bluuebunny/crossref_metadata_2025 huggingface dataset:
Elimination of Sitotroga cerealella (Olivier) by Sitophilus zeamais Motschulsky from mixed laboratory cultures on maize
Authors: Ayertey J. N.
Published: October 2006

This paper describes a series of experiments conducted to determine why Sitophilus zeamaisMots. and Sitotroga cerealella (Oliv.) could not survive together in maize cultures in the laboratory. The effect of S. zeamais on different developmental stages of S. cerealella was investigated. The presence of adult S. zeamais slightly affected moth copulation, egg laying and moth eggs in a mixed culture, but large numbers of developing moths inside maize grains were killed by the adult weevil through feeding on the grains. The major cause of elimination of S. cerealella by S. zeamais from mixed cultures was therefore found to be damage to the immature moths in grain and such moth mortality increased as the developing moths became bigger in the grains. A weevil: grain ratio of approximately 1.4∶1 was found to be the critical weevil density at which the moth disappeared from the mixed cultures.
Estimation of population size and survival of sheep blowfly, Lucilia cuprina, in the field from serial recoveries of marked flies affected by weather dispersal and age‐dependent trappability
Authors: Vogt W. G. , Morton R.
Published: October 2006

A model is presented for analysis of mark‐recapture data of mobile insects which, unlike the Lincoln Index, does not require marked individuals to remain within the sampling area or to mix uniformly with the wild population. The model assumes a single or multiple releases of marked insects from the centre of the sampling area and that captured individuals are not returned to the population. Dispersal rates of marked insects are estimable from serial recaptures and, for catches that are either unaffected by or have been corrected for weather effects, the model also provides estimates of mortality and age‐dependent trappability. Application of the model is illustrated using mark‐recapture data for adults of the Australian sheep blowfly Lucilia cuprina.
Contest and scramble competitions in Callosobruchus maculatus (Coleoptera: Bruchidae)
Authors: Toquenaga Yukihiko , Fujii Koichi
Published: October 2006

Larval competition curves and resource sharing patterns of 5 strains of Callosobruchus maculatus (iQ, yQ, aaQ, wQ, and tQ) were examined. Offspring emergences as a function of the initial larval density were recorded to construct competition curves. Elytron length of emerged adults was used as the indicator of resource sharing patterns among competing larvae inside a bean.

In the large beans, strain iQ showed a saturated competition curve and tQ strain showed a humped curve. Competition curves of the other 3 strains (yQ, aaQ, and wQ) were between those two extremes. In the small beans, strains iQ and tQ also showed a saturated and a humped competition curves, respectively, whereas the competition curves of the 3 intermediate scramble strains could not be distinguished from that of the iQ strain. Thus, the classification based on competition curves was sensitive to the resource condition (bean size). In both the large and the small beans, the elytron lengths of iQ strain remained constant irrespective of initial larval density. On the contrary, the elytron lengths of the 4 other strains decreased monotonically with higher initial larval density. Thus, the judgment based on the resource sharing pattern was shown to be robust. Only iQ strain should be designated as a contest type, and the remaining strains as scaramble types. Contest and scramble types in C. maculatus were also compared with those observed in C. analis and C. phaseoli using competition curves, resource sharing patterns, and other physiological characters.
Heritability estimates of life history traits in small white butterfly Pieris rapae crucivora
Authors: Tanaka Yoshinari
Published: October 2006

Heritabilities and genetic correlations of life history characters (pupal weight, age‐specific fecundities, and egg weight) of small white butterfly Pieris rapae crucivora are estimated by a quantitative genetic method (sib analysis). The results indicate moderate or high heritabilities and a largely negative genetic correaltion in age‐specific fecundities.
Egg cluster size variation in relation to the larval food abundance in Luehdorfia puziloi (Lepidoptera: Papilionidae)
Authors: Matsumoto Kazuma , Ito Fuminori , Tsubaki Yoshitaka
Published: October 2006

Mean egg cluster size of Luehdorfia puziloi yessoensis varied among habitats. The mean egg cluster size tended to be large when abundance of the larval food leaves expressed as the fresh weight of leaves per unit area at a given habitat was high. Since this variation was observed among closely located study plots (butterflies can easily move between study plots), the egg cluster size variation among habitats is likely to be a result of flexible response by females to varying food abundance for larvae.
Population field studies of the aphidophagous ladybird beetleHarmonia axyridis(Coleoptera: Coccinellidae): Life tables and key factor analysis
Authors: Osawa Naoya
Published: October 2006

Life tables of the predatory ladybird beetleHarmonia axyridiswere analysed by taking samples from twenty or twenty four sites colonized by eight species of aphids for two years.

Larval mortality was a key factor in theH. axyridispopulations. Mortality of all the stages tended to be density‐dependent when life cycles were divided into four developmental stages, except in the case of mortality at hatching due to sibling cannibalism.

