Vinícius Albano Araújo

Ultrastructure and heteromorphism of spermatozoa in five species of bugs (Pentatomidae: Heteroptera)

Pentatomidae is one of the largest Heteroptera families, comprising about 10% of the species estimated for the suborder. In spite of existing studies, doubts remain regarding the systematics of Pentatomomorpha. In this study, five species of Pentatomidae spermatozoa were examined to achieve characteristics that enable inferences in the phylogeny of the group and in behavioral issues associated with the presence of polymorphisms. Spermatozoa polymorphisms, characterized by two classes of sizes, are found in Podisus nigrispinus, Podisus distinctus, and Brontocoris tabidus, whereas Thynacanta marginata (Dallas) and Supputius cincticeps have single-size spermatozoa. The head region consists of an acrosome, a nucleus, and part of the centriolar adjunct. In the more anterior region, the nucleus is parallel to the centriolar adjunct. In the nucleus-flagellum transition region, the nucleus overlaps the anterior region of the mitochondrial derivatives, just above the axoneme. The mitochondrial derivatives and the axoneme run the entire extent of the flagellum. In species in which the spermatozoa are polymorphic, the larger spermatozoa have derivatives mitochondrial approximately 3-fold larger than the smaller spermatozoa. Characteristics derived from the morphology of spermatozoa indicate synapomorphies and are promising for systematic studies.

Relationship between invertebrate fauna and bromeliad size

Several bromeliads species store water and organic substrates, allowing the establishment of phytotelmata and associated fauna on their leaves. In this study, we sampled 70 individuals of Vriesea sp. (Carrière) (Bromeliaceae), in rupestrian fields in the Serra de Ouro Branco-MG, Brazil. The relationships between invertebrate species richness and abundance and size of bromeliads were tested using multiple regression. We found 19 species associated with bromeliads, mainly Diptera larvae. The abundance of the phytotelmate fauna increased principally in relation to the volume of water in the bromeliad reservoir. Phytotelmata richness was affected principally by diameter of the reservoir. There was a significant relationship between the abundance and richness of invertebrates associated with leaves with diameter and height of the plant. Invertebrate richness was better explained by abundance of individuals. These results suggest that the increase of richness was attended by higher numbers of microhabitats and more space for colonization of bigger bromeliads. Additionally, there was more chance of sampling different species in locales with greater abundance of individuals.

Ultrastructural characterization of the spermatozoa of Aethalion reticulatum Linnaeus 1767 (Hemiptera: Auchenorrhyncha: Aethalionidae).

The Hemiptera order is currently divided into four suborders. Among them the Auchenorrhyncha suborder is considered to be paraphyletic. Morphology of insect spermatozoa has provided promising characteristics that can be used for phylogenetic inference. In this study, Aethalion reticulatum (Aethalionidae) spermatozoa were examined by light and electron microscopy. The head of the spermatozoa is composed of an acrosome and a nucleus. The nucleus is linear and filled with compact chromatin but has electron-lucid spaces. The centriole adjunct initiates parallel to the nucleus and terminates in the region anterior to the mitochondrial derivatives. Flagella consist of an axoneme, two mitochondrial derivatives and two accessory bodies and the axoneme has the typical 9+9+2 microtubule pattern. The mitochondrial derivatives are symmetric. The accessory bodies are long and are shaped like a half moon when viewed from a cross-section. The presence of accessory bodies differs from other species of Cicadomorpha previously studied. Spermatozoa morphology of other Auchenorrhyncha families can reveal synapomorphies and contribute to systematics of the suborder.

Structure and ultrastructure of the spermatozoa of Trypoxylon (Trypargilum) albitarse Fabricius 1804 (Hymenoptera: Apoidea: Crabronidae).

