bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reproduction and egg diapause of the oriental chinch bug, Cavelerius saccharivorus okajima (Heteroptera: Lygaeidae), in the subtropical winter season in relation to its wing polymorphism
Authors: Fujisaki Kenji 
Published: October 2006

SummaryReproduction and egg diapause of the oriental chinch bug, Cavelerius saccharivorus, in the subtropical winter season were investigated in relation to its wing polymorphism. Macropterous females collected from the southern part of Okinawa Is. in the autumn season delayed their oviposition and were less fecund early in the adult life period, but survived much longer than brachypterous females collected from the same locality. The total fecundity was not significantly different between wing morphs. The diapause of eggs laid by brachypters tended to be terminated more easily at a high temperature than that of eggs laid by macropters. This indicated that the eggs laid by macropters were more intense in their diapause than those laid by brachypters. However, irrespective of the parental wing form, diapause showed considerable variation in its intensity within and between clutches.
Lek mating system and its impact on male annihilation technique
Authors: Horng Shwu‐Bin , Plant Richard E. 
Published: October 2006

SummarySimulation models were presented which describe the matings inside a lek. The size of the lek was assumed to follow a poisson distribution, the dominance factor of each of the males was drawn from a gamma distribution, and the mating probability for each male was determined by its mating effectiveness raised to female mating factor divided by the sum of all the mating effectivenesses raised to this power. The mating probatility for each male and the actual matings were determined by Monte Carlo simulation. Based on the simulation data, the effects of female mating factor and size of the lek on the frequency of actual matings accomplished by the males inside the lek were discussed. In the case of male annihilation, the mean number of effective matings per male in the lek, calculated from the frequency of actual matings weighted by the effective mating ratio, was used to evaluate the efficiency of male annihilation method.
Theoretical consideration of effect of fishing mortality on growth and reproduction of fish populations
Authors: Hiyama Yoshiaki , Kitahara Takeru 
Published: October 2006

SummaryAn increase in fish mortality due to fishing can theoretically change the growth and reproduction of fish populations from the viewpoint of adaptation. We address the issue of how an iteroparous fish should convert surplus energy into somatic growth and reproduction at each age under given conditions of mortality. A model of life history, which maximizes the net reproductive rate using the discrete maximum principle, is improved employing a new relationship between body weight and surplus energy which we have recently proposed. The model is applied to the North Sea plaice Pleuronectes platessa, for which it has been reported that the average length of young fish had increased whereas that of old ones had decreased for some decades. Although the model cannot directly explain the former phenomenon, the two phenomena can be interpreted as a change in the optimal life history due mainly to an increase in mortality.
Genetic correlation of wing polymorphism between females and males in the oriental chinch bug, Cavelerius saccharivorus Okajima (Heteroptera: Lygaeidae)
Authors: Fujisaki Kenji 
Published: October 2006

SummaryGenetic correlations of the wing form and the relative wing length between females and males were estimated in the oriental chinch bug, Cavelerius saccharivorus, by calculating the correlation between the sexes of the proportion macropterous or the mean relative wing length in full‐sib families obtained from different wing forms of parents emerged in a high density population. There was a significantly positive genetic correlation between the sexes in both the proportion macropterous and the mean relative wing length. However, the appearance rate of macropters tended to be much lower in males than in females under the rearing conditions which promote the appearance of macropters. This was evident especially in the offspring of brachypterous parents. These indicated that in C. saccharivorus the wing polymorphism of males is not a simple result of the genetic correlation of wing morphology between the two sexes. It was considered that both of the female and male fitness advantages to wing reduction, as well as the genetic correlation between the sexes, would influence the evolution of wing polymorphism in this species.
Relative humidity as an environmental factor determining the microhabitat of the nymphs of the rice brown planthopper, Nilaparvata lugens (Stål) (Homoptera: Delphacidae)
Authors: Isichaikul Somchai , Ichikawa Toshihide 
Published: October 2006

