ElGhali_177-185.indd INTRODUCTION Little publish information on ticks infesting camels is available. Camels in Egypt were found to be mainly infested by Hyalomma dromedarii (95 %) together with Hyalomma marginatum subspecies, Hyalom- ma anatolicum excavatum and Hyalomma species nymphs (Van Straten & Jongejan 1993). In the same area and on the same animal species Diab, El Kady & Shouky (2001) reported that H. dromedarii, Hy a- lomma impeltatum, H. a. excavatum and H. a. ana- tolicum represented 96 % of the tick population with a higher infestation in March to November and a mean monthly total of 22–78 ticks per animal. About 62 % of adult ticks were collected from the tail, anus, brisket and udder, and 91 % of nymphs were found infesting humps, neck, ears and sides. In Saudi Arabia, a total of 1 045 adult H. dromedarii and 174 H. a. excavatum together with 110 ticks that in- cluded H. a. anatolicum, H. impeltatum, Hyalomma schulzei, Hyalomma truncatum, Hyalomma mar gi- na tum rufipes and Hyalomma marginatum turanicum as well as 143 Hyalomma spp. nymphs were col- lected from 10 camels (El Khalifa, Al Asgah & Diab 1985). In Yemen, Arab Republic, the most abundant livestock ticks were Hyalomma spp., particularly on camels, but with a very low burden (MacAr tan, Hun- ter, Pegram & Bourne 1987). In the Sudan, Karrar, Kaiser & Hoogstraal (1963) reported that H. drom- edarii was the main tick species of camels together with Amblyomma lepidum, H. impeltatum, Rhipi- 177 Onderstepoort Journal of Veterinary Research, 76:177–185 (2009) Ticks (Acari: Ixodidae) infesting camels (Camelus dromedarius) in Northern Sudan A. ELGHALI1* and S.M. HASSAN2 ABSTRACT ELGHALI, A. & HASSAN, S.M. 2009. Ticks (Acari: Ixodidae) infesting camels (Camelus dromedarius) in Northern Sudan. Onderstepoort Journal of Veterinary Research, 76:177–185 Monthly total body tick collections from 13-20 camels were conducted for 2 consecutive years (2000– 2001) in Northern Sudan. Tick populations were correlated with locality, season, predeliction site, sex and coat colour. Hyalomma dromedarii was found to be the predominant (89 %) tick species infesting the camels. Other tick species found in very low numbers were Hyalomma impeltatum (7.7 %), Hy a- lomma anatolicum anatolicum (3.3 %), Hyalomma truncatum (0.29 %), Hyalomma marginatum rufipes (0.25 %), Rhipicephalus praetextatus (0.30 %) and Rhipicephalus sanguineus group (0.09 %). Nymphs of the genus Hyalomma were collected in significant numbers. Adult ticks significantly preferred to attach to the lower parts of the camel’s body for feeding while the nymphs preferred the back of the animal. Female camels harboured more ticks than males while higher infestations were recorded on camels with a grey coat colour compared to those with a brown coat colour. Ticks were found on camels throughout the year and increased in numbers during March to October with a peak in Sep- tember. Keywords: Camels, Hyalomma spp., Rhipicephalus spp., Sudan, ticks * Author to whom correspondence is to be directed. E-mail: elghaliaahmed@hotmail.com 1 Atbara Veterinary Research Laboratory, P.O. Box 121, At- bara, Sudan 2 Department of Parasitology Faculty of Veterinary Medicine Uni versity of Khartoum, Sudan Accepted for publication 1 September 2008—Editor 178 Ticks (Acari: Ixodidae) infesting camels (Camelus dromedarius) in Northern Sudan Atbara SUDAN Tiyat Abu Ho Sam Wadi Abu Rigaiba Ed Damer Camel grazing area Gangari River Al Basli Nikhilas R iv e r 17°45’ 17°50’ 34°00’ Scale 1 250 000 34°15’ W Mukabrab Al drou sa L Halag Al humer Al u Shera Gersi 34°00’ N IL E Muuran Alrouk Al Gezen Al Shaet