Sebei_87-92.qxd INTRODUCTION Lice are divided into sucking and biting species (Anoplura: Linognathidae and Ischnocera: Tricho- dectidae). Both biting and sucking lice are ectopar- asites that adversely affect low productivity in goats (Pandita & Ram 1990). The actual loss resulting from louse infestation of goats is not easy to quan- tify but it was estimated to be UD$800 000 in the USA (Steelman 1976). Zumpt (1970) describes losses in sheep during winter on the highveld regions in South Africa and O’Callaghan, Beveridge, Barton & McEvan (1989) describe the effects of experimental infestations with Linognathus vituli on undernourished calves. Unhygienic conditions, increased population density and inadequate hous- ing promote the spread of louse infestations. Infes- tation can result in anaemia, hypoproteinaemia, secondary infestation, nutritional deficiencies and reduced vigour as well as in bacterial or fungal infections of bite wounds (Howell, Walker & Nevill 1978; Pandita & Ram 1990; Oberem & Schröder 1993). In South Africa infestations with Linognathus africanus (the blue sucking louse of goats) and Bovicola limbatus (the red biting louse of goats) have been described in a commercial herd of Angora goats in the Eastern Cape Province (Horak, McIvor & Greeff 2001). Scanning electron microscopic descriptions of lice have rarely been made. Previously morphological 87 Onderstepoort Journal of Veterinary Research, 71:87–92 (2004) Use of scanning electron microscopy to confirm the identity of lice infesting communally grazed goat herds P.J. SEBEI1, C.M.E. MCCRINDLE1, E.D. GREEN2 and M.L. TURNER3 ABSTRACT SEBEI, P.J., McCRINDLE, C.M.E., GREEN, E.D. & TURNER, M.L. 2004. Use of scanning electron microscopy to confirm the identity of lice infesting communally grazed goat herds. Onderstepoort Journal of Veterinary Research, 71:87–92 Lice have been described on goats in commercial farming systems in South Africa but not from flocks on communal grazing. During a longitudinal survey on the causes of goat kid mortality, con- ducted in Jericho district, North West Province, lice were collected from communally grazed indige- nous goats. These lice were prepared for and viewed by scanning electron microscopy, and micro- morphological taxonomic details are described. Three species of lice were found in the study area and identified as Bovicola caprae, Bovicola limbatus and Linognathus africanus. Sucking and biting lice were found in ten of the 12 herds of goats examined. Lice were found on both mature goats and kids. Bovicola caprae and L. africanus were the most common biting and sucking lice respectively in all herds examined. Scanning electron microscopy revealed additional features which aided in the identification of the louse species. Photomicrographs were more accurate aids to identification than the line drawings in the literature and facilitated identification using dissecting microscope. Keywords: Bovicola spp., goat, lice, Linognathus africanus, scanning electron microscope 1 Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderste- poort, 0110 South Africa 2 Department of Anatomy, Medical University of Southern Africa, Box 232, MEDUNSA, 0204 South Africa 3 Electron Microscope Unit, Medical University of Southern Africa, Box 232, MEDUNSA, 0204 South Africa Accepted for publication 23 October 2003—Editor features used for the taxonomic differentiation of lice species were described using the standard light microscope (Green, Turner & Sebei 2001; Turner, Baker & Marais 2002). Light microscopy does not show in sufficient detail the morphology required for their classification. Because the taxonomic differ- ences between Bovicola caprae and B. limbatus are based on the structure of their genital organs it has led to difficulty in identifying these louse spe- cies from the field. MATERIALS AND METHODS During a longitudinal survey on the causes of mor- talities in goat kids in the Jericho district, North West Province, South Africa (Sebei 2002), live lice were collected from 12 herds of communally grazed indigenous type goats. As lice can easily be seen with the naked eye when the fleece is parted (Zumpt 1970) goats were visually and manually examined for external parasites in the coat of the animal. Areas sampled were the dorsal neck from behind the ear, tail area, back and rump, flanks, the dew- lap/brisket area, buttock and the midline laterally (Price & Graham, 1997). Live lice were collected by means of forceps dabbed in 70 % alcohol and were then preserved in 70 % alcohol. Fixed specimens were inspected under a dissection microscope. Undamaged adult males and females were select- ed for scanning electron microscopy (SEM), which has successfully been used for the identification of lice (Green & Baker 1996; McCrindle, Green & Bry- son 1999; Turner et al. 2002). Lice were processed for SEM using the method described by Turner et al. (2002). A structured interview with the farmers was conducted in order to evaluate the stock man- agement practices (including dipping) they used. RESULTS It was found that 83 % (n = 10) of the herds inves- tigated (n = 12) were infested with biting and/or sucking lice. Three species of lice were found, namely B. caprae, B. limbatus and L. africanus (Table 1). Lice were found on both mature goats and kids. Bovicola caprae and L. africanus were the most common biting and sucking lice respectively in the herds examined. Five species of lice have been described on goats throughout the world (Price & Graham 1997), but no records could be found of simultaneous infesta- tions by three or more species. Horak et al. (2001) have found mixed infestations of B. limbatus and L. africanus. In this study two species of biting lice (Fig. 1 and 2) and one species of sucking louse (Fig. 3) infested one herd, and all three species were collected from individual goats in the herd. For epidemiological studies it was necessary to accu- rately identify these three species. O’Callaghan et al. (1989) specifically mentioned difficulties in iden- tifying species on goats using the line-drawings made from light microscopy that are available in the literature. Distinguishing micro-morphological fea- tures used for species identification under SEM are shown (Fig. 1–12). The sucking louse was