Afrotropical Culicoides: C (Avaritia) miombo sp. nov., a widespread species closely allied to C. (A.) imicola Kieffer, 1913 (Diptera: Ceratopogonidae)

Culicoides (Avaritia) miombo sp. nov. is described and illustrated from both sexes collected in northern Malawi. Two references in the literature have previously referred to this new species as either C. brosseti Vattier & Adam or C. imicola Kieffer. A further 4 references are discussed that most likely deal with C. miombo sp. nov. and not C. brosseti. C. miombo sp. nov. is apparently widespread in subtropical and tropical Africa and is now recorded from Zimbabwe, Botswana, South Africa, Nigeria and the Ivory Coast. There are also probable records from Angola, Burkina Faso, Zambia and eastern Madagascar. On the African mainland, both north and south of the equator, the pattern of distribution of C. miombo sp. nov. correlates strongly with that of drier Guineo-Congolian rainforest, and Sudanian and Zambezian woodlands, the latter known as miombo in southern Africa. These phytochoria and associated biota are sensitive to frost and experience relatively high temperatures and rainfall-3 factors that appear to limit the distribution of C. miombo sp. nov. to north of the 20-22 degrees C mean annual temperature isotherms in southern Africa. The new species is a member of the Imicola group which consists of 6 species confined to the Afrotropical (including Madagascar), Oriental and eastern Palaearctic regions. One species has in historic times spread to Australia. The worldwide distribution of each species is briefly discussed. It is suggested that the Imicola and Orientalis groups are separate lineages within the subgenus Avaritia. Culicoides miombo sp. nov. is compared with its closest African congeners C. imicola, C. pseudopallidipennis Clastrier and C. bolitinos Meiswinkel; 15 character states are used to separate C. miombo sp. nov. and C. imicola. The female antennal and palpal measurements of C. miombo sp. nov. are subjected to statistical analysis to highlight their taxonomic usefulness. The larval habitat of C. miombo sp. nov. is unknown.     

Comparative descriptions of the pupae of five species of the Culicoides imicola complex (Diptera, Ceratopogonidae) from South Africa

The viruses causing the economically important livestock diseases of African horse sickness (AHS) and bluetongue (BT) are transmitted by biting midges of the genus Culicoides (Diptera, Ceratopogonidae). In the Old World the most important vectors of these diseases are Culicoides imicola Kieffer, 1913, Culicoides brevitarsis Kieffer, 1917 and Culicoides bolitinos Meiswinkel, 1989. All three of these vectors belong to the Imicola complex of the subgenus Avaritia Fox, 1955. This species complex now comprises 12 sibling species; ten occur in sub-Saharan Africa and are difficult to identify (based mostly on subtle variations in the wing latterns) and so additional methods of reliable identification are needed. The pupal exuviae of the five commonest sibling species (C. imicola, C. bolitinos, Culicoides loxodontis Meiswinkel, 1992, Culicoides tuttifrutti Meiswinkel, Cornet & Dyