24 results on '"Sasakawa, Kôji"'
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2. Inferring feeding habits of Carabidae (Coleoptera) larvae based on mandible morphology: Case studies of Lesticus magnus and Chlaenius costiger.
- Author
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Sasakawa, Kôji
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LARVAE , *GROUND beetles , *INSECT larvae , *BEETLES , *LIFE history theory , *MANDIBLE , *MORPHOLOGY , *INSECT rearing - Abstract
In the beetle family Carabidae, feeding habits are important life history traits that determine their role in ecosystems and suitability as bioindicators. However, they have not been elucidated for most species, especially in the larval stages. Using laboratory‐rearing experiments, this study examined the larval feeding habits of two large carabid species: Lesticus magnus (tribe Pterostichini) and Chlaenius costiger (tribe Chlaeniini). Although previous studies failed to rear these larvae on insect larva diets, the mandible morphology of the first instars described in those studies, together with subsequently obtained knowledge of the relationship between mandible morphology and feeding habits in other carabid larvae, suggests that they are earthworm feeders. Rearing experiments with three types of animal diet (insect larvae, mixed snail and slug, and earthworm diets) showed that as expected, their larvae are earthworm feeders. In L. magnus, although the larvae accepted the mixed snail and slug diet and the earthworm diet, only larvae reared on the earthworm diet reached adulthood. In C. costiger, the larvae accepted only the earthworm diet and reached adulthood. This is the first report of earthworm feeding during the larval stage for the genus Lesticus (tribe Pterostichini) and tribe Chlaeniini. The importance of these results is discussed from ecological and evolutionary perspectives. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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3. The identities of two species in the Pterostichus macrogenys species group of subterranean carabid beetles (Coleoptera, Carabidae) revealed by external morphometric analysis and comparative genital morphology.
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Sasakawa, Kôji and Itô, Hirotarô
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GROUND beetles , *COMPARATIVE anatomy , *BEETLES , *SPECIES , *COMPARATIVE studies , *MORPHOMETRICS - Abstract
The Pterostichus macrogenys species group is an endemic subterranean Japanese carabid lineage that shows marked regional differentiation, but unresolved taxonomic issues remain, even at the species level. Based on morphological examinations of the genital structures of newly collected specimens and an external morphometric analysis of all the species concerned, P. falcispinus Sasakawa, 2005 syn. nov. is synonymized with P. asahinus Habu & Baba, 1960, and P. awashimaensis sp. nov. is described from Awashima Island, a small island off the coast of Honshu. Based on external morphometrics, P. awashimaensis was determined to be most similar to P. yahikosanus Sasakawa, 2009, but its external and genital features differ distinctly from the latter species and it is thought to be more ancestral. [ABSTRACT FROM AUTHOR]
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- 2022
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4. Effects of diet on female fecundity and larval development in the carrion beetle Necrophila japonica.
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Watahiki, Yôhei and Sasakawa, Kôji
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INSECT feeding & feeds , *INSECT fertility , *CARRION insects , *EARTHWORMS , *MEAL worms , *BEETLES , *SILPHIDAE , *INSECT larvae - Abstract
The carrion beetle subfamily Silphinae (Coleoptera: Silphidae) contains dominant macroinvertebrates of soil ecosystems in temperate zones. However, their feeding habits, which determine the role of each species in the ecosystem, have not been sufficiently studied. Moreover, although a diet shift from necrophagy on vertebrate carcasses to predatory feeding on invertebrates is known to occur in this subfamily, the processes and mechanisms of this shift have also been inadequately addressed. We examined female fecundity and larval development on various diets in a Silphinae species, Necrophila (Eusilpha) japonica (Motschulsky). The experimental diets included a meat diet and various invertebrate diets, which reflect the 'ancestral' feeding habit in Silphinae, necrophagy, and the 'derivative' feeding habit, predatory feeding. Female fecundity was significantly higher on the meat diet (minced beef) than on an insect larvae diet (mealworms and dipteran larvae) but did not significantly differ from that on an earthworm diet. Larval developmental performance was significantly higher on the earthworm diet than on the meat and insect larvae diets. Our results for larval development were consistent with those of previous stable isotope analyses of the same species, in which isotopic values of larval samples agree with those of hypothetical consumers that utilize earthworms. The consistency of results among different methods indicates that N. japonica larvae are most likely earthworm feeders. In contrast, our results for the female fecundity experiment differed from those of previous stable isotope analyses, in which vertebrate carcasses unlikely serve as the staple diet of adults in the field; thus, the feeding habits of N. japonica adults remain unresolved. Our observations that females and larvae performed best on the meat and earthworm diets, respectively, may indicate that, in Silphinae, the diet shift from necrophagy to predatory habits occurs earlier in larvae than in adults. We examined female fecundity and larval development on various diets in Necrophila (Eusilpha) japonica (Coleoptera: Silphidae, Silphinae) with laboratory rearing experiments. Female fecundity was highest on the minced beef diet, simulating a vertebrate carcass, whereas larvae performed best on the earthworm diet, a model for predatory feeding on invertebrates. The results were compared to those of previous studies of this beetle species and discussed from methodological, ecological, and evolutionary perspectives. [ABSTRACT FROM AUTHOR]
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- 2019
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5. Does the host's developmental stage affect host preference following an ovipositioning experience in Heterospilus prosopidis?
