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At least 235 records · Page 13Linked to original sources
PubMed1991

Artificial feeding of Ornithodoros concanensis (Acari: Argasidae) nymphs on bovine blood and morphological changes in erythrocytes undergoing hemolysis in the tick midgut.

The morphology of bovine erythrocytes undergoing hemolysis in the midgut of the argasid tick Ornithodoros concanensis Cooley & Kohls was examined after feeding nymphal ticks artificially on parafilm and latex membranes. Percentage of successful feeding was significantly higher on parafilm (63%) than on latex (43%) membrane. However, there was no difference in the amount of blood taken per tick. Scanning electron microscopy was used to follow the morphological changes of red blood cells in the tick gut during an 80-h postfeeding period. Erythrocytes converted from normal discocytes to spiculated cells (echinocyte stage III) within 20 h. During the development of spicules (echinocytosis), erythrocytes lost membrane surface area by the release of microvesicles. At 30 h after feeding, the first spherocytes appeared and after 80 h, only smooth spheres of different sizes were present. Reasons for the observed modifications in red blood cell morphology are discussed.

Animals↗
PubMed2005

Three multiplex assays for detection of Borrelia burgdorferi sensu lato and Borrelia miyamotoi sensu lato in field-collected Ixodes nymphs in North America.

Two hundred fifty New Jersey field-collected Ixodes scapularis Say ticks and 17 Colorado Ixodes spinipalpis Hadwen & Nuttall ticks were tested using three separate multiplex real-time polymerase chain reaction (PCR) assays. One assay targets the rrs-rrlA IGS region of Borrelia spp. to detect Borrelia burgdorferi sensu lato (s.l.) and Borrelia miyamotoi s.l. The second assay targets the ospA region of B. burgdorferi s.l. to detect B. burgdorferi sensu stricto (s.s.), Borrelia bissettii, and Borrelia andersonii. The final assay targets the glpQ region of B. miyamotoi s.l. to differentiate B. miyamotoi LB-2001 and Borrelia lonestari. A testing scheme combining these tests yielded 18% of tested I. scapularis ticks surveyed from New Jersey positive for B. burgdorferi s.s., 3.2% I. scapularis ticks positive for B. miyamotoi LB-2001, and 41.2% I. spinipalpis ticks positive for B. bissettii surveyed from Colorado.

Animals↗
PubMed1999

Biology of nymphs of Rhodnius robustus Larrousse, 1927 (Hemiptera, Reduviidae), fed on pigeon or on Swiss mouse blood in laboratory conditions.

The duration of the life cycle of Rhodnius robustus Larrousse, 1927 as well as the mortality rate of each nymphal instar were studied comparing groups fed on pigeon or on mouse blood weekly or fortnightly. This species showed a better development and lower mortality rate when fed on swiss mouse. The intervals between feedings apparently did not have influence on the shortening of the cycle. We suggest that laboratory colonies and experiments with R. robustus are better maintained when these triatomines are fed on swiss mouse.

Animal Nutritional Physiological Phenomena↗
PubMed2001

Transfer of toxicants from exposed nymphs of the drywood termite Incisitermes snyderi (Isoptera: Kalotermitidae) to unexposed nestmates.

Two formulations of spinosad (NAF-85 and NAF-371) were evaluated to determine the effect of concentration, deposit condition (dried, wet, or topical), and exposure time (0.1-10 h) for toxicant transfer among nestmates in the drywood termite Incisitermes snyderi (Light). Spinosad treatments were compared with two formulations of disodium octaborate tetrahydrate (DOT) (10% aqueous dilution, 98% dust) and with 35% calcium arsenate dust. Termites were dyed and individually exposed to different treatments for 0.1, 1.5,1.0, 5.0, 10.0 h, or 0.1 and 1.0 h (DOT and calcium arsenate dust) and then placed with 10 unmarked, untreated nestmates in a petri dish. Spinosad formulations also were evaluated by topical application to dyed termites. Transfer of lethal doses of toxicants between termites was indicated by significant mortality of untreated termites in 25 of 28 treatments by 28 d after introduction of dyed, treated termites. Only three treatments, one spinosad treatment (NAF-371, wet, 1 h) and both DOT 10% solution treatments, resulted in mortality of untreated termites that was not significantly different than that of water-treated controls. Two spinosad treatments and both calcium arsenate dust treatments resulted in >90% (94-98%) mortality of untreated termites by 28 d after introduction. Mortality of untreated termites was significantly different from controls for the two spinosad formulations, depending on condition of deposit and duration of dyed termite exposure to treatments.

