Structure of the male reproductive accessory glands of Pterostichus nigrita (Coleoptera: Carabidae), their role in spermatophore formation

Accessory gland secretions of male insects have many important functions including the formation of spermatophores. We used light and electron microscopy to investigate the structure of the accessory glands and posterior vasa deferentia of the carabid beetle Pterostichus nigrita to try to determine where spermatophore material is produced. Each accessory gland and posterior vas deferens had an outer layer of longitudinal muscle, beneath which was a layer of connective tissue and a thin band of circular muscle, all of which surrounded a layer of epithelial cells lining the lumen of the ducts. Based on the ultrastructure of the epithelial cells, and their secretory products, we identified two epithelial cell types in each region (distal and proximal) of the accessory glands and four types in the posterior vas deferens. Most secretory products, which stained positively for proteins and some mucins, were released into the lumen of the ducts by apocrine secretion. The accessory glands produced one type of secretory product whereas in posterior vasa deferentia, four types of secretory products were found layered in the lumen. Our results suggest that most of the structural material used to construct a spermatophore is produced by the cells of the posterior vasa deferentia.     

Chromosomes and identification of the sibling species Pterostichus nigrita (Paykull) and P. rhaeticus Heer (Coleoptera: Carabidae)

The karyotypes of Pterostichus nigrita (Paykull) and P. rhaeticus Heer are described. Both species have eighteen pairs of autosomes, sex chromosomes which are XO (♂) and XX (♀), plus a variable number of totally heterochromatic B chromosomes. Males may be identified by the form of the inflated endophallus, but the shape of the right paramere is not a reliable character. Females may be identified by the form of the eighth abdominal sternite.     

Light‐microscopic examinations of sperm in several lineages of Carabidae (Insecta: Coleoptera): Implications for the evolution of sperm conjugation

Sperm show marked morphological diversity, but the processes and mechanisms driving this diversity have not been fully elucidated. The beetle family Carabidae represents a potential model system for studying sperm trait evolution. In this study, sperm traits (mainly conjugation and sperm conjugate gross morphology) of 42 species from nine subfamilies of Carabidae were examined using light microscopy. Except in Harpalinae, the type of conjugation was shared by all members of a particular subfamily: in Carabinae, Elaphrinae, Patrobinae and Brachinae, sperm conjugates were observed in which variable numbers of sperm clumped together; in Nebriinae, Cicindelinae and Trechinae, sperm were not organized as conjugates but were present individually; and in Broscinae, both individual sperm and sperm conjugates were observed. In the remaining subfamily, Harpalinae, sperm conjugates were formed in most species, but a loss of conjugation was observed in some species. Mapping the observed sperm traits onto within‐family molecular phylogenetic trees suggested that sperm conjugation was ancestral, with loss of conjugation evolving in several lineages. In sperm conjugates, a short spermatostyle (the axis of sperm conjugates) was the ancestral state, while a long spermatostyle evolved in subsequent lineages. In the long spermatostyle trait, the flexible type without a conspicuous 3D structure was ancestral, while the type with a conspicuous 3D structure, such as the spiral structure, evolved in derived lineages.     

Taxonomic studies of Pterostichus ishikawai Nemoto (Coleoptera: Carabidae)

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.     

Immune challenges trigger cellular and humoral responses in adults of Pterostichus melas italicus (Coleoptera,Carabidae)

The present study focuses on the ability of Pterostichus melas italicus Dejean to mount cellular and humoral immune responses against invading pathogens. Ultrastructural analyses revealed the presence of five morphologically distinct types of hemocytes: prohemocytes, plasmatocytes, granulocytes, oenocytoids and macrophage-like cells. Differential hemocyte counts showed that plasmatocytes and granulocytes were the most abundant circulating cell types and plasmatocytes exhibited phagocytic activity following the latex bead immune challenge. Macrophage-like cells were recruited after the immune challenge to remove exhausted phagocytizing cells, apoptotic cells and melanotic capsules formed to immobilize the latex beads. Total hemocyte counts showed a significant reduction of hemocytes after latex bead treatment. Phenoloxidase (PO) assays revealed an increase of total PO in hemolymph after immune system activation with lipopolysaccharide (LPS). Moreover, the LPS-stimulated hemocytes showed increased protein expression of inducible nitric oxide synthase, indicating that the cytotoxic action of nitric oxide was engaged in this antimicrobial collaborative response. These results provide a knowledge base for further studies on the sensitivity of the P. melas italicus immune system to the environmental perturbation in order to evaluate the effect of chemicals on non-target species in agroecosystems.     

Wild flower seed predation by Pterostichus madidus (Carabidae: Coleoptera)

The objective of the study was to investigate the ability of Pterostichus madidus, one of the most abundant carabid beetles in the United Kingdom, to consume wildflower seeds. The plant species chosen are commonly included in wildflower seed mixes sown to enhance the biodiversity of arable field margins, and hence any seed predation could potentially reduce successful seedling establishment. The study combined cafeteria style laboratory feeding experiments with predation studies in an established field margin. In laboratory studies the Pterostichus madidus consumed both unimbibed and imbibed seeds of Centaurea scabiosa, Galium verum, Leucanthemum vulgare and Primula veris. Seed consumption was still evident when Drosophila pupae were also supplied, although there was significant preference for the pupae. Placement of seeds in the field showed high levels of seed consumption, although part of this was attributed to slugs. Carabid beetles may have a significant role as wild flower seed predators and thus may affect establishment of re‐seeded flower‐rich meadows.     

