bluuebunny/crossref_metadata_2025_split huggingface dataset:
Converting visual census data into absolute abundance estimates: a method for calibrating timed counts of a sedentary insect population
Authors: Yoo Ho Jung S. , Stewart‐Oaten Allan , Murdoch William W. 
Published: July 2003

Abstract.  1. Visual surveys for small organisms on complex substrates often yield serious underestimates of true counts. When both visual counts (relative estimates of abundance) and absolute counts can be obtained from the same sample, however, the visual counts can be calibrated such that absolute estimates can be obtained in the future from visual surveys alone.2. A method is presented for converting quick, timed, visual counts of a sedentary insect on a shrub into absolute estimates of abundance.3. Analogies were drawn from simple, well‐known predation theories to develop a two‐parameter non‐linear model. Parameter estimates were obtained by both inverse prediction and direct estimation methods; the latter were found to yield more accurate predictions of absolute abundance.4. The calibration model is mechanistic in its approach, and thus has potential for application in other systems in which all individuals are visible, but able to be missed during timed counts.
Recognition of host‐specific chemical stimulants in two sympatric host races of the pea aphid Acyrthosiphon pisum
Authors: Del Campo M. L. , Via S. , Caillaud M. C. 
Published: July 2003

Abstract.  1. In ecological speciation, adaptation to variation in the external environment provides the crucial push that starts the process of genetic divergence and eventually leads to speciation. This emphasis on the role of ecological specialisation in speciation events has brought with it a renewed interest in its proximate mechanisms in recently diverged groups such as host races. Here, the proximate mechanisms of feeding specialisation are investigated in two host races of the pea aphid Acyrthosiphon pisum.2. Using alfalfa and clover extracts, enclosed in diet chambers or applied on whole plants, it is shown that feeding specialisation depends on recognition of stimulants specific to the host plant, not on deterrents or toxins specific to the non‐host plants.3. Because pea aphids mate on their host plant, feeding specialisation leads to de facto assortative mating. This study suggests that behavioural recognition of host‐specific chemicals, rather than avoidance of deterrents or/and plant toxins, contributes to gene flow restriction between the alfalfa and clover host races.
Sampling subterranean termite species diversity and activity in tropical savannas: an assessment of different bait choices
Authors: Dawes‐Gromadzki Tracy Z. 
Published: July 2003

Abstract.  1. Cellulose baits are commonly used for semi‐quantitative sampling of subterranean wood‐feeding termites, with a single food choice sampling programme implemented most often. In most situations, however, the composition and feeding preferences of the subterranean termite assemblage remain unknown.2. The diversity, frequency, foraging activity, and intensity of attack of termites were assessed regularly at 144 baits representing 12 different bait choices over 8.5 months, in two northern Australian tropical savanna sites that differed in vegetation structure (closed vs open). Baits differed in type (paper rolls, cardboard, wooden stakes), position (surface, buried), and moisture status at installation (wet, dry).3. Sixteen species were recorded, including 11 wood‐feeders. Average species diversity, foraging activity, and bait consumption were greater at buried baits than at surface baits. Wooden baits were most attractive early in the experiment, and paper baits more attractive later. Mean species diversity was greatest at wooden stakes in the closed site. Species frequency of occurrence varied across bait choices.4. A composite bait sampling protocol of stakes and paper rolls installed above and below ground gave an accurate assessment of the activity, diversity, and structure of the termite guild sampled across all baits over 8.5 months.5. The choice of bait, its presentation, and time of examination are critical to the success of a termite baiting programme. If the aim is to characterise the structure and foraging activity of the subterranean termite assemblages that are attracted to baits, composite baiting protocols should be implemented.
Evolutionary conservatism of geographic variation in host preference in Callosobruchus maculatus
Authors: Kawecki Tadeusz J. , Mery Frederic 
Published: July 2003