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Sasakawa, Kôji, Abe, Masato S., and Shimada, Masakazu
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BRACONIDAE , *ADZUKI bean beetle , *COWPEA weevil , *COMPARATIVE studies , *BEETLES , *CHRYSOMELIDAE , *HYMENOPTERA - Abstract
Many parasitoid wasps exhibit 'oviposition learning,' whereby females associate host-related cues with oviposition and use them in subsequent searches for hosts. This is affected by various factors that have yet to be fully elucidated. We examined the effects of host developmental stage on oviposition learning in parasitoid wasps that utilize both larval and pupal hosts using Heterospilus prosopidis Viereck ( Hymenoptera: Braconidae), an ectoparasitoid of Bruchinae beetles ( Coleoptera: Chrysomelidae), as a model. First, we examined whether the induction of host species preference differs between oviposition on larval and pupal hosts. Oviposition choice experiments were performed for both larval and pupal hosts using two equally preferred host species - Callosobruchus chinensis (L.) and Callosobruchus maculatus ( Fabricius) - and wasps that were conditioned by an oviposition experience on either of the two host species. We found an induction of host species preference in wasps conditioned with pupal hosts but not in wasps conditioned with larval hosts. Next, we examined whether the induced preference was host-stage-specific. Oviposition experiments with pupal-host-conditioned wasps and larval hosts as choice hosts indicated that learned cues were not used when searching for larval hosts. Similar results were obtained for larval-host-conditioned wasps. We compared oviposition behavior on larval and pupal hosts but found no behavioral differences that could contribute to the observed difference in host preference induction. Our results indicate that larval and pupal hosts have different effects on host preference following an oviposition experience in H. prosopidis, although the detailed mechanisms remain unclear. These findings are notable because in parasitoid wasps that utilize both larval and pupal hosts, host developmental stages have attracted little attention as factors affecting oviposition learning. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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6. Notes on the Reproductive Ecology and Description of the Preimaginal Morphology of Elaphrus sugai Nakane, the Most Endangered Species of Elaphrus Fabricius (Coleoptera: Carabidae) Ground Beetle Worldwide.
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Sasakawa, Kôji
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ECOLOGY , *MORPHOLOGY , *GROUND beetles , *WETLANDS , *MEAL worms - Abstract
Elucidating the basic life-history of endangered species is the first important step in the conservation of such species. This study examined the reproductive ecology and the preimaginal morphology of the endangered ground beetle Elaphrus sugai Nakane (Coleoptera: Carabidae); currently, the Watarase wetland of the central Kanto Plain, Japan is the only confirmed locality of this beetle species. Laboratory rearing of reproductive adults collected in early April revealed that females can lay more than 131 eggs. Eggs were laid in mud, without an egg chamber. Larvae reached adulthood when fed a diet of mealworms, indicating that E. sugai larvae are insect larvae feeders. An earthworm diet, the optimal diet for larvae of a congeneric species (E. punctatus Motschulsky), was lethal to E. sugai larvae. The egg stage was 3–4 days in duration under a 16L8D cycle (22°C). The duration from hatching to adult eclosion was 23–42 days at various temperatures simulating those of the reproductive period. Larval morphology was similar to that of consubgeneric species described previously. The pupa is unusual, in that the setae on the abdominal tergites are long (twice as long as those of the abdominal segment) and have somewhat “coiled” apices. Finally, the current endangered status of E. sugai was compared to that of E. viridis Horn, which has been regarded as the most endangered species of the genus worldwide. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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7. Utility of geometric morphometrics for inferring feeding habit from mouthpart morphology in insects: tests with larval Carabidae (Insecta: Coleoptera).