N FIG. 1 Map of the study area in Nothern Sudan showing the localities from where ticks were colected (●) and Atbara Research Laboratory (■) 179 A. ELGHALI & S.M. HASSAN cephalus sanguineus sanguineus, Rhipicephalus si- mus, H. a. excavatum, H. truncatum and H. m. ru fi- pes. Dolan, Wilson, Schwart, Newson & Field (1983) collected H. dromedarii, H. m. rufipes and Rhipi- cephalus pulchellus from camels in Kenya. The ob- jective of this study was to conduct population stud- ies of ticks infesting camels in Northern Sudan. MATERIALS AND METHODS The study area extends along the western banks of River Atbara starting from Ed Damer in Northern Su dan (Fig. 1). This area is in the arid (desert) zone (annual rainfall ranges between 0–100 mm) with very poor vegetation cover which mainly consists of scattered bushes and small trees, i.e. Prosopis chi- len sis and Capparis decidua. Large acacias such as Acacia nilotica nilotica, Acacia seyal, Acacia tortilis tortilis, Acacia tortilis raddiana, Ziziphus spina chris- ta and Hyphaena thebaica are abundant (El Amin 1989). Small-scale farms are cultivated along the river banks where camels graze. They graze on grass and post-harvest agricultural residues and browse on bushes and trees. During the wet sea- sons they move to the Butana area, approximately 300 km to the south-east, where the grazing is bet- ter. Tick collection and identification Total body collections of ticks from 13–20 adult camels were carried out on a monthly basis bar for 2 consecutive years (2000–2001). Ticks from each predilection site were put into separate vials con- taining 70 % ethanol. The vials were labeled to indi- cate date, time, locality, animal number, sex, host coat colour and predilection site. The predilection sites included head (head and neck), back (hump region and flank), tail (tail shaft and perineum), low- er parts (brisket, belly, udder or scrotum and inner sides of thigh) and feet (knee to pad). The ticks were identified according to Hoogstraal (1956), Hoogstraal & Kaiser (1959) and Walker et al. (2003), and results were recorded according to TABLE 1 Means (± SE) of ticks collected from camels along the River Atbara and Ed damer in 2000–2001 Year Tick species River Atbara (123) Ed damer (62) 2000 H. dromedarii (m) H. dromedarii (f) H. dromedarii (t) H. impeltatum (m) H. impeltatum (f) H. impeltatum (t) H. a. anatolicum (m) H. a. anatolicum (f) H. a. anatolicum (t) Hyalomma nymphs 125.0 ± 12.2a 40.4 ± 5.1a 165.4 ± 16.3a 12.4 ± 1.1a 5.7 ± 0.6a 18.2 ± 1.4a 3.8 ± 0.5a 7.3 ± 0.8a 11.1 ± 1.1a 5.0 ± 0.8a 49.5 ± 5.9b 13.6 ± 1.9b 63.1 ± 7.2b 3.3 ± 0.7b 0.45 ± 0.2b 3.8 ± 0.7b 1.1 ± 0.3b 0.2 ± 0.1b 1.2 ± 0.3b 2.5 ± 0.9b Mean total ticks 194.7 ± 17.3a 68.1 ± 7.8b Ratio (male:female) 3.1 ± 0.21b (105) 7.1 ± 1.2a (56) 2001 H. dromedarii (m) H. dromedarii (f) H. dromedarii (t) H. impeltatum (m) H. impeltatum (f) H. impeltatum (t) H. a. anatolicum (m) H. a. anatolicum (f) H. a. anatolicum (t) Hyalomma nymphs 111.4 ± 9.5a 43.4 ± 4.1a 154.9 ± 12.9a 10.8 ± 1.1a 0.37 ± 0.1a 11.2 ± 1.1a 1.02 ± 0.6a 0.88 ± 0.2a 1.9 ± 0.8a 7.9 ± 1.0a 40.2 ± 4.0b 13.7 ± 1.6b 53.9 ± 5.1b 2.8 ± 0.4b 0.02 ± 0.02b 2.9 ± 0.38b 0.02 ± 0.02b 0.07 ± 0.03b 0.1 ± 0.04a 4.9 ± 0.9b Mean total ticks 168.0 ± 13.7a 56.8 ± 5.3b Ratio (male:female) 3.6 ± 0.24a 4.6 ± 0.6a Means ( ± SE) followed by the same letter in each row are not significantly different at 5 % level, based on Ryan’s Q test (REGWQ) ( ) = no. of camels used m = male f = female t = m + f 180 Ticks (Acari: Ixodidae) infesting camels (Camelus dromedarius) in Northern Sudan TABLE 2 Total tick burdens on camels in River Nile State, Northern