bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sociometry and sociogenesis of colonies of the harvester ant, Pogonomyrmex badius: distribution of workers, brood and seeds within the nest in relation to colony size and season
Authors: Tschinkel Walter R. 
Published: May 2003

Summary1. The vertical distribution in the nest of chambers, workers, callow workers, brood and seeds was studied in the harvester ant, Pogonomyrmex badius, in northern Florida. On each of four sample dates (May, July, October, January), six to seven colonies, chosen to represent the full range of sizes, were excavated. All chamber contents were collected and counted. Chambers were mapped and measured. In a preliminary study, two nests were excavated after preventing vertical migration by driving barriers into the wall of a pit next to the nest, severing the vertical tunnels. The vertical distribution of these barrier‐nests differed little from unrestrained nests, indicating that unrestrained excavation produced a reasonable picture of vertical distributions.2. Nest depth, chamber number and total area increased with colony size. Chamber area declined sharply with depth, as did chamber number, such that more than half of the total area was found in the upper quarter of the nest.3. The proportion of dark‐coloured (older) workers also declined strongly with depth, but this decline was weaker in the spring, and depended to a modest degree on colony size. Conversely, in the distribution of callow (young) workers, the proportion increased towards the bottom of the nest. Mean worker age was inversely related to the depth at which workers were found. The proportion of the brood also increased towards the bottom of the nest, with worker brood, sexual brood, pupae and larvae all being distributed similarly.4. By contrast, seeds were stored at a preferred absolute depth between 40 and 100 cm. Colonies shallower than 100 cm stored seeds in their deepest chambers. Larger colonies stored most seeds in the upper third of the nest, but patterns were somewhat erratic because chambers were either filled completely with seeds or were empty.5. Because chamber area decreased sharply with depth, the densities (individuals cm–2) of all colony members, including dark workers, were lowest near the surface and highest in the deepest parts of the nest. Here, worker densities ranged from 2 to 8 cm–2, and brood from 2 to 25 cm–2.6. The regularity of the patterns of distribution suggests that harvester ant colonies have considerable spatial and temporal structure, which serves or is the outcome of important colony processes. A simple mechanism that could generate several of these patterns is discussed. New workers produced deep in the nest move upwards as they age. As they leave the brood zone they change from brood care to general nestduties, including increased nest excavation, leading to the top‐heavy pattern of nest area. As they appear at the surface, they change to guarding and foraging. Thus, age polyethism may be partly the result of this upward migration of workers.
Mixture models of soybean growth and herbivore performance in response to nitrogen–sulphur–phosphorous nutrient interactions
Authors: Busch Johannes W. , Phelan P. Larry 
Published: May 2003

Summary1. It is widely established that plant‐mineral nutrition is an important determinant of herbivore developmental performance and behavioural preference. Unfortunately, the specific effects of minerals on herbivory have been variable and few unifying principles have emerged. Advances in this area may be impeded in part by an experimental approach that emphasises single nutrients without regard to nutrient ratios.2. In this study, mixture‐design experiments were adapted to the study of mineral nutrition and herbivore performance. The interactive effects of nitrogen, sulphur, and phosphorous on the development of soybean looper(Pseudoplusia includens)and two‐spotted spider mite(Tetranychus urticae)feeding on soybeans (Glycine max) were quantified by polynomial regression.3. Although significant effects of individual minerals were measured, the actual responses to these nutrients depended on the proportions of the other components in the nutrient solution. For example, over a range of decreasing nitrogen concentration, resulting soybean looper pupal mass first declined then increased when replaced by a high sulphur : phosphorous blend, but just the opposite response was measured when replaced with high phosphorous : sulphur ratio.4. Moreover, responses to mineral proportions were generally nonlinear and the effects of mineral proportion were not only species‐specific, but varied for different responses within a species.5. These studies demonstrate that understanding the role of mineral nutrients in host‐plant quality requires that mineral proportions be considered in addition to concentration. Mixture modelling, which is largely unknown to ecologists, is a powerful new tool that could significantly advance the study of the interactive effects of mixture components, such as in plant‐nutrient blends.
Invertebrate communities in a tropical rain forest canopy in Puerto Rico following Hurricane Hugo
Authors: Schowalter T. D. , Ganio L. M. 
Published: May 2003