SummaryMicrohabitat of the nymphs and the adults of the rice brown, planthopper, Nilaparvata lugens is known to be the lower parts of rice plants. In this study, possible environmental factors determining the range of the microhabitat were experimentally analyzed by using the nymphs under laboratory conditions. Thirty individuals of the 1st or the 3rd instar nymphs were released to a potted rice plant covered with a transparent acrylic cylinder. When the top of the cylinder was kept opening (open condition), the temperatures in the cylinder were almost constant, and relative humidities in the cylinder decreased with the increase of the height from the water surface of the pot. In the open condition, most nymphs and all exuviae were found on the basal parts of rice plants where the humidity was more than ca. 90% r.h. When the top of the cylinder was kept closing with parafilm (closed condition), the temperatures in the cylinder were almost constant, and relative humidities in the cylinder were more than 95% r.h. In the closed condition, the nymphs and the exuviae were distributed sparsely to the whole parts of rice plants. In both of the open and the closed conditions, patterns of nymphal distributions on rice plants during the dark regime were the same as those during the light regime under 25±2°C and 16L∶8D. Four different temperatures ranging from 20°C to 35°C did not influence on the microhabitat in the open condition. It was concluded from the results that relative humidity is the important environmental factor to determine the microhabitat of the nymphs of N. lugens which showed to prefer very humid condition more than ca. 90% r.h.
Breeding and egg survival of a population of a salamander, Hynobius nebulosus tokyoensis Tago
Authors: Kusano Tamotsu 
Published: October 2006

Summary
A population of a salamander, Hynobius nebulosus tokyoensisTago was studied at Habu, Hinodemachi, in Tokyo during the breeding seasons from 1976 to 1978. Adults appeared in the pond were captured and marked individually by toe‐clipping. Egg sacks were counted and tagged with vinyl tapes for the marking.
The annual egg production of this population was found to be constant, about 6500 eggs, and total number of breeding adults appeared in the pond also varied little during three years.
The appearance of breeding adults in the pond and oviposition seemed to be influenced by the rise of temperature and rainfall.
Males appeared earlier in the pond and stayed there for approximately 10 to 20 days. On the other hand, females appeared later in the pond and left there soon after laying eggs.
Mean clutch size and body length of breeding adults appeared in the pond showed a tendency to decrease as time proceeded, which seemed to show that the smaller and younger the salamander was, the later it appeared in the pond.
Owing to low temperature, the eggs laid earlier took more time to hatch than those laid later.
The survival rate of eggs was 67.2% in 1976, 86.4% in 1977 and 81.2% in 1978. The loss rate of eggs laid in the early and late periods of oviposition was higher than that of eggs laid in the middle period.
The population characteristics of the East African red legged diplopod Metiche tanganyciense Kraus (Diplopoda: Spirobolidae)
Authors: Banerjee Barundeb 
Published: October 2006

SummaryA marked variation exists in the numbers and distribution of East African red legged millipede Metiche tanganycienseKraus on the surface and in the lower layer (15 cm) of the soils. Stadia 5 cm and lesser in length are found in the lower layer and those 5 cm and above on the surface soil. Adults are common in varying numbers in both the habitats.It is suggested that after becoming surface active during March–August, and mating, adults migrate to lower layer during September to oviposit. Eggs and early developmental stages are passed here, and when they are 5 cm in length, the stadia move to the surfface soil to complete their development. In keeping with this behaviour, spatial distribution of the adults may change from non‐aggregation on surface soil to aggregation in the lower layer. The simulataneous presence of adults and developing stadia in the two habitats suggests and overlapping of generations.
A model descriptive of gregariousness of colonial insect larvae
Authors: Tsubaki Yoshitaka , Yamamura Norio 
Published: October 2006