The ultrastructure of the spermatozoa of Trypoxylon (Trypargilum) albitarse is described here for the first time within this genus. Testes and seminal vesicles were dissected and processed for transmission electron microscopy. In the testicular follicles, the spermatids are arranged in a maximum number of 32 for each cyst. The spermatozoa are slender and they measure approximately 150 microm in length. The head is about 17 microm long and is formed by the acrosome and the nucleus. The flagellum consists in an axoneme, two mitochondrial derivatives, two accessory bodies and, at the nucleus-flagellum transition, a symmetric centriolar adjunct. The axoneme presents the typical 9+9+2 microtubule pattern. In the terminal region, the central microtubules and nine doublets finish first, followed by the accessory microtubules. Both mitochondrial derivatives begin together and are inserted in the base of the centriolar adjunct. Along the middle region, the larger derivative has almost twice the area of the smaller one and includes a discrete paracrystalline region. At the tip, the smaller derivative ends before the larger one and both before the axoneme. The characters derived from the ultrastructure of the spermatozoa of T. albitarse show synapomorphies shared with the Apoidea and present characters that are probably apomorphic for the Crabroninae subfamily.

Structural and ultrastructural characteristics of male reproductive tract and spermatozoa in two Cryptinae species (Hymenoptera: Ichneumonidae)

This study represents the first characterization of male reproductive tracts and ultrastructural description of sperm of Cryptinae species. In Lymeon dieloceri and Pachysomoides sp., the male reproductive tract is formed by a pair of testis, two deferent ducts, two accessory glands and one ejaculatory duct. The spermatozoa are similar to those described for other Hymenoptera, with: (1) the acrosome formed by the acrosomal vesicle covering the perforatorium, which has its base inserted in a cavity located in the nucleus point; (2) a thin nucleus with electron-dense chromatin; (3) an electron-dense centriolar adjunct located between the nucleus and one of the two mitochondrial derivatives; (4) an axoneme with a 9 + 9 + 2 microtubule arrangement; (5) two long mitochondrial derivatives with peripheral cristae and; (6) two accessory bodies located between the two mitochondrial derivatives and the axoneme. These ichneumonids present structural characteristics similar to other parasitic wasps, such as presence of a single follicle per testis, layer of extracellular material enveloping the acrosome and accessory microtubules ending before others in final portion of the flagellum. However, male reproductive system and the spermatozoa presented morphological characteristics that allowed their differentiation, such as oval shapes accessory glands and the symmetric mitochondrial derivatives in L. dieloceri compared to the spherical accessory glands and asymmetrical derivatives observed in Pachysomoides sp. Taken together, data presented here demonstrates that diversity of morphological characteristic from the male reproductive tract and spermatozoa in Hymenoptera might provide a character system that can be used, in association with other systems, to resolve various uncertainties about the evolutionary relationships of this insect group.

Morphology of male reproductive system in three species of Trypoxylon (Trypargilum) Richards (Hymenoptera: Crabronidae)

Variations in the adult male reproductive system among different groups of Hymenoptera offer characteristics that help studies on behavior and phylogenetics. The objective of this study was to describe the adult male reproductive system of three Trypoxylon (Trypargilum) species. For that, tissues were disseced, fixed in 2.5% glutaraldehyde in 0.1 M sodium cacodylate buffer, pH 7.2 and postfixed in 1% osmium tetroxide. The material was dehydratated and embedded for light and electron transmission microscopes. The species have similar reproductive systems, which are formed by a pair of testes, each one with three fusiforme follicles, from which emerges an efferent duct that later joins forming a deferent duct. The deferent duct opens into an ejaculatory duct. The first half of the deferent duct is enlarged and differentiated in a region specialized in sperm storage, the seminal vesicle. The accessory gland flows in the post-vesicular region of the deferent duct. The testes and vesicles are both covered with a conjunctive capsule. Sexually mature individuals have all spermatogenesis stages in their follicles. Sperms are released from testes in bundles which are disorganized inside seminal vesicles.

