Aspectos biológicos de Leucothyreus dorsalis Blanchard (Coleoptera, Scarabaeidae, Rutelinae)

No Brasil existe uma escassez de informações sobre a bioecologia da maioria das espécies de Scarabaeidae. O objetivo do presente trabalho foi estudar os aspectos biológicos de Leucothyreus dorsalis Blanchard, 1850 em laboratório e a campo. A dinâmica populacional dos adultos foi avaliada de janeiro de 2006 a dezembro de 2007, com uso de armadilha luminosa. Adultos coletados em campo foram mantidos em recipientes de plástico contendo solo e mudas de Brachiaria decumbens Stapf, para obtenção de ovos e dar início aos estudos. Todos os estágios de desenvolvimento foram acompanhados e adultos e imaturos foram mensurados para obtenção de dados biométricos. Foram coletados 3.607 adultos e os picos populacionais de coleta ocorreram em novembro de 2006 e outubro de 2007, com média de 145 e 241 indivíduos coletados, respectivamente. O período embrionário durou em média 15,5 dias, o primeiro instar 32,4 dias, o segundo 38,9 dias, o terceiro 52,7 dias, a fase de pré-pupa 130,7 dias, a fase pupal 23,5 dias e a longevidade 18 dias. O ciclo biológico completou-se em 273,5 dias, o que caracteriza a espécie como univoltina. Verificou-se que do primeiro ao terceiro instar houve um aumento de 4,5 vezes no comprimento e de 3,5 vezes na largura das larvas. Observou-se um aumento de 53,1 vezes no peso larval do primeiro para o terceiro instar. As pupas das fêmeas foram significativamente maiores e mais pesadas que a dos machos. As fêmeas adultas foram maiores que os adultos machos, porém, apresentaram peso semelhante.

Agonistic-like responses from the torus semicircularis dorsalis elicited by GABA A blockade in the weakly electric fish Gymnotus carapo

Findings by our group have shown that the dorsolateral telencephalon of Gymnotus carapo sends efferents to the mesencephalic torus semicircularis dorsalis (TSd) and that presumably this connection is involved in the changes in electric organ discharge (EOD) and in skeletomotor responses observed following microinjections of GABA A antagonist bicuculline into this telencephalic region. Other studies have implicated the TSd or its mammalian homologue, the inferior colliculus, in defensive responses. In the present study, we explore the possible involvement of the TSd and of the GABA-ergic system in the modulation of the electric and skeletomotor displays. For this purpose, different doses of bicuculline (0.98, 0.49, 0.245, and 0.015 mM) and muscimol (15.35 mM) were microinjected (0.1 µL) in the TSd of the awake G. carapo. Microinjection of bicuculline induced dose-dependent interruptions of EOD and increased skeletomotor activity resembling defense displays. The effects of the two highest doses showed maximum values at 5 min (4.3 ± 2.7 and 3.8 ± 2.0 Hz, P < 0.05) and persisted until 10 min (11 ± 5.7 and 8.7 ± 5.2 Hz, P < 0.05). Microinjections of muscimol were ineffective. During the interruptions of EOD, the novelty response (increased frequency in response to sensory novelties) induced by an electric stimulus delivered by a pair of electrodes placed in the water of the experimental cuvette was reduced or abolished. These data suggest that the GABA-ergic mechanisms of the TSd inhibit the neural substrate of the defense reaction at this midbrain level.

Produção de frutos de espécies da floresta de Várzea da Amazônia Central importantes na alimentação de Peixes

Com o objetivo de quantificar a contribuição que quatro espécies, Cassia leiandra Benth., Crescentia amazonica Ducke, Macrolobium acaciifolium (Benth.) Benth. e Vitex cymosa Bert. ex Spreng., oferecem através de seus frutos à alimentação dos peixes, foram marcados, aleatoriamente, dez indivíduos adultos destas quatro espécies da floresta de várzea na ilha da Marchantaria - Amazônia Central. O período de maior produção de frutos dá-se no período do alto nível das águas, entre janeiro e maio. A espécie Cassia leiandra apresentou a maior produção com 1.836 kg/ha e amplo consumo pela população local. Os principais peixes consumidores de frutos são tambaqui (Colossoma macropomum), matrinxã (Brycon cephalus), pirapitinga (Piaractus brachypomus), pirarara, (Phractocephalus hemioliopterus), bacu (Lithodoras dorsalis, Megalodoras sp.), pacu (Mylossoma sp., Myleus sp., Metynnis sp., Mylesinus sp.) e sardinha (Triportheus elongatus). As espécies de plantas estudadas apresentam potencial de aproveitamento como fonte de alimento para peixes.