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Sasakawa, Kôji
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INSECT morphology , *INSECT larvae , *MORPHOMETRICS , *INSECT feeding & feeds , *PTEROSTICHUS - Abstract
Feeding habits are important life-history traits in animals; however, methods for their determination are not well established in many species. The larvae of the beetle family Carabidae are an example. The present study tested the utility of geometric morphometrics of mouthpart morphology to infer the feeding habits of carabid larvae. Using Pterostichus thunbergi as a model system, larval feeding habits were inferred using geometric morphometrics of mouthparts and the results were compared with those obtained from rearing experiments. The rearing experiments indicated that P. thunbergi larvae are carnivores that require snails as an essential part of the diet. Through geometric morphometrics, associations between mouthpart morphology and larval feeding habits were confirmed for species in which these two traits are known. A discriminant analysis using these associations classified P. thunbergi larvae as snail/slug feeders, which is a result compatible with the rearing experiments. Geometric morphometrics also revealed that morphological integration and ontogenetic shape change might play roles in the diversification of mouthpart morphology. Overall, these results demonstrate the utility of the geometric morphometrics of mouthparts to infer feeding habit and to clarify the mechanisms of mouthpart morphological diversification in the study group, and the results also serve as a basis for future studies of other insect groups. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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8. Two new species of the ground beetle subgenus Sadonebria Ledoux & Roux, 2005 (Coleoptera, Carabidae, Nebria) from Japan and first description of larvae of the subgenus.
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Sasakawa, Kôji
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NEBRIA , *CLASSIFICATION of insects , *INSECT larvae , *INSECT morphology , *INSECT eggs - Abstract
Sadonebria Ledoux & Roux, 2005 is one of the more diverse subgenera of the genus Nebria Latreille, 1802 in East Asia, and its taxonomy remains unrevised at the subgeneric and specific levels. In this paper, two new species of this subgenus are described from Japan. Nebria quinquelobata sp. n. is described from Mt. Myôkô and is externally similar to Nebria saeviens Bates, 1883, to which specimens of this new species previously had been assigned. Nebria yatsugatakensis sp. n. is described from the Yatsugatake Mountains and is externally similar to locally adjacent species that had been recognized as Nebria sadona Bates, 1883 and were recently revealed as separate species. Both new species are distinguished by morphological (the shape of the endophallus) and morphometric (geometric morphometrics of the pronotum and aedeagus) features. For N. yatsugatakensis, the morphology of all larval instars is described based on specimens reared from eggs laid by collected adults. These results, together with previous studies of the species-level taxonomy of Sadonebria and larval morphology of other Nebria subgenera, suggest (i) the utility of geometric morphometrics in species-level taxonomy; (ii) the importance of larval secondary setae in the subgeneric taxonomy of the genus Nebria; and (iii) the presence of further cryptic species in Sadonebria. [ABSTRACT FROM AUTHOR]
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- 2016
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9. A Novel Technique for Identifying the Instar of Field-Collected Insect Larvae.
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Sasakawa, Kôji
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INSECT larvae , *MOLECULAR biology , *DEVELOPMENTAL biology , *BIOLOGICAL evolution , *POPULATION ecology , *ENTOMOLOGY , *ANIMAL classification - Abstract
Many field studies of insects have focused on the adult stage alone, likely because immature stages are unknown in most insect species. Molecular species identification (e.g., DNA barcoding) has helped ascertain the immature stages of many insects, but larval developmental stages (instars) cannot be identified. The identification of the growth stages of collected individuals is indispensable from both ecological and taxonomic perspectives. Using a larval–adult body size relationship across species, I present a novel technique for identifying the instar of field-collected insect larvae that are identified by molecular species identification technique. This method is based on the assumption that classification functions derived from discriminant analyses, performed with larval instar as a response variable and adult and larval body sizes as explanatory variables, can be used to determine the instar of a given larval specimen that was not included in the original data set, even at the species level. This size relationship has been demonstrated in larval instars for many insects (Dyar’s rule), but no attempt has been made to include the adult stage. Analysis of a test data set derived from the beetle family Carabidae (Coleoptera) showed that classification functions obtained from data sets derived from related species had a correct classification rate of 81–100%. Given that no reliable method has been established to identify the instar of field-collected insect larvae, these values may have sufficient accuracy as an analytical method for field-collected samples. The chief advantage of this technique is that the instar can be identified even when only one specimen is available per species if classification functions are determined for groups to which the focal species belongs. Similar classification functions should be created for other insect groups. By using those functions together with molecular species identification, future studies could include larval stages as well as adults. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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10. Laboratory studies on the larval food habits of the ground beetle Amara ( Curtonotus) gigantea (Motschulsky) (Coleoptera: Carabidae: Zabrini).