Sibling and non‐sibling cannibalism played an important role on population stability and persistence.
The sterile insect release method on species with two‐stage life cycles
Authors: Barclay Hugh J.
Published: October 2006

A continuous‐time density dependent model was constructed of a species with a two stage life cycle. This model has a unique stable equilibrium. With the introduction of steriles at constant rate a second positive unstable steady state appears; this condition does not depend on the mode of action within the life cycle of the density dependence or its relative strength.

A comparison was made of the effects of having the density dependence in each of larval and adult recruitment and larval and adult losses. It was found that if only adult recruitment is denisty dependent, then adult numbers can actually increase with the release of steriles provided density independent recruitment greatly exceeds density independent losses. Sterile releases were often more effective against larvae than against adults, although in some cases not importantly so.

Density dependence in recruitment gives much lower equilibrium values than when density dependence of comparable strength is in the mortality.

The release rates needed to cause extinction were generally between 0.1 and 0.5 of the larval equilibrium with no sterile releases except when the density dependence is predominantly in adult recruitment, in which case much higher release rates are required.
Sampling techniques and the use of Tang's procedure in insect population dynamics studies
Authors: Swartz Joel B. , Dahlsten Donald L.
Published: October 2006

Some calculations were performed usingTang's method as an aid in planning experiments for studying the population dynamics of the Jeffrey pine beetle. The population dynamics studies were aimed at detecting the importance of specific effects, e. g., tree diameter, tree height. TheTang procedure is a method of estimating the sample size required to detect effects of a given magnitude with analysis of variance tests. Using this procedure some sample calculations were performed which indicated the sample size needed, and the efficacy of different strategies of improving the results, e. g., increasing the number of trees sampled versus increasing the area of the tree sampled. The statistical parameters used in the calculations were estimated from some preliminary sampling data. Use of this procedure is recommended in insect population studies as a method of optimally planning experiments, and as a method of making precise conclusions about the significance of specific effects.
Population dynamics of the swallowtail butterfly, Papilio xuthus L., in a deforested area
Authors: Watanabe Mamoru
Published: October 2006

The long‐term population dynamics of the swallowtail butterfly, Papilio xuthus, were studied by means of life table analysis in a deforested area, where the host tree, Zanthoxylum ailanthoides, was growing. The number of eggs laid on host trees in the deforested area decreases as secondary succession progresses. When the trees were classified into three groups, i. e. tall, medium and short, according to their height relative to the surrounding vegetation, less eggs were laid on tall than on short host trees. Life tables for the natural populations in each generation were developed on the basis of mean values for 6 years. Eggs and larvae in early stages were attacked chiefly by small‐ and middle‐sized predators, such as ants, spiders, bugs and orthopterids, while later stage larvae were attacked chiefly by birds or Polistes wasps. An inchneumonid wasp was the most important mortality factor in the pupal stage. Key‐factor analysis was tested on the life table data of each immature stage. The late larval stage was a key stage, and most mortality factors were considered to operate independently. The test for density dependency did not show any tendencies. The analysis of variance in two‐way classifications was carried out for the difference of survival rate among the tree groups. It was suggested that tall host trees were unsuitable for P. xuthus. The construction of life tables for artificially inoculated populations on large host trees showed that high physiological death rate were characteristic of such trees in comparison with natural populations on smaller trees. The characteristics of the population dynamics of P. xuthus in the deforested area are compared among some kinds of the habitat, and the interrelationship between P. xuthus and its host plant are discussed.
The sterile release method for population control with interspecific competition
Authors: Barclay Hugh J.
Published: October 2006

A differential equations model of competing species with the release of sterile individuals of one of the species is examined. The system is found to have two positive steady states for certain parameter values; one of these is stable and the other is unstable. The system is quite resilient around the stable steady state. The release of steriles causes the nontarget species to increase in numbers. There exists a value of the release rate above which the pest species collapses to extinction. The existence of the competitor species assists the sterile release program since the pest equilibrium at any release rate is lower with the competitor species present than without it; in addition the release rate required to cause collapse of the pest species is lower with the competitor species present than without it.

The effects of the parameters on the ease of eradication were examined. It was found that the ideal competitor species should have a high rate of increase, a large carrying capacity and exert strong competitive depression on the pests. The ideal pest would have a low rate of increase, a low carrying capacity and be a poor competitor.
Inquiry into effects of prebaiting on removal census in a vole population
Authors: Tanaka Ryo , Kanamori Masaomi
Published: October 2006

A field work with two plots of grid, a snap trap being set on each station spaced 5 m apart, was executed in the summer of 1968 to evaluate prebaiting in census trapping by comparing the result in one plot, prebaited for three days, with that in the other not prebaited. Since the population was as high as some 230 per acre on the average in density and formed of the vole, Microtus montebelli, alone, sufficient samples were gathered irrespective of the plot size as small as 50×50 m.