Comportamento do Heterocromossômio em alguns Ortópteros do Brasil

In the present paper the behavior of the heterochromoso-mes in the course of the meiotic divisions of the spermatocytes in 15 species of Orthoptera belonging to 6 different families was studied. The species treated and their respective chromosome numbers were: Phaneropteridae: Anaulacomera sp. - 1 - 2n = 30 + X, n +15+ X and 15. Anaulacomera sp. - 2 - 2n - 30 + X, n = 15+ X and 15. Stilpnochlora marginella - 2n = 30 + X, n = 15= X and 15. Scudderia sp. - 2n = 30 + X, n = 15+ X and 15. Posldippus citrifolius - 2n = 24 + X, n = 12+X and 12. Acrididae: Osmilia violacea - 2n = 22+X, n = 11 + X and 11. Tropinotus discoideus - 2n = 22+ X, n = 11 + X and 11. Leptysma dorsalis - 2n = 22 + X, n = 11-J-X and 11. Orphulella punctata - 2n = 22-f X, n = 11 + X and 11. Conocephalidae: Conocephalus sp. - 2n = 32 + X, n = 16 + X and 16. Proscopiidae: Cephalocoema zilkari - 2n = 16 + X, n = 8+ X and 8. Tetanorhynchus mendesi - 2n = 16 + X, n = 8+X and 8. Gryliidae: Gryllus assimilis - 2n = 28 + X, n = 14+X and 14. Gryllodes sp. - 2n = 20 + X, n = 10- + and 10. Phalangopsitidae: Endecous cavernicola - 2n = 18 +X, n = 94-X and 9. It was pointed out by the present writer that in the Orthoptera similarly to what he observed in the Hemiptera the heterochromosome in the heterocinetic division shows in the same individual indifferently precession, synchronism or succession. This lack of specificity is therefore pointed here as constituting the rule and not the exception as formerly beleaved by the students of this problem, since it occurs in all the species referred to in the present paper and probably also m those hitherto investigated. The variability in the behavior of the heterochromosome which can have any position with regard to the autosomes even in the same follicle is attributed to the fact that being rather a stationary body it retains in anaphase the place it had in metaphase. When this place is in the equator of the cell the heterochromosome will be left behind as soon as anaphase begins (succession). When, on the contrary, laying out of this plane as generally happens (precession) it will sooner be reached (synchronism) or passed by the autosomes (succession). Due to the less kinetic activity of the heterochromosome it does not orient itself at metaphase remaining where it stands with the kinetochore looking indifferently to any direction. At the end of anaphase and sometimes earlier the heterochromosome begins to show mitotic activities revealed by the division of its body. Then, responding to the influence of the nearer pole it moves to it being enclosed with the autosomes in the nucleus formed there. The position of the heterochromosome in the cell is explained in the following manner: It is well known that the heterochromosome of the Orthoptera is always at the periphery of the nucleus, just beneath the nuclear membrane. This position may be any in regard of the axis of the dividing cell, so that if one of the poles of the spindle comes to coincide with it, the heterochromosome will appear at this pole in the metaphasic figures. If, on the other hand, the angle formed by the axis of the spindle with the ray reaching the heterochromosome increases the latter will appear in planes farther and farther apart from the nearer pole until it finishes by being in the equatorial plane. In this way it is not difficult to understand precession, synchronism or succession. In the species in which the heterochromosome is very large as it generally happens in the Phaneropteridae, the positions corresponding to precession are much more frequent. This is due to the fact that the probabilities for the heterochromosome taking an intermediary position between the equator and the poles at the time the spindle is set up are much greater than otherwise. Moreover, standing always outside the spindle area it searches for a place exactly where this area is larger, that is, in the vicinity of the poles. If it comes to enter the spindle area, what has very little probability, it would be, in virtue of its size, propelled toward the pole by the nearing anaphasic plate. The cases of succession are justly those in which the heterochromosome taking a position parallelly to the spindle axis it can adjust its large body also in the equator or in its proximity. In the species provided with small heterochromosome (Gryllidae, Conocephalidae, Acrididae) succession is found much more frequently because here as in the Hemiptera (PIZA 1945) the heterochromosome can equally take equatorial or subequatorial positions, and, furthermore, when in the spindle area it does offer no sereous obstacle to the passage of the autosomes. The position of the heterochromosome at the periphery of the nucleus at different stages may be as I suppose, at least in part a question of density. The less colourability and the surface irregularities characteristic of this element may well correspond to a less degree of condensation which may influence passive movements. In one of the species studied here (Anaulacomera sp.- 1) included in the Phaneropteridae it was observed that the plasmosome is left motionless in the spindle as the autosomes move toward the poles. It passes to one of the secondary spermatocytes being not included in its nucleus. In the second division it again passes to one of the cells being cast off when the spermatid is being transformed into spermatozoon. Thus it is regularly found among the tails of the spermatozoa in different stages of development. In the opinion of the present writer, at least in some cases, corpuscles described as Golgi body's remanents are nothing more than discarded plasmosomes.