Abstract.  1. A study of host preference of four pairs of populations of the cowpea weevil Callosobruchus maculates was carried out. The pairs had different geographical origins.2. One population of each pair had been maintained for about 110 generations on cowpea Vigna unguiculata, the other population had been maintained on mung bean V. radiata. Half of the tested females from each population were raised on cowpea and exposed to this host prior to the assay; the other half was raised on mung bean. This design permitted assessment of the relative contributions of geographical origin, recent host use in the laboratory, and individual experience, to variation in host preference.3. Host preference was assayed by letting the females oviposit on an equal‐weight mixture of cowpea and mung seeds; two experiments were performed six generations apart.4. Both experiments revealed a strong effect of geographical origin: populations originating from Nigeria laid a much greater proportion (68–86%) of their eggs on cowpea than those originating from Uganda and Yemen (30–42%); those from Cameroon were intermediate (56–60%). These preferences were not affected consistently by about 110 generations of laboratory evolution on one or the other host, or by experience of individual females.5. These results indicate considerable geographical variation in host preference, and suggest that host preference is behaviourally inflexible and evolutionarily conserved.
How does insect visitation trigger floral colour change?
Authors: Nuttman Clive , Willmer Pat 
Published: July 2003

Abstract.  1. Visitation by the key pollinator, Bombus terrestris, was implicated in inducible flower colour change in Lupinus pilosus. Behaviour at the flower and rate of visitation by these bumble bees had specific effects; exclusion of this flower visitor led to retarded onset, and reduced rate, of colour change.2. The foraging behaviour of B. terrestris was influenced by floral colour change in L. pilosus. Choice of pre‐change flowers was greater than random in relation to the proportion of colour phases available within the plant population.3. Levels of floral manipulation that mimicked the flower handling characteristics of visiting bumble bees confirmed that triggering of the pollen release mechanism is necessary for the instigation of colour change.4. Moreover, this study suggests that, in L. pilosus, an aspect of pollination (pollen deposition by bees and/or subsequent pollen tube growth within the style) is linked with colour change and may act as the trigger for such change.
Effects of prescribed fire on an ant community in Florida pine savanna
Authors: Izhaki Ido , Levey Douglas J. , Silva Wesley R. 
Published: July 2003

Abstract. 1. The effects of prescribed fire on ant community structure were examined in a regenerating longleaf pine savanna in Florida, U.S.A. The presence of ants on 20, 10 × 10 m plots was determined by baiting every 1–3 months from 18 months before a fire until 6 months afterwards.2. Expected species richness (based on rarefaction) and species density 6 months post‐fire were significantly lower than for the same month (September) 6 months before the fire.3. Cluster analysis revealed that the effects of fire were far less important predictors of ant community structure than seasonality and unexplained inter‐annual variation. Thus, overall, the impacts of fire were relatively minor and short term at the community level.4. Different functional groups of ants (as defined by Andersen, 1997) responded to fire in strikingly different ways. Generalised Myrmicinae (e.g.Pheidolespp.,Monomorium viride) were affected more severely by fire than were the other functional groups. In contrast, the dominant Dolichoderinae (Forelius pruinosus) exhibited a large increase after the fire and seemed to be responsible for the decline in abundance of several species.5. A strong negative correlation betweenF. pruinosusand other groups of ants immediately after the fire suggested more intense competition among ants at that time. Six months post‐fire, the abundance ofF. pruinosusdecreased markedly and the abundance of other species rebounded.6. The rapid post‐fire recovery of the ant community probably reflects adaptations of ants to a chronic fire regime.
The size‐grain hypothesis: a phylogenetic and field test
Authors: Parr Z. J. E. , Parr C. L. , Chown S. L. 
Published: July 2003

Abstract. 1. The size‐grain hypothesis predicts that environmental rugosity results in positive allometric scaling of leg length on body length because of changes in locomotion costs.2. The scaling of leg length and body length in ants was re‐examined using phylogenetic independent contrast methods, and the allometric relationship found by Kaspari and Weiser (Functional Ecology,13, 530–538, 1999) was supported.3. The size‐grain hypothesis was tested further by comparing the body sizes of ants from areas of contrasting habitat complexity in two different savanna habitats. No support for the size‐grain hypothesis was found. Small body size classes were no more speciose in the rugose than in the more planar environment, and small ants were more abundant in the planar environment.
Colonisation of pitcher plant leaves at several spatial scales
Authors: Trzcinski M. Kurtis , Walde Sandra J. , Taylor Philip D. 
Published: July 2003

