Morphology of the Male Reproductive System and Spermiogenesis of Dendroctonus armandi Tsai and Li (Coleoptera: Curculionidae: Scolytinae)

Anatomical and Histological Structures of Male Reproductive System in Long-Horned Beetle Isotomus speciosus (Schneider, 1787) (Coleoptera: Cerambycidae): Light and Scanning Electron Microscopic Study

Isotomus speciosus is a polyphagous insect that damages coniferous and deciduous trees. There is no study on the male reproductive system of I. speciosus although it is an important pest. For this purpose, the male reproductive system anatomy and histology of I. speciosus were investigated using light and scanning electron microscopy. According to the results obtained, the male reproductive system of I. speciosus consists of a pair of testes (each with a pair of separate testis lobes), two pairs of vasa efferentia, a pair of vasa deferentia, an ejaculatory duct, an aedeagus, and three pairs of accessory glands. Each testis lobe has about 65 testis follicles. Testis lobe has sperm development stages (growth, maturation, and differentiation). Each testis lobe is connected to the vas deferens via the vas efferens. There are masses of mature sperm that completely fill lumen of the vas deferens. The vas efferens has cylindrical epithelium, and the vas deferens has cubic epithelium. The vas deferens then opens into the aedeagus by an ejaculatory duct. The ejaculatory duct has an intima layer with spines, monolayer of epithelium, and muscle layer. In this study, similarities and differences in anatomy and histology of male reproductive organs of I. speciosus with other coleopteran species were revealed.

Structural and histological observations on the male reproductive system of adult red poplar leaf beetle Chrysomela populi Linnaeus, 1758 (Coleoptera: Chrysomelidae)

This study described the anatomy and histology of the male reproductive system in Chrysomela populi, which is an economically important species belonging to the family Chrysomelidae. Therefore, reproductive biology has been studied to combat this insect. As well as, the characters associated with the reproductive tract have been potential to discuss aspects of the system and to better understand the reproductive dynamics. The male reproductive system of C. populi has a pair of testes, a pair of vas efferentia and deferentia, a pair of seminal vesicles, a pair of accessory glands, an ejaculatory bulb, an ejaculatory duct, and an aedeagus. The testis consists of two flower-shaped lobes. Each testis has 20 sperm tubules (testicular follicles) containing cysts of germ cells at various developmental stages within the light orange peritoneal sheath. Testicular follicles are composed of three different (growth, maturation, and differentiation) zones. In the middle region of each testis joins with the vas efferens. The testis is attached to the seminal vesicle by a small stalk like vas efferens. In the lumen of the vas efferens, seminal vesicle, and vas deferens, sperms form clumps in the form of thin threads. The proximal end of the vas deferens is connected to the common ejaculatory duct. It joins with the ejaculatory bulb. Around the ejaculator bulb, there is a pair of convoluted, flat-surface tubular structure accessory glands. Posterior ejaculatory duct joins with the aedeagus.

Karyotypes of water scavenger beetles (Coleoptera: Hydrophilidae): new data and review of published records

This study summarizes available data on karyotypes of water scavenger beetles (Coleoptera: Hydrophiloidea: Hydrophilidae), based on newly acquired data of 23 genera and 64 species. We combine these data with previously published data, which we review. In total, karyotypes are available for 33 genera and 95 species, covering all subfamilies and tribes. Available data indicate that most groups of the Hydrophilidae are diploid and sexually reproducing, with XY (♂) and XX (♀) sex chromosomes; the Y chromosome is always minute and does not recombine with X during meiosis. Exceptions are known in Anacaena, with parthenogenetic diploid or triploid populations in some species and sex chromosomes fused with autosomes in others. The diploid number of chromosomes is 2n = 18 in the subfamilies Acidocerinae, Chaetarthriinae, Enochrinae and Hydrophilinae. Variations are known in species of Anacaena and Berosus (both usually with 2n = 18) and in Hydrochara and Hydrophilus with an increased number of chromosomes (2n = 30). The number of chromosomes is increased in the subfamily Cylominae (2n = 24–30) and in all subclades of the subfamily Sphaeridiinae (2n = 22–32). We summarize protocols for obtaining chromosome slides used for this study and provide step-by-step guidelines to facilitate future cytogenetic studies.