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SASAKAWA, Kôji
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INSECT food , *GROUND beetles , *FOOD habits , *INSECT larvae , *OMNIVORES , *BIOTIC communities , *INSECT ecology , *STARVATION - Abstract
Ground beetles (Coleoptera: Carabidae) are important components of soil ecosystems in temperate zones, but our knowledge regarding the ecology of many species is limited. This study examined larval food habits in the ground beetle Amara ( Curtonotus) gigantea (Motschulsky) using laboratory-rearing experiments. Because this beetle is a member of the tribe Zabrini, which includes several species that exhibit granivory during larval and/or adult stages, three diet types were tested, with starvation as a control: Tenebrio larvae, mixed seeds ( Bidens pilosa (Asteraceae), Setaria spp., Digitaria ciliaris (both Poaceae), and Humulus scandens (Moraceae)), and Tenebrio larvae + mixed seeds. Because of high larval mortality during overwintering under laboratory-rearing conditions, survival and the duration of development through pre-overwintering stages (first and second instars) were compared. Larvae fed the diet of Tenebrio larvae + mixed seeds showed the highest survival (89%), followed by the diet of Tenebrio larvae (83%), but the difference between the two treatments was not significant; similarly, developmental durations did not differ between these two diets. Larvae fed the mixed-seeds diet showed markedly lower survival, and no larvae reached the second instar. Therefore, for A. gigantea larvae, animal food results in high larval performance, whereas seeds provide a low value diet; animal food is essential for larval development, but seeds provide no benefit, even as a dietary supplement. Overall, the present results suggest that A. gigantea larvae are omnivorous but with a mainly carnivorous food habit. [ABSTRACT FROM AUTHOR]
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- 2010
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11. Marked sperm dimorphism in the ground beetle Scarites terricola: a novel type of insect sperm polymorphism.
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SASAKAWA, KÔJI
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GENETIC polymorphisms , *SPERMATOZOA , *INSECTS , *ANIMAL morphology , *BEETLES - Abstract
Sperm polymorphism describes the phenomenon of male ejaculates containing two or more distinct types of sperm. In insects, four types of sperm polymorphism are recognized in species from the orders Diptera, Hemiptera, Hymenoptera, Lepidoptera and Coleoptera. The present study describes dimorphic sperm of the ground beetle Scarites terricola (Coleoptera: Carabidae) as a novel type of sperm polymorphism in insects. Sperm from the spermatophore and male seminal vesicles are examined at the light-microscopic level, and both display marked dimorphism. One type has sperm formed into bundles, in which the head of numerous spermatozoa are ‘glued’ together, with tails free-moving. The other type are free as single spermatozoa and have a disproportionately large-sized head and an elongated tail. Both types are motile in Ringer's solution. The adaptive and phylogenetic importance of these findings is discussed. [ABSTRACT FROM AUTHOR]
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- 2009
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12. Phylogeny of ground beetles subgenus Nialoe ( s. lat.) Tanaka (Coleoptera: Carabidae; genus Pterostichus): A molecular phylogenetic approach.
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SASAKAWA, Kôji and KUBOTA, Kôhei
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PHYLOGENY , *BIOLOGY , *GROUND beetles , *BEETLES , *INSECTS - Abstract
We constructed a phylogeny of the ground beetle subgenus Nialoe ( s. lat.), genus Pterostichus (Coleoptera: Carabidae) based on two mitochondrial (cytochrome oxidase I and 16S ribosomal DNA) and one nuclear (28S ribosomal DNA) gene sequences. Thirty-three representative species of the group and three outgroup species were analyzed. The resultant trees (maximum parsimonious, maximum likelihood and Bayesian trees of the combined data of the three gene sequences) indicated that there are two large and three small lineages in the group, some of which were supported by a previous morphology-based phylogeny. In all the analyses, the small lineage composed of two Korean species is sister to the rest of the subgenus, but relationships of other four lineages differed among the analyses and remained unresolved. The implications of the present results are discussed in terms of taxonomy and biogeography of the group. [ABSTRACT FROM AUTHOR]
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- 2009
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13. Diet affects male gonad maturation, female fecundity, and larval development in the granivorous ground beetle Anisodactylus punctatipennis.