Morphology of the Male Reproductive System of the Social Wasp, Polistes Versicolor Versicolor, with Phylogenetic Implications

Abstract Variation in the morphology of the adult male reproductive system among different groups of Hymenoptera offer characteristics that help studies of behavior and the evolutionary history of this group. The objective of this study was to describe the adult male reproductive system of the wasp Polistes versicolor versicolor Olivier (Vespidae: Polistini). The reproductive systems were dissected, fixed and embedded for light microscopy. In P. v. versicolor, the reproductive system includes a pair of testes, each one with three fusiform follicles. From each follicle emerges an efferent duct that later join together, forming a deferent duct. The first half of the deferent duct is enlarged and differentiated into a region specialized for sperm storage, the seminal vesicle. At the post-vesicular region of each of the deferent ducts an accessory gland emerges. The seminal vesicle and the accessory gland are covered with a capsule forming a vesicle-gland complex, also observed in some species of North American Polistes. Sperm are released from testes in bundles, which are disorganized inside seminal vesicles. In the testicular follicles, 95 spermatozoa were observed per cyst on average.

Proliferation and cell death in the midgut of the stingless bee Melipona quadrifasciata anthidioides (Apidae, Meliponini) during metamorphosis

This study quantitatively compared proliferation and cell death in the remodeling of the midgut epithelium in Melipona quadrifasciata anthidioides during metamorphosis to elucidate the renewal mechanism of the midgut in bees during postembryonic development. An anti-phosphohistone H3 antibody was used to mark mitotic cells. An apoptotic cell marking kit was used (Apo-TRACE®) to identify cells undergoing the process of cell death. The ultrastructural aspects of cell death were also analyzed. The highest proliferative and apoptotic rates were observed in pink-eyed pupae. An increased number of cells and rebuilding of regenerative cell nests at the end of metamorphosis is a consequence of cell division in black-eyed pupae because cell division occurs at this stage in the absence of apoptosis. During metamorphosis, midgut epithelial cell death in M. quadrifasciata anthidioides occurs as a result of apoptosis and autophagy.

Oviductal Structure and Ultrastructure of the Oviparous Gecko, Hemidactylus mabouia (Moreau De Jonnès, 1818)

Lizards of the family Gekkonidae display a variety of reproductive patterns, as evidenced by the presence of viviparous and oviparous species. The species Hemidactylus mabouia is oviparous. We examined, in vitellogenic females, oviductal structure by light microscopy after routine histological and histochemical techniques, as well as by scanning and transmission electron microscopy. The oviduct is composed of four different regions: the infundibulum, which opens into the coelomic cavity and receives the oocyte released at the time of ovulation; the uterine tube, where sperm storage takes place; the uterus, which is responsible for the eggshell production; and the vagina, the final portion of the oviduct that leads to the cloaca. The oviductal structure of H. mabouia is similar to that of other oviparous lizard species and can be useful for morphological comparative analysis among reptile species. Anat Rec,, 2011.

Acaricidal properties of vetiver essential oil from Chrysopogon zizanioides (Poaceae) against the tick species Amblyomma cajennense and Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

Ticks are arthropods widely distributed in tropical and subtropical regions, which can transmit infectious agents also responsible for zoonoses. Excessive use of conventional acaricides has resulted in the onset of drug resistance by these parasites, thus the need to use alternative methods for their control. This study evaluated the acaricidal activities of Chrysopogon zizanioides (vetiver) essential oils containing different zizanoic and khuzimol (high and low acidity) acid concentrations on Amblyomma cajennense and Rhipicephalus microplus (Acari: Ixodidae). To this aims, toxicity tests of different concentrations of examined essential oils were conducted on adult females and larval stages. Results showed that the essential oils of C. zizanioides with high and low acidity reduced oviposition of females, eggs hatch and larval survival, being more effective than some commercial products widely used to control these ectoparasites. These results indicate that the C. zizanoides essential oils are promising candidates as acaricidal agents and represent also an add value to vetiver oil with high acidity, which is commercially undervalued in the cosmetic industry.