Owning to the circumstances, multiple collisions inflicted so intense influence on sampling especially in the prebaited plot that z‐equation for census adjusted to the effect was well applicable to the data in either plot. In sampling, the fact that small voles are apt to be caught later than large voles was statistically evidenced in either sex, and yet any proof that males tend to be caught prior to females was not offered. It was ascertained in either plot that the daily catch was realized according to the same rule through the whole period of trapping in both external belt and internal square within the plot; hence it follows that no considerable immigration occurred.

One of the beneficial effects of prebaiting is sure to be that the probability of capture was markedly enhanced in the prebaited plot, and a second is supposed, though inconclusively, to be that a good sampling could be executed consistently through the census period giving rise to no inordinate catches perhaps due to heterogeneous sampling as was seen in earlier days in the not prebaited plot. The supposition has derived from the condition that most of the whole population is trappable, which is established by interrelation among population density, size of home range and trap spacing. It was suggested that the effect of prebaiting should be evaluated from the view‐point of the interrelation, because the basic utility of prebaiting consists in that it may help to our utlimate purpose to estimate the whole population.
Canonical correlation between groups of acarine, fungal and environmental variables in bulk grain ecosystems
Authors: Sinha R. N. , Wallace H. A. H. , Chebib F. S.
Published: October 2006

Interrelations among acarine, fungal, and environmental components of bulk grain ecosystems were determined by canonical correlation analyses. Twenty‐seven variables were measured monthly in samples collected from 2 identical grain bulks in a granary in Winnipeg during the years 1959–67. The relationships between 9 kinds of arthropods and 6 environ mental variables, and between the same arthropods and 12 kinds of actinomycetes and fungi were examined. The maximum canonical correlation between arthropods and environmental factors was 0.35, and between arthropods and microorganisms was 0.28; both are highly significant (p<0.001). In the first analysis correlations of the variables with the canonical variates revealed that correlations of the variables with the canonical variates revealed that sampling location, depth, and temperature are the primary environmental antecedents involved, and the criterion is primarily composed of mites Tarsonemus spp.,Tydeus interruptus and the psocid, Lepinotus reticulatus. In the second analysis the fungi Nigrospora sphaerica, Aspergillus spp., and Cochliobolus sativus are involved with the mites Cheyletus eruditus and Acarus siro. Generally, the results of these analyses complement the findings of factor and regression analyses of the same data reported earlier.
Factors affecting oviposition rate in the flour beetle Tribolium castaneum and the origin of the population regulation mechanism
Authors: Sonleitner Frank J. , Gutherie Janis
Published: October 2006

The effects of egg cannibalism, conditioned medium and the presence of quinone secretions on oviposition rate were studied using single pairs of adults to eliminate any direct crowding effects. Most measurements were made on beetles confined to the surface of the flour medium in plastic towers. Oviposition rate was decreased by about 58% when pairs were transferred from fresh to conditioned medium; lowered about 25% when only quinones were present and the medium was still fresh; and enhanced 35% in dry conditions when beetles were provided with eggs to eat. Both the lowered oviposition rate in confined cultures and egg‐eating may be explained by natural selection at the individual level. Cannibalizing eggs boosts a female's oviposition rate. The presence of quinones or conditioned medium indicates high population densities and acts as a signal for ceasing oviposition and dispersing to avoid high egg mortality. In confined populations, this results in population regulation, while in open populations, this strategy is a mechanism to avoid competition. It implies that the resource shortages normally experienced by such organisms are relative, not absolute.
Some strange properties of the logistic equation defined with r and K: Inherent defects or artifacts?
Authors: Kuno Eizi
Published: October 2006

In some situations the logistic equation in the usual expression, dN/dt=r(1−N/K)N, exhibits properties that are biologically unrealistic. For example, when r≦0 the population can no longer show any normal, negative response in per‐capita growth rate to increasing density. Also, when the equation is employed in the Volterra's competition model, a familiar but incredible conclusion is derived which says that the outcome of competition is entirely independent of the reproductive potential r of each species. It is shown that all such strange properties are mere artifacts arising peculiarly in this r‐K model from its misleading implicit supposition that K could be independent of r, and they can be readily removed by alternative use of a plainer, classical form of the model, dN/dt=(r−hN)N.
Fertility schedules of unaspis yanonensis (Hemiptera: Diaspididae) in relation to daily temperature
Authors: Adachi Ishizue , Korenaga Ryoji
Published: October 2006

Fertility schedules of Unaspis yanonensis on citrus leaves were investigated from 1962 to 1971 for the first generation and from 1964 to 1971 for the second generation, at the Okitsu Branch of the Fruit Tree Research Station in Shizuoka Prefecture. The fertility curves were commonly characterized by a first major peak and a few subsequent minor peaks, although their shapes differed from year to year. Models estimating these fertility curves of each generation were constructed in relation to the fluctuations in average daily temperature, on the assumption that the curve was composed of two peaks, i.e., bimodal. Estimated curves were well fitted to observed ones.
Density yield relationships and economic injury level model for the Colorado potato beetle larvae on potatoes
Authors: Mailloux G. , Binns M. R. , Bostanian N. J.
Published: October 2006