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SASAKAWA, KÔJI
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DIET , *FOOD habits , *GROUND beetles , *GONADS , *FERTILITY , *ANISODACTYLUS , *LARVAE , *BEETLES , *INSECTS - Abstract
1. Granivory is a specialised food habit in the Carabidae and is considered to have evolved from ancestral carnivory. Despite recent investigations, the mechanisms underlying this peculiar feeding shift have not been sufficiently elucidated. In particular, no studies have examined the effects of diet composition on male reproductive traits. 2. This study examined male gonad maturation, female fecundity, and larval development under different diets (insect larvae, mixed seeds, and insect larvae + mixed seeds) for Anisodactylus punctatipennis (Coleoptera: Carabidae). 3. Whereas sperm-bundle length, the durations of larval stages, and adult weight did not differ among diets, the weights of seminal substance-producing organs, fecundity, and larval survival were higher with diets containing seeds compared to the pure-animal diet. These findings provide the first conclusive evidence for granivory in Anisodactylus. 4. This study is the first that demonstrates the effects of diet on male reproductive traits in a granivorous carabid. The results were consistent with similar observations for fecundity and larval performance in this and other studies. Thus, in addition to the female and larval traits, the dietary effects on male reproductive traits may also have played an important role in the evolution of granivory in the Carabidae. [ABSTRACT FROM AUTHOR]
- Published
- 2009
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14. Notes on two species of the subgenus Lyrothorax Chaudoir (Coleoptera: Carabidae; genus Pterostichus), Pterostichus amagisanus Tanaka and Ishida and Pterostichus fujitai Tanaka and Ishida.
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SASAKAWA, Kôji
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BEETLES , *GROUND beetles , *PTEROSTICHUS , *PHYLOGENY - Abstract
Two species of the subgenus Lyrothorax Chaudoir (Coleoptera: Carabidae; genus Pterostichus), Pterostichus amagisanus Tanaka and Ishida and Pterostichus fujitai Tanaka and Ishida, were revised based on the male endophallus (inner sac everted from aedeagus). P. amagisanus was newly recorded based on a single male from Kyushu, southwest Japan, far from its known distribution (Honshu; the Fuji-Hakone-Izu volcano area), although additional materials are necessary to confirm this record. Despite a highly disjunct distribution, no conspicuous difference was recognized in either external or genital characters between the materials from Honshu and Kyushu. The nominal species P. fujitai was separated into two species, P. fujitai (Honshu) and Pterostichus eoyoritomus sp. nov. (Shikoku; type locality: Mount Jingayama); these two species have some significant differences in the endophallic structures. Character states in male genitalia suggest a sister relationship between P. eoyoritomus sp. nov. and Pterostichus yoritomus Bates. [ABSTRACT FROM AUTHOR]
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- 2009
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15. Effects of maternal diet on fecundity and larval development in the ‘primitive’ granivorous carabid Amara ( Curtonotus) macronota.
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Sasakawa, Kôji
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DIET , *NUTRITION , *FERTILITY , *LARVAE , *DEVELOPMENTAL biology , *FOOD habits - Abstract
Granivory is one of the most specialized food habits in the Carabidae and has been reported for species from the tribes Zabrini and Harpalini. Most studies of carabid granivory have been conducted using specialized granivorous species, and few have examined primitive ones. This study examined effects of maternal diet on fecundity and larval development in Amara ( Curtonotus) macronota (Solsky) (Coleoptera: Carabidae), a member of the most basal clade of the tribe Zabrini; a previous study indicated that larvae of this species are omnivores with a tendency toward carnivory. Three diet types, Tenebrio molitor L. larvae, mixed seeds [ Bidens frondosa L. (Asteraceae), Setaria spp., and Digitaria ciliaris (Retz.) Koeler (both Poaceae)], and T. molitor larvae + mixed seeds, were used as maternal diets, and larvae were reared on T. molitor larvae + mixed seeds (optimal diet) or T. molitor larvae (suboptimal diet). Fecundity differed significantly among treatments, with individuals fed the T. molitor larvae + mixed seeds diet having the highest fecundities and the mixed seeds diet producing the lowest values. Larval development [survival and duration of development through pre-overwintering stages (first and second instars)] was not significantly affected by either maternal or larval diets, but the addition of seeds to the maternal diet had a weak negative effect on larval survival. These results are in contrast with findings from specialized granivorous carabids, in which both adults and larvae performed best with pure-seed diets. Recent molecular phylogenies indicate that these specialized granivorous carabids belong to derived lineages, while A. macronota is the most basal clade of each tribe. These results are compatible with the hypothesis that carabid granivory has evolved gradually from ancestral carnivory, with omnivorous habits occurring as a transient state. [ABSTRACT FROM AUTHOR]
- Published
- 2009
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16. Taxonomic studies of Pterostichus ishikawai Nemoto (Coleoptera: Carabidae).