Habitat characteristics of grassland Pterostichus species (Coleoptera, Carabidae)

Abstract.

• 1 Pterostichus species were sampled on ninety-two sites distributed throughout north-east England using pitfall trapping.
• 2 The incidence of each species was related to measured site environmental variables using logistic regression.
• 3 Four species groups were identified on the basis of size. The extent of overlap in habitat types between species in each group varied. Two large species overlapped considerably whilst the smaller species showed different responses to one or more environmental variable.
• 4 Possible causes of the differences in habitat overlap between Pterostichus species are discussed.

     

Effect of light quality on movement of Pterostichus melanarius (Coleoptera: Carabidae)

Abstract Behaviour of nocturnal insects is routinely observed under red light, but it is unclear how the behaviour under red light compares to behaviour in complete darkness, or under a source of white light. Here, we measure movement behaviour of the nocturnal carabid beetle Pterostichus melanarius Illiger (Coleoptera: Carabidae) using camera recording under a near‐infrared (nir), red or white radiation source. Red light significantly reduced movement speed in females similar to the effect of white light and different from nir. Also movement activity and pause length were affected by radiation source, with a significant difference between nir and white light, and with intermediate values in red light. The results presented here indicate that P. melanarius has different movement behaviour under the three radiation sources and suggest that nir rather than red radiation is most appropriate for measuring behaviour in total darkness. However, in the field total darkness is rare both because of natural light sources such as the moon and stars but increasingly also because of ecological light pollution, and therefore red light may still be of use for observing ecologically and practically relevant natural night‐time behaviour.     

Geographic variability of the life cycle in Pterostichus melanarius (Coleoptera, Carabidae)

In Pterostichus melanarius, the seasonal dynamics of activity is characterized by two peaks (in mid-June-early July and in late July-mid-August). In southwestern Moldova, these peaks were registered twenty days later than in Moscow Province. In both regions, larvae and adults hibernate. Both hibernated immature adults and adults that had already bred before wintering start reproduction simultaneously. In hibernated immature individuals, the average number of eggs per female constituted 1.5 times that in the postgenerative females. In the steppe zone, the total number of eggs laid by immature females was closed to that laid by previously bred females, while in the southern taiga zone, hibernated immature females laid a greater number of eggs. In the steppe zone, females of a new generation lay a somewhat lower number of eggs in comparison with hibernated immature females, whereas the total number of laid eggs is significantly higher. In the southern taiga zone, both the average number of laid eggs and their total number are equal in females of a new generation and hibernated immature females. In Moldova, the majority of individuals of a new generation breed in the current season, whereas in Moscow Prov., about half the individuals hibernate without breeding. Over the largest part of the range, the life cycle of P. melanarius combines the one-year development with hibernating larvae with two-year development with the hibernating immature and postgenerative adults. The two subpopulation groups, wintering at different phases of the ontogenesis, are totally isolated at the northern border of the range. Within each subpopulation., individuals are characterized by the biennial life cycle; as a result, the polyvariant character of the life cycle turns into the monovariant one. We suggest that such a life cycle should be designated as the compensatory monovariant cycle, and populations, in which it is realized, as byside populations (from the English “side by side”).     

Cryptic species of the subgenus Morphnosoma Lutshnik (Coleoptera: Carabidae; genus Pterostichus) from Japan

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.     

Sensilla on the aedeagus of the ground beetle Carabus (Ohomopterus) arrowianus arrowianus (Breuning) (Coleoptera: Carabidae)

Sensilla on the aedeagus of the ground beetle Carabus (Ohomopterus) arrowianus arrowianus (Breuning) were investigated by scanning electron microscopy. On the aedeagus, a total of six types of sensillum were confirmed: five basiconic and one coeloconic. The external features and distributional patterns of the sensilla are described.     

Preliminary experiments on the olfactory responses of Pterostichus melanarius Illiger (Coleoptera: Carabidae) to intact plants

1 In two successive years, the olfactory responses of Pterostichus melanarius Illiger (Coleoptera: Carabidae) to intact cabbage and white clover plants were studied, using a four‐arm olfactometer. 2 The first set of experiments tested the response to the odours of cabbage, white clover and the two plants grown together against potting compost; in the second and third sets of experiments, white clover and cabbage were tested, respectively. 3 The results indicate that female P. melanarius individuals are arrested by the combined odours of cabbage and white clover, spending significantly more time in the cabbage with white clover odour field than in either the cabbage, white clover or control odour fields. 4 Similar results were not found for males. 5 Cabbage plants alone did not elicit significant responses in either sex. 6 White clover alone did not elicit significant responses by females and the responses of males were not uniform in the two successive years.     

