Molecular screening for rickettsial bacteria and piroplasms in ixodid ticks surveyed from white-tailed deer (Odocoileus virginianus) and nilgai antelope (Boselaphus tragocamelus) in southern Texas

A survey of ixodid ticks parasitizing white-tailed deer (Odocoileus virginianus) and nilgai antelope (Boselaphus tragocamelus) was completed during the 2018–2019 public hunt season on the Laguna Atascosa National Wildlife Refuge (Cameron County, Texas) and the East Foundation's El Sauz Ranch in nearby Willacy County (Texas). Anocenter nitens was the predominant tick species identified with 5% of these ticks collected from nilgai. All life stages were encountered in high numbers on white-tailed deer, indicating that deer may be a primary host in this region. Amblyomma maculatum and Amblyomma inornatum were identified from both hosts, while Ixodes scapularis was encountered only on white-tailed deer. This is the first published record of A. inornatum on nilgai. A subset of ticks was used in PCR assays to detect Rickettsia spp., family Anaplasmataceae, Borrelia spp., and Theileria-Babesia spp. Borrelia spp. were not detected in any of the ticks analyzed. Rickettsia parkeri was detected in three A. maculatum adult ticks from deer, Rickettsia sp. endosymbiont sequences were present in all I. scapularis ticks, and Rickettsia amblyommatis was detected in three A. inornatum adult ticks from deer. Sequence analysis of Anaplasmataceae-positive amplicons from A. nitens and A. maculatum had low percent identity to published Anaplasma spp. sequences, suggesting a unique Anaplasma sp. may be circulating in the population. Anaplasma platys was detected from A. nitens larvae and an Ehrlichia sp. Delta strain was present in A. maculatum, both of unknown pathogenicity towards deer. Theileria cervi was detected in all stages of A. nitens ticks, and positive ticks originated from 27 of 31 deer and a single nilgai sampled from throughout the survey site. The primary vector for T. cervi is absent from this region, suggesting T. cervi is possibly maintained by a different tick species.

•

Anocenter nitens predominates on white-tailed deer and nilgai in southern Texas.

•

Theileria cervi was detected in Anocenter nitens ticks from deer and a single nilgai.

•

Three Theileria cervi genotypes were detected in this region of southern Texas.

•

Unique Anaplasma sp. detected in A. nitens; low identity to known Anaplasma sp.

•

Amblyomma inornatum ticks were identified on nilgai; a first record on this host.

Tick development on sexually-active bull moose is more advanced compared to that of cow moose in the winter tick, Dermacentor albipictus

We performed a complete survey of ticks on 100 cm² skin samples collected from 30 moose (Alces alces) harvested in 2017 in central and northern Maine, U.S.A. The samples were collected from 15 bulls, 13 cows, and 2 calves in mid-October when moose are breeding and winter ticks (Dermacentor albipictus) quest for a host. We identified only winter ticks with 99.2% in a juvenile stage; 3 adult ticks were found. Unfed nymphs were most common on bulls, whereas most ticks were fed larvae on cows and calves. The mean total count on bull samples was 21 ± 4.4 (range = 0–55) and higher than on cows (6 ± 0.5; range = 2–8). Unlike previous surveys, tick abundance was lowest on calves. Tick abundance was independent of age or weight of adult moose. The higher abundance and more rapid development of winter ticks on adult bulls likely reflects the seasonal influence of increased movements and hormonal cycles associated with reproduction.

•

First study that compares tick stages on bulls, cows, and calves during the breeding season.

•

Tick abundance on calves is low during this time (first report).-

tick abundance: bulls >> cows > calves.

•

There is a developmental lag (first report of occurrence).-

post-larvals (nonfed nymphs, fed nymphs, a few adults) dominate on bulls.

-

unfed and fed larvae dominate on cows and calves.

•

Tick abundance is independent of moose age and weight.

•

Only winter ticks (Dermacentor albipictus) were found; no Ixodes in particular.