A three year study revealed that the relationship between the density of Colorado potato beetle larvae per stalk and a decrease in the yield of potatoes can be described by a model comprised of two straight lines. Potato cv. Superior was found to have a damage boundary of 12 larvae per stalk, which is the maximum level of injury or pest density below which no noticeable yield loss occurs. The economic injury level was estimated as a function of larval density in relation to yield, cost of protection, efficacy of treatment, value of the crop and expected harvest in the absence of any loss.
A model of the plant‐to‐plant movement of aphids II. Estimation of parameters and the application
Authors: Shiyomi Masae
Published: October 2006

It was shown in the previous report that the statistical model of the plant‐to‐plant movement of aphids could be fitted well to the actual population of barley aphids (Shiyomi, 1967). To examine validity of the model, results of the further experiments were analysed and the methods of estimation of parameters were given in this paper.

Comparing the estimates of the parameters obtained by the moment method with those obtained by the maximum likelihood method, the estimates from the latter method were somewhat precise.

The theoretical frequency distributions calculated from the model were fitted very well to the observed ones.

The model was reexamined with reference to the results obtained byItô (1954, 1960). When the distance between plants was less than 4.5 cm, the farther was the distance between plants, the smaller was the rate of the plant‐to‐plant movement of aphids. When the distance was greater than 4.5 cm, however, the rate of the plant‐to‐plant movement was independent of the distance. This result is similar to that ofItô.
Competitive exclusion through reproductive interference
Authors: Kuno Eizi
Published: October 2006

A simple differential equation model was developed to describe the competitive interaction that may occur between species through reproductive interference. The model has the form comparable to Volterra's competition equations, and the graphical analysis of the outcome of the two‐species interaction based on its zero‐growth isoclines proved that: (1) The possible outcome in this model, as in usual models of resource competition, is either stable coexistence of both species or gradual exclusion of one species by the other, depending critically upon the values of the activity overlapping coefficient cij; (2) but, for the same cij‐values, competitive exclusion is much more ready to occur here than in resource competition; (3) and moreover, the final result of the competition is always dependent on the initial‐condition due to its non‐linear isoclines, i.e., even under the parameter condition that generally allows both species to coexist, an extreme bias in intial density to one species can readily cause subsequent complete exclusion of its counterparts. Thus, it may follow that the reproductive interference is likely to be working in nature as an efficient mechanism to bring about habitat partitioning in either time or space between some closely related species in insect communities, even though they inhabit heterogeneous habitats where resource competition rarely occurs so that they could otherwise attain steady coexistence.
Why does only Athalia Japonica enter summer diapause among three sympatric Athalia sawflies feeding on crucifers?
Authors: Nagasaka Koukichi
Published: October 2006

This report assesses the primary factor for the evolution of summer diapause of the three species of sawfly, Athalia japonica, A. rosae and A. infumata that feed on cruciferous plants and coexist in the same area. A. japonica has two discrete spring and autumn generations, but A. rosae and A. infumata 5–6 generations. Only A. japonica enters summer diapause in response to the long daylengths in spring. Although these three sawflies usually feed on the same cultivated crucifers, they differ markedly in the utilization of wild crucifers. They oviposit only on young leaves. A. japonica mainly uses Cardamine plants which sprout in spring and autumn. A. rosae and A. infumata primarily use hosts with new leaves all the year round, i.e. cultivated crucifers and Rorippa indica, respectively. The thermal threshold for development is lower in A. japonica than in the other two species. The low heat tolerance of A. japonica is adapted only to cool shady habitats where Cardamine grows. Presumably, summer diapause of A. japonica is adaptation to the deterioration of the primary host plants rather than unfavorable climatic conditions. This interpretation is supported by the movement patterns of the three Athalia sawflies, alternative means to escape from deteriorated habitat conditions.
Binomial sampling plans for estimating Bemisia tabaci populations in cantaloupes
Authors: Tonhasca Athayde , Palumbo John C. , Byrne David N.
Published: October 2006

Early season infestations of the sweet potato whitefly, Bemisia tabaci (Gennadius), on cantaloupes, Cucumis melo L., were determined by counts of the number of adults per leaf in fields near Yuma, Arizona. We used these data to develop binomial sampling plans based on the relationship between mean densities of whiteflies per leaf, m, and proportion of leaves infested with more than I whiteflies, PI, according to the empirical model ln m=a′+b′ ln[−ln(1−PI)]. The models were developed for the presence‐absence approach (I=0) and for a cutoff value of three whiteflies per leaf (I=3). Four independent data sets were used to evaluate the models. Both methods yielded reliable predictions at low infestation levels, but some of the higher m values were overestimated. As the tentative economic threshold for B. tabaci is three adults per leaf, which corresponds to low PI values, results of the binomial sampling were satisfactory for pest management purposes.
Reproductive behavior of the Japanese treefrog, Rhacophorus arboreus (Anura: Rhacophoridae)
Authors: Kasuya Eiiti , Hirota Mariko , Shigehara Hideko
Published: October 2006