identified as L. africanus by the following characteristics which distinguish it from Linognathus stenopsis (O’Callaghan et al. 1989). The shape of the head, with the prominent bulging ocular points posterior to the antenna, is typical and was confirmed by SEM (Fig. 3), together with the rounded female gonopods (Fig. 5) (Ferris 1951; Kim, Pratt & Stojanovich 1986). The female termi- nal gonopod of L. africanus is rounded and lacks the “tooth-like” process described for L. stenopsis (Kim et al. 1986). The gonopods of the male includ- ed a pair of terminal tubercles with setae (Fig. 6) and are characteristic of L. africanus (Price & Gra- ham 1997). Differentiating between the Bovicola spp. was more difficult as the adult females are difficult to separate (Price & Graham 1997). None of the Bovicola spp. were densely covered with setae or large enough to be identified as Bovicola crassipes which is one of the three Bovicola spp. infesting goats (Ledger 1980). Under the stereoscopic microscope the males of B. caprae and B. limbatus were only dis- tinguishable by the number of sclerotized sternites (Ledger 1980). All the paratergites of both sexes of 88 Lice infesting communally grazed goat herds TABLE 1 Distribution of lice in different herd Farmer Bovicola Bovicola Linognathus code caprae limbata africanus 1 Negative Negative Negative 2 Positive Negative Positive 3 Positive Negative Negative 4 Negative Negative Positive 5 Positive Positive Positive 6 Positive Positive Positive 7 Positive Negative Positive 8 Positive Negative Positive 9 Positive Positive Positive 10 Positive Negative Positive 11 Negative Negative Negative 12 Positive Positive Positive 89 P.J. SEBEI et al. FIG. 1 Ventral surface of Bovicola caprae attached to a hair by paired mandibles (*) FIG. 2 Anteroventral surface of Bovicola limbatus showing mandibles (*) and tarsal claws FIG. 3 Ventral view adult female Linognathus africanus show- ing prominent ocular processes (<<) on head and legs ending in large single claws FIG. 4 Dorsal view of adult male Linognathus africanus show- ing ocular processes (<<) on the head and pseudope- nis (black arrow on abdomen) FIG. 5 Ventral view of the female gonopods of Linognathus africanus which lacks the apical tooth at (*) as found in Linognathus stenopsis FIG. 6 Ventral view of male gonopods of Linognathus afri- canus showing the tubercles (*) and pseudopenis (P) 90 Lice infesting communally grazed goat herds FIG. 7 Dorsal view of male Bovicola limbatus showing the conical male gonopods (G) FIG. 8 Enlarged view of the conical male gonopods of Bovi- cola limbatus showing the characteristic long setae FIG. 9 Dorsal view of male Bovicola caprae showing the con- ical male gonopods (G) FIG. 10 Enlarged view of the conical male gonopods of Bovi- cola caprae showing the terminal flaps (T) covered with short setae closing the genital opening (O) FIG. 11 Enlarged view of the antennal sensilla coeloconica of Bovicola caprae showing the two pore organs with the tuft organs (P) and two plates organs enclosed in a single plate (*) FIG. 12 Enlarged view of the antennal sensilla coeloconica of Bovicola caprae showing the two pore organs with the tuft organs (P) and three plate organs each enclosed in their own plates (*) B. caprae were well-sclerotized and brown in colour while in B. limbatus only the anterior two parater- gites were sclerotized in both sexes. These para- tergites were not previously identifiable from the line drawings published in the literature (Werneck 1950). However, once accurate micro-morphology was determined by SEM, the two species could easily be differentiated under the stereoscopic microscope. According to Price & Graham (1997) B. caprae and B. limbatus can be differentiated only by examining the genitalia. The male gonopods of both species, when viewed under low magnification, are conical in shape (Fig. 7–9). This was confirmed with SEM. The conical gonopods of B. limbatus have scat- tered long setae (Fig. 8) while the posterior end of the gonopods of B. caprae are densely covered with short setae (Fig. 10). The distinctive charac- teristic of B. caprae is the presence of two terminal flaps, which close over the genital opening (Fig. 10). The antennal sensilla coeloconica were similar in both species with two pore organs each containing a tuft organ (Fig. 11–12). The three adjacent plate organs, however, were different. In B. limbatus the anterior three plate organs share one plate (Fig. 11) while the two plate organs in B. caprae are each surrounded by their own plate (Fig. 12) (Ferris 1951; Miller & Frederick 1971). DISCUSSION The main aim of this investigation was to study by SEM the micro-morphological features which could aid in identification or differentiation of louse spe- cies found on communally grazed goat herds. Micrographs illustrating taxonomic morphological differences between B. limbatus, B. caprae and L. africanus show details of micro-morphology not obvious under the light microscope. The differ- ences between morphological features seen in micrographs obtained from SEM and the line draw- ings seen in the literature could be attributed to the difference in the resolution power of light and elec- tron microscopes (Green et al. 2001; Turner et al. 2002), and SEM thus allowed for more accurate species identification. Once positively identified by SEM, it was found that specimens of B. caprae could also be distinguished from B. limbatus under the stereoscopic microscope on the basis of colour. This will be useful for field studies of the epidemiol- ogy of two the species. Micrographs obtained using SEM can be used to update the literature refer- ences used for the identification of these lice spe- cies. Many of the line drawings, which are current- ly the only taxonomic references, were published in obscure journals, textbooks and memoirs of many years ago (Werneck 1950; Ferris 1951; Kim et al. 1986). Although the three goat louse species identified in this study have been recorded from commercial goat production systems, this is the first record from goats in a communal grazing system. According to Seddon (1967) lice infestation occurs more fre- quently on young animals. This was also the case in this study. 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