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SASAKAWA, Kôji, Jung-Lark KIM, Jong-Kuk KIM, and KUBOTA, Kôhei
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PTEROSTICHUS , *ANIMAL classification , *GENITALIA , *ANIMAL specialists - Abstract
A macrocephalic pterostichine carabid, Pterostichus ishikawai Nemoto, endemic to the Korean Peninsula, is taxonomically revised based mainly on the membranous parts of the genitalia (male endophallus and female vagina). Two species are separated from P. ishikawai (type locality: Mount Taebaegsan) and newly described: P. ishikawaioides (type locality: Mount Sobaeksan) and P. jiricola (type locality: Mount Jirisan). Since comparative male genital morphology does not support monophyly for these three species, the two novel species should be treated as distinct species, not subspecies of P. ishikawai. [ABSTRACT FROM AUTHOR]
- Published
- 2008
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17. Effects of pitfall trap preservatives on specimen condition in carabid beetles.
- Author
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Sasakawa, Kôji
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INSECT trapping , *GROUND beetles , *GENITALIA , *GONADS , *INSECTS , *ENTOMOLOGY - Abstract
The article examines the experiment concerning the effects of pitfall trap preservatives in carabid beetles. The experiment have indicated that the three pitfall trap preservatives can change the conditions of both gonads and genitalia. Furthermore, acetic acid appears to be the most suitable preservative for the preservation of key morphological characteristics.
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- 2007
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18. Phylogeny and Genital Evolution of Carabid Beetles in the Genus Pterostichus and Its Allied Genera (Coleoptera: Carabidae) Inferred from Two Nuclear Gene Sequences.
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Sasakawa, Kôji and Kubota, Kôhei
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GROUND beetles , *PTEROSTICHUS , *PHYLOGENY , *APTERYGOTA , *DNA , *INSECT anatomy , *SPERMATHECA - Abstract
The phylogeny and genital evolution of carabid beetles in the tribe Pterostichini, mainly the genus Pterostichus (Coleoptera: Carabidae), were studied using two nuclear gene sequences: wingless and 28SrDNA. Phylogenetic results suggest that the genera Molops, Poecilus, Stomis, Myas, Lesticus, and Trigonotoma and the subgenus Bothriopterus of the genus Pterostichus form basal lineages, with genus Molops sister to the rest of the tribe. The genus Pterostichus, with the exception of the subgenus Bothriopterus, was monophyletic and occupied more derived lineages. Examinations of the membranous parts of the genitalia (male endophallus and female spermatheca) revealed that endophalli and spermathecae are classified into four and five types, respectively. Reconstructions of genital character evolution on the trees obtained suggest that the ancestor of Pterostichini had a straight endophallus and a short cylindrical spermatheca and that the elaborated genitalia seen in some species evolved in more derived lineages. [ABSTRACT FROM AUTHOR]
- Published
- 2007
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19. Cryptic species of the subgenus Morphnosoma Lutshnik (Coleoptera: Carabidae; genus Pterostichus) from Japan.
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Sasakawa, Kôji and Kubota, Kôhei
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GROUND beetles , *PTEROSTICHUS , *BEETLES , *MOLECULAR phylogeny , *ENTOMOLOGY - Abstract
Pterostichus thunbergi Morawitz and its related species of Japan are revised based on the structure of membranous parts of their genitalia for the first time, under the name of the thunbergi species group. This species group is monophyletic and is placed in the subgenus Morphnosoma Lutshnik. The monotypic subgenus Moritapterus Berlov, erected for P. thunbergi, is synonymized with Morphnosoma. Comparative study of the endophallus revealed that P. thunbergi michinoku Nakane is a junior synonym of P. habui and that four species should be recognized in this group. Three of them are sympatric with P. thunbergi and one of them, Pterostichus (Morphnosoma) robustistylis, is described as a new species. Molecular phylogeny based on the COI gene (mitochondrial [mt]DNA) supported its independence as a distinct species. The resultant trees of mtDNA and comparative study of morphology revealed that P. thunbergi is probably non-monophyletic. In the present study we suggest the presence of further cryptic species of Morphnosoma in Japan. [ABSTRACT FROM AUTHOR]
- Published
- 2005
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20. Factors Affecting Thanatosis in the Braconid Parasitoid Wasp Heterospilus prosopidis.