Reproductive behavior of the foam‐nesting treefrog, Rhacophorus arboreus, is described. Oviposition was made either by an amplectant pair (a female, and an amplectant male) alone or by an amplectant pair and other males (joiners). The snout‐vent length of males and females was negatively correlated with the date of the first appearance in the pond. The period of staying in the pond in males was longer than that in females. Physical body contacts of other males, and encounter calls by ampletant males were frequently observed before oviposition with joiners. Snout‐vent length of the female and an amplectant male were positively correlated. Encounter calls by amplectant males were likely to precede movement of females. There was no difference of snout‐vent length between amplectant males and joiners. Females moved the hindlimbs more frequently than males during oviposition. Amplectant males made encounter cells more frequently in oviposition with joiners, than oviposition without joiners. The patterns of transitions between acts of females and amplectant males were similar between oviposition with and without joiners. Females more frequently responded to amplectant males than joiners. Both the duration of a bout of the movements of hindlimbs of females and the interval between the bouts were longer in oviposition without joiners than that with joiners. The number of the movements per bout in oviposition without joiners was smaller than that with joiners. Encounter calls by amplectant males during oviposition tended to precede the hindlimb movements of females.
Population dynamics of the whitebacked planthopper, Sogatella furcifera (Hemiptera: Delphacidae) with special reference to the relationship between its population growth and the growth stage of rice plants
Authors: Matsumura Masaya
Published: October 2006

A population census was conducted to describe the effects of the growth stage of rice on the population dynamics of S. furcifera, in particular, on immigration, seasonal abundance, population growth rate, and wing‐form expression. The number of immigrants was highest on rice plants 17 to 30 days after transplanting (DAT), which suggested that immigrants prefer to settle or remain more on rice plants at the tillering stage (approximately 20–30 DAT). Population growth rate from immigration to the 1st generation decreased with an increase in rice plant age. In contrast, population growth rate from the 1st to 2nd generation was not influenced by rice plant age and was negatively density‐dependent. The percentage of macropters (flyers) was positively related to the growth stage of rice when rice was in the vegetative or early part of the reproductive stage, and reached 100% at about 10 days before heading (booting stage). Threafter, most adult females molted into macropters regardless of population density. The roles of host plant age and crowding effect on the population dynamics of S. furcifera are discussed.
Competitive habitat utilization in the damselfly, Mnais nawai (Zygoptera: Calopterygidae) coexisting with a related species, Mnais pruinosa
Authors: Nomakuchi Shintaro , Higashi Kazunori
Published: October 2006

Reproductive behaviors related to habitat utilization were studied in males of the damsefly, Mnais nawai, which has two male forms, territorial orange‐winged males (nawai) and non‐territorial pale‐orange‐winged males (sahoi), at the upper part of a mountain stream where they partiallycoexist with a related species, Mnais pruinosa, which also has two male forms, territorial orange‐winged males (esakii) and non‐territorial hyaline‐winged males (strigata). These two species showed parapatric distribution; the lower part of the stream was occupied by M. nawai, and the upper part by M. pruinosa. In the present study, cross‐matings occurred between both Mnais species, although normal intraspecific matings occurred more frequently than cross‐matings. Territorial males of both species copulated with conspecific females that entered their territory and guarded the ovipositing females, probably to avoid sperm displacement resulting from subsequent copulations. Severe competition for oviposition sites by territorial males even occurred between the two species. On the other hand, non‐territorial males of both species have alternative mating strategies (including several tactics such as sneaking, takeover and interception). The possible benefits from conflict among territorial males of both species is discussed.
Nutritional contribution to females of14C‐labeled male secretions transferred during mating in Menida scotti (Heteroptera: Pentatomidae)
Authors: Koshiyama Yozo , Tsumuki Hisaaki , Fujisaki Kenji , Nakasuji Fusao
Published: October 2006

Menida scotti (Puton) males have been shown to transfer secretions from their bulbus ejaculatorius and reservoir of ectodermal accessory gland to females by mating during hibernation. In the present study, the major components of the secretions were found to be proteins and lipids. To specify the female organ incorporating the male secretions, a radiotracer experiment in which the male secretions were labeled by [14C]valine was conducted in nine tissues of females collected in the fall and spring of the hibernation period. Relatively high radioactivities were detected in the haemolymph and the residual carcass (head, legs, air‐sacs, exoskeleton, etc.) in the fall females, and in CO2 gas evolved and carcasses in the spring females. The radioactivities in the fat body were significantly higher in the fall mating females than in the spring mating females, and vice versa in the ovary. The radioactivities in six fractions (lipids, proteins, glycogen, sugars, free amino acids and the residues) were also assayed in the five organs of females that had a relatively high radioactivity. The highest radioactivity was detected in the protein fraction of the haemolymph in fall and spring females. There were significant differences in the radioactivities incorporated into the lipid fractions of the carcass between fall and spring females.
Mating and diapause in hibernating adults of Menida scotti puton (Heteroptera: Pentatomidae)
Authors: Koshiyama Yozo , Fujisaki Kenji , Nakasuji Fusao
Published: October 2006