Sudan, 2000 and 2001 Year Location H. dromedarii H. impeltatum H. a. anatolicum Hyalomma nymphs 2000 River Atbara Ed damer 20 295 3 906 2 214 236 1 353 74 615 155 Total no. of ticks 24 201 2 450 1 427 770 % of adults 86.2 8.7 5.1 – Ratio (nymphs:adults) 1:36.5 2001 River Atbara Ed damer 16 275 3 024 1 176 162 200 6 830 274 Total no. of ticks 19 299 1 338 206 1 104 % of adults 92.6 6.4 1.0 – Ratio (nymphs:adults) 1:18.9 Total 43 500 3 788 1 633 1 874 % of grand total abundant adults 88.9 7.7 3.3 – Ratio (nymphs:adults) 1:26.1 TABLE 3 Total numbers of tick species collected from camels in very low numbers during 2000 and 2001 in River Nile State, Northern Sudan Tick species Males Females Total % of total adult ticks H. truncatum H. marginatum rufipes R. praetextatus R. sanguineus group 127 78 84 26 16 46 65 16 143 124 149 42 0.29 0.25 0.30 0.09 TABLE 4 Means ( ± SE) of ticks collected from male and female camels in River Nile State, Northern Sudan, 2000–2001 Year Tick species n Male camels n Female camels 2000 H. dromedarii H. impeltatum H. a. anatolicum 63 63 63 82.2 ± 12.3b 8.4 ± 1.1b 5.7 ± 1.2b 122 122 122 156.4 ± 16.0a 15.9 ± 1.4a 8.9 ± 1.1a Hyalomma nymphs 63 3.0 ± 1.0a 122 4.8 ± 0.8a Total ticks 63 96.3 ± 3.4b 122 181.2 ± 17.3a Ratio (male:female) 63 5.5 ± 1.0a 122 3.8 ± 0.4b 2001 H. dromedarii H. impeltatum H. a. anatolicum 33 33 33 89.8 ± 13.2b 6.8 ± 2.1a 1.1 ± 0.4a 128 128 128 127.5 ± 11.2a 8.7 ± 0.9a 1.3 ± 0.6a Hyalomma nymphs 33 7.9 ± 1.9a 128 6.5 ± 0.8a Total ticks 33 97.7 ± 14.5b 128 137.5 ± 12.0a Ratio (male:female) 33 3.4 ± 0.3a 128 4.1 ± 0.3a Means ( ± SE) followed by the same letter in each row are not significantly different at 5 % level, based on Ryan’s Q test (REGWQ) n = no. of animals used 181 A. ELGHALI & S.M. HASSAN T A B L E 5 M e a n ( ± S E ) n u m b e rs o f tic ks c o lle ct e d f ro m c a m e ls in R iv e r N ile S ta te in 2 0 0 0 a n d 2 0 0 1 M o n th n H . d ro m e d a ri i H . im p e lt a tu m H . a . a n a to li c u m H y a lo m m a n y m p h s T o ta l ti c k s R a ti o ( m a le :f e m a le ) 2 0 0 0 Ja n u a ry F e b ru a ry M a rc h M a y Ju n e Ju ly A u g u st S e p te m b e r O ct o b e r N o ve m b e r D e ce m b e r 2 0 2 0 1 7 1 6 1 9 1 6 1 6 1 4 1 7 1 5 1 5 7 0 .9 ± 8 .4 b 7 0 .4 ± 1 0 .1 b 8 2 .2 ± 1 7 .3 b 8 4 .6 ± 1 7 .6 b 1 0 4 .7 ± 2 2 .4 b 1 2 4 .2 ± 2 4 .9 b 1 3 6 .3 ± 4 2 .1 a b 2 5 6 .6 ± 7 3 .0 a 2 5 2 .5 ± 6 3 .7 a 1 7 1 .1 ± 5 1 .5 a b 1 3 7 .9 ± 3 3 .2 a b 1 7 .3 ± 3 .4 a 1 0 .9 ± 2 .1 a 1 1 .4 ± 3 .2 a 1 4 .1 ± 3 .6 a 8 .6 ± 1 .9 a 9 .9 ± 2 .6 a 1 1 .1 ± 3 .4 a 1 8 .1 ± 5 .3 a 1 7 .4 ± 4 .7 a 1 2 .7 ± 3 .8 a 1 6 .6 ± 4 .5 a 1 5 .5 ± 3 .5 a 9 .5 ± 3 .0 a b 7 .0 ± 1 .7 a b 1 4 .0 ± 5 .1 a 6 .9 ± 2 .0 a b 9 .4 ± 2 .9 a b 4 .8 ± 1 .3 a b 1 .8 ± 0 .7 b 2 .4 ± 0 .7 b 6 .7 ± 1 .8 a b 4 .7 ± 2 .0 a b 1 .8 ± 0 .6 b 0 .4 ± 0 .2 b 3 .4 ± 2 .3 a b 3 .6 ± 1 .2 a b 3 .7 ± 1 .7 a b 2 .4 ± 1 .0 a b 9 .3 ± 4 .0 a b 3 .6 ± 2 .0 a b 2 .9 ± 1 .5 a b 1 1 .3 ± 3 .6 a 5 .9 ± 2 .4 a b 1 0 3 .7 ± 1 1 .8 b 9 0 .8 ± 1 4 .1 b 1 0 0 .6 ± 1 .9 b 1 1 3 .1 ± 2 4 .1 b 1 2 0 .2 ± 2 5 .7 b 1 4 3 .5 ± 2 9 .4 a b 1 5 2 .2 ± 4 5 .9 a b 2 7 6 .5 ± 7 8 .2 a 2 7 2 .4 ± 6 8 .2 a 1 9 0 .6 ± 5 5 .7 a b 1 5 9 .3 ± 3 9 .9 a b 2 .9 ± 0 .3 b 5 .8 ± 1 .4 a b 6 .6 ± 1 .6 a b 2 .1 ± 0 .2 b 4 .6 ± 1 .1 a b 8 .1 ± 3 .0 a 3 .8 ± 0 .8 b 6 .5 ± 1 .7 a b 3 .0 ± 0 .3 b 2 .4 ± 0 .4 b 2 .7 ± 0 .3 b 2 0 0 1 Ja n u a ry F e b ru a ry M a rc h A p ri l M a y Ju n e Ju ly O ct o b e r N o ve m b e r D e ce m b e r 1 3 1 4 1 6 1 5 1 6 1 9 1 7 1 6 1 8 1 7 1 5 4 .8 ± 4 2 .6 a b 8 9 .4 ± 2 6 .4 a b 1 7 0 .8 ± 4 7 .6 a 1 5 8 .5 ± 4 9 .2 a b 1 1 5 .3 ± 2 1 .5 a b 1 2 1 .2 ± 2 .9 a b 