SummaryA model is constructed to describe gregariousness of colonial insect larvae which occure in discrete natural habitat units. The model is based on the assumption that the distribution of individuals in a clump is determined by a balance between aggregative and dispersing movements of individuals. The model includes three parameters, i.e., clump size, carrying capacity of habitat units and intensity of aggregation against dispersal. The modes of effects of these parameters on the distribution of individuals are analyzed.Several methods are developed to estimate these parameters from observed data, and their applicabilities are investigated. Application of these methods are described on the larval distribution of a colonial insect Pryeria sinicaMoore.
Relationship between female body size and demographic parameters in Bactrocera Malaysian A (Diptera: Tephritidae)
Authors: Chua Tock H. 
Published: October 2006

SummaryThe effect of body size, as measured by the head width, of the female Bactrocera sp. Malaysian A (kept separately in sexual pairs) on the demographic parameters was investigated in the laboratory under ambient conditions of 28–30°C, 78–85% RH and natural photoperiod. Body size was shown to influence significantly all the demographic parameters. The expectation of life of females at eclosion from pupae was respectively for head widths of 1.6, 1.8, 1.9, 2.0 and 2.1 mm: 76.2, 73.4, 73.8, 102.4 and 115.2 days. The mean number of eggs laid per female in its life time was respectively: 86.4±48.7, 181.8±56.1, 229.7±72.6, 364.3±69.4 and 477.5±109.3 which was significantly different from one another (F=3.73,P<0.05) especially the two smaller sizes from the two larger sizes. The regression line for total eggs laid (Y) against head width (X) was Y=785.2X−1208.7 (R2=0.35,P<0.001). The net reproductive rate (R0) was respectively 15.8, 34.0, 43.5, 66.9 and 88.8 eggs, while the intrinsic rate of increase (r) was respectivley 0.0435, 0.0538, 0.0670, 0.0665 and 0.0711. The results confirm that for mass rearing purposes, larger females which produce more offspring are to be preferred.
Spatial pattern indices based on distances between individuals on a line‐segment with finite length
Authors: Shiyomi Masae , Yamamura Kohji 
Published: October 2006

SummaryLet us consider a strip‐wise habitat of line‐segment, like a corridor, to simplify the subject mathematically, and assume that the length of the habitat is γ and there are n individuals. Here, we assume that the spatial pattern of the individuals is random if the n distances from the left end of the habitat to each individual follow a uniform distribution on the strip. Under such an assumption, the variance of the distances between any two neighbors is represented by the formula nθ2(n+1)−2(n+2)−1 and the variance between n+1 distances between n individuals from the left end to the right end to the strip, is represented by the formula nθ2(n+1)−2(n+2)−1. These two kinds of variances can be used for determining (1) the spatial pattern of a population on the strip and (2) the spatial structure within the population, by comparison with the variances calculated from the data. Two examples cited from the literature, a cattle population on a pasture and an aphid population on a sycamore leaf, are presented.
Effects of interspecific competition on development and reproduction in two giant water bugs, Diplonychus japonicus vuillefroy and Diplonychus major esaki (Hemiptera: Belostomatidae)
Authors: Okada Hiroaki , Fujisaki Kenji , Nakasuji Fusao 
Published: October 2006

SummaryWe studied the interpecific competition between 2 species of predatory aquatic bugs, Diplonychus japonicus and D. major by conducting a field experiment. We set up 3 types of experimental plots in the paddy fields where D. major predominated. The two plots contained single species of either D. japonicus or D. major, respectively, and one plot had both species in equal number. We compared the development and the reproductive performance between plots in each species.In D. japonicus, the number of eggs and early instar nymphs were significantly smaller in the plots containing both species than in the monospecific plots. However, the numbers of late instar nymphs and newly emerged adults were not significantly different between plots. The proportions of starved nymphs in both plots were larger than those in the D. japonicus's natural habitats. The final densities of adults in both plots were lower than those in the natural habitats. These results suggest that lower density of D. japonicus in these paddy fields is due to the lack of available food for nymphs rather than the effects of interspecific competition with D. major.In D. major, significant differences were not found in the number of eggs, each instar nymphs and adults. These results suggest that the effects of interspecific competition did not affect the reproductive performance of D. major.
The evolution of dispersal polymorphisms in insects: The influence of habitats, host plants and mates
Authors: Denno Robert F. 
Published: October 2006

