bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ant effects on three‐trophic level interactions: plant, galls, and parasitoids
Authors: Fernandes G. W. , Fagundes M. , Woodman R. L. , Price P. W. 
Published: March 2003

Summary1. Ants have evolved mutualistic relationships with a diverse array of plant and animal species. Usually, the predatory/aggressive behaviour of ants near food sources can limit herbivore damage.2. Galls of Disholcaspis edura on Quercus turbinella produce a secretion that is harvested by three species of ants (Formica neorufibarbis, Liometopium apiculatum, and Monomorium cyaneum) in the chaparral vegetation of Arizona, U.S.A. The study reported here provides evidence of a mutualistic relationship between these species of ants and the gall‐forming wasp Disholcaspis edura.3. An ant exclusion experiment showed that when ants tended galls, the rate of parasitism by Platygaster sp. on Disholcaspis edura was nearly halved in comparison to a treatment in which ants were excluded.4. In the presence of ants, galls with the largest diameter suffered a lower mortality rate due to parasitoid attack than when ants were excluded. Thus, ant presence reduced the selective pressure imposed by Platygaster sp. on the galls with larger diameter.
Niche differentiation in nectar‐collecting stingless bees: the influence of morphology, floral choice and interference competition
Authors: Biesmeijer Jacobus C. , Richter Juliette A. P. , Smeets Martin A. J. P. , Sommeijer Marinus J. 
Published: March 2003

Summary1. Dozens of social bee species, most of them stingless bees, occur sympatrically in the tropics. The proximate mechanisms through which they partition their resources are, apart from aggressive interactions betweenTrigonaspecies, not well studied. In the work reported here, niche differentiation at patch level was studied, using two species ofMeliponathat occur sympatrically in the Central Pacific part of Costa Rica. Foragers ofMelipona beecheiiare known to collect more concentrated nectar than doMelipona fasciataforagers, even from the same plant species. This observation raises the question of what mechanism leads to such partitioning of nectar resources? To address this question, the roles of bee morphology, floral preferences, and interference competition in partitioning of nectar sources were studied.2. It was shown experimentally that the feeding rate of both species was highest at 60% nectar concentration.Melipona fasciatapreferred 60–70% concentrations to less concentrated solutions, whereasM. beecheiiignored 20% solutions and visited the other solutions equally often. Both species preferred sucrose to glucose and fructose.Melipona beecheii,with a yellowish coloured body, preferred sunny patches, whereasM. fasciata, with a dark brown body, preferred shady patches. Interference competition between the species occurred when they visited the same sugar‐water feeder:M. fasciatawas dominant overM. beecheii.3. The nectar foraging strategies of the two species can be summarised as follows:M. beecheiiis able to visit sunlit patches, due to its lighter body colour, and is thus able to collect nectar of optimal or near optimal sugar concentration (40–65%). Individuals do not actively choose nectar with a high concentration of sugar, but the average sugar concentration in bee‐collected nectar will typically be high in sunlit patches.Melipona fasciata,on the other hand, avoids sunlit patches, but actively chooses the richest nectar in shady patches and tries to dominate such patches. Thus, niche differentiation occurs according to the radiation regime at flower patches, and interference competition will occur rarely under natural conditions. The role of similar mechanisms in other closely related stingless bees is discussed.
Age‐related cannibalism and horizontal transmission of a nuclear polyhedrosis virus in larval Spodoptera frugiperda
Authors: Chapman Jason W. , Williams Trevor , Escribano AnA. , Caballero Primitivo , Cave Ronald D. , Goulson DavE. 
Published: March 2003

