PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Phthiraptera”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources
PubMed1995

Matrilineal distribution of louse egg-handling techniques during grooming in free-ranging Japanese macaques.

Grooming behavior of which the primary function appears to be the removal of lice on other (Tanaka and Takefushi [1993] Anthropological Science 101:187-193) was studied in Japanese maceques at Jigokudani Monkey Park, Japan, June 1990-July 1993. Several louse egg-handling techniques used during grooming were identified (with differences in efficiency) in a free-ranging group. In the low-ranking maternal lineages, the distribution of these techniques is quite homogeneous, suggesting social transmission with goal emulation (one form of social learning) based on maternal kin. However, there is considerable variation in the high-ranking matriline. The social system of dominance--the tendency of subordinates to groom more often than to be groomed--may result in oblique transmission of more effective techniques from low-ranking monkeys to some offspring of high-ranking females.

Animals↗
PubMed1996

Outdoor experimental ponds (mesocosms) designed for long-term ecotoxicological studies in aquatic environment.

Outdoor artificial ponds (mesocosms) of 12 m3 were designed for long-term ecotoxicological studies. Sediment, macrophytes (Typha angustifolia and Elodea canadensis), and free and caged freshwater snails [Lymnaea palustris (Müller)] and wood lice (Asellus aquaticus L.) were collected in nearby natural ecosystems and introduced in the mesocosms. Sixty goldfish (Carassius auratus L.) were caged in each pond. Introduced species developed and reproduced in every mesocosm. Animal species (mainly insects and amphibians) spontaneously colonized the ponds, developed, and reproduced. The resulting communities qualitatively resemble those living in natural lentic systems in the surrounding area. Homogenity in physical and chemical conditions and in abundance of phytoplanktonic, periphytic, and macroinvertebrate communities between the different mesocosms was assessed during the stabilization period (8 months). Except for periphyton biomass, no divergent evolution was observed between the ponds. Mesocosm water was slightly eutrophic, alkaline (mean pH: 8.47 +/- 0.09), and moderately hard and mineralized. The homogenous and realistic environmental conditions and high ecological representativity of the outdoor experimental ponds were suitable for extensive ecotoxicological studies. Considerations on the choice and origin of introduced species and on possible interactive effects of the transfer of organisms from natural environments, maintainance conditions, and pollutant exposure are discussed.

Animals↗
PubMed1998

Histopathological effects of Bacillus thuringiensis on the alimentary canal of the sheep louse, Bovicola ovis.

Sequential observations were made of the ultrastructural effects of Bacillus thuringiensis (Bt) subsp. kurstaki strain WB3S16 on midgut epithelial cells of the sheep biting louse, Bovicola ovis, after the lice were fed, ad libitum, a powdered preparation of Bt spores, delta-endotoxin crystals, and lysed cellular components. Light microscope observations revealed cytopathological changes to the midgut epithelial cells 4 h postfeeding. Transmission electron micrographs showed that the microvilli of the midgut epithelial cells became disrupted 4-8 h postfeeding, after which the cells became vacuolated and swollen, and the cell organelles lost definition and disappeared. Paralysis and death of B. ovis occurred between 8 and 12 h postfeeding, coincident with midgut cells lysis and release of cellular contents into the midgut lumen. The histopathological effects reported here are similar to those reported in lepidopteran and coleopteran larvae affected by the delta-endotoxin crystal proteins. The constituent fractions of the Bt preparation were tested for toxicity to B. ovis using a feeding bioassay. Native delta-endotoxin crystals were not toxic to B. ovis and remained intact in the midgut of the insect. There was no evidence that the native Bt crystal was involved in the cytopathology and death of the lice. However, in vitro solubilized delta-endotoxin crystal proteins were significantly toxic to B. ovis. In addition, a louse active toxin was associated with the Bt membranes and culture supernatant.

Adenosine↗
PubMed1991

Ecological questions concerning rickettsiae.

The past ten years were characterized by the appearance of several "new" transmissible spotted fever group (SFG) rickettsioses, e.g. Israeli, Japanese and Astrakhan fevers. The factors responsible for their establishment probably include the introduction of chemicals from industry, agriculture and the timber industry into natural habitats. Such factors may influence the pathogenicity of these rickettsiae. In this case, in addition to the human influence, the mechanism of the circulation of the agents under natural conditions of both abiotic (climate, etc.) and biotic (flora and fauna) components may play a decisive role. The modern management of breeding domestic animals, indoor and outdoor maintenance, seasonal migrations, new animal foods, stress, etc., can be important factors affecting the biological properties of the Q fever agent. Nonpathogenic rickettsiae, rickettsia-like symbionts and other microorganisms circulating in nature may also influence the pathogenic rickettsiae. Studies on their interrelationships in hosts and vectors may markedly contribute to the understanding of the circulation of pathogenic rickettsiae in nature. Recognition of factors causing the appearance of new rickettsial agents or differences in pathogenicity of rickettsial strains is important not only for the prognosis of rickettsial diseases but also for the prognosis of other infectious diseases.

Animals↗
PubMed1991

Control of rickettsial diseases.

Prevention of rickettsial infections is aimed at individual control and epidemic measures (especially in epidemic typhus), vector and rodent control, milk pasteurization (in Q fever), chemoprophylaxis and immunoprophylaxis. In vector and rodent control, the main obstacle is the rise in resistance to insecticides and rodenticides. For this reason in vector control, apart from insecticides, enhancement of the natural immunity acquired by animals in response to tick infestation and vaccination with concealed tick antigens as well as the use of hormones, chemosterilants and genetic manipulation can also be considered. For short-term high-risk exposure, doxycycline may be an effective prophylaxis of illness but may not prevent infection with scrub typhus or spotted fever group rickettsiae. At present, for specific prevention by vaccination, only Q fever vaccines are available for common use. However, development of subunit vaccines, namely immunogenic rickettsial proteins, cloned and expressed in Escherichia coli, seems to be very promising.

Animals↗