AbstractWing‐dimorphic, delphacid planthoppers were used to test hypotheses concerning the effects of habitat persistence and architectural complexity on the occurrence of dispersal. For reasons concerning both the durational stability of the habitat and the reduced availability of mates, selection has favored high levels of dispersal in species occupying temporary habitats. Flightlessness predominates in species occupying persistent habitats, and is promoted by a phenotypic trade‐off between reproductive success and flight capability. Wings are retained in tree‐inhabiting species, probably for reasons concerning the more effective negotiation of three‐dimensional habitats. In contrast, flightlessness is characteristic of those species inhabiting low profile host plants. For several delphacid genera, migratory species are larger than their sedentary congeners. Because body size and fecundity are positively related in planthoppers, the large body size observed in migratory taxa may result from selection for increased fecundity in colonizing species.
The physiological costs of flight capability in wing‐dimorphic crickets
Authors: Zera Anthony J. , Mole Simon 
Published: October 2006

AbstractNutritional indices, triglyceride levels and flight muscle developmental profiles were compared between long‐winged (LW) and short‐winged (SW; flightless) morphs of the crickets Gryllus rubens Scudder and G. firmus Scudder. This was done to identify potential physiological costs of flight capability in adults. The LW morph of each species converted a lower proportion of assimilated nutrients into biomass (reduced ECD) than did the SW morph. This documents increased respiratory metabolism in the LW morph. Triglyceride concentration was higher in LW vs. SW adults. This suggests that the elevated respiration in the LW morph may be at least partially due to the increased biosynthesis of this high energy substance. Preliminary data indicate higher respiration rates of LW functional vs. SW vestigial flight muscles. Collectively, these data suggest that the energetic cost of flight capability in adults results from biosynthesis of triglyceride flight fuel and flight muscle maintenance but not flight muscle growth. No flight muscle growth was observed in adults.
Insect migration: Variability and success in a capricious environment
Authors: Gatehouse A. G. 
Published: October 2006

AbstractStochastic effects of climate and weather have a pervasive influence on the induction, performance and evolution of migration. In wing‐dimorphic species, their influence on habitat quality, and on rates of development of the migrant itself, maintains variation in responses to environmental cues determining wing‐form and migratory behaviour. Migrants flying above their flight boundary layer rely on winds to disperse them across landscapes in which their habitats are distributed. Patterns of distribution of habitat patches, and the influence of changing windspeeds and direction on the displacements of migrants, result in selection for variation in migratory potential at each migration. In subsequent migrations, this variation and stochastic effects of the winds on groundtracks of individual migrants ensure that their destinations ‘sample’ the landscapes they travel over. The extent and resolution of this sampling, by which migrants reach favourable habitats, depend on the components of migratory potential, their mode of inheritance, and genetic correlations between them, as well as on the characteristics of the winds on which they travel.
Habitat fragmentation promotes fluctuating asymmetry but not morphological divergence in two geckos
Authors: Sarre Stephen 
Published: October 2006

AbstractThe process of species formation is often ignored in discussions on the conservation of biodiversity. Yet the clearance of vegetation may promote divergence among populations of a species through isolation, providing conditions for rapid genetic drift and novel selection pressures. Here, stepwise discriminant function analysis and fluctuating asymmetry are used to examine variation in morphology within and among non fragmented and recently fragmented populations of two species of gecko, Oedura reticulata and Gehyra variegata. High reclassification error rates using discriminant function analysis, indicate that fragmentation has had no detectable effect on morphological differentiation among populations of either species. In contrast, remnant populations of both species exhibit higher mean levels of fluctuating asymmetry than do populations in undisturbed habitat. For Oedura reticulata, levels of fluctuating asymmetry are negatively correlated with the log of adult population size. These results suggest that the changes following habitat clearance have been severe enough to cause increased developmental instability in populations of both species but not detectable morphological divergence. Given the high rate of extirpation of gecko populations in the study region and the extreme vulnerability of the remaining populations, it is unlikely that species formation will be significant in maintaining reptile diversity in that region.
Contest competition in Drosophila subobscura
Authors: Jones T. H. , Langefors Å. , Bonsall M. B. , Hassell M. P. 
Published: October 2006