Summary1. Canopy invertebrate responses to Hurricane Hugo, tree species, and recovery time were examined at the Luquillo Experimental Forest in Puerto Rico during 1991–92 and 1994–95. Six tree species representing early and late successional stages were examined in paired plots representing severe hurricane disturbance (most trees toppled) and light hurricane disturbance (all trees standing and most branches intact).2. Hurricane disturbance affected invertebrate abundances significantly. Sap‐suckers and molluscs were more abundant, and defoliators, detritivores, and emergent aquatic insects were less abundant in recovering tree‐fall gaps than in intact forest during this 5‐year period. These changes in functional organisation are consistent with comparable studies of arthropod responses to canopy removal during harvest in temperate forests.3. Tree species also affected invertebrate abundances significantly, but invertebrate communities did not differ significantly between the three early successional and three later successional tree species.4. Most taxa showed significant annual variation in abundances, but only two Homoptera species showed a significant linear decline in abundance through time, perhaps reflecting long‐term trends during recovery.5. Leaf area missing, an indicator of herbivore effect on canopy processes, showed significant seasonal and annual trends, as well as differences among tree species and hurricane treatments. Generally, leaf area missing peaked during the wet season each year, but reached its highest levels during an extended drought in 1994. Leaf area missing also tended to be higher on the more abundant tree species in each disturbance treatment.6. Herbivore abundances and leaf area missing were not related to concentrations of nitrogen, phosphorous, potassium, or calcium in the foliage.7. This study demonstrated that invertebrate community structure and herbivory are dynamic processes that reflect the influences of host species and variable environmental conditions.
Modification of coevolved insect–plant interactions by an exotic plant pathogen
Authors: Storer Andrew J. , Wood David L. , Gordon Thomas R. 
Published: May 2003

New perspectivesNew Perspectives is intended to allow the communication of comments, viewpoints, and speculative interpretation of issues in ecology pertinent to entomology. Comments, viewpoints, or suggestions arising from published papers intended to fuel discussion and debate are also welcome. Contributions should be as concise as possible, normally not exceeding two thousand words. Formal research reports will not be acceptable, but summarised novel data, suitably supported by statistics, may be allowed.
The role of body size in mating success of Sphenarium purpurascens in Central Mexico
Authors: Del Castillo Raúl. Cueva , Núñez‐Farfán Juan. , Cano‐Santana Zenón 
Published: May 2003

Summary1. The effect of body size on the assortative mating and reproductive behaviour of the univoltine grasshopper Sphenarium purpurascens (Charpentier) was studied in Central Mexico.2. Assortative mating by size was observed in the field. Evidence of positive assortative mating in relation to body size was found in laboratory experiments. Female fecundity and male success in contests were also correlated with body size.3. Larger females had a higher number of eggs per pod. Larger males usually won fights and were able to take over females from other males, and to resist takeovers by other males while guarding.4. Individuals of both sexes were observed copulating with more than one sexual partner in the field, suggesting polygamy. Male–male contests determined access to females, and males exhibited a postcopulatory prolonged mate‐guarding behaviour lasting up to 18 days.5. In a 2‐year study, sex ratio was male‐biased at the beginning of the reproductive season and decreased to 1:1 by the end of the season, suggesting that the population is protandrous.6. The results of this study indicate that assortative mating results from male–male competition and female availability, and suggests that body size is a potential target of natural and sexual selection.
Behavioural responses of the leaf‐chewing guild to the presence of Eriocrania mines on silver birch (Betulapendula)
Authors: Fisher A. E. I. , Hartley S. E. , Young M. 
Published: May 2003