In Menida scotti aduts which mate during hibernation, we examined the effect of photoperiod on diapause induction in terms of the developmental degree of reproductive organs and corpora allata. In a hibernating population, mating season and physiological changes related to dipause were investigated. When newly emerged adults were reared under long‐ or short‐day conditions, reservoir of the ectodermal accessory gland and corpora allata in males developed, while the developments of ovary and corpora allata in females were suppressed under both conditions. This suggests that diapause of this species is induced only in females independently photoperiodic conditions during adult stage. In a hibernating population, mating was observed from early to late November and from late March to early May. Observations of the development of reproductive organs and corpora allata suggest that diapause is induced only in females in the former period, while both sexes are not in diapause in the latter period.
Parental care and EGG size in salamanders: An examination of the safe harbor hypothesis
Authors: Nussbaum Ronald A.
Published: October 2006

The safe harbor hypothesis includes the suggestion that parental care causes the embryonic stage to be the safest harbor, and, therefore, egg size will increase in populations with parental care to decrease the duration of subsequent, higher risk stages. Neither the safe habor hypothesis nor r and K theory seem adequate to explain the correlation between egg size and the presence/absence of parental care among salamanders, a group in which there is a further correlation between the larval (hatchling) habitat and egg size/parental care. Pond‐breeding salamanders generally have small eggs and lack parental care, and stream‐breeding salamanders generally have large eggs and parental care. I argue that the fundamental difference in the food available to hatchling salamanders between lentic (plankton‐rich) and lotic (plankton‐poor) environments selects for relatively lower parental investment in the lentic environment. From the standpoint of parental fitness, small (more numerous) hatchlings have a greater payoff where the available food is mall and dense (zooplankton in lentic environments), and large hatchlings are selectively advantageous where the food is of large size and less dense (benthic invertebrates in lotic environments). Selection for larger hatchlings in lotic environments results in longer embryonic periods and, ceteris paribus, greater total embryonic mortality. Embryo hiding and guarding have evolved among lotic‐breeding salamanders as compensatory mechanisms to reduce the rate of embryonic mortality. In this view, parental care is a consequence of selection for larger egg size and not an umbrella that allows egg size to increase, contrary to the safe harbor hypothesis.

The relationship between variance in parental investment and food available to offspring, developed here for salamanders, may be of general significance. YosiakiItô, a critic of r and K theory, independently arrived at a similar conclusion from a broader data base.
Extraordinary effects of fertilization status on the reproduction of an arrhenotokous and sub‐social spider mite (Acari: Tetranychidae)
Authors: Saitō Yutaka
Published: October 2006

Experimental observations on the arrenotokous reproductive patterns of two spider mite species (Acari: Tetranychidae), the long‐seta form of Schizotetranychus celarius (Banks) and Tetranychus urticaeKoch, revealed that reproduction of unfertilized females of the former is very differnt from that of the latter. Unfertilized females of S. celarius, which has a subsocial life, laid a few eggs and then became inactive. In contrast, the fecundity of unfertilized T. urticae females was only slightly reduced as compared with fertilized females. Mother‐son matings may thus sometimes occur in natural S. celarius populations.

A two‐year field survey revealed that, in the absence of males, overwintering females of S. celarius occasionally remain unfertilized until early spring. Furthermore, nest foundation observed in late spring indicated that most of the season's first nests were founded by single females. These two sets of observations strongly suggest that motherson mating takes places in nature, corresponding to the reproductive trait seen in the experiment.

Mother‐son mating inevitably increases the relatedness between nest members. The estimated father's relatedness to its offspring is extraordinarily high under such condition. The possibility that kin‐selection in the long seta‐form of S. celarius led to subsociality, especially paternal care, is suggested.
Mating patterns of a sphragis‐bearing butterfly, Luehdorfia japonica leech (Lepidoptera: Papilionidae), with descriptions of mating behavior
Authors: Matsumoto Kazuma
Published: October 2006

