophila species produced larger, fewer eggs than the other species, and egg number increased slowly with body size. The Protopiophila species did not deviate from expected egg sizes and numbers, and egg number increased steeply with body size.4. An interspecific egg size–egg number trade‐off resulted in a tight linear scaling of ovary volume to body size, suggesting common physiological constraints on relative ovary mass.5. Within each species, egg size was nearly constant whereas egg number increased with female body size, suggesting species‐specific stabilising selection on egg size.
Influence of host size on oviposition behaviour and fitness of Elachertus cacoeciae attacking a low‐density population of spruce budworm Choristoneura fumiferana larvae
Authors: Fidgen Jeffrey G. , Eveleigh Eldon S. , Quiring Dan T. 
Published: March 2003

Summary1. Oviposition behaviour and host size − fitness relationships of a gregarious, idiobiont ectoparasitoid, Elachertus cacoeciae (Howard) (Hymenoptera: Eulophidae), were studied by implanting one fourth‐, fifth‐, and sixth‐instar spruce budworm Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae) larva per tree in a stand where the density of the wild C. fumiferana population was low.2. Development time of E. cacoeciae larvae was quickest on fifth‐instar C. fumiferana larvae, which were the preferred hosts for oviposition.3. Brood sex ratio (proportion of females) was related positively to increasing C. fumiferana instar, indicating that more females were laid on larger hosts.4. Parasitoid offspring size increased with increasing C. fumiferana instar and decreased with increasing brood size on smaller hosts. Female but not male size was related positively to increasing brood sex ratio (proportion of females).5. Under laboratory conditions, parasitoid longevity was related positively to parasitoid size and realised lifetime fecundity, and clutch size was related positively to host size.6. These results suggest that selection of intermediate‐sized C. fumiferana larvae may be adaptive for E. cacoeciae.
The effects of abiotically induced changes in host plant quality (and morphology) on a salt marsh planthopper and its parasitoid
Authors: Moon Daniel C. , Rossi Anthony M. , Stiling Peter 
Published: March 2003

Summary1. In this study, the effects of shading and fertilisation on the density of the salt marsh planthopperPissonotus quadripustulatus(Homoptera: Delphacidae), which is monophagous onBorrichia frutescens(Asteraceae), were assessed. The effects of these abiotic factors on the rate at whichPissonotuseggs were parasitised byAnagrussp. nrarmatus(Hymenoptera: Mymaridae) were also examined.2. Field plots were shaded by shade cloth suspended above the plots, and fertilised by the application of NH4NO3fertiliser. Both shading and fertiliser increased plant foliar nitrogen levels significantly. Both shading and fertiliser also increased the density ofPissonotus, presumably because of their effect on plant quality.3. In addition, both shading and fertiliser increased the percentage ofPissonotuseggs parasitised byAnagrus. This increase in parasitism is probably attributable to changes in host plant morphology induced by the treatments.4. The results of this study suggest that in stressful environments such as salt marshes, changes in the abiotic environment may play an important role in shaping the community by directly affecting organisms on multiple trophic levels.
The relationship between host selection behaviour and offspring fitness in a koinobiont parasitoid
Authors: Rivero Ana 
Published: March 2003

Summary1. When host quality varies, optimal foraging theory assumes that parasitic wasps select hosts in a manner that increases their individual fitness. In koinobiont parasitoids, where the hosts continue developing for a certain period of time after parasitisation, host selection may not reflect current host quality but may be based on an assessment of future growth rates and resources available for the developing larvae.2. When presented with hosts of uniform quality, the koinobiont parasitoid Leptomastix dactylopii exhibits a characteristic host‐selection behaviour: some hosts are accepted for oviposition on first encounter, while others are rejected several times before an egg is laid in them, a behaviour that is commonly associated with a changing host acceptance threshold during the course of a foraging bout.3. The fitness of the offspring that emerged from hosts accepted immediately upon encounter was compared with the fitness of offspring emerged from hosts rejected several times before being accepted for oviposition.4. The pattern of host acceptance and rejection was not related to any of the measured fitness parameters of the offspring emerging from these hosts (development time, size at emergence, sex ratio at emergence, and female offspring egg load).5. While complex post facto adaptive explanations can be devised to explain the nature of such a time and energy consuming host selection process, it is suggested that physiological constraints on egg production or oviposition may provide an alternative, purely mechanistic, explanation for the results obtained.
Foraging behaviour of caterpillars given a choice of plant genotypes in the presence of insect predators
Authors: Stamp Nancy E. , Bowers M. Deane 
Published: March 2003

