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At least 253 records · Page 14Linked to original sources
PubMed2003

Occurrence of Dermacentor variabilis (Acari: Ixodidae) around a porcupine (Rodentia: Erthethizontidae) carcass at Camp Ripley, Minnesota.

In May 2000, a dead porcupine (Erethizon dorsatum Culiver) was found on an infrequently traveled dirt road at Camp Ripley, MN. The presence of late instar Calliphoridae suggested that the porcupine died within the past 4 to 7 d. Adult carrion (Silphidae) and rove (Staphylinidae) beetles were observed under the carcass. In June, a large number of adult American dog ticks, Dermacentor variabilis (Say), were observed questing on the porcupine and the surrounding grass. Six zones were established around the carcass, and each zone was sampled for ticks once a month from June through September. Ticks were captured in June and July, and 93% were captured within 2 m of the carcass. Gases released as part of the decomposition process were believed to attract the ticks to the carcass.

Animals↗
PubMed2001

Vexillata liomyos n. sp. (Nemata: Ornithostrongylidae) from Liomys pictus (Rodentia: Heteromyidae) from Mexico, with comments on the synlophe of Vexillata armandae.

Individuals of a new species of Vexillata were collected from the small intestines of Liomys pictus from the Estaci6n de Biología Chamela, in Jalisco State, Mexico. The new species shows an array of characters that allow us to recognize it as a member of Vexillata; however, it can be distinguished from other species of the genus in that males possess an asymmetrical caudal bursa, females possess a characteristic cuticular inflation at the level of the ovijector, and both sexes possess a synlophe with 9 ridges at the midbody. Additional detail of the synlophe of Vexillata armandae Gardner et al., 1994 from Chaetodipus hispidus in New Mexico shows that both sexes have 12 cuticular ridges just posterior to the cephalic inflation, and in the posterior region of the body, females have 9 ridges of equal size while males possess 11 equal-sized ridges. In both sexes, the carene disappears at the posterior end of the body.

Animals↗
PubMed2003

Bots (Diptera: Oestridae) infesting a neotropical forest rodent, Proechimys semispinosus (Rodentia: Echimyidae), in Panama.

Botfly larvae (Cuterebra sp.) infesting spiny rats (Proechimys semispinosus) in 8 small islands in the Panama Canal were studied. Rats were live trapped monthly on each island from January 1991 through February 2000 and visually examined for the presence of bots. Overall, bot prevalence was 4.6% and differed statistically among island rat populations. Rats were simultaneously infested by as many as 4 bots. Overall bot intensity was 1.3 bots per infested rat and did not differ among islands. Mean bot density across all islands was 0.0111 and was greater during the dry seasons than during the rainy seasons, but it did not differ among islands. Bots were found during all the 12 calendar months, suggesting a multivoltine reproductive schedule. Although bot activity varied seasonally, there was little synchrony of bot activity among islands. Bot density was related negatively to rainfall but was not related to host density, suggesting that drier ambient conditions may promote reproduction by adult bot flies in this system.

Animals↗
PubMed2005

A new species of Vexillata (Nematoda: Trichostrongylina: Ornithostrongylidae) parasite of Heteromys desmarestianus (Rodentia: Heteromyidae) from Costa Rica.

In July 1999, 2 heteromyid rodents Heteromys desmarestianus Gray, 1868, were collected from the Area de Conservación Guanacaste, Costa Rica, and examined for parasites. Individuals of a new species of Vexillata (Travassos, 1937) Durette-Desset, 1970, were found from the intestine of hosts. Vexillata brooksi n. sp. differs from all other congeners by the presence of spicules divided at the tip instead of simple spicules. The new species closely resembles Vexillata legallae Denke, 1977, and Vexillata convoluta (Caballero and Cerecero, 1943); however, it can be distinguished from both species by possessing a smaller number of cuticular ridges at the posterior part of the body in males (9 vs. 11 and 12, respectively) and by the absence of a carene at this level.

Animals↗
PubMed2004

Gametogenesis and nucleotypic effects in the tetraploid red vizcacha rat, Tympanoctomys barrerae (Rodentia, Octodontidae).

Nucleotypic effects link DNA content with nuclear size and cell dimensions of reproductive cells in polyploid organisms. We studied the gametogenesis of the allotetraploid rodent Tympanoctomys barrerae, aiming to determine these effects in reproductive cells. The species' cofamily members, Octodon degus and Spalacopus cyanus were used as control. Spermatogenesis and oogenesis in T. barrerae follows the pattern of differentiation and sequence of events of the control species, but varied nucleotypic effects were observed. Exceedingly large, spatulated spermatozoa with a submedially attached flagellum are characteristic of male T. barrerae. The diameter of the nuclei of primordial and growing follicles as well as those of the Graaff follicles, of the granulose, and of luteal cells are significantly larger and heavily heterochromatic. Moreover, the width of the pellucid zone is 108% thicker in T. barrerae than in S. cyanus. Binucleation was recorded in 26% of luteal bodies examined whereas no binucleated cells are detected in the diploid control. Likewise, large heterochromatic nucleoli were observed in the follicle cells but not in S. cyanus. This finding and the high heterochromatin content of reproductive cells in the red vizcacha rat is probably associated with its genome complexity so that redundant genetic information is silenced through heterochromatinization.

Animals↗
PubMed2000

Spermatogenesis in the grasscutter, Thryonomis swinderianus (Rodentia).