1 5 8 .6 ± 2 7 .0 a b 9 3 .5 ± 8 .3 a b 6 0 .8 ± 1 0 .9 b 8 6 .5 ± 1 6 .1 a b 1 3 .1 ± 3 .4 a b 3 .7 ± 2 .7 a b 1 5 .8 ± 5 .1 a 8 .4 ± 3 .1 a b 7 .1 ± 2 .2 a b 5 .6 ± 1 .2 b 4 .5 ± 0 .9 b 7 .3 ± 1 .7 a b 8 .4 ± 1 .1 a b 6 .0 ± 1 .4 a b 2 .8 ± 1 .0 a 1 .3 ± 0 .5 a 2 .1 ± 0 .6 a 0 .7 ± 0 .3 a 0 .6 ± 0 .3 a 0 .2 ± 0 .1 a 0 .4 ± 0 .3 a 0 .0 ± 0 .0 a 4 .4 ± 4 .4 a 0 .4 ± 0 .2 a 9 .0 ± 2 .2 a b 9 .5 ± 3 .0 a b 5 .7 ± 1 .8 a b 6 .0 ± 1 .8 a b 4 .3 ± 1 .8 a b 8 .0 ± 2 .6 a b 1 2 .4 ± 4 .0 a 3 .2 ± 0 .8 b 3 .6 ± 1 .6 b 6 .6 ± 1 .7 a b 1 7 0 .7 ± 4 6 .0 a 9 9 .4 ± 2 9 .2 a 1 8 8 .6 ± 5 1 .9 a 1 6 7 .8 ± 5 2 .4 a 1 2 3 .0 ± 2 3 .4 a 1 2 6 .9 ± 2 3 .0 a 1 6 3 .5 ± 2 7 .7 a 1 0 0 .8 ± 8 .9 a 7 3 .6 ± 1 1 .8 a 9 2 .9 ± 1 6 .7 a 2 .4 ± 0 .3 3 .8 ± 0 .6 2 .8 ± 0 .3 3 .6 ± 1 .3 3 .4 ± 0 .5 4 .1 ± 0 .7 5 .8 ± 0 .8 4 .3 ± 0 .9 5 .2 ± 0 .7 3 .4 ± 0 .9 M e a n s (± S E ) fo llo w e d b y th e s a m e le tt e r in e a ch c o lu m n a re n o t si g n ifi ca n tly d iff e re n t a t 5 % le ve l, b a se d o n R ya n ’s Q t e st ( R E W G Q ) n = n o . o f a n im a ls u se d T A B L E 6 M e a n ( ± S E ) n u m b e r o f tic ks c o lle ct e d f ro m d iff e re n t si te s o n c a m e ls T ic k s p e c ie s H e a d B a c k T a il a n d u n d e r ta il L o w e r p a rt s F e e t H . d ro m e d a ri i H . im p e lta tu m H . a . a n a to lic u m 2 2 .7 ± 1 .7 b 1 .7 ± 0 .1 6 b 0 .0 6 ± 0 .0 2 b 1 .7 ± 0 .4 2 c 0 .0 9 ± 0 .0 2 c 0 .0 3 ± 0 .0 2 b 2 3 .8 ± 1 .6 b 1 .9 ± 0 .2 b 0 .2 4 ± 0 .0 4 b 7 6 .9 ± 7 .4 a 5 .4 ± 0 .6 a 1 .2 ± 0 .2 a 1 8 .6 ± 1 .6 b 1 .2 ± 0 .1 b 0 .2 5 ± 0 .0 6 b H ya lo m m a n ym p h s 1 .0 4 ± 0 .2 6 b 4 .5 ± 0 .5 a 0 .3 ± 0 .1 b 0 .9 ± 0 .2 b 0 .2 4 ± 0 .1 5 b R a tio ( m a le :f e m a le ) 4 .1 ± 0 .3 a b 2 .8 ± 1 .1 b 3 .4 ± 0 .2 a b 3 .2 ± 0 .2 b 4 .6 ± 0 .9 a M e a n s (± S E ) fo llo w e d b y th e s a m e le tt e r in e a ch r o w a re n o t si g n ifi ca n tly d iff e re n t a t 5 % le ve l, b a se d o n R ya n ’s Q t e st ( R E W G Q ) N o . o f a n im a ls = 2 4 9 182 Ticks (Acari: Ixodidae) infesting camels (Camelus dromedarius) in Northern Sudan TABLE 7 Mean (± SE) number of ticks collected from male and female camels of different coat colour in River Nile State in 2000 and 2001 Camel gender Tick species Grey Brown Female H. dromedarii (m) H. dromedarii (f) H. dromedarii (t) H. impeltatum (m) H. impeltatum (f) H. impeltatum (t) H. a. anatolicum (m) H. a. anatolicum (f) H. a. anatolicum (t) 140.3 ± 14.6a 54.8 ± 6.2a 195.0 ± 19.7a 13.7 ± 1.4a 1.1 ± 0.3a 14.8 ± 1.5a 1.3 ± 0.6a 2.0 ± .3a 3.3 ± 0.8a 71.4 ± 6.0b 26.7 ± 3.1b 98.2 ± 8.3b 5.6 ± 0.6b 0.54 ± 0.4b 6.2 ± 0.9b 0.2 ± 0.1b 0.6 ± 0.3b 0.8 ± 0.3b Hyalomma nymphs 7.8 ± 1.1a 6.0 ± 0.8a Total 213.2 ± 21.1a 105.1 ± 8.9b Ratio adult 3.8 ± 0.3a 4.0 ± 0.4a Male H. dromedarii (m) H. dromedarii (f) H. dromedarii (t) H. impeltatum (m) H. impeltatum (f) H. impeltatum (t) H. a. anatolicum (m) H. a. anatolicum (f) H. a. anatolicum (t) 79.0 ± 13.1a 27.2 ± 3.8a 106.2 ± 16.0a 6.5 ± 1.3a 0.9 ± 0.2a 7.4 ± 1.3a 0.9 ± 0.2a 1.1 ± 0.3a 1.9 ± 0.4a 42.9 ± 7.9a 12.5 ± 3.2b 55.4 ± 10.8a 6.4 ± 3.6a 0.4 ± 0.4a 6.8 ± 3.5a 0.2 ± 0.2b 0.7 ± 0.5a 0.9 ± 0.7a Hyalomma nymphs 7.7 ± 1.7a 2.9 ± 0.8a Total 115.5 ± 17.3a 63.1 ± 13.4a Ratio (male:female) 4.0 ± 0.6a 4.4 ± 0.7a Means (± SE) followed by the same letter in each row are not significantly different at 5% level, based on Ryan’s Q test (REWGQ Females : grey 108, brown 74 Males: grey 50, brown 17 m = male, f = female and t = m + f TABLE 8 Correlation analysis between ticks collected from camels with monthly meteorological values in 2000–2001 in River Nile State Year Met. data H. nymphs