Summary1. Experiments were carried out to investigate the incidence of cannibalism throughout the larval development of the noctuid moth Spodoptera frugiperda, and to examine the risk of infection from consuming conspecifics infected with a nuclear polyhedrosis virus (SfNPV).2. Cannibalism was observed commonly even when food was not limiting, but occurred more frequently at low food quantities and/or high rearing densities. The sex of the larvae had no effect on the incidence of cannibalistic behaviour, however the probability of cannibalism occurring was affected by larval stage. The frequency of cannibalism was significantly higher among fifth‐ and sixth‐instar larvae than among earlier instars, and larvae were more likely to consume younger conspecifics than larvae of the same stage.3. Fifth‐instar larvae offered fourth‐instar victims fed equally on healthy larvae, virus‐infected larvae (2 days post‐infection), uninfected corpses, and virus‐killed corpses (6 days post‐infection). Horizontal transmission of SfNPV was only recorded in larvae offered virus‐killed corpses, however, and total mortality in this treatment was only 32%.4. In a similar experiment, fourth‐instar larvae avoided cannibalising virus‐killed corpses. Horizontal transmission of SfNPV was recorded in fourth‐instar larvae that consumed 2‐day post‐infected larvae. The low incidence of cannibalism observed in fourth‐instar larvae, however, suggests that this is unlikely to provide an important route for the transmission of SfNPV.
Can nectar properties explain sex‐specific flower preferences in the Adonis Blue butterflyLysandra bellargus?
Authors: Rusterholz Hans‐Peter , Erhardt A.N.dreas 
Published: March 2003

Summary1. Field observations in the Swiss Jura mountains showed that males and females of the bivoltine Adonis Blue butterflyLysandra bellargusRott. differed significantly in their flower visitation patterns.2. In both generations, females visited a broader range of available nectar plants than did males. The specific flower visitation patterns of males and females were not affected by the general availability and abundance of potential nectar plant species during both flight periods, indicating high selectivity for nectar plants by both males and females.3. In addition, the sexes differed in their nectar foraging behaviours: distances between successively visited flowers were significantly longer in males than in females, indicating that male and female butterflies have different foraging strategies.4. Investigations of nectar characteristics showed that the sexes preferred flowers with different nectar compositions. Males of both generations preferred flowers with high proportions of sucrose and high amounts of total sugar, whereas females preferred flowers with high portions of glucose in their nectar, and, in the spring generation, flowers rich in amino acids.5. Flowers visited exclusively by males or females in spring differed significantly in their amino acid composition.6. This clear‐cut pattern did not hold for the autumn generation, most probably due to the limited availability of flowers.7. The observed nectar foraging patterns underline the importance of adult feeding for longevity and reproduction in butterflies. The findings are particularly relevant for conservation, becauseL. bellargusis an increasingly threatened species in many European countries.
The effect of spatial scale on interactions between two weevils and their parasitoid
Authors: Norowi H. Mohd , Perry Joe N. , Powell W. , Rennolls K. 
Published: March 2003

Summary1. The effect of spatial scale on the interactions between three hymenopteran parasitoids and their weevil hosts was investigated. The parasitoid Mesopolobus incultus (Walker) parasitised Gymnetron pascuorum Gyll.; the parasitoids Entodon sparetus (Walker) and Bracon sp. parasitised Mecinus pyraster Herbst. Both of these weevils develop inside the seedhead of Plantago lanceolata L. but occupy different niches. Seedheads were sampled annually from 162 plants at each of two experimental sites consisting of a series of habitat patches of two distinct sizes. Data were analysed from three site‐years.2. Parasitoid densities at each site‐year were closely related to the abundance of their respective weevil hosts. The overall proportion of hosts parasitised was more variable for M. incultus than for E. sparetus and Bracon sp.3. Changes in spatial scale affected the variability of parasitoid densities. For M. incultus, there was generally a greater degree of additional heterogeneity for all increases of scale; for E. sparetus, this was true only at the largest scales; for Bracon sp., all components of variance were negative.4. The rate of parasitism was related to host density in different ways at different spatial scales. Mesopolobus incultus exhibited inverse density dependence at the finest (seedhead) scale, direct density dependence at the intermediate (plant) scale, and density independence at the large (habitat area 729 m2) scale. Entodon sparetus showed no response to variation in host density at any spatial scale. Bracon sp. showed direct density dependence only at the intermediate and largest scales.5. Parasitoids E. sparetus and Bracon sp. seemed able to detect more than one M. pyraster individual in seedheads with multiple host occupancy; a greater incidence of conspecific parasitoids than expected emerged from such seedheads.
Health food versus fast food: the effects of prey quality and mobility on prey selection by a generalist predator and indirect interactions among prey species
Authors: Eubanks Micky D. , Denno Robert F. 
Published: March 2003