Mating frequency of both sexes in a natural population of the papilionid butterfly Luehdorfia japonica was studied with special attention to the role of sphragis in preventing multiple matings by females. Males patrolled continuously within a patchy habitat throughout the warm daylight period in search for females. Mating took place without specialized courtship behavior. Males also attempted to copulate forcibly with previously mated females, but the presence of sphragis and/or the escape reaction of females prevented copulation. There was no specialized mate rejection behavior. Females mated early in their adult life, mainly on the day of emergence, and the frequency of mated females reached 100% within the first two or three weeks of their flight period. Spermatophore counts based on dissections of wild females possessing a sphragis indicated that they had never remated. Males were sexually active throughout their adult life. Male mating frequency was estimated from an index of scale‐loss from the claspers and frequencies of males which had not mated, and those which had mated once, twice or three or more times were respectively estimated to be 33.7%, 40.3%, 18.2% and 7.8%.
Dispersion distance of queens from natal sites in the two haplometrotic paper wasps Polistes riparius and P. snelleni (Hymenoptera: Vespidae)
Authors: Makino Shun'ichi , Yamane Seiki , Sunose Tsukasa , Aoki Shigeyuki
Published: October 2006

Dispersion capabilities of new queens were studied in the two haplometrotic paper wasps Polistes riparius and P. snelleni. New queens were marked on the nests in the late summer and located in the next spring. Dispersion distances greatly varied among queens: although a large part of recovered queens nested in close proximity to their natal sites, some did disperse over 100–300 m. This suggests that queens' emigration from and immigration into the censused areas occurred to a substantial extent. On the whole, these species exhibited a weaker “philopatric” tendency than those so far studied for dispersion distance, and seem to have the potential for a long‐distance dispersion.
Control of insecticide resistance in a field population of houseflies, Musca domestica, by releasing susceptible flies
Authors: Imai Chobei
Published: October 2006

Susceptible houseflies, Musca domestica, were released at a waste disposal site to control insecticide resistance in a field housefly population. In the first experiment, a total of 163,000 pupae of the susceptible Takatsuki strain were released in October–November 1977. LD50 values to fenitrothion and diazinon decreased to about one‐sixth in April 1978, five months after the releases, of those before the releases. For the second experiment, a susceptible colony was derived by cross and backcross between a white‐eyed substrain of the Takatsuki and a field colony. This susceptible colony consisted of whiteeyed flies with low activity and normal‐eyed flies bearing no or one white eye gene. The results of large cage experiments suggested that the normal‐eyed males of the susceptible colony had half the mating competitiveness of wild males. Approximately 31,000–46,000 susceptible pupae were used in each of five releases from October to November 1980. The population number of each sex, estimated by a mark‐release‐recapture method, increased from 12,000 in late September to 35,000–43,000 in middle November and then decreased to 5,000–8,000 in early December. The frequency of field‐collected males bearing one white eye gene and those bearing one male determining factor, which were characteristics of the susceptible colony released, increased gradually during the period of releases. The susceptibility of the field population to fenitrothion and diazinon was examined five times in the period from September to December 1980. With time, the dosage‐mortality regression gradually shifted towards that of the susceptible colony after starting the releases. LD50 values to fenitrothion and diazinon decreased to about one‐sixth and one‐fifth, respectively, in June 1981, six months after the second series of susceptible fly releases, of those before the releases. Ratios of the wild flies to the released fiies were estimated to be between 4.7∶1 and 9.8∶1 in males and between 3.0∶1 and 3.9∶1 in females by taking the quality of the released colony and the population parameters of the field houseflies into consideration. Under several assumptions, the manner of resistant phenotype reduction was discussed, based on the dosage‐mortality regressions and the ratios of released flies. These results showed that the releases of susceptible flies were successful in suppression of insecticide resistance in the field housefly population.
Genetic variation of density responses in relation to wing polymorphism in the oriental chinch bug, Cavelerius saccharivorus Okajima (Heteroptera: Lygaeidae)
Authors: Fujisaki Kenji
Published: October 2006

Responses to nymphal density in the determination of wing form were compared between the offspring from brachypter x brachypter crosses and those from macropter x macropter crosses of the oriental chinch bug, Cavelerius saccharivorus.

In the offspring from crosses between macropters, there was a strong tendency for macropters to increase to a rather high level with increasing nymphal density in both sexes. In contrast to this, in the offspring from crosses between brachypters, the appearance rate of macropters attained a maximum value in moderately crowded conditions and conversely decreased to a lower level in more crowded conditions in both sexes. Thus density response patterns concerning the determination of wing form were quite different between the offspring from different crosses in the wing form, indicating that there is a genetic basis underlying wing polymorphism in this species.

As for the body size of emerged adults, macropters tended to be larger than brachypters in the same crowded condition. Moreover, the rate of decrease of body size with nymphal density was lower in the offspring from crosses between macropters than in the offspring from crosses between brachypters. This indicated that the former offspring are more tolerant of nymphal crowding than the latter. The difference in such a tolerance against nymphal crowding between the offspring from different crosses was considered to be related to the difference in the appearance of macropters in the crowded conditions between them.
Adult populations of the sugi bark borer, Semanotus japonicus Lacordaire (Coleoptera: Cerambycidae), in Japanese cedar stands: Population parameters, dispersal, and spatial distribution
Authors: Shibata Ei'ichi
Published: October 2006

Adult populations of the sugi bark borer, Semanotus japonicusLacordaire, which attacks the trunks of Japanese cedar and cypress, were studied in two cedar stands in 1981 and 1984, using a band‐trapping method developed by the author.