H. d. H. i. H. a. a. Total ticks 2000 Min. (185) Max. (168) Rh9 (185) Rh3 (185) Rain (185) 0.02 0.06 –0.003 –0.13 0.24*** 0.16* 0.12 0.01 –0.05 0.08 –0.02 –0.06 0.1 0.11 –0.01 –0.02 –0.1 0.001 0.08 –0.03 0.15* 0.1 0.01 –0.04 0.07 2001 Min. (172) Max. (172) Rh9 (172) Rh3 (172) Rain (172) 0.02 –0.01 0.09 0.02 0.11 0.02 0.04 –0.11 –0.16* –0.1 –0.17* –0.16* –0.003 –0.01 –0.07 –0.1 –0.11 0.08 0.08 –0.07 –0.005 0.2 –0.09 –0.14 –0.1 * P < 0.05, ** P < 0.01 and *** P < 0.001 H. d. = H. dromedarii H. i. = H. impeltatum H. a. a. = H. a. anatolicum Min. = minimum temperature Max. = maximum temperature Rh9 = relative humidity at 900 h Rh3 = relative humidity at 1 500 h ( ) = no. of observations 183 A. ELGHALI & S.M. HASSAN the body site and genus, species, gender and de- velopmental stage of each tick collected. The pa- rameters studied included tick species infesting camels, seasonality, effects of camel gender and coat colour and preferred attachment sites of each tick species. The number of ticks was correlated with the mean monthly minimum ambient tempera- tures, mean monthly maximum ambient tempera- tures, and mean ambient relative humidity and total monthly rainfall. RESULTS In the 2 study years 2000 and 2001, H. dromedarii represented 86.2 % and 92.6 %, respectively, of the ticks infesting the camels (Table 1), with a mean of 88.9 % (Table 2). Mean tick numbers per camel were 165.4 ± 16.3 and 154.9 ± 12.9 in 2000 and 2001, respectively. Other ticks collected in some numbers were H. impeltatum (7.7 %) and H. a. ana- tolicum (3.3 %) (Table 2). Tick species found in very low numbers were H. truncatum, H. marginatum rufipes, Rhipicephalus praetextatus and R. san- guineus group (Table 3). The ratio of male to female ticks ranged between 3.1 ± 0.21 and 7.1 ± 1.2 for the 2 years, respectively. The total ratio of Hyalomma nymphs to adults of all Hyalomma species was 1:26.1. Female camels were found to carry more ticks than males. This result was highly significant for H. dromedarii (Table 4). Hyalomma dromedarii numbers increased from April and reached a peak in September and October in 2000 (Table 5). In 2001, the highest infestation was recorded in March although there was no significant difference between months. Hyalomma impeltatum showed no significant differences between months in 2000 but the least mean tick numbers were col- lected in July and August. Peak numbers of this species were collected in March 2001 (Table 5) and the least in February, June and July. More H. a. anatolicum were collected in January 2000 and in November 2001 with no significant differences be- tween months. Hyalomma nymphs were prevalent throughout 2000 and 2001 with peaks in November 2000 and July 2001 (Table 5). The total numbers of adult ticks collected were significantly higher in 2000 during September and October and from January to June but in 2001 there were no signifi- cant differences in the total numbers ticks collected per month. During the collection period, male ticks outnumbered females with the exception of H. a. anatolicum (Table 5). The udder, scrotum, belly and brisket were the pre- ferred sites for feeding of H. dromedarii (53.5 %), H. impeltatum (52.5 %), and H. a. anatolicum (65.4 %) (Table 6). The hump and sides was much less pre- ferred (1.2 %, 0.9 % and 1.7 % of H. dromedarii, H. impeltatum and H. a. anatolicum, respectively) while the nymphs preferred the back (64.5 %) (Table 6). Female camels with a grey coat colour harboured significantly more ticks than females with a brown coat colour (Table 7). This was shown clearly by in- dividual tick species, their gender and also with mean total ticks