Summary1. To examine the effects of predators and plant genotype on the behaviour, patterns of herbivory, growth, and survivorship of caterpillars, an experiment was conducted under semi‐natural conditions, with two host plant genotypes (low vs. high iridoid glycosides) of plantain Plantago lanceolata, two kinds of herbivores (noncryptic specialist Junonia coenia vs. cryptic generalist Pyrrharctia isabella), and two levels of caterpillar predation (with and without Podisus maculiventris stinkbugs).2. Choice tests conducted in the laboratory showed that in three out of four cases, caterpillars preferred leaves from the low iridoid glycoside genotype.3. In the field experiment, the presence of predators affected the amount of leaf material eaten per plot and the proportion of leaf material eaten by the caterpillars as expected, but it did not affect the use of plant genotypes by Junonia caterpillars within the plots. In contrast, the caterpillar density–predation treatments affected the proportion of leaves eaten by Pyrrharctia caterpillars that were of the low iridoid glycoside genotype, but not entirely as expected. The caterpillars used both genotypes equally when predators were present but the high iridoid glycoside genotype was used more by caterpillars at low density and without predators.4. The message then is that on the scale that caterpillars could be choosy about intake of iridoid glycosides they were not choosy among plant genotypes; however they were choosy between leaves, which can differ in iridoid glycoside concentration via plant genotype and leaf age.
The role of olfactory stimuli in the location of weakened hosts by twig‐infestingPityophthorusspp.
Authors: Bonello Pierluigi , Mcnee William R. , Storer Andrew J. , Wood David L. , Gordon Thomas R. 
Published: March 2003

Summary1. Senescing, shade‐suppressed, or broken branches of Monterey pinePinus radiataare infested by twig beetles in the genusPityophthorus(Coleoptera: Scolytidae). The studies reported here tested whether twig beetles can discriminate between healthy and pitch canker‐diseased branches, whether diseased branch tips produce more ethylene than undamaged controls, and whether ethylene and other volatiles, produced by the plant in response to tissue damage, are utilised by twig beetles in host location.2. Significantly greater numbers of twig beetles were reared from pitch canker‐symptomatic than from pitch canker‐asymptomatic branches of Monterey pine collected in the field.3. Needles of Monterey pine branches inoculated with the pitch canker fungal pathogenFusarium circinatumproduced significantly higher levels of ethylene than needles of control branches, and this was evident just prior to, and during, symptom expression.4. In trapping studies in which pheromone production was prevented, there was no evidence of attraction of twig beetles to a source of ethylene alone, to cut host branches, or to cut branches treated with the ethylene‐releasing compound, ethephon. The results suggest that twig beetles identify weakened branches after landing.
The response of Hyssopus pallidus to hosts previously parasitised by Ascogaster quadridentata: heterospecific discrimination and host quality
Authors: Zaviezo Tania , Mills Nick 
Published: March 2003

Summary1. Two basic tenets of competition among parasitoids, that taxonomically distinct parasitoids are unable to discriminate against hosts that have previously been attacked by a competitor and that previous parasitism reduces the quality of a host, were tested by monitoring the oviposition response of Hyssopus pallidus, a gregarious ectoparasitoid, to healthy codling moth larvae and codling moth larvae that had previously been parasitised by a solitary endoparasitoid, Ascogaster quadridentata.2. Hyssopus pallidus accepted both categories of host larva for oviposition when its competitor was constrained as a first‐instar larva by the diapause development of its host, but discriminated against previously parasitised host larvae when its competitor was present as a larger larva in a non‐diapausing host.3. Hyssopus pallidus distinguished between the two categories of host larva by allocating twice as many eggs to host larvae previously parasitised by A. quadridentata, a response that was not influenced by previous oviposition experience.4. The larger clutch sizes allocated to previously parasitised host larvae produced twice as many female progeny, each of a typical size, such that the total biomass was twice that produced from the smaller clutches laid on healthy host larvae. Possible confounding influences of host age and diapause are discounted.5. These results demonstrate that interspecific discrimination does occur in H. pallidus and that host quality can be improved through previous parasitism by an endoparasitoid. Although interspecific discrimination appears rare among insect parasitoids, it may have been overlooked among ectoparasitoids and requires examination of the fitness consequences of interspecific interactions to clarify its adaptive significance.
Detrimental effects of latex and cardiac glycosides on survival and growth of first‐instar monarch butterfly larvae Danaus plexippus feeding on the sandhill milkweed Asclepias humistrata
Authors: Zalucki Myron P. , Brower Lincoln P. , Alonso‐M Alfonso 
Published: March 2003