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Amemiya, Mio and Sasakawa, Kôji
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BRACONIDAE , *ANTIPREDATOR behavior , *HYMENOPTERA , *PREDATORY animals , *INSECTS , *LIFE history theory , *ICHNEUMONIDAE - Abstract
Simple Summary: Thanatosis is an antipredator behavior widely recognized in insects, but our knowledge of this behavior in Hymenoptera is insufficient. We examined the effects of sex, age, temperature, and background color on thanatosis in the parasitoid wasp Heterospilus prosopidis under laboratory conditions, and found that some of these factors have significant effects on thanatosis of this species. Thanatosis, also called death feigning, is often an antipredator behavior. In insects, it has been reported from species of various orders, but knowledge of this behavior in Hymenoptera is insufficient. This study examined the effects of sex, age (0 or 2 days old), temperature (18 or 25 °C), and background color (white, green, or brown) on thanatosis in the braconid parasitoid wasp Heterospilus prosopidis. Thanatosis was more frequent in 0-d-old individuals and in females at 18 °C. The duration of thanatosis was longer in females, but this effect of sex was weaker at 18 °C and in 0-d-old individuals. The background color affected neither the frequency nor duration. These results were compared with reports for other insects and predictions based on the life history of this species, and are discussed from an ecological perspective. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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21. Unexpected Species Identities and Interspecific Relationships in a Subterranean Beetle Lineage, the Pterostichus macrogenys Species Group (Coleoptera, Carabidae), Revealed by Fine-Scale Field Sampling and Detailed Morphological Comparisons.
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Sasakawa, Kôji, Mitsuduka, Yoshiji, and Itô, Hirotarô
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COEXISTENCE of species , *GROUND beetles , *MALE reproductive organs , *INSECT diversity , *SPECIES , *BEETLES , *STAPHYLINIDAE ,BEETLE anatomy - Abstract
Simple Summary: Morphological and ecological features are highly specialized among subterranean insect species. Studies of such features reveal the vast diversity of insect taxa and can also provide insight into the general mechanisms associated with species diversity. The Pterostichus macrogenys species group is an endemic subterranean Japanese carabid beetle lineage that shows marked regional differentiation. However, to date, its diversity has not been fully elucidated, partly due to the difficulty of sample collection. We examined 103 specimens from this species group, which were collected by fine-scale field sampling, and classified these into one new and eight known species. The results of this study revealed that some of these species have disjunct distributions, which have not been reported in this species group. More importantly, some species of this group coexisted in some localities; in most such cases, two species with different body sizes coexisted, implying a role of differential body size in promoting coexistence. In the remaining case, one large and two small species coexisted, and the two small species have male genitalia of different sizes; in this system, body and genital size differences appear to have different effects on coexistence, implying a species coexistence mechanism that has rarely been reported in insects. An endemic subterranean Japanese carabid beetle lineage, the Pterostichus macrogenys species group, was recently revealed to have marked regional differentiation. Studies of such features reveal insect species diversity and provide insight into the mechanisms driving species diversity. We examined specimens of this species group collected from the southern Tohoku District of Honshu, Japan, where its diversity has not yet been fully elucidated, using fine-scale field sampling and detailed comparative morphological analysis of male genitalia. In total, 103 specimens from 13 localities were classified into one new (P. monolineatus sp. n.) and eight known species. In four of the known species, we observed disjunct distributions, which have not previously been reported in this species group and may be more common than previously recognized. Species coexistence was observed at four sites, with two species of different body sizes coexisting at three sites and three species coexisting at the remaining site. The three coexisting species included one large and two small species, the latter of which have male genitalia of a different size. This newly discovered coexistence pattern implies separate effects of differential body and genital size in species coexistence, which has rarely been reported in insects. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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22. Additional notes on Anisopteromalus sp. (Hymenoptera: Pteromalidae), the sibling species of a parasitic wasp of stored-product pests, Anisopteromalus calandrae (Howard): A new alternative host, an eye color mutant and DNA barcodes.