collected. However, there were no significant differences in the numbers of nymphs harboured by grey and brown female camels. Male grey coloured camels harboured more ticks than brown coloured males but the difference was only significant for female H. dromedarii and for male H. a. anatolicum. Hyalomma dromedarii infestation was positively correlated in 2000 with mean minimum and maxi- mum ambient temperatures, relative humidity and rainfall (Table 8) while in 2001, this was positively correlated only with mean minimum and mean max- imum ambient temperatures. Hyalomma impeltatum in 2000 and H. a. anatolicum in both years were found to increase with increased humidity and de- creased temperature. Generally, tick infestation was not strongly correlated with meteorological values. It was, however, observed that Hyalomma nymphs significantly increased in number with rainfall during 2000. DISCUSSION This study was conducted in a semi-desert zone where rainfall is very low and of short duration (July to September). The River Atbara is a factor in that it creates suitable microhabitats for ticks with acacia trees, bushes, few grasses and cultivated areas and plays a role with the movement of camels to Butana from July to November in impacting on the seasonal population changes of ticks. In the present study, H. dromedarii represented the main tick species infesting camels (88.9 %) followed by H. impeltatum (7.7 %) and H. a. anatolicum (3.3 %). It was also found that H. dromedarii fe- males were the main tick species found engorged on the camels, while females of the other species (H. impeltatum, H. a. anatolicum, H. m. rufipes and Rhipicephalus spp.) were not engorged or only par- tially engorged. This could be due the fact that cam- 184 Ticks (Acari: Ixodidae) infesting camels (Camelus dromedarius) in Northern Sudan els are not the preferred hosts of the latter tick spe- cies. Other tick species found in this study in small num- bers were H. truncatum, H. m. rufipes, R. sanguin- eus group and R. praetextatus. In Egypt, the main tick species infesting camels is H. dromedarii repre- senting up to 95 % of ticks (Van Straten & Jongejan, 1993; Diab et al. 2001). In Eastern Sudan, Karrar et al. (1963) reported that H. dromedarii is the main tick species feeding on camels. Other tick species they found on camels were R. sanguineus, R. si- mus, H. a. excavatum and Amblyomma lepidum. In the current study, A. lepidum was not found despite the fact that some camels are taken each year to the Butana area where this tick species was previ- ously found (Karrar et al. 1963). Ahmed (1999) studied tick infestations on sheep in the study area and found that 74 % of the ticks were H. a. anatoli- cum, 15 % R. sanguineus group, 2 % R. simus, 9 % Rhipicephalus evertsi evertsi and 0.5 % H. drome- darii. This strongly implies that sheep are not pre- ferred hosts for H. dromedarii, while camels are not preferred hosts for H. a. anatolicum. He also report- ed that sheep were not infested with H. impeltatum, H. truncatum and H. m. rufipes. In the current study R. e. evertsi was not found feeding on the camels. These two studies in the same ecological zone where camels and sheep co-exist imply that there is a strong host preference of these ticks. In this study most ticks were collected from the low- er parts of the camels. Unlike other animal species (Hoogstraal 1956), the tail, despite the fact that it is short in camels, was found to be an important feed- ing site of ticks particularly the edges. This could be due the fact that the tail of camels has a less fat component or that due to the physiological