Abstract.  1. The effect of meso‐scale (zone within bog and local plant density) and fine‐scale (leaf length and resource availability) factors on the colonisation of pitcher plant leaves by arthropods was examined in an eastern Canadian bog.2. In spring, the abundances of three arthropods, the mosquito Wyeomyia smithii, the midge Metriocnemus knabi, and the mite Sarraceniopus gibsoni, were determined for plots with low, moderate, and high densities of pitcher plants. All overwintering inhabitants were then removed from the plots. Newly opening leaves were colonised from outside the plots, and arthropod abundances were assessed again in autumn.3. Pitcher plant fauna varied in their response to the meso‐scale factors. In autumn (soon after colonisation), midges were more abundant in areas with high densities of pitcher plants. The relationship between mosquito abundance and plant density, and the variation in abundance among zones within the bog in the spring, were probably due to overwintering mortality.4. All taxa responded to the fine‐scale factors, leaf length, and capture rate, in the autumn, but the strength of the responses frequently depended on a meso‐scale factor (plant density), in which responses were usually strongest where plants were sparse. Thus, the interaction between meso‐ and fine‐scale processes needs to be considered when interpreting patterns of species abundance within arthropod assemblages in pitcher plant leaves.
Movement patterns of the bush cricketPlatycleis albopunctatain different types of habitat: matrix is not always matrix
Authors: Hein Silke , Gombert Julia , Hovestadt Thomas , Poethke Hans‐Joachim 
Published: July 2003

Abstract. 1. Inter‐patch movement is usually assumed to be homogeneous across a landscape. As the intervening area between suitable patches is usually richly textured, it cannot be assumed to be uniform in real landscapes.2. In an experimental mark‐and‐resight study, the movement behaviour of the bush cricketPlatycleis albopunctatain four habitat types as well as at the border between two of these habitat types was observed.3. Analysis of recapture data indicated differences in mortality risk (or emigration rates) between habitat types.4. When released at the border between suitable habitat and a crop field,P. albopunctatadid not show a consistent preference for the suitable habitat. This suggests that the crop field is at least temporarily attractive forP. albopunctata.5. Movement in suitable habitat was not always different from movement in the matrix, and movement between different types of matrix also differed.6. The results indicate that the movement behaviour ofP. albopunctatais influenced not only by suitability for breeding but also by structural resistance and other factors (e.g. food availability or habitat‐specific mortality risk).
The community‐wide and guild‐specific effects of pubescence on the folivorous insects of manzanitas Arctostaphylos spp.
Authors: Andres Melissa R. , Connor Edward F. 
Published: July 2003

Abstract.  1. Insect communities on 26 species of manzanita Arctostaphylos spp. (Ericaceae) were sampled in order to examine the effects of variation in foliar pubescence traits on a community of folivorous insects. Manzanitas vary widely in pubescence density, length, and glandularity both within and between species.2. Linear models were fitted and evaluated to determine whether pubescence traits are associated with the species richness and abundance of folivorous insects after accounting for the effects of other relevant habitat and host‐plant related characteristics.3. Pubescence traits were clearly associated with both community‐wide and guild‐specific variation in the structure of the folivorous insect community of manzanitas, however the effects of pubescence were manifested primarily as effects on the abundance of folivores not on species richness. The species richness of folivorous insects on manzanitas was not associated with pubescence density or length but was associated positively with glandularity.4. The abundance of all guilds except leaf‐mining insects was lower on manzanitas having longer pubescence. In contrast, the abundance of external‐chewing insects was higher on plants having denser pubescence and on plants having glandular pubescence.5. Overall, the results suggest that both longer pubescence and the amount of contact between an insect and pubescence act quantitatively to decrease the abundance of external‐feeding guilds of folivorous insects. The abundance of species in internal‐feeding guilds that oviposit directly on leaves is unrelated to foliar pubescence traits in the host plant.
Does parasitoid attack strategy influence host specificity? A test with New World braconids
Authors: Althoff David M. 
Published: July 2003