Animals↗
PubMed2006

Recruitment of Hexagenia mayfly nymphs in western Lake Erie linked to environmental variability.

After a 40-year absence caused by pollution and eutrophication, burrowing mayflies (Hexagenia spp.) recolonized western Lake Erie in the mid 1990s as water quality improved. Mayflies are an important food resource for the economically valuable yellow perch fishery and are considered to be major indicator species of the ecological condition of the lake. Since their reappearance, however, mayfly populations have suffered occasional unexplained recruitment failures. In 2002, a failure of fall recruitment followed an unusually warm summer in which western Lake Erie became temporarily stratified, resulting in low dissolved oxygen levels near the lake floor. In the present study, we examined a possible link between Hexagenia recruitment and periods of intermittent stratification for the years 1997 2002. A simple model was developed using surface temperature, wind speed, and water column data from 2003 to predict stratification. The model was then used to detect episodes of stratification in past years for which water column data are unavailable. Low or undetectable mayfly recruitment occurred in 1997 and 2002, years in which there was frequent or extended stratification between June and September. Highest mayfly reproduction in 2000 corresponded to the fewest stratified periods. These results suggest that even relatively brief periods of stratification can result in loss of larval mayfly recruitment, probably through the effects of hypoxia. A trend toward increasing frequency of hot summers in the Great Lakes region could result in recurrent loss of mayfly larvae in western Lake Erie and other shallow areas in the Great Lakes.

Animals↗
PubMed2006

Host usage and seasonal activity patterns of Ixodes kingi and I. sculptus (Acari: Ixodidae) nymphs in a Colorado prairie landscape, with a summary of published North American host records for all life stages.

We examined host usage and seasonal activity patterns of the nymphal stage of the ticks Ixodes kingi and I. sculptus within a prairie rodent community in north-central Colorado. Ixodes kingi was commonly encountered on both northern grasshopper mice (Onychomys leucogaster) and thirteen-lined ground squirrels (Spermophilus tridecemlineatus), whereas I. sculptus frequently infested S. tridecemlineatus but was absent from O. leucogaster. Low numbers of ticks of both species were collected from deer mice (Peromyscus maniculatus) and Ord's kangaroo rats (Dipodomys ordii). Nymphal loads of I. kingi and I. sculptus increased dramatically on commonly infested rodent species from spring (May-June) to summer (July-August). Further, rodents trapped on prairie-dog towns tended to experience increased nymphal loads of I. kingi (O. leucogaster, S. tridecemlineatus) but decreased loads of I. sculptus (S. tridecemlineatus) following plague epizootics among prairie dog populations. A summary of published North American host records revealed that I. kingi has been recorded from humans, domestic animals (cat, dog), 17 species of carnivores, 40 species of rodents, and four species of lagomorphs, and that I. sculptus has been recorded from humans, domestic animals (cat, dog, goat), 13 species of carnivores, 34 species of rodents, and three species of lagomorphs. In accordance with our observations from Colorado, I. kingi commonly has been found to infest heteromyid and murid rodents (such as grasshopper mice), whereas I. sculptus most frequently has been collected from ground-dwelling sciurid rodents, especially Spermophilus ground squirrels. The potential roles of I. kingi and I. sculptus as enzootic vectors of human pathogens, particularly the agents of tularemia (Francisella tularensis), Q fever (Coxiella burnetii), and Colorado tick fever (CTF virus), are discussed.

Animals↗