status of camels in that the body temperature fluctuates dur- ing the day and that of the tail is possibly the least affected. The high percentage (64.5 %) of nymphs found on the back particularly the hump also differs from other animal species. This is could be due to the fact that the nymphs ( which attached as larvae) seek shelter within the hairy hump area and that it provides more humidity, or it may be that H. drom- edarii nymphs prefer the back of their hosts. For in- stance, Hassan (1997) working on cattle, found that nymphs of Rhipicephalus appendiculatus and Am- blyomma variegatum preferred the head region and the underside of the hosts, respectively. The high number of ticks collected from under the tail in this study is in agreement with the findings of Diab et al. (2001). Hylomma m. rufipes was found mainly un- der the tail particularly around the anus. The predi- lection site of this tick species is not different from that of cattle (Hoogstraal 1956; Hassan 1997). Seasonality of ticks infesting camels was observed by Diab et al. (2001) who reported that high tick infestations in Egypt occurred during March to November. In the present study, there was no clear pattern of seasonality. Ticks were found on camels throughout the year but it was observed that the highest infestation occurred from March to October. This could be attributed to the fact that the non-par- asitic flat stages could survive well during winter which was reflected as infestations during the fol- lowing summer. On the other hand, it was observed that ticks do not go into diapause during winter when ambient temperature drops to about 10 °C. Hylomma a. anatolicum feeding on sheep in the same area were also not found to go into diapause, according to Ahmed (1999) who found high infesta- tions in winter. It is also possible that H. dromedarii unlike R. appendiculatus (Pegram & Banda 1990) does not go into diapause. This study revealed that female camels carried sig- nificantly more ticks than the males. This was true for all adult tick species. Hassan (1997) reported similar findings for cows with higher loads of R. appendiculatus and A. variegatum than oxen. Preg- nancy and lactation stress may lower the resistance of females to tick infestation (Ali 2004). However, this was not true for nymphs as both genders of camels carried loads the differences of which were not significant. This could be due to differences in resistance of male and female camels against lar- vae that feed and moult on the host, but not against nymphs. Camels with a grey coat colour carried significantly more ticks than those with a brown coat colour. This was true for all tick species particularly those which were found feeding on female camels. Working with cattle, Hassan (1997) found that hosts with a black coat colour were infested with fewer R. append icu- latus and A. variegatum compared to cattle of a brown and white coat colour. He attributed this phe- nomenon to the fact that a dark coat colour absorbs more heat, changing the microhabitat of the ticks which leads to a high mortality rate or the ticks drop- ping off without feeding. Camels in this area are of two types, namely brown and grey, and the differ- ence in tick load may indicate a difference in their innate resistance to tick infestation. The current study revealed that male ticks of all spe- cies except H. a. anatolicum outnumbered females. Similar results were reported by Hoogstraal (1956), 185 A. ELGHALI & S.M. HASSAN Kaiser, Sutherst, Bourne, Gorissen & Floyd (1988) and Hassan (1997). This is due to the fact that fe- males detach from the hosts