Chorioptes mites: re-evaluation of species integrity.

Chorioptes mites (Acari: Psoroptidae) are non-burrowing agents of mange which parasitize a wide range of domesticated and wild ungulates. Considerable historical confusion has surrounded the description and naming of the various species of Chorioptes. Here, the opisthosomal setae of male adult Chorioptes mites from a range of host species and geographic locations were subjected to detailed analysis. Discriminant analysis suggests the existence of three clear morphotypes. The first, Chorioptes bovis, is characterized by a very long seta 1 (ae) and short spatulate setae 2 (l4 and d5), whereas, in the second, Chorioptes texanus, setae 2 (l4 and d5) are longer and narrower than in C. bovis, but most of the other setae are shorter; this is particularly true for seta 1 (ae). A third morphotype is characterized by a seta 1 (ae) that is shorter than in C. bovis but longer than in C. texanus, long setae 2 (l4 and d5) and a long seta 6 (l5). The data are compared with previously published measurements. Although this analysis supports the validity of C. bovis and C. texanus as morphologically distinct, it also supports the existence of a proposed third species of Chorioptes, as described by Hestvik et al. in 2007, and suggests that the mites described by Sweatman in his classic 1958 description of C. texanus, which were obtained from the ears of semi-domesticated reindeer, are likely to have been specimens of this as yet unnamed species. The results show that there is a high degree of phenotypic plasticity in setal lengths. It is concluded that a statistical difference in the absolute measurement of any one seta is not a reliable species indicator; the relative sizes of groups of setae would appear to be more taxonomically informative and should be used when identifying Chorioptes morphologically.

Mange in alpacas, llamas and goats in the UK: incidence and risk.

A retrospective postal questionnaire was used to obtain information about the prevalence of mange and its association with husbandry-related risk factors, in alpaca, llama and goat herds in the UK. In total 1797 questionnaires were sent out to members of the British Alpaca Society, the British Llama Society and the British Goat Society, giving response rates of 40.4%, 29.3% and 22.8% from the three groups, respectively. Between January and December 2007, mange was reported in 52.2% (151 of 292), 14% (9 of 66) and 21% (41 of 194) alpaca, llama and goat herds, respectively. However, these figures must be treated with some caution as only 37-51% of the farmers had their diagnosis of mange confirmed by a veterinarian or animal health laboratory. In herds where the causal agent was confirmed: psoroptic, sarcoptic, chorioptic and mixed infections were all reported, with chorioptic mange reported most frequently. Risk analysis showed that the prevalence of reported cases mange in alpacas was significantly associated with herd size and the country from which the animals were imported. Alpaca farmers who had larger herds were more likely to report mange and farmers who imported their animals from Peru were 1.5 times more likely to report mange than farmers who imported animals from elsewhere or who did not import. There was no significant confounding between these two risk factors. The results show that mange continues to be a major problem for camelids and goats in the UK, and suggests that inadequate control on farms and lack of control when in quarantine are two factors that contribute to ongoing problems with mange. However, given the relatively low contribution of imported animals to the national herd each year, it is likely that poor on-farm control may be of greatest importance.