Abstract.  1. Parasitoid attack strategy has been divided into two broad categories, koinobiosis and idiobiosis, based on the arrest of host development and the intimacy of larval contact. Koinobionts allow the host to continue developing and larvae usually feed within the host body, whereas idiobionts stop host development and larvae usually feed externally.2. Comparisons of host ranges from rearings of parasitoids from specific host communities have shown that koinobionts are more host specific than idiobionts. These tests suggested that parasitoid attack strategy influenced specialisation in parasitoid–host interactions within certain host communities.3. To determine whether this pattern was consistent within a single parasitoid lineage that utilises hosts from many different communities, the host ranges of koinobiont and idiobiont braconid genera of the New World were compared. Koinobiont genera utilised fewer host families than idiobionts, suggesting that parasitoid attack strategy may direct the evolution of host specificity throughout the evolutionary history of parasitoid lineages.
The influence of legacy effects and recovery from perturbations in a tritrophic salt marsh complex
Authors: Moon Daniel C. , Stiling Peter 
Published: July 2003

Abstract.  1. Much has been learned in recent years regarding the influence of environmental conditions on top‐down and bottom‐up effects acting on insect herbivores. Temporal variation in environmental conditions, however, has gone largely unstudied in spite of undoubtedly strong influences in most systems.2. A 2‐year study was conducted to examine the legacy effects of previous manipulations of host plant quality and parasitism pressure on the top‐down and bottom‐up effects influencing population densities of the salt marsh planthopper Pissonotus quadripustulatus.3. For 10 months in 1998, a 2 × 2 factorial experiment was carried out, in which host plant quality was increased by the addition of nitrogen fertiliser, and parasitism pressure was decreased through the use of yellow sticky traps. This was followed by 2 months in the winter with no treatment applications. Treatments were then reversed in 1999 for a further 10 months.4. In 1998, fertilisation treatments increased plant quality significantly, which resulted in strong effects on P. quadripustulatus density. Parasitism reduction treatments had weaker and time‐dependent effects on the herbivore, increasing planthopper density in late summer and autumn.5. After 2 months without treatments, previous fertilisation treatments were still influencing all response variables measured significantly. The legacy effects of fertilisation persisted for at least 7 months for the host plant, and at least 5 months for the herbivore and parasitoid.6. Fertilisation treatments in 1999 increased P. quadripustulatus density by approximately the same percentage as in 1998, suggesting that previous reductions in parasitism had no influence on herbivore responses to increased nutrients. Parasitism reduction treatments in 1999, however, resulted in greater increases in herbivore density than in 1998, suggesting that previous increases in nutrients enabled greater responses to reductions in top‐down pressure.7. The results show that the top‐down effects of parasitism attenuated more quickly than did the bottom‐up effects of increased plant quality through greater nutrient availability. They also suggest that the recent history of nutrient status in an ecosystem may be important in determining the relative strengths of top‐down and bottom‐up forces.
Superparasitism in Cotesia glomerata: response of hosts and consequences for parasitoids
Authors: Gu Hainan , Wang Qun , Dorn Silvia 
Published: July 2003

Abstract.  1. Superparasitism occurs in Cotesia glomerata (Hymenoptera: Braconidae), a gregarious endoparasitoid of Pieris spp. (Lepidoptera: Pieridae). The response of P. brassicae larvae to superparasitism and the consequences for the parasitoid were examined in order to elucidate the ecological significance of this behaviour.2. Field surveys of a Swiss population revealed that C. glomerata brood sizes from P. brassicae larvae ranged from three to 158, and both the female ratio and the body weight of emergent wasps correlated negatively with brood size. In the laboratory, single oviposition on P. brassicae larvae did not produce any brood size larger than 62, but brood size increased with superparasitism.3. Laboratory experiments demonstrated that both naive and experienced female wasps were willing to attack hosts that had been newly parasitised by themselves or conspecifics. Superparasitism reduced survivorship but increased food consumption and weight growth in P. brassicae larvae. Superparasitism lengthened parasitoid development and prolonged the feeding period of host larvae.4. Despite a trade‐off between maximising brood size and optimising the fitness of individual offspring, two or three ovipositions on P. brassicae larvae resulted in a greater dry female mass than did a single oviposition on the host. Thus, superparasitism might be of adaptive significance under certain circumstances, especially when host density is low and unparasitised hosts are rare in a habitat.
Passive immunization of rainbow trout, Oncorhynchus mykiss (Walbaum), against Flavobacterium psychrophilum, the causative agent of bacterial coldwater disease and rainbow trout fry syndrome
Authors: LaFrentz B R , LaPatra S E , Jones G R , Cain K D 
Published: July 2003