Spermatogenesis in the grasscutter, Thryonomis swinderianus, is characterized by remarkable diversification of the endoplasmic reticulum. In spermatocytes, besides the usual form with flat cisternae and vesicles, this membrane system forms unusually wide cisternae and vacuoles containing moderately electron dense material near the Golgi apparatus and the cell membrane. In spermatids a whorl of smooth cisternae enclosing aggregates of granular electron dense material appears as another specialization. Although all parts of the endoplasmic reticulum are in connection with each other, their distinct structural differences suggest functionally different subcompartments. Once established, the structures persist even after cytoplasm has been discarded from the nearly mature sperm. In the elongating spermatid a thin plica of the Sertoli cell begins to separate the developing structures from the remainder of the cytoplasm containing the endomembrane systems, part of which is further ensheathed when this fold enroles to form an incomplete tube. Occasionally, in late spermatids a spindle-shaped body of paracrystalline structure occurs temporarily around the flagellum at the beginning of the main piece.

Acrosome↗
PubMedDate not supplied

[Structural characteristics of certain Rodents spines (Rodentia: Myomorpha, Hystricomorpha)].

The architectonics of spines and hair was studied in Neacomys spinosus, Arvicanthis somalicus, Leopoldamys sabanus, L. edwardsi, Maxomys moi, M. surifer, Niviventer fulvescens, N. confucianus, N. cremoriventer, Acomys cahirinus, A. somalica, Hystrix indica, H. cristata, Atherurus macrourus, Erethizon dorsatum, Proechimys steerei, and Lonchotrix emiliae. The presence of a dorsal longitudinal furrow covered by a modified cuticle is a common structural feature of spines in all studied species except E. dorsatum, H. indica, and the frontal surface of the mosaic (scales located side by side) and terrace cuticle (steps between scales) varies in different species from smooth to rib-folded. A terminology has been proposed to describe the main structures of spine and hair. The adaptive significance of the spine architectonics in rodents is discussed.

Animals↗
PubMed2001

A comparative analysis of the rate of meiosis, chiasma frequency and terminalization in the Jerboas Allactaga and Jaculus (Rodentia: Dipodidae) in Egypt.

The rate of seven meiotic stages (zygotene-pachytene, diplotene-diakinesis, metaphase I, anaphase I, metaphase II, anaphase II, and quartet) was studied in the jerboas Jaculus jaculus jaculus, Jaculus orientalis, and Allactaga tetradactyla, chiasma frequency and terminalization being examined only in J. jaculus and J. orientalis, and compared with the previous data concerning A. tetradactyla. Significant differences in the rate of meiosis, frequency of bivalent types, and frequency of interstitial and distal or terminal chiasmata per genome length were observed between A. tetradactyla and the two congeneric species J. jaculus and J. orientalis. Differences of these parameters among individuals within each species are also discussed in detail.

Animals↗
PubMedDate not supplied

[Helminth fauna in small rodents (Mammalia: Rodentia) of canal banks in meliorated territories].

A helminth fauna of small rodents inhabiting channel banks have been investigated in soil improvement territories (Belorussian Polesie) in the period 1996-1999. 41 helminth species have been found in animals. Generally, there are specific helminths of rodents of the Cricetidae and Muridae families. These animals also participate in life cycles of bird's and carnivore's helminths.

Animals↗
PubMedDate not supplied

[Annual follow-up of the gastrointestinal parasitosis of the tepezcuintle, Agouti paca (Rodentia: Agoutidae) in captivity in the Mexican tropic].

Previous reports showed that the tepezcuintle (Agouti paca) is commonly infested by gastrointestinal parasites (GIP), mainly Eucoccidiida and helminths. However, there is no available information on the frequency of those parasites and their faecal egg excretions at different moments during the year. These information would provide a valuable baseline for the establishment of control strategies against GIP in tepezcuintles under captivity. The objectives of the present study were to determine the prevalence of GIP orders and genera that infest tepezcuintles under captivity and, to describe the dynamics of faecal egg and oocyst excretion in a year. Ten tepezcuintles were sampled (faeces) twice every month for twelve months. The faecal samples were processed by the flotation and McMaster techniques. Two orders of parasites were determined: Strongylida and Eucoccidiida. Two genera of nematodes were also determined: Strongyloides and Trichuris. The prevalence of Strongylida eggs, Eucoccidiida oocysts and Trichuris sp. eggs reached 10-20% of animals in certain months. The most important genus was Strongyloides, found in 60 to 100% of the animals year round. The average excretion of eggs in the group was 45 to 372 eggs per gram. Tepezcuintles kept under captivity in Yucatan are parasited with Strongyloides sp throughout the year, but only occasionally had oocysts of Eucoccidiida and eggs of Strongylida and Trichuris sp.

Animals↗
PubMedDate not supplied

[Ectoparasites of the zokor Myospalax myospalax (Rodentia) in northern Altaĭ].

Following ectoparasites have been recorded on the zokor in the Northern Altay: specific fleas--Ctenophthalmus dilatatus, Rhadinopsylla ioffi, Brachyctenonotus myospalacis; a flea distributed on various rodents; ixodid ticks--Ixodes crenulatus, I. persulcatus; gamasid mites--Hirstionyssus myosplalacis. The C. dilatatus carried hypopi of acaroid mites.

Animals↗
PubMed1992

[Reproductive cycle of the pocket gophers Orthogeomys cherriei (Rodentia: Geomyidae) in Costa Rica].

Pocket gophers (Orthogemys cherriei) is a pest in agriculture in Limón, Costa Rica; 232 animals were trapped in several farms. They reproduce continuously throughout the year. Adults of both sexes are found in reproductive condition at any time. The females produce at least 2 litters per year (1-4 newborns each). There is no correlation between position of testes and production of sperm. The position of the testes is not a reliable factor to establish the reproductive condition in males. There is a correlation between length of os penis (baculum) and length of the testes, irrespectively of its reproductive condition. These pocket gophers disperse above-ground.

Animals↗