Summary1. Interactions between early season leaf‐miners from the genus Eriocrania Zeller (Eriocraniidae: Lepidoptera), and the leaf‐chewing guild of silver birch (Betula pendula Roth) were investigated.2. Field observations indicated that a negative association between damage caused by Eriocrania, and leaf‐chewers could be observed under certain conditions, namely at higher damage densities in the final week of mine development on trees with relatively high densities of mines.3. Experimental manipulation of Operophtera brumata L. (Geometridae: Lepidoptera) densities in the field confirmed the negative association between established mines of Eriocrania, and this species of free‐living folivore.4. The behaviour of O. brumata was modified further in the presence of mines. On branches where mined leaves were present, O. brumata larvae consumed a larger proportion of leaf tissue, by continuing to feed on the same leaf longer rather than shifting to a new leaf. Increased consumption may indicate some modification of leaf quality beyond the leaves occupied by Eriocrania. Alternatively, it may indicate an association between Eriocrania, and higher quality leaf material.
Movement of the Apollo butterflyParnassius apollorelated to host plant and nectar plant patches
Authors: Brommer Jon. E. , Fred Marianne S. 
Published: May 2003

Summary1. The movement of adults of the endangered Apollo butterfly,Parnassius apollo, was studied using mark–recapture data, within a population consisting of discrete patches of the species’ host plant (n = 43), which were segregated spatially from patches of the species’ main nectar plants (n = 14).2. The Apollo routinely moved large distances (median 260 m, maximum 1840 m), and moved frequently between the two types of patches. Only 27% (28/105) of the recaptures were made on the same host plant patch as the release.3. The population acts as a patchy population where the adults mix over the whole area, but successful reproduction can only take place in the discrete host plant patches.4. Occurrence on a host plant patch was restricted by the area size of the host plant patch and the spatial configuration of nectar plant patches. Thus, although the Apollo is a good flyer, its movement over the patches is still constrained by the segregation of adult and larval resources.
Dung pad residence time covaries with male morphology in the dung beetle Onthophagus taurus
Authors: Hunt John. , Kotiaho Janne S. , Tomkins Joseph L. 
Published: May 2003

Summary1. The immigration and emigration behaviours of Onthophagus taurus were investigated in a combination of field and laboratory experiments to examine patterns of dispersal in this species.2. On average, the mean proportion of major males immigrating to baited pitfall traps decreased significantly with time. In contrast, the mean proportion of minor males and females did not change with time.3. The time taken to emigrate from a dung pad differed significantly among major males, minor males, and females. This difference arose because major males spent a significantly shorter period of time residing within the dung pad. On average, more than 50% of major males had emigrated from the dung pads after 30 h, some 4 h earlier than minor males and females.4. When the effects of body size were controlled, major males with longer horns were shown to have longer wings. Because major males spend more time in flight, longer wings may be an adaptation to more frequent dispersal. Alternatively, longer wings in major males may compensate for the production of aerodynamically costly horns.
Influenza– and Respiratory Syncytial Virus–Associated Morbidity and Mortality in the Nursing Home Population
Authors: Ellis Shelley E. , Coffey Christopher S. , Mitchel Edward F. , Dittus Robert S. , Griffin Marie R. 
Published: May 2003