after a few days of feeding to oviposit while males remain for several weeks before dropping (Hoogstraal 1956). However, H. a. anatolicum females were found to outnumber males. This could be due to the fact that camels are probably not their preferred hosts and hence males either do not attach or drop off without attaching. Very few engorged H. a. anatolicum females were collected indicating that few males were available for mating with females to complete engorgement. REFERENCES AHMED, B.M. 1999. Studies on epizootiology of Theileria (Lesto- quardi Nomen Novum) hirci (Apicomplexa: Theileriidae) in River Nile State. M.Sc. thesis, Nile Valley University. ALI, A. 2004. Studies on immune response of rabbits to Hylomma anatolicum anatolicum and Hylomma dromedarii (Acari: Ixo- didae). Ph.D. thesis, University of Khartoum. DIAB, F.M., EL KADY, G.A. & SHOUKY, A. 2001. Bionomics of ticks collected from Sinai. 2. Abundance, attachment sites and density of ticks infesting Arabian camels. Journal of Egyptian Society of Parasitology, 31:479–489. DOLAN, R., WILSON, A.J., SCHWART, H.J., NEWSON, R.M. & FIELD, E.R. 1983. Camel production in Kenya and its con- straints. Tick infestations. Animal Health, 15:179–183. EL AMIN, H.M. 1989. Trees and shrubs of the Sudan. Exeter: Ithaca Press. EL KHALIFA, M.S., AL ASGAH, N.A. & DIAB, F.M. 1985. Ticks (Acari: Ixodidae) infesting common domestic animals in Al Gasim Province, Saudi Arabia. Journal of Medical Ento mol- ogy, 21:114–115. HASSAN, S.M. 1997. Ecological studies on Rhipicephalus ap- pen diculatus and Amblyomma variegatum (Acari: Ixo di dae): Drop-off rhythms, development, survival and seasonal popu- lation dynamics. Ph.D. thesis, Kenyatta University. HOOGSTRAAL, H. 1956. African Ixodoidea. 1. Ticks of the Sudan with special reference to Equatoria Province and with preliminary reviews of the genera Boophilus Margaropus and Hyalomma. Washington D.C.: US Navy. HOOGSTRAAL, H. & KAISER, M.N. 1959. Observations on Egyptian Hyalomma ticks (Ixodoidea: Ixodidae ). 5. Biological notes and differences in identity of Hyalomma anatolicum and its subspecies anatolicum Koch and excavatum Koch among Russian and other workers identity of Hyalomma lusi- tanicum Koch. Entomological Society of America, 52:243– 261. KAISER, M.N., SUTHERST, R.W., BOURNE, A.S., GORISSEN, L. & FLOYD, R.B. 1988. Population dynamics of ticks on Ankole cattle in five ecological zones in Burundi and strate- gies for their control. Preventive Veterinary Medicine, 6:199– 222. KARRAR, G., KAISER, M.N. & HOOGSTRAAL, H. 1963. Ecol o- gy and host-relationship of ticks (Ixodoidea) infesting domes- tic animals in Kassala Province, Sudan with special refer- ence to Amblyomma lepidum Donitz. Bulletin of Entomological Research, 54:509–522. MACARTAN, B.M., HUNTER, A.G., PEGRAM, R.G. & BOURNE, A.S. 1987. Tick infestation on livestock in Yemen Arab Re- public and potential as vectors of livestock diseases. Tropical Animal Health and Production, 19:21–31 PEGRAM, R.G. & BANDA, D.S. 1990. Ecology and phenology of cattle ticks in Zambia: Development and survival of free living stages. Experimental and Applied. Acarololgy, 8:291–301. VAN STRATEN, M. & JONJEGAN, F. 1993. Ticks (Acari: Ixo- didae) infesting the Arabian camel (Camelus dromedarius) in Sinai, Egypt with a note on acaricidal efficacy of ivermectin. Experimental and Applied Acarololgy, 17:605–612. WALKER, A.R., BOUATOUR, A., CAMICAS, J.L., ESTRADA PEÑA, A., HORAK, I.G., LATIF, A.A., PEGRAM, R.G. & PRESTON, P.M. 2003. Ticks of domestic animals in Africa. A guide to identification of species. 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