- Author
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SASAKAWA, Kôji, SATÔ, Masumi, and SHIMADA, Masakazu
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HYMENOPTERA , *ANIMAL species , *PARASITIC wasps , *PLOIDY , *PHENOTYPES , *GENETIC markers - Abstract
A parasitic wasp of stored-product pests, Anisopteromalus calandrae (Howard), is known to have a sibling species with a different chromosome number. Here, we report establishment and characterization of an eye color mutant in this sibling species. The phenotype of the mutant is red eye in adults, and crossing experiments revealed that the mutant phenotype is recessive to wild type (brown eye color). We also report DNA barcode sequences (a partial sequence of mitochondrial cytochrome- c oxidase subunit I) of A. calandrae and the sibling species to enable accurate identification of these morphologically similar species. Analyses of our laboratory strains showed that 12.6% of the analyzed sequences (82 of 652 bp) differed between the two species. Finally, we note that the seed beetle Callosobruchus chinensis (Linné) (family Bruchidae), host of our laboratory strains of the sibling species, is a new record of alternative host at the family-level for the wasp (known hosts: Anobiidae (natural host) and Curculionidae (alternative host)). [ABSTRACT FROM AUTHOR]
- Published
- 2012
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23. A new record, sperm bundle morphology and preliminary data on the breeding type of the ground beetle Jujiroa estriata Sasakawa (Coleoptera: Carabidae: Platynini).
- Author
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SASAKAWA, Kôji and TOKI, Wataru
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GROUND beetles , *BEETLES , *INSECTS - Abstract
Jujiroa estriata Sasakawa (Coleoptera: Carabidae: Platynini) was recently described based on a single male from a mountain in Kyushu, southwest Japan (type locality: Hagi, Gokanoshô). Here we report collection of the species from a new locality, Mount Osuzuyama. We also describe some reproductive traits based on the materials obtained (one male and four females, collected in late May). The male formed sperm bundles in which the head of each spermatozoon was embedded in a rod-shaped structure (spermatodesm). Each spermatodesm was elongate (average length 2.44 mm; cf. male body length 10.8 mm), without a conspicuous spiral structure. Three of the females were dissected, and were found to have 11 or 12 mature eggs in their oviducts. This study provides the first description of sperm bundle morphology for a species of the tribe Platynini and preliminary data on the breeding type of Jujiroa Uéno. [ABSTRACT FROM AUTHOR]
- Published
- 2008
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24. Monitoring of the ground-dwelling beetle community and forest floor environment in 22 temperate forests across Japan.
- Author
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Niwa, Shigeru, Toyota, Ayu, Kishimoto, Toshio, Sasakawa, Kôji, Abe, Shin, Chishima, Takeshi, Higa, Motoki, Hiura, Tsutom, Homma, Kosuke, Hoshino, Daisuke, Ida, Hideyuki, Kamata, Naoto, Kaneko, Yohei, Kawanishi, Motohiro, Kobayashi, Kazutaka, Kubota, Kaname, Kuraji, Koichiro, Masaki, Takashi, Niiyama, Kaoru, and Noguchi, Mahoko
- Subjects
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GROUND beetles , *FOREST insects , *TEMPERATE forests , *CLIMATIC zones - Abstract
This data paper reports census data of ground-dwelling beetle and other fauna of the forest floor environment; collections were made from a network of 22 forest sites in Japan. To our knowledge, this represents the largest dataset for long-term monitoring of a ground-dwelling beetle community and other taxa in a ground environment in forests, which covers a broad climatic range in the temperate zone and is freely available. The network forms part of the Monitoring Sites 1000 Project launched by the Ministry of the Environment, Japan. It covers subalpine, cool- and warm-temperate and subtropical climatic zones and the four major forest types of Japan. Thirty-three permanent plots usually 1 ha in size were established in old-growth, secondary natural and a few plantation forests. Censuses of the ground-dwelling beetle community were conducted using pitfall trapping and forest floor environment monitoring every year from 2004 to the present. During the initial 9 years of the census (2004-2012), 59,762 beetle individuals (including 3182 larvae) of more than 314 species were recorded. This dataset includes taxonomy and biomass of each beetle individual and each taxonomic group of other invertebrates coincidently captured in pitfall trapping. The dataset also includes data related to ground coverage by forest floor vegetation, dry mass of the accumulated organic litter layer, and carbon and nitrogen contents and cellulose decomposition rate in organic layer and surface mineral soil. The data could be used to investigate geographical patterns and intra- and inter-annual dynamics of individual body mass, populations and community structures of ground-dwelling beetles, and their relationships with the forest floor environment. Furthermore, the data could be analyzed with other open datasets related to tree community dynamics and litter fall continuously measured in the same study plots. This dataset also provides information related to the distribution and average body mass of each beetle species. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
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