Objectives: To estimate winter viral‐related morbidity and mortality in Tennessee nursing home residents during 4 consecutive years.Design: A retrospective cohort study.Setting: Three hundred eighty‐one Tennessee nursing homes.Participants: Nursing home residents.Measurements: Viral surveillance data were used to define three seasons: influenza (influenza and respiratory syncytial virus (RSV) cocirculating), RSV (RSV alone circulating), and non winter‐viral (neither virus circulating). Adjusted seasonal differences in rates of cardiopulmonary hospitalizations, antibiotic prescriptions, and deaths during these three seasons were calculated to estimate annual hospitalizations, courses of antibiotics, and deaths attributable to influenza and RSV from 1995 to 1999.Results: Nursing home residents had 81,885 person‐years of follow‐up. In the 63% of residents with comorbid conditions that increase influenza morbidity, influenza infection contributed to an estimated average of 28 hospitalizations, 147 courses of antibiotics, and 15 deaths per 1,000 persons annually. Similarly, RSV accounted for an annual average of 15 hospitalizations, 76 courses of antibiotics, and 17 deaths per 1,000 persons. Influenza and RSV accounted for 7% of cardiopulmonary hospitalizations and 9% of total deaths in high‐risk residents during the 4 study years. Absolute morbidity and mortality were lower in residents without identified comorbid conditions but accounted for 15% of hospitalizations and 14% of deaths. These estimates depend on the assumption that morbidity and mortality from other respiratory viruses were distributed evenly between the three defined seasons.Conclusion: Influenza and RSV substantially increased hospitalization rates, antibiotic use, and deaths in elderly nursing home residents each winter. These data should encourage persistent efforts toward disease prevention, and thoughtful study of vaccine development and delivery, diagnostic tools, and methods of prophylaxis and therapy.
Horizontal movements of bigeye tuna (Thunnus obesus) near Hawaii determined by Kalman filter analysis of archival tagging data
Authors: Sibert John R. , Musyl Michael K. , Brill Richard W. 
Published: May 2003

AbstractGeolocation data were recovered from archival tags applied to bigeye tuna near Hawaii. A state‐space Kalman filter statistical model was used to estimate geolocation errors, movement parameters, and most probable tracks from the recovered data. Standard deviation estimates ranged from 0.5° to 4.4° latitude and from 0.2° to 1.6° longitude. Bias estimates ranged from −1.9° to 4.1° latitude and from −0.5° to 3.0° longitude. Estimates of directed movement were close to zero for most fish reaching a maximum magnitude of 5.3 nm day−1 for the one fish that moved away from its release site. Diffusivity estimates were also low, ranging from near zero to 1000 nm2 day−1. Low values of the estimated movement parameters are consistent with the restricted scale of the observed movement and the apparent fidelity of bigeye to geographical points of attraction. Inclusion of a time‐dependent model of the variance in geolocation estimates reduced the variability of latitude estimates. The state‐space Kalman filter model appears to provide realistic estimates of in situ geolocation errors and movement parameters, provides a means to avoid indeterminate latitude estimates during equinoxes, and is a potential bridge between analyses of individual and population movements.
Vertical movements of bigeye tuna (Thunnus obesus) associated with islands, buoys, and seamounts near the main Hawaiian Islands from archival tagging data
Authors: Musyl Michael K. , Brill Richard W. , Boggs Christofer H. , Curran Daniel S. , Kazama Thomas K. , Seki Michael P. 
Published: May 2003

AbstractTo learn more about the movement patterns of bigeye tuna (Thunnus obesus), we deployed archival tags on 87 fish ranging in fork length from 50 to 154 cm. Thirteen fish were recaptured, from which 11 archival tags were returned, representing in aggregate 943 days‐at‐liberty. We successfully retrieved data from 10 tags, representing 474 days in aggregate. The largest fish recaptured was 44.5 kg [131 cm fork length (FL)] and the smallest 2.8 kg (52 cm). The deepest descent recorded was 817 m, the coldest temperature visited 4.7°C, and minimum oxygen level reached ∼1 mL L−1. Fish spent little time at depths where water temperatures were below 7°C and oxygen levels less than ∼2 mL L−1. Five fish were recaptured near the offshore weather buoy where they were tagged. Based on vertical movement patterns, it appeared that all stayed immediately associated with the buoy for up to 34 days. During this time they remained primarily in the uniform temperature surface layer (i.e. above 100 m). In contrast, fish not associated with a floating object showed the W‐shaped vertical movement patterns during the day characteristic of bigeye tuna (i.e. descending to ∼300–500 m and then returning regularly to the surface layer). Four fish were tagged and subsequently recaptured near Cross Seamount up to 76 days later. These fish exhibited vertical movement patterns similar to, but less regular than, those of fish not associated with any structure. Bigeye tuna appear to follow the diel vertical movements of the deep sound scattering layer (SSL) organisms and thus to exploit them effectively as a prey resource. Average night‐time depth was correlated with lunar illumination, a behaviour which mimics movements of the SSL.
Latitudinal differences in the duration of development of Neocalanus plumchrus copepodites
Authors: Batten Sonia D. , Welch David W. , Jonas Tanya 
Published: May 2003