Summary1. A novel experimental method was developed to study negative physical and chemical effects of latex and cardiac glycosides on first‐instar monarch butterfly larvae in their natural environment in north central Florida. Forceps were used to nibble through the petioles of leaves of the sandhill milkweed Asclepias humistrata, mimicking the behaviour of mature monarch larvae. This notching cut off the supply of latex to the leaves without significantly reducing either their cardiac glycoside concentration or water content.2. The mean cardiac glycoside concentration in larvae that fed on intact leaves was nearly two and a half times greater than in larvae that fed on notched leaves. This was probably because more latex is present in the gut of the larvae that fed on the intact leaves. Supporting this is the fact that the mean concentration of cardiac glycosides in the latex was 34–47 times that in the leaves.3. Wet weights, dry weights, and growth rates of first‐instar larvae that fed on intact leaves over a 72‐h period were less than half those of larvae that fed on notched leaves.4. Mortality due to miring in the latex was 27% on the intact leaves compared with 2% on the notched leaves.5. Latex, cardiac glycosides, and other as yet undetermined plant factors all have a negative effect on first‐instar larval survival.6. Video‐analyses indicated that ingestion of latex caused the larvae to become cataleptic and increased their chances of being mired on the leaf by the setting latex glue. Dysfunction resulting from latex ingestion may lead to the larvae falling off the plant and being killed by invertebrate predators.7. The difficulty of neonate monarch larvae surviving on A. humistrata – one of the principal milkweed species fed on each spring as monarchs remigrate from Mexico into the southern U.S.A. – is evidence that a co‐evolutionary arms race is operating in this plant–herbivore system.
Behavioural changes in Schistocerca gregaria following infection with a fungal pathogen: implications for susceptibility to predation
Authors: Arthurs Steven , Thomas Matthew B. 
Published: March 2003

Summary1. Field observations have indicated that infection of locusts and grasshoppers by the fungal entomopathogen Metarhizium anisopliae var. acridum may result in a substantial increase in the host's susceptibility to predation, before death is caused directly by the disease.2. Laboratory experiments were conducted to examine how the behaviour of the desert locust Schistocerca gregaria Forskål changes following infection by M. anisopliae var. acridum to explore some potential mechanisms underlying this phenomenon.3. In the first experiment, which involved monitoring general locust activity in small cages throughout the disease incubation period, infected locusts were observed to increase locomotion and bodily movement from 3 days after infection until death (average survival time of 11 days). There was some evidence of reduced feeding and mating behaviour following infection.4. In a second experiment, locusts were exposed individually to a simulated predator attack and the initiation and strength of any escape responses were measured. Infected locusts were observed to have a reduced escape capability (both the propensity to escape and the strength of the response). In contrast to the relatively early changes in general activity observed in the first experiment, this was only apparent at the late stages of infection shortly before death.5. Both an increase in movement and general apparency early in the infection process, and reduced escape capability late on, suggest mechanisms whereby the susceptibility of locusts and grasshoppers to predation might be enhanced following infection with M. anisopliae var. acridum.
Variability in egg‐to‐adult development time in the bee Ptilothrix plumata and its parasitoids
Authors: Martins Rogério Parentoni , Guerra Sidnei Tadeu Mendes , Barbeitos Marcos Soares 
Published: March 2003

Summary1. Ptilothrix plumata (Hymenoptera) is a neotropical solitary bee that nests in bare, sandy soils. Data on the biology and behaviour of this species are provided. Egg‐to‐adult development time of a neotropical solitary bee and its parasitoids is quantified for the first time.2. The bee showed huge variability in egg‐to‐adult development time. There are two categories of eggs relative to adult emergence. The same season eggs are those from which adults emerge in the same reproductive season in which the eggs were laid. Adults from next season eggs emerge in the next dry reproductive season. This variability in egg‐to‐adult development time is reached through prepupal diapause. The bee larval parasitoids Leucospis genalis (Hymenoptera) and Anthrax sp. (Diptera) showed similar range in their development times. The data show that diapause is controlled by season.3. By synchronising adult emergence, this variability in egg‐to‐adult development time facilitates mate finding, and population recruitment is a consequence of the bees avoiding the unfavourable reproductive season.
Apparent widespread gene flow in the predominantly flightless planthopper Tumidagena minuta
Authors: Peterson Merrill A. , Denno Robert F. , Robinson Laura 
Published: March 2003

Summary1. To determine whether dispersal biology can predict the pattern of population‐genetic variation among insect populations accurately, allozyme variation was assayed for populations of a saltmarsh planthopper, Tumidagena minuta, in which > 99% of the adults are flightless.2. The pattern of genetic isolation by distance in T. minuta was compared with that in other insects, to determine whether it was similar to isolation by distance in other sedentary insects.3. In contrast to predictions, the pattern of isolation by distance in T. minuta was most similar to that seen in the most mobile insects in a recent review of population‐genetic variation in insects. Furthermore, population‐genetic subdivision over a spatial scale of > 400 km was weak.4. Possible causes of the apparent contradiction between dispersal biology and population‐genetic structure in this species are discussed. The results for T. minuta highlight the fact that although mobility is generally correlated with gene flow in insects, studies of population‐genetic variation must be combined with direct studies of dispersal to understand fully the degree to which populations exchange individuals.
Egg deposition patterns of fig pollinating wasps: implications for studies on the stability of the mutualism
Authors: Jousselin Emmanuelle , Hossaert‐Mckey Martine , Vernet Didier , Kjellberg Finn 
Published: March 2003

