The effect of habitat on the helminth parasites of an island population of the Polynesian rat (Rattus exulans)

Seasonal variation of Mastophorus muris (Nematoda: Spirurida) in the water vole Arvicola amphibius from southern Sweden

This study focused on the spirurid nematode Mastophorus muris in water voles (Arvicola amphibius) trapped in three regions in southern Sweden during spring and fall 2013. The collection of water voles formed part of a larger project (EMIRO) on the cestode Echinococcus multilocularis in rodents. The voles' stomach contents were examined for the presence of M. muris. Prevalence, mean abundance and mean intensity of infection were calculated. A generalized linear model model was used to examine the effects of sex, functional group, season and region on the number of M. muris individuals in each vole. Forty-seven of 181 (26%) voles were infected with M. muris, with up to 74 worms each. The overall mean intensity (worms per infected vole) was 15 (95% CI 10-21), and abundance (mean number of worms in all voles) was 4 (95% CI 2-6). Model output indicated a significant effect of season and region with respect to abundance of nematode infection, which was independent of sex and functional group of the investigated host.

Stomach nematodes (Mastophorus muris) in rats (Rattus rattus) are associated with coconut (Cocos nucifera) habitat at Palmyra Atoll

Black rats ( Rattus rattus ) and their stomach nematodes (Mastophorus muris) were historically introduced to islets at Palmyra Atoll in the central Pacific Line Islands. To investigate patterns of parasitism, we trapped rats and quantified nematodes on 13 islets of various sizes and habitat types. Most rats were parasitized (59%) with an average of 12 worms per infected rat. Islet size did not greatly influence parasite population biology. Nematodes also did not appear to affect rat condition (weight to skull length). The only strong and consistent factor associated with the mean abundance of nematodes in rats was habitat (dominant cover and locally dominant plant species). Thus, nematodes were much more abundant in rats from sites dominated by coconut trees (Cocos nucifera). Coconut trees may also be an introduced species at Palmyra Atoll.

Microparasite assemblages of conspecific shrew populations in southern California

The microparasite component communities of 2 species of shrews, Notiosorex crawfordi and Sorex ornatus, were investigated for the first time in 2 isolated and 3 continuous landscapes in southern California. With microscopical examination, a total of 6 parasite species was found in N. crawfordi and 8 species in S. ornatus. The highest number (5) of parasite species was detected in the lungs. The corrected estimate of parasite species richness did not significantly correlate with the host abundance in either shrew species. Altitude, and also latitude in N. crawfordi, appeared to be significantly positively associated with the parasite species richness, but this could be due to a false association because of the rare occurrence of some of the parasites or the small altitude range (or both). No other landscape variable analyzed (location, size of the study site, disturbance) was significantly associated with the parasite species richness of the shrews. The parasite assemblages of the 2 shrew species were similar despite the fact that N. crawfordi has a lower metabolic rate than S. ornatus.

The parasites of the Polynesian rat within and beyond New Zealand

A list of the ecto- and endoparasites of the Polynesian rat, Rattus exulans, from throughout its geographical range is presented here. The majority of the New Zealand populations included in this survey came from 'exulans only' islands while all but one of the non-New Zealand reports came from places where other rodent species are sympatric. This information is intended among other things to highlight gaps in our knowledge of and stimulate an interest in the parasitology of this rat.