AbstractQuasi‐synoptic sampling along a transect from Alaska to California carried out in spring and summer 2000 using Continuous Plankton Recorders reveals that the abundant calanoid copepod Neocalanus plumchrus (Marukawa) reaches the surface at approximately the same time across the region. However, monthly sampling also reveals that the timing of peak biomass (when 50% of the population consists of copepodites at stage CV) occurs about 5 weeks earlier at the southernmost part of its range than at the northernmost part, with intermediate areas having intermediate timings. Surface water temperature differed by about 4°C between the warmer south and the cooler north, and we suggest that such a difference would reduce development duration by about 3 weeks. If food supply in the north is more conducive to lipid accumulation, as seems possible from phytoplankton biomass data, then the use of the differences in timing of peak N. plumchrus biomass in each area as a measure of the differences in development time may not be accurate. We find that the estimate of the time of peak biomass varying by about 5 weeks between north and south may be an exaggeration of the actual difference in the development duration. Temperature is probably the most important factor governing the shorter development duration of N. plumchrus in southern latitudes.
The effect of vertical and horizontal distribution on retention of sardine (Sardinops sagax) larvae in the Northern Benguela – observations and modelling
Authors: Stenevik Erling Kåre , Skogen Morten , Sundby Svein , Boyer David 
Published: May 2003

AbstractIn the present study, a modelling experiment is conducted to simulate the transport of sardine (Sardinops sagax) eggs and larvae in the Northern Benguela. Based on historical and newly obtained data, different scenarios of vertical and horizontal distribution are applied and the effects on retention are discussed. The simulations showed that vertical and horizontal distribution were important for retention of sardine larvae in the Northern Benguela. By using age‐dependent data on vertical distribution, it was shown that retention of particles in the simulation was substantially enhanced compared with a scenario where particles were distributed in the offshore moving Ekman layer. Retention was lowest during October–December (when upwelling intensity is high) and highest during February–April (when upwelling intensity is somewhat lower). When different spawning areas were considered, highest retention was observed in an area near Walvis Bay. It is concluded that the behaviour of sardine larvae is adapted to the circulation system in the Northern Benguela in a way that promotes retention of the larvae in inshore nursery areas.
Modelling the effect of buoyancy on the transport of anchovy (Engraulis capensis) eggs from spawning to nursery grounds in the southern Benguela: an IBM approach
Authors: Parada C. , Van Der Lingen C.D. , Mullon C. , Penven P. 
Published: May 2003

AbstractAn individual‐based model (IBM) was used to investigate the effects of physical and biological variables on the transport via a jet current of anchovy (Engraulis capensis) eggs from spawning to the nursery grounds in the southern Benguela ecosystem. As transport of eggs and early larvae is considered to be one of the major factors impacting on anchovy recruitment success, this approach may be useful to understand further the recruitment variability in this economically and ecologically important species. By coupling the IBM to a 3D hydrodynamic model of the region called Plume, and by varying parameters such as the spatial and temporal location of spawning, particle buoyancy, and the depth range over which particles were released, we could assess the influences of these parameters on transport success. A sensitivity analysis using a General Linear Model identified the primary determinants of transport success in the various experimental simulations, and model outputs were examined and compared with patterns observed in field studies. Model outputs compared well with observed patterns of vertical and horizontal egg distribution. Particle buoyancy and area of particle release were the major single determinants of transport success, with an egg density of 1.025 g cm−3 maximizing average particle transport success and the western Agulhas Bank being the most successful spawning area. This IBM may be useful as a generic prototype for other upwelling ecosystems.