External Features of the First Instar Larva of Damaster (Coptolabrus) jankowskii jankowskii (Coleoptera; Carabidae)

ABSTRACT Larval features of the carabid beetle, Damaster (Coptolabrus) jankowskii jankowskii (Oberthür) were investigated for the first time. For accomplishing the purpose, the adult beetles were collected by pitfall traps in the deciduous forest of Mt. Palgongsan, southern Korea. They have been reared under the laboratory condition of 16L: 8D at 20°C. The first instar larvae were obtained by isolating eggs after oviposition and were kept at the same condition. In the present study, external morphology of the first instar larva of this subspecies are described and its important character states and comparisons with the kin species are also discussed.     

Complete mitochondrial genome of a carabid beetle,Damaster mirabilissimus mirabilissim (Coleoptera: Carabidae)

In the present study, we report the 16 823‐bp long complete mitochondrial genome (mitogenome) of a carabid beetle, Damaster mirabilissimus mirabilissim (Coleoptera: Carabidae), which is endangered in Korea. The gene arrangement of D. m. mirabilissim mitogenome is identical to the most common type found in insects. The start codon of the D. m. mirabilissim COI gene is a typical ATN codon. On the other hand, the initiation codon for ND1 gene is TTG, instead of ATN. All transfer RNAs (tRNAs) exhibit a stable canonical clover‐leaf structure, except for tRNA^Ser(AGN), the dihydrouridine arm of which forms a simple loop. The 1703‐bp long A+T‐rich region is the second longest among the complete adephagan mitogenome sequences, next to Macrogyrus oblongus belonging to Gyrinoidea. One of the unusual features of the genome is the presence of a tRNA^Leu(UUR)‐like sequence in the A+T‐rich region. This sequence displays the proper anticodon sequence and the potential to form secondary structures, but also harbors many mismatches in the stems.     

Morphology and development of the male reproductive tract in Callinectes danae (Crustacea: Brachyura)

The aim of this study was to characterize the morphology and function of each section of the reproductive system of male Callinectes danae, as well as the stages of reproductive development and their relation to secondary sexual characteristics. Development of their reproductive system begins after completion of the pubertal moult. The growth of the gonopodium showed negative allometry for both juveniles and adults. The reproductive system is divided into portions with different functions. There is a germinal zone in the testes containing spermatogonia, a zone of maturation containing spermatocytes, spermatids or spermatozoa, as well as a collecting duct, which carries spermatozoa to the vas deferens. There are two matrices in the anterior vas deferens that initiate the separation of spermatozoa groups, one composed of polysaccharide acids (matrix I) and another consisting of neutral polysaccharides (matrix II). In the median vas deferens, the matrix II forms an acellular capsule, which forms the spermatophores. In the posterior vas deferens, the matrices are accumulated, initially with a granular texture and are homogenous for the final portion. The ejaculatory duct and penis have muscle lining to expel the spermatophores at copulation. Even after copulation, males retain a stock of spermatophores, allowing copulation with other females.     

Occurrence of hypogean trechine beetles in Hanzhong Tiankeng Cluster,southwestern Shaanxi,China (Coleoptera: Carabidae: Trechinae)

Qianaphaenops (Tiankengius) xigouicus Tian & Huang, n. subgen., n. sp. is described from a limestone cave in the Hanzhong Tiankeng Cluster, southwestern Shaanxi Province in the western part of Daba Shan Mountains, northern China. Tiankengius n. subgen. is related to Qianaphaenops (s. str.) Uéno, 2000 (a lineage of Guizhaphaenops Complex which ranges in northeastern Guizhou Province) instead of the genera Boreaphaenops Uéno, 2002 Yanzaphaenops Uéno, 2010 which are known from Shennongjia (eastern range of Daba Shan Mountains). However, Tiankengius is markedly distinct by several important features from Qianaphaenops. This is the first report of a troglobitic trechine beetle from Shaanxi Province, northern China.     

Histology of the spermateca and stored sperm of Tenuisvalvae notata (Coleoptera: Coccinellidae)

The predatory ladybird beetle Tenuisvalvae notata (Coleoptera: Coccinellidae) (Mulsant) is a polygamous species and its morphology, as well as the storage capacity of seminal fluid in the spermatheca, may affect its reproductive performance. Thus, the present study evaluates the spermatheca morphology of virgin and mated T. notata females using light and scanning microscopy. The results show that the spermatheca of T. notata is kidney shaped and consists only of the receptacle and spermathecal duct, being morphologically similar in virgin and mated females. There is no secretion in the spermathecae of virgin females and, in mated females, only once it was not possible to observe the presence of spermatozoa. By contrast, females mate multiple times it is possible to observe spermatozoa in the lumen of the spermatheca surrounding the secreted material. Polygamy in T. notata might be related to the maintenance of viable spermatozoa in the spermatheca, in which case the female would prefer to copulate more times during its adult life than to store spermatozoa for a longer period of time.     

Notes on two species of the subgenus Lyrothorax Chaudoir (Coleoptera: Carabidae; genus Pterostichus), Pterostichus amagisanus Tanaka and Ishida and Pterostichus fujitai Tanaka and Ishida

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.