The Sperm Structure and Spermatogenesis of Trypophloeus klimeschi (Coleoptera: Curculionidae: Scolytinae)

The male reproductive system, sperm structure, and spermatogenesis of Trypophloeusklimeschi (Coleoptera: Curculionidae: Scolytinae), which is one of the most destructive pests of Populus alba var. pyramidalis (Bunge), were investigated using light microscopy, scanning electron microscopy, and transmission electron microscopy. The male reproductive system of T.klimeschi is composed of testes, seminal vesicles, tubular accessory glands, multilobulated accessory glands, vasa deferentia, and a common ejaculatory duct. In spermatogenesis, two phenomena are apparent: The nuclear chromatin condenses into two different patterns, and an oval preacrosomal vesicle is present at the flank of the Golgi apparatus. The sperm are short, measuring 76.7 ± 1.8 μm in length, and are 508.1 ± 12.9 nm in width. The sperm are composed of a three-layer acrosomal complex, a cylindrical nucleus, two mitochondrial derivatives, a 9 + 9 + 2 axoneme, and two accessory bodies with a large "puff"-like expansion. Mature sperm are individually stored in seminal vesicles. During spermiogenesis, the similarities in the nuclear chromatin condensation characteristics of Curculioninae and Scolytinae are indicative of their close phylogenetic relationship. It appears that the preacrosomal vesicle being flanked by the Golgi apparatus is a characteristic of spermatogenesis in Curculionidae.

Discovery of a complex sclerotized sperm pump in Monotomidae (Coleoptera): Functional morphology and phylogenetic value

In insects, a long ductus ejaculatorius surrounded by a muscular sheath transfers seminal fluids and sperms from the testes into the male copulatory organ, the aedeagus. In several unrelated coleopteran families, a section of the ductus has evolved to form a specialized pumping organ. The most complex forms of this "sperm pump" was known in Lepiceridae and two subfamilies of evolutionary distant Staphylinidae; in these groups two sclerotized funnels situated on ends of the sperm pump provide attachment sites for a remarkably robust compressor muscle. A sperm pump with two funnels and a previously unknown spiral ridge, representing the most complex sperm pumping apparatus among Coleoptera, is for the first time reported to occur in the superfamily Cucujoidea, family Monotomidae. The compressor muscle is particularly large, and the pump shows features more advanced than those in any other beetle. Not the entire section between funnels is compressed, but only a pair of specialized thin-walled, unsclerotized and resilin-rich regions within the pump. The spiral ridge stores mechanical energy to decompress the pump when the muscle relaxes, and provides a sclerotized scaffold for the entire structure. The pumps do not occur in all Monotomidae, but seem to be restricted to the subfamily Monotominae. Two distinct forms were found, each in a different tribe (with one notable exception; Mimemodes having a sperm pump typical of Monotomini, not Europini). Moreover, the shapes of the pumps were found to be species-specific. The phylogenetic value of this structure is discussed, as sperm pumps may help defining monophyletic lineages within this poorly studied family. An evolutionary scenario for a development of sperm pumps in Coleoptera from an undifferentiated ductus ejaculatorius to the most complex "monotomid form" is proposed, assuming several distinct stages exemplified by structures found in other beetle families.

Anatomy and histology of reproductive system of adult male mint leaf beetle Chrysolina herbacea (Duftschmid, 1825) (Coleoptera: Chrysomelidae)

In this study, anatomy and histology of the male reproductive system of Chrysolina herbacea (Duftschmid 1825) (Coleoptera: Chrysomelidae) are described and illustrated by using light and scanning electron microscopies. Data from the male gonad of this species provide more extended and precise knowledge regarding the histoanatomical structure of the reproductive system in Chrysomelidae. The male reproductive system in C. herbacea consists of paired bilobed testes, two paired vas efferentia, paired seminal vesicles, paired vas deferentia, paired tubular accessory glands, a ductus ejaculatorius, and an aedeagus. Each testis consists of 40 follicles enveloped in a yellow pigmented sheath. In the light and scanning electron microscope examinations of male reproductive system of C. herbacea, different spermatogenesis stages (spermatocytes, spermatids, and spermatozoa) are found. Each testes follicle joins with the vas efferens surrounded by monolayered cubic epithelium with oval nuclei. Epithelial cells are covered from the outside with a thin layer of muscle and sheath. Vas efferens connect to vas deferens that may have an enlarged and differentiated region = seminal vesicle. Mature spermatozoa are seen in the lumen of the vas efferens, seminal vesicle, and vas deferens. There is a pair of accessory glands with a convoluted appearance in the tubular structure around the vas deferens. The vas deferens is a straight tube which leads into the proximal end of the ductus ejaculatorius. Ductus ejaculatorius wall is surrounded by intima, monolayer epithelium, and a thick muscle layer with many nuclei. The distal section of the ductus ejaculatorius is housed within the aedeagus.

