Trace elements in king eiders and common eiders in the Canadian arctic.

We determined concentrations of selected trace elements in tissues of king and common eiders at three locations in the Canadian arctic. Renal and hepatic cadmium concentrations in king eiders at a location in the eastern arctic were among the highest ever recorded in eider ducks: there, they were higher in king eiders than in common eiders. Cadmium concentrations were lower in king eiders from the western arctic than in those from the east. In the western arctic, cadmium concentrations did not differ between species. Hepatic mercury and zinc were higher in king eiders than in common eiders. Zinc and selenium were higher in eiders from the western arctic than in those from the eastern arctic. Trace element concentrations in these two duck species were below published toxicity thresholds. Positive correlations in trace element concentrations in both species were found between total and organic hepatic mercury, renal and hepatic cadmium as well as hepatic zinc, copper, mercury, and cadmium. Body mass of common but not king eiders and spleen mass of both species were negatively correlated with mercury concentrations. In common eiders, the number of nematode parasites was positively correlated with total and organic mercury. Histopathological evidence of kidney or liver lesions that are typical of trace metal poisoning was not found. We did not find evidence to support the hypothesis that trace metal exposure may be contributing to adverse effects on the health of individuals of these species.

Replication and tissue tropisms of Crimean-Congo hemorrhagic fever virus in experimentally infected adult Hyalomma truncatum (Acari: Ixodidae).

Adult Hyalomma truncatum Koch ticks were inoculated intracoelomically with Crimean-Congo hemorrhagic fever (CCHF) virus to examine tissue tropisms of this virus in ticks. Virus was recovered from all 185 ticks examined between 2 and 42 d after inoculation with CCHF virus. Titers or virus recovered from unfed male and female ticks were essentially the same (means, 10(2.4) and 10(2.5) plaque-forming units [PFU] per tick, respectively). Infection rates and titers recovered per gland for both salivary glands and reproductive tissues (ovaries and testes) were positively associated with blood feeding; average titers were 10-fold greater in organs from fed compared with those from unfed individuals. In contrast, neither the tick's sex nor feeding status (unfed or engorged) affected the titer of virus recovered from hemolymph (mean, 10(1.6) PFU/microliters). Although virus was recovered from Malpighian tubules, midgut, muscle, and nervous tissues from nearly all of the ticks tested, viral titers were consistently low. The increase in viral titer associated with blood feeding by ticks appeared to be due primarily to proliferation of tissue (e.g., salivary gland and reproductive tissues), rather than to increased replication in tissue already present.

Recoverability of Rift Valley fever and sandfly fever Sicilian viruses from infected Phlebotomus papatasi (Diptera: Psychodidae) trapped in various oils.

We studied the effects of various oils used to trap sand flies on the recovery of virus from infected adult Phlebotomus papatasi. Both Rift Valley fever and sandfly fever Sicilian viruses were readily recovered from virus-inoculated specimens held at 26 degrees C on mineral, olive or castor oil-soaked sheets for up to 12 h. However, after 50 h on oil-soaked paper, significantly greater titers were recovered from sand flies trapped with mineral oil than from sand flies trapped with either of the other oils. This indicates that sand flies trapped on oil-soaked paper would be suitable for virus isolation attempts and that mineral oil had the least effect on virus recovery.

Feeding efficiency of larval Hyalomma truncatum (Acari: Ixodidae) on hosts previously exposed to ticks.

The effect of guinea pig response to feeding larval Hyalomma truncatum Koch ticks was studied by measuring the percentage of ticks engorging and molting, their engorged weight, and hemoglobin content. Four guinea pigs were infested with 100, 200, 400, and 1,000 larvae, respectively, on three occasions at 21-d intervals, followed by a fourth infestation with 500 larvae. During the second, third, and fourth infestations, significantly fewer ticks engorged on each guinea pig than during the first infestation. The greatest reduction in percentage molting occurred during the fourth infestation on the animal with successive exposure to 400 larvae; only 24% of the ticks that fed molted. Ticks with the lowest mean weight and hemoglobin content also engorged on this animal during the fourth infestation. Guinea pigs exposed to 200 and 400 H. truncatum larvae elicited the greatest change in feeding efficiency during the fourth infestation. However, these hosts had no effect on a single subsequent fifth infestation with Amblyomma cajennense (F.) nymphs, as greater than 95% successfully engorged.

Development of Amblyospora campbelli (Microsporida: Amblyosporidae) in the mosquito Culiseta incidens (Thomson).

The complete life cycle of Amblyospora campbelli (Kellen and Wills, 1962) (Microsporida: Amblyosporidae) requires a two-host system involving the mosquito host, Culiseta incidens (Thomson), and an obligatory intermediate copepod host. The parasite has dimorphic spore development producing meiospores (haploid condition) and binucleated spores (diploid condition), either as an exclusive infection or simultaneously (within females only). This is the 1st known report of concurrent spore development within an adult mosquito host, and, therefore, shows the Amblyospora campbelli system to be uniquely different from other Amblyospora spp. cycles previously described. The significance of dimorphic spore development is discussed. In females, diplokaryotic meronts may invade oenocytes, causing a benign-type of infection. A blood-meal is required to initiate sporulation of the binucleate spore. The binucleate spore contains the sporoplasm involved in transovarial transmission. A 2nd sporulation sequence, primarily in adipose tissue, may involve both males and females. In this sequence, repeated merogonic division greatly increased the density of diplokaryotic meronts and generally involved most of the body of the host. Production of meiospores, unlike that for the binucleate spore, appeared to be spontaneous (i.e. no obligatory blood meal). Survivorship of male and female larval mosquitoes was nearly equal. Adult females spread the parasite in three ways: transovarial, transovum, and by meiospore deposition.