Nota sôbre o comportamento do heterocromossômio em Leptysma (Acrididae)

Studying the spermatogenesis of Leptysma sp. and Leptysma dorsalis, the writer was able to observe primary spermatocytes in anaphase with the heterochromosome in precession, synchronism or succession, confirming in this way what was observed by Prof. Piza in several other species of Orthoptera.

Notas e descrições em Bisaltes Thomson, 1868 e Ptericoptus Lepeletier & Audinet-Serville, 1830 (Coleoptera, Cerambycidae, Lamiinae, Apomecynini)

The following new species are described in the subgenus Bisaltes (Bisaltes): B. (B.) picticornis sp. nov. from Bolivia; B.(B.) taua sp. nov. from Brazil (Paraná and Santa Catarina) and B. (B.) unicolor sp. nov. from Ecuador. Bisaltes (B.) pictus Breuning, 1940 is transferred to the subgenus Craspedocerus. In Ptericoptus, P. hybridus hybridus Breuning, 1939 is considered a synonym of P. acuminatus (Fabricius, 1801); P. dorsalis Audinet-Serville, 1835 previously in the synonymy of P. acuminatus is revalidated and Saperda vitta Newman, 1838 is considered its synonym; P. corumbaensis sp. nov. is described from Brazil (Mato Grosso do Sul).

Revisão de Ceyxia Girault, stat. rev. (Hymenoptera, Chalcididae, Brachymeriini)

O gênero Ceyxia Girault é revalidado e 27 espécies são combinadas a ele. Sete espécies previamente descritas são diagnosticadas (ou redescritas) e discutidas, e 20 espécies novas são descritas. Ceyxia flaviscapus Girault, 1911 and C. ventrispinosa Girault, 1911 stat. rev. foram originalmente combinadas com Ceyxia e as seguintes são combinações novas: C. belfragei (Crawford, 1910) comb. nov., stat. rev.; C. concitator (Walker, 1862) comb. nov.; C. decreta (Walker, 1862) comb. nov.; C. dorsalis (Walker, 1861) comb. nov.; e C. villosa (Olivier, 1790) comb. nov. Ceyxia paraguayensis Girault, 1911 é consyiderada sinônimo júnior de Ceyxia flaviscapus Girault, 1911. As novas espécies são: C. acutigaster sp. nov.; C. amazonica sp. nov.; C. atuberculata sp. nov.; C. bellissima sp. nov.; C. dentiformis sp. nov.; C. diminuta sp. nov.; C. fusidentata sp. nov.; C. gibbosa sp. nov.; C. laminata sp. nov.; C. laticlipeata sp. nov.; C. latilabra sp. nov.; C. longiarticulata sp. nov.; C. longiscutellaris sp. nov.; C. longispina sp. nov.; C. nigropetiolata sp. nov.; C. paraensis sp. nov.; C. parvidentata sp. nov.; C. perparva sp. nov.; C. pseudovillosa sp. nov.; e C. tibiodilatata sp. nov. Dados sobre a associação com hospedeiros são apresentados para algumas espécies do gênero. Uma chave para as espécies do gênero é incluída.

Immatures of Acanthocinini (Coleoptera, Cerambycidae, Lamiinae)

Immatures of Acanthocinini (Coleoptera, Cerambycidae, Lamiinae). Larva and pupa of Eutrypanus dorsalis (Germar, 1928), collected in trunks of Pinus elliottii Engelm., and Paratenthras martinsi Monné, 1998, collected in spathes of Scheelea phalerata (Mart. ex Spreng.) Burret, are described and illustrated. Larva and pupa of Lophopoeum timbouvae Lameere, 1884, collected in Hymenaea corbaril L., Enterolobium contortisiliquum (Vell.) Morong and Pterogyne nitens Tul., are redescribed and illustrated. A table with all described immatures of Lamiinae, and a comparison among the immatures of Acanthocinini are presented. Biological notes and new records are also included.