Publications by authors named "KOji Sasakawa"

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 .

View Article and Find Full Text PDF

An endemic subterranean Japanese carabid beetle lineage, the 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.

View Article and Find Full Text PDF

The ground beetle genus Pterostichus Bonelli has diversified in regions including the Far East, but taxonomic issues remain even at the species level. This study presents taxonomic and nomenclatural changes in three species of Pterostichus from the Far East: P. (Petrophilus) eximius Morawitz, P.

View Article and Find Full Text PDF

Nebria (Falcinebria) reflexa Bates (Carabidae), a Japanese endemic flightless ground beetle, is geographically polytypic and was thought to be composed of four subspecies (including nominotypical subspecies). Populations from Honshû recognized as three subspecies were taxonomically revised based primarily on the shape of the endophallus, a membranous inner sac everted from the aedeagus. Three known taxa, , Bates, and Nakane, are redefined based on endophallus morphology, and the latter two are described as distinct species rather than subspecies of .

View Article and Find Full Text PDF
Article Synopsis
  • Ecological speciation in insects, particularly phytophagous and parasitic species, can be influenced by learning-induced host preferences, especially in females.
  • Recent research on the parasitoid wasp Anisopteromalus calandrae shows that male wasps also develop host preferences through learning, particularly when conditioned with mating rewards.
  • The study indicates that the timing and context of learning (preimaginal vs. early adult stages) significantly affect the development of host preferences in males, suggesting males play a crucial role in maintaining genetic separation and promoting speciation.
View Article and Find Full Text PDF

Bates, 1883, a Japanese endemic genus in the subtribe Synuchina (Coleoptera, Carabidae, Sphodrini), is revised taxonomically based mainly on the shape of the endophallus, a membranous inner sac everted from the aedeagus of the male genitalia. Three known species from central Honshu, Habu, 1954; Habu, 1978; and Habu, 1978, are re-defined based on this genital character, and five new species are described from the region: Sasakawa, . .

View Article and Find Full Text PDF

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.

View Article and Find Full Text PDF

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.

View Article and Find Full Text PDF

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.

View Article and Find Full Text PDF

Many parasitoid wasps learn host-associated cues and use them in subsequent host-searching behavior. This associative learning, namely "oviposition learning," has been investigated in many studies. However, few studies have compared multiple species, and no comparative study has previously been conducted on ectoparasitoid species.

View Article and Find Full Text PDF
Article Synopsis
  • Granivory is a unique feeding behavior in the largely carnivorous carabid beetle family, yet most research has been in lab settings, leaving field knowledge lacking.
  • During field studies in eastern Japan (2008), 176 carabid beetles were observed, revealing that 108 individuals primarily fed on various plant seeds and flowers, with specific species linked to particular plants.
  • Notably, female carabids showed a preference for feeding, often seen copulating on plants while feeding, indicating that females may forage more than males, suggesting different roles in their climbing behavior.
View Article and Find Full Text PDF

The morphological characteristics of sperm and reproductive organs may offer clues as to how reproductive systems have evolved. In this paper, the morphologies of the sperm and male reproductive organs of carabid beetles in the tribe Pterostichini (Coleoptera: Carabidae) are described, and the morphological associations among characters are examined. All species form sperm bundles in which the head of the sperm was embedded in a rod-shaped structure, i.

View Article and Find Full Text PDF
Article Synopsis
  • The study explores the relationship between the structure of male genitalia and the shape of ejaculates in certain beetle species, providing insights into their function and evolution.
  • Researchers analyzed 15 species of Pterostichini and two species of Platynini, categorizing their spermatophores into three types based on size and structural characteristics.
  • Findings indicate that species with a notably bent endophallus consistently produced a plug-like spermatophore, suggesting that this unique shape plays a critical role in creating the structure of the sperm packet.
View Article and Find Full Text PDF
Article Synopsis
  • The study revises the Pterostichus (Nialoe) asymmetricus species using detailed analysis of their genital structures.
  • Four new species within this group are introduced, including P. (N.) ovaliphallus and P. (N.) fujimurai ibukiyamanus.
  • A cladistic analysis shows that a related group, Daisenilaoe, is part of the Nialoe clade, and the paper discusses how these species evolved and spread.
View Article and Find Full Text PDF

A phylogenetic hypothesis of the subgenus Nialoe (s. lat.) of genus Pterostichus is proposed based on a cladistic analysis of seventeen morphological characters.

View Article and Find Full Text PDF