Adults began to emerge and fly earlier in 1981 than in 1984 because of the higher temperature after hibernation in 1981. Population size wasestimated by a markrelease‐recapture method. The daily survival rate ranged from 0.86 to 0.92 and the mean longevity from 7.0 to 11.9 days. Females were fewer than males throughout the season, especially early in the flight period, because males consistently emerged earlier. The mean distances traversed among the cedar trees were 9.2 m for males and 16.3 m for females; maximum dispersal was 79.5 m for males, 149.5 m for females. There are two different patterns in their dispersal movement: the small‐scale movement which consists of walking at cool temperatures and large‐scale flight at warm temperatures. Adults of this species are somewhat sluggish and between‐tree movement is infrequent. This lack of movement resulted in a contagious distribution pattern of adults.
Studies on the color variation in larvae of Ephestia kühniella Zeller (Lepidoptera: Phycitidae) III. Fitness of different larval color strains
Authors: Imura Osamu
Published: October 2006

The population fitness in terms of the intrinsic rate of increase rm was measured in eight pure (homogenic) strains of Ephestia kühniellaZeller with different larva color at an optimal temperature of 25°C, and in three strains at unfavorble temperatures of 15, 17, 28, and 30°C, to understand a mechanism of maintenance of a larval color variation found in wild populations. The survival rate, hatchability, and gross rate of reproduction were poorly correlated with the fitness but the mean generation time and net reproduction rate were correlated with the fitness significantly at 25°C. Intermediate color (pink) strain(s) grew faster, initiated reproduction earlier and had shorter longevities than other strain(s) under the range of 15 and 28°C; the fitness was highest in the intermediate larval color strains except at 30°C in which all strains had a negative rate of increase. The results were discussed with reference to the relationship between the larval color and fitness along with a maintenance mechanism of the variation.
The adaptive significance of leaf‐mining pattern as an anti‐parasitoid strategy: A theoretical study
Authors: Katô Makoto
Published: October 2006

An adaptive significance of linear leaf mining patterns as the anti‐parasitoid strategy is theoretically analysed. In the model, a leaf‐miner is allowed to move in one of four ways; mining ahead in unexploited area of a leaf, backtracking, branching off from the backtracking mine, and crossing the previous mine. The model parasitoid searches for the leaf‐miner by tracing the mine by the tactile cue of mine surface after detecting the mine. The average duration from detecting the mine to finding the leaf‐miner host is calculated for various patterns of mining, changing numbers of branches and of crosses. This average duration becomes longer when the leaf‐miner stays near either end of the mine compared with when staying near its center. It is also prolonged as the numbers of branches and of crosses increase.
Further improvements to a method for analysing stage‐frequency data
Authors: Manly B. F. J.
Published: October 2006

An iterative procedure for correcting stage‐frequency data is described to allow for situations where the period during which a population is sampled begins after some individuals have entered stage 2 or ends before all individuals are dead. The reason for correcting data in this way is to enableKiritani andNakasuji's method for estimating stage‐specific survival rates, with extensions proposed byManly (1976, 1977), to be used to analyse the data.

The proposed procedure is illustrated on data obtained by sampling a population of the grasshopper Chorthippus brunneus passing through four instar stages to reach the adult stage.
Reproductive compatibility between populations of the citrus red mite, Panonychus citri (McGregor) (Acarina: Tetranychidae)
Authors: Takafuji Akio , Fujimoto Hiroaki
Published: October 2006

Reproductive compatibility was studied among populations of different types of the citrus red mite, Panonychus citri (McGregor), i.e., the diapausing type from pear (DP), the non‐diapausing type from citrus (C) and that from pear (NP).

Copulation was also observed between mates of different types (DP and C). Only in crosses between C ♀ and DP ♂, was copulation occasionally broken off prematurely; duration of copulation varied considerably between pairs and the average duration was much shorter than that between DP ♀ and C ♂ and than that in crosses between mates of the same types.

No F1 adult females were produced at all from crosses between DP and C, showing that there was a complete reproductive isolation between the two types. There was a significant reciprocal difference in the egg hatchability and survival rate of immatures in the F1 progeny; mortality in the eggs and that in the immature stage were significantly higher in crosses between DP ♀ and C ♂, as compared to those in the reciprocal cross. This suggested that fertilization may have occurred in the former cross, whereas it seemed that eggs were not fertilized in crosses between the C ♀ and DP ♂.

The NP was compatible with the C, whereas it was completely incompatible with the DP. Thus, there was a complete reproductive incompatibility between the diapausing and non‐diapausing type of P. citri.