Abstract Flavobacterium psychrophilum, the causative agent of bacterial coldwater disease (CWD) and rainbow trout fry syndrome (RTFS), causes high mortality in cultured salmonids. The present study was designed to determine the role antibody plays in conferring protection to rainbow trout fry, Oncorhynchus mykiss (Walbaum), by passive immunization with convalescent serum or serum from adult rainbow trout immunized with F. psychrophilum, and goat anti‐F. psychrophilum serum. In each experiment, rainbow trout fry were injected intraperitoneally with antiserum and challenged by subcutaneous injection with a virulent strain (CSF‐259‐93) of F. psychrophilum 24‐h post‐immunization. Relative percentage survival (RPS) ranged from 9–42% when rainbow trout fry (mean weight 1.3 g) were injected with a 1:2 dilution of 25 μL of convalescent serum ranging in enzyme‐linked immunosorbent assay antibody titres from 1600–102 400. Rainbow trout fry (mean weight 1.0 g) passively immunized with 25 μL of serum from immunized adult fish exhibited RPS values of up to 57%. In each of these experiments, RPS increased with increasing antibody titres against F. psychrophilum. Passive immunization with 25 or 50 μL goat anti‐F. psychrophilum serum, however, did not confer protection to fry (mean weight 1.3 g). These results suggest that trout antibody plays a role in conferring protection to F. psychrophilum, but antibody alone is unable to provide complete protection.
Larvae and early post‐larvae of Penaeus monodon (Fabricius) experimentally infected with white spot syndrome virus (WSSV) show no significant mortality
Authors: Yoganandhan K , Narayanan R B , Sahul Hameed A S 
Published: July 2003

AbstractThe pathogenicity of white spot syndrome virus (WSSV) was tested with different developmental stages of Penaeus monodon, i.e. nauplius, protozoeae, mysis, early post‐larvae (PL1‐10), late post‐larvae (PL11‐20) and juveniles. WSSV challenge was done by immersion and oral routes. No disease occurred in the larvae and early post‐larvae but they were positive for WSSV by nested polymerase chain reaction (PCR) assay. Significant mortality was observed in late post‐larvae and juveniles and both single and nested PCR assays gave positive results with these samples. The results demonstrated that WSSV virulence in P. monodon increases with advancing stages of development and that WSSV infection does not result in disease for larvae and post‐larvae younger than PL10.
A rapid immunoperoxidase‐based virus neutralization assay for salmonid alphavirus used for a serological survey in Northern Ireland
Authors: Graham D A , Jewhurst V A , Rowley H M , McLoughlin M F , Todd D 
Published: July 2003

AbstractA modified virus neutralization (VN) assay was developed to replace an existing assay read on the presence or absence of virus‐induced cytopathic effect (CPE). The modified assay used a monoclonal antibody to salmon pancreas disease virus as the first layer of an immunoperoxidase (IPX)‐based immunostaining technique to detect viral growth. The IPX‐based VN assay required only 3 days to perform, and the adoption of a 96‐well microtitre format facilitated a high throughput of samples requiring small volumes of serum, cells and virus. When 352 sera from farmed salmon and 302 sera from farmed trout were tested by both the modified and the original CPE‐based assays, overall correlations of 97.72 and 96.03% were, respectively, obtained (96.94% combined). When the modified assay was used to test 188 sera collected from wild salmonids in freshwater river systems in Northern Ireland, no positive results were recorded.