Summary1. In order to understand the relative importance of prey quality and mobility in indirect interactions among alternative prey that are mediated by a shared natural enemy, the nutritional quality of two common prey for a generalist insect predator along with the predator's relative preference for these prey was determined.2. Eggs of the corn earworm Helicoverpa zea (Lepidoptera: Noctuidae) were nutritionally superior to pea aphids Acyrthosiphum pisum (Homoptera: Aphididae) as prey for big‐eyed bugs Geocoris punctipes (Heteroptera: Geocoridae). Big‐eyed bugs survived four times as long when fed corn earworm eggs than when fed pea aphids. Furthermore, only big‐eyed bugs fed corn earworm eggs completed development and reached adulthood.3. In two separate choice experiments, however, big‐eyed bugs consistently attacked the nutritionally inferior prey, pea aphids, more frequently than the nutritionally superior prey, corn earworm eggs.4. Prey mobility, not prey nutritional quality, seems to be the most important criterion used by big‐eyed bugs to select prey. Big‐eyed bugs attacked mobile aphids preferentially when given a choice between mobile and immobilised aphids.5. Prey behaviour also mediated indirect interactions between these two prey species. The presence of mobile pea aphids as alternative prey benefited corn earworms indirectly by reducing the consumption of corn earworm eggs by big‐eyed bugs. The presence of immobilised pea aphids, however, did not benefit corn earworms indirectly because the consumption of corn earworm eggs by big‐eyed bugs was not reduced when they were present.6. These results suggest that the prey preferences of generalist insect predators mediate indirect interactions among prey species and ultimately affect the population dynamics of the predator and prey species. Understanding the prey preferences of generalist insect predators is essential to predict accurately the efficacy of these insects as biological control agents.
Bryophyte use by an insect herbivore: does the crane‐fly Tipula montana select food to maximise growth?
Authors: Smith R. M. , Young M. R. , Marquiss M. 
Published: March 2003

Summary1. Growth rates of immature invertebrates can be of profound importance to subsequent reproductive success in the adult stage. If diet selection in herbivores is a principal means of maximising growth and rate of development, individuals should select food of the highest quality.2. If disparities are found between performance and preference, these may be the result of individuals balancing nutritional gain against other demands on their behaviour, such as a need for shelter. The responses of the crane‐fly herbivore Tipula montana Curtis (Diptera: Tipulidae) to a range of moss genera from an upland environment were investigated to determine whether diet selection was determined by food quality alone, as measured by its effect on larval growth and survival.3. Larvae were reared individually on single moss genus diets, and their growth, development, and survival were measured. Each of the mosses supported growth and development although the mean weights achieved differed by a factor of two between food genera. In two‐choice preference experiments, individuals broadly chose bryophyte foods as expected from their quality. One notable exception was the moss Pleurozium schreberi, which gave the best growth performance but was among the least preferred.4. The two methods of assessing preference gave different results: observations of larvae showed relatively greater selection for dense mosses than faecal pellet analysis. A strong dietary preference for an angiosperm, the sedge Carex bigelowii, over all mosses supported the interpretation that crane‐fly larvae benefit from bryophytes as a refuge, and that this factor may override dietary quality.
Multiple mating reduces longevity of females of the windmill butterfly Atrophaneura alcinous
Authors: Kawagoe Tetsuhiro , Suzuki Nobuhiko , Matsumoto Kazuma 
Published: March 2003

