A case of domestic goat parasitism by Neotrombicula heptneri (Acariformes: Trombiculidae) in Turkey

A chigger mite Neotrombicula heptneri Kudryashova, 1973, which was originally described from three gerbillid species in Iran, is for the first time recorded in Turkey and on the domestic goat Capra hircus L. It is the second chigger species found infesting livestock in Turkey

Although chigger mites parasitize a wide variety of mammal species, their records on ungulate animals (including livestock) are rare (e.g. Kolomiyets 1948;Brennan and Yunker 1964;Takahashi et al. 2008;Rehbein et al. 2011;Shatrov and Stekolnikov 2011;Gomez-Puerta et al. 2012). Therefore, each new such finding contributes greatly to knowledge on the veterinary and medical importance of these mites, known as causative agents of trombiculiasis in domestic animals and humans.
The present report is based on a chigger sample collected at a goat farm (37°9.784' N, 36°21.941' E, 270 -280 m a.s.l.) in the east part of the Mediterranean region of Turkey, Osmaniye Province. The grazing area around the farm is partly covered with Mediterranean vegetation, predominantly maquis (a characteristic shrubland biome). According to personal communications of the farm owners, they saw chiggers on goats for many years between November and April, with the peak abundance in January and February.
Chiggers were collected by S. Kar between 15-25 February in three consecutive years (2013, 2014, and 2015). Visual examination of 80 goats (55 ♀ and 25 ♂, aging from 1 to 4 years old) carried out in February 2013 showed a 100 % prevalence of infestation with chiggers. The mites were observed in the eyelids of all examined goats (20-80 specimens per animal). Groups of parasites were found attached around the hair follicles ( Figure 1). Stekolnikov A.A. and Kar S. Additionally, chiggers were observed in the posterior fossa of hind leg pastern of 12 animals, and on both front and hind legs of 4 animals (4-10 mites per animal). In total, about 50 chigger specimens from several goats were collected; the host animals and their individual characteristics were not documented. Twelve specimens fixed in 70 % ethanol were sent to A.A. Stekolnikov for identification. All specimens were mounted on microscopic slides in Faure-Berlese medium and examined with the use of a compound microscope MBI-3 (LOMO plc, St Petersburg, Russia) supplied with phase contrast optics, drawing tube, and ocular micrometer. The microphotograph ( Figure 2) was made by a Leica DM5000B microscope equipped with a DFC320 digital camera (Leica Microsystems Wetzlar GmbH), using differential interference contrast microscopy.
Because all mites in the sample were fully engorged, the quality of a half of slides was not good enough to make measurements. Therefore, standard measurements were taken from six specimens only. Abbreviations for morphometric variables are given after Stekolnikov and Daniel (2012) with few modifications. The sample is deposited in the collection of Zoological Institute RAS, Saint Petersburg, Russia (Nos. 9787-9798).
All 12 chiggers were identified as Neotrombicula heptneri Kudryashova, 1973 on the basis of the original description and our measurements of the holotype and one paratype deposited in the Zoological Museum of Moscow State University, Moscow, Russia (ZMMU). According to our experience, presence of several chigger species with the same pattern of localization and the same shape (e.g. sympatric Neotrombicula species) in a sample from one host species can usually be revealed by the first ten slides. Therefore, we believe that infestation of the goats with only one chigger species is highly probable in our case.
According to the original description, N. heptneri is characterized by nude galeal seta, branched setae on palpal femur, genu, and tibia, three genualae I, presence of mastitarsala on the leg tarsus III, fD = 2H-6-6-8-2-4-(4)-2- (2)   Our measurements taken from the Turkish sample (Table 1) are somewhat larger than those of the type series given by Kudryashova et al. (1973). However, because our metric data for the N. heptneri holotype systematically exceed the original ones, these morphometric differences should be regarded as a measurement artifact. Using our measurements exclusively, we can conclude that N. heptneri from Turkey differs from the type series in somewhat shorter legs (variables pa-Ip and TaIIIL), in slightly more numerous ventral (VS) and, consequently, total idiosomal setae (NDV), while values of all other variables are very close or coincide in these two samples. Moreover, our material differs from the type series of N. heptneri in generally more angulate posterior scutal margin (Figure 2), although some variation of this trait in the Turkish sample suggests that it is not reliable. The last probable difference between Iranian and Turkish N. heptneri is the presence of nude dorsal palpal tibial setae in the latter vs. having few branches (fPp = B/B/NBB vs. B/B/BBB). However, in the holotype, according to our examination, this paired seta is nude on one side and invisible on the other; therefore, this trait can also be variable in N. heptneri, as in N. autumnalis (Shaw, 1790) (Imaz et al. 2006) and all species of the N. talmiensis (Schluger, 1955) species group (Stekolnikov 1996). Thus, there are no sufficient grounds for a description of Turkish N. heptneri as a new species.
Neotrombicula heptneri is very similar to N. kepkai Kolebinova, 1971 described from two mouse species in Bulgaria and differs from it in the proportions of the scutum, which is much narrower in N. heptneri than in N. kepkai, and in the dorsal palpal tibial seta with few branches (or nude) in N. heptneri vs. heavily branched in N. kepkai. The relationship between these two species requires further investigation.