AbstractThe role of larval intraspecific competition in laboratory populations of Drosophila subobscura was investigated. Mortality is density‐independent during the first 3 days after hatching but becomes density dependent as development proceeds to pupation. Although total biomass per patch was independent of initial egg density, competition between Drosophila larvae leads to the formation of smaller pupae. This resulted in a population that was dominated by suppressed individuals. Development rate of D. subobscura larvae was not affected by high larval densities. Smaller pupae give rise to females with fewer eggs in their ovarioles. A simple simulation model, predicting the effects of intraspecific competition on the fecundity of the next Drosophila generation is described.
Resolution of evolutionary conflict: a general theory and its applications
Authors: Higashi Masahiko , Yamamura Norio 
Published: October 2006

AbstractWhile many cases in which conflict over the evolution of social behavior exists even between closely related individuals (e.g., parent‐offspring conflict) have been pointed out, little attention has been paid on the problem of where such conflict should lead. A general theory of conflict resolution, however, has recently been developed. The key idea of the theory is the incorporation of conflict costs in the inclusive fitness evaluation. The theory shows that if both sides engaged in the conflict can potentially control the other at a cost, the coevolutionary game of escalating the fight with increased conflict costs always leads either side to give in to the other, resolving the conflict. Here we examine the logical basis of the theory in terms of a simplest example, donor‐recipient conflict over the evolution of altruism, and to show its different types of application we review two more specific examples: reproductive‐worker conflict over true (sterile) worker evolution in termites and insider‐outsider conflict over group size determination. The latter exemplifies the resolution of conflict over the value of a variable (group size in this case) rather than a behavior, suggesting extended applicability of the basic theory.
Influences of wild crucifers on life history traits and flight ability of the diamondback moth, Plutella xylostella (Lepidoptera: Yponomeutidae)
Authors: Muhamad Omar , Tsukuda Ritsuko , Oki Yoko , Fujisaki Kenji , Nakasuji Fusao 
Published: October 2006

AbstractThe larvae of Plutella xylostella were fed on five wild crucifers, Capsella bursa‐pastoris, Lepidium virginicum, Cardamine flexuosa, Rorippa indica, R. islandica and a crop, cabbage. The developmental period of the immature stages, adult longevity, preoviposition period, fecundity and morphometrical characters of the adults were measured. The flight activity of the adults was also measured by the tethered flight method. All the wild plants except for R. islandica were less suitable host plants than cabbage, and larvae which were fed on these less suitable plants emerged as smaller adults with shorter wings. The smaller female adults had lower fecundity but a higher flight activity. Smaller adults measured in terms of their pupal weight among individuals fed on the same host plant had longer wings. These smaller adults with longer wing flew more actively.
Simultaneous estimation of mortality and dispersal rates of an artificially released population
Authors: Matsuda Hiroyuki , Akamine Tatsuro 
Published: October 2006

AbstractMark‐recapture methods cannot estimate both mortality and dispersal rates of a wild population simultaneously. However, when an artificially cultured population is released into an area, the initial population size and the initial population distribution are usually known. If artificially cultured individuals are released with marks or distinguished from wild individuals or if no wild individual exists in the study area, we can estimate both the mortality and dispersal rates of the artificial population. The numbers of dispersed and dead individuals are estimated from the dispersal rate from the diffusion model and the total decreasing rate estimated from a mark‐recapture data. We can estimate both the time‐dependent and time‐independent dispersal rates from the data. We choose the best fit model that has the smallest value of Akaike's Information Criteria. We also consider ‘concentric circles approximation” of spatial distribution, in which the cumulative and frequency distributions are analytically obtained.