Summary1. The effects of successive matings by females on their performance were tested in laboratory experiments and field censuses for the windmill butterfly Atrophaneura alcinous.2. In laboratory experiments, newly eclosed females were hand‐paired either once or twice successively. The number of eggs laid and the sucrose solution intake of these females were examined daily. Fecundity and sucrose solution intake did not differ significantly between once‐ and twice‐mated females, however the longevity of twice‐mated females was significantly shorter than that of once‐mated females, implying that successive matings involve a physiological cost.3. The results of a mark–release–recapture census in a natural population also indicated that multiply mated females could not survive for as long as once‐mated females.4. The results did not support the general consideration that multiple mating is beneficial to females in Lepidoptera. The importance of the timing of remating by females on the consequences of multiple mating is discussed.
Fitness costs and stability of resistance to Bacillus thuringiensis in a field population of the diamondback moth Plutella xylostella L.
Authors: Sayyed Ali H. , Wright Denis J. 
Published: March 2003

Summary1. The stability of resistance to Bacillus thuringiensis Crystal (Cry) toxins in highly and moderately resistant sub‐populations of a Plutella xylostella field population (SERD4) was compared under laboratory conditions. The relative rate of decrease in resistance was greater in a highly resistant Cry1Ac‐selected population than in moderately resistant Cry1Ab‐ and Cry1Ca‐selected populations.2. The intrinsic rate of population increase (rm) was similar in all populations tested.3. These results suggest that there are no obvious overall fitness benefits as the frequency of the resistance alleles is reduced.
Risk‐sensitive decisions during nesting may increase maternal provisioning capacity in the subsocial shield bug Parastrachia japonensis
Authors: Filippi Lisa , Hironaka Mantaro , Nomakuchi Shintaro 
Published: March 2003

Abstract 1. Females of the monophagous shield bug Parastrachia japonensis Scott provision their nymph‐containing nests with high‐quality drupes of the single host tree, Schoepfia jasminodora, a resource that is poor and unstable, under an array of variable environmental constraints.2. Although the number of drupes provisioned is correlated positively with enhanced nymphal development and survival, there is great variability in the number of drupes that females provide.3. The ability to adjust behaviour and/or physiology, i.e. make risk‐sensitive decisions, should be adaptive for organisms such as P. japonensis that are confronted with extreme variability in food availability and in the conditions under which they must forage. To assess whether females of this species use risk‐sensitivity to improve their provisioning success, data on the parameters of provisioning activity obtained during a long‐term field study were analysed. The relationships between variation in three female‐controlled factors during nesting (nest site, active stage during the provisioning season, duration of provisioning activity) and the conditions of three environmental factors (drupe availability, intraspecific competition, weather) were examined. The relationships between all of these factors and provisioning capacity of females were investigated.5. Nest site, intraspecific competition, and timing of provisioning activity only affected provisioning capacity when drupe availability was extremely good or bad or weather was particularly bad.6. The findings suggest that females use risk‐sensitive decisions to increase provisioning capacity under extreme conditions of low and high drupe availability and inclement weather.
Dung beetles in a Central Amazonian rainforest and their ecological role as secondary seed dispersers
Authors: Andresen Ellen 
Published: March 2003

Abstract1. The role of several factors that affect the composition of the dung beetle assemblages in an Amazonian rainforest was quantified, together with the effect of these factors on the role that dung beetles play as secondary seed dispersers.2. A total of 61 dung beetle species was captured during 3360 h of trapping. During nocturnal trapping periods, more dung beetles, of larger mean size, and more species were captured per trap than during diurnal trapping periods.3. During the rainy season, more dung beetle species were captured per trap than during the dry season, but the number of individuals and their mean size did not vary between seasons.4. Bait size had a significant effect on the mean number of beetles and mean number of species but not on mean beetle size. As bait size increased from 5, 10, 25, to 50 g, more beetles and more species were captured per trap.5. Between 6 and 73% of plastic beads, used as seed mimics, were buried by dung beetles at depths that ranged from 0.5 to 7 cm. Both the proportion of beads buried and burial depth decreased with increasing bead size, and increased with increasing amounts of dung surrounding each bead (5, 10, and 25 g).6. The proportion of buried seeds for three species varying in size between 5 and 27 mm, increased with increasing dung beetle size, using beetles of seven sizes, varying between 10 and 25 mm.7. Seeds surrounded by dung were buried more often and more deeply when placed on the forest floor during the late afternoon than when placed during the early morning. Seeds were also buried more often when placed on the forest floor during the rainy season than when placed during the dry season, but season had no effect on burial depth.8. Forests in Central Amazonia hold a rich dung beetle community that plays an active role in secondary seed dispersal, and consequently in plant regeneration. The interaction between seeds and beetles is complex because it is affected by many factors.
Preference and performance are correlated in the spittlebug Aphrophora pectoralis on four species of willow
Authors: Craig Timothy P. , Ohgushi Takayuki 
Published: March 2003

Abstract 1. There was a positive correlation between oviposition and feeding preferences and offspring performance in the spittlebug Aphrophora pectoralis Matsumura (Homoptera: Cercopoidea, Aphrophoridae) on four species of willow Salix sp. (Salicaceae) growing near Sapporo, Japan. Spittlebugs preferred rapidly growing shoots where performance was highest.2. When the effects of shoot length were removed, egg densities on willow species were associated with offspring performance on three of four species. Egg densities and survival rates were low on Salix integra and Salix miyabeana. Survival rates were high on Salix sachalinensis, which had high egg densities, and Salix hultenii, which had low egg densities.3. Aphrophora pectoralis formed mating aggregations almost exclusively on S. sachalinensis but then dispersed to other willow species to oviposit.4. Nymphs dispersed from the oviposition site to feed on nearby shoots within the same plant but they did not disperse to other willow plants. Nymphs had the same preference for rapidly growing shoots as ovipositing females, so they were able to refine the maternal choice by moving to larger shoots near the shoot on which they had eclosed.5. The spittlebugs were highly aggregated at all life stages so that even at high densities only a small proportion of the most vigorously growing shoots was utilised.
Parasitism by the mite Trombidium breei on four U.K. butterfly species
Authors: Conradt L. , Corbet S. A. , Roper T. J. , Bodsworth E. J. 
Published: March 2003

Abstract 1.  The incidence of parasitism by larvae of the mite species Trombidium breei was reported in one population of the lycaenid butterfly Polyommatus icarus, four populations of the satyrine butterfly Maniola jurtina, one population of the satyrine butterfly Aphantopus hyperanthus, and two populations of the satyrine butterfly Pyronia tithonus, as well as on one specimen of the dipteran Alophorus hemiptera. A considerable proportion of butterflies (11‐50%) was infested in all study populations.2. The pattern of infestation was examined in detail in M. jurtina. Males had a significantly higher incidence of infestation than females, and middle‐aged butterflies had a higher incidence of infestation than old or young butterflies. The incidence of infestation peaked in the middle of the flight season, and this seasonal effect was independent of the effect of butterfly age.3. Using a model based on capture‐recapture data, it was estimated that a hypothetical ideal male M. jurtina that lives exactly the mean expected lifespan of 9‐10 days has an approximately 75% chance of becoming infested with mites at least once during its lifetime, a mean time to first infestation of 3‐4 days, and an average infestation persistence time of 2‐3 days.4. Capture‐recapture data failed to show any effect of mite infestation on the lifespan or within‐habitat movement rate of M. jurtina.5. In experiments in which individual butterflies were taken out of their normal habitat and released, M. jurtina and P. tithonus that were infested with mite larvae did not differ from uninfested individuals in the efficiency with which they returned to suitable habitat. Thus, parasitism by T. breei larvae had no detectable effects on flight performance or orientation ability.6. The results suggest that trombidiid mite larvae have limited potential in the biological control of insect pests.