The histomorphological structure of the male reproductive system of maize leaf weevil Tanymecus dilaticollis Gyllenhal, 1834 (Coleoptera: Curculionidae)

The histomorphology of the reproductive system and the germ cells has been useful to establish phylogenetic relationships in many insects. However, these elements remain little known in the Curculionidae. In this study, histomorphological structure of the male reproductive system of Tanymecus dilaticollis, which is economically important, is described, illustrated using stereomicroscopy, light microscopy, and scanning electron microscopy techniques, and discussed in relation to other Coleoptera species. Results showed that distinctive features of the male reproductive system of T. dilaticollis consist of a pair of yellowish testes, a pair of seminal vesicles, a pair of vasa deferentia, an ejaculatory duct, accessory glands, prostate glands, and aedeagus. Each testis is subdivided into two testicular follicles, enclosed by a peritoneal sheath. Each follicle of the mature testes is full sperm cysts with germ cells at various stages development of spermatogenesis. The testes have four types of germ cells (spermatogonia, spermatocytes, spermatids, and spermatozoa). They are occupied by the growth zone containing spermatogonia and spermatocytes, the maturation zone containing spermatids, while differentiation zone containing spermatozoa. There is a seminal vesicle at the center of each testis. Most mature sperms are stored in the seminal vesicle. Each testis is attached to the vas deferens by a stalk-like seminal vesicle. In the distal part, vasa deferentia fuse with the ejaculatory duct. It is linked to the aedeagus. The provided results will contribute to the understanding of the reproductive cell biology of Curculionidae.

Can exposure to neem oil affect the spermatogenesis of predator Ceraeochrysa claveri?

Novel biological control methods and integrated pest management strategies are basic requirements for the development of sustainable agriculture. As a result, there is a growing demand for research on the use of plant extracts and natural enemies such as the green lacewing, Ceraeochrysa claveri, as natural pest control methods. Studies have shown that although natural compounds such as neem oil (Azadirachta indica) are effective as pest control strategies, they also cause sublethal effects on nontarget insects, such as C. claveri. The aim of this study was to examine the effects of neem oil on C. claveri testes. C. claveri larvae were fed Diatraea saccharalis eggs, which were pretreated with 0.5%, 1%, and 2% neem oil. Testes were collected from larvae, pupae, and adults and analyzed using light and electron (transmission and scanning) microscopy. Changes in cellular stress and possible cell death were also determined by TUNEL assay and the marker HSP-70. The results showed that neem oil affects the organization and distribution of cysts in the testes and the normal sequence of cyst development, causing a delay in spermatogenesis in the testes of treated insects. Tests for cellular stress and DNA fragmentation indicated there was no cellular alteration in the treated groups. Although neem oil does not induce cell death or changes in HSP-70 expression, this biopesticide negatively impacts the process of spermatogenesis and could decrease the perpetuation of this species in the agroecosystem, indicating that the use of neem oil in association with green lacewings as a biological control should be carefully evaluated.

Male reproductive system and spermatogenesis of Limodromus assimilis (Paykull 1790)

Based on advanced light and electron microscopy, we describe the male reproductive system and sperm development of Limodromus assimilis. The genital tract consists of pairs of uni-follicular testes, spermatic ducts with diverticula regions, seminal vesicles, accessory glands, an unpaired ejaculatory duct and an aedeagus containing an internal sac equipped with sclerotic scales. Based on their morphology, we draw conclusions about their functions. After spermatogenesis within the follicle, the spermatozoa become released from the sperm cysts. The single spermatozoa move into the diverticula of the vasa deferentia I. Here, they become attached to central rods (spermatostyles), forming secondary conjugates (spermiozeugmata). The coordinated flagella movement of the conjugates possibly improves sperm velocity. Using super-resolution microscopy, we identified highly condensed reticulate chromatin in the lancet-shaped spermatozoa heads and the mitochondrial derivates of the flagella, likely formed by genomic and mitochondrial DNA, respectively. The results show, for the first time, sperm bundle formation in a Platynini species mainly corresponding to that found in Pterostichini species.