Summary1. Fig pollinating wasps (Agaonidae) enter Ficus inflorescences (figs), oviposit in some of the flowers, and pollinate in the process. Each larva completes its development within a single flower. In most cases, an inflorescence entered by a wasp will represent its only egg‐laying site. The mechanisms that prevent pollinating wasps from exploiting all the flowers inside a fig are not understood. In this study, hypotheses about flower use by pollinating fig wasps were tested by investigating egg deposition patterns in three species.2. Either one or three wasps were introduced into figs. The figs were then harvested. Serial sections allowed assessment of the presence or absence of a wasp egg in a sample of flowers in each fig. The overall proportion of flowers with eggs and the spatial distribution of eggs were then compared in single wasp figs and three foundress figs.3. In all species, the proportion of flowers with a wasp egg increased with foundress number but less than three‐fold.4. In all species, at least in single foundress figs, flowers near the fig cavity were more likely to receive a wasp egg than were flowers near the fig wall.5. In two species, when the number of foundresses was multiplied by three, there was an increase in the use of flowers near the fig wall, while in the third species, the increase was spread evenly among flowers.6. Factors affecting wasp egg deposition patterns and the potential of investigating such patterns for studying the stability of the mutualism are discussed.
Effects of meadow suitability on female behaviour in the alpine butterfly Parnassius smintheus
Authors: Fownes S. , Roland J. 
Published: March 2003

Abstract  1. Many butterfly populations persist in networks of naturally fragmented habitat patches. Movement and reproductive decisions made by adult females are critical to the persistence of these populations because colonisation of extinct habitat patches in the network requires emigration of fecund adult females from their natal meadow and their subsequent establishment in the extinct patch.2. Movement and oviposition behaviours of mated Parnassius smintheus females released in suitable meadows (a good‐ and a poor‐quality meadow) and an unsuitable meadow were compared, to determine whether adult females consider meadow suitability for their offspring despite frequent oviposition events off the larval host plant.3. Bootstrap and correlated random walk analyses of female step lengths and turn angles demonstrated that females flew more randomly in the unsuitable meadow than in the suitable meadows. Although females tended to turn the sharpest angle between landing sites in the good‐quality meadow, and fly the smallest distance between landing sites and displace the smallest distance from the release site in the suitable meadows, no significant differences were detected in turn angle, step length, and dispersal rates between suitable and unsuitable meadows.4. Results from female flight observations and a caged oviposition study suggest that females lay significantly more eggs in suitable habitat than in unsuitable habitat despite not ovipositing on the host plant, and support the above findings.5. Movement and oviposition behaviours of adult female P. smintheus promote their retention within meadows that can support their offspring.
Testing for context‐dependence in a processing chain interaction among detritus‐feeding aquatic insects
Authors: Daugherty Matthew P. , Juliano Steven A. 
Published: March 2003

Abstract 1. Scirtid beetles may benefit mosquitoes Ochlerotatus triseriatus (Say) by consuming whole leaves and leaving behind fine particles required by mosquito larvae. Such interactions based on the sequential use of a resource that occurs in multiple forms are known as processing chains.2. Models of processing chains predict that interactions can vary from commensal (0, +) to amensal (0, –), depending on how quickly resource is processed in the absence of consumers.3. The scirtid–O. triseriatus system was used to test the prediction derived from processing chain models that, as consumer‐independent processing increases, scirtids benefit mosquitoes less. Consumer‐independent processing rate was manipulated by using different leaf species that vary in decay rate, or by physically crushing a single leaf type to different degrees.4. Although scirtids increased the production of fine particles, the effects of scirtids on mosquitoes were weak and were not dependent on consumer‐independent processing rate.5. In the leaf manipulation experiment, a correlation between scirtid feeding and consumer‐independent processing was detected. Numerical simulations suggest that such a correlation may eliminate shifts from commensal to amensal at equilibrium; because mosquito populations are typically not at equilibrium, however, this correlation may not be important.6. There was evidence that mosquitoes affected scirtids negatively, which is inconsistent with the structure of processing chain interactions in models. Processing chain models need to incorporate more detail on the biology of scirtids and O. triseriatus, especially alternative mechanisms of interaction, if they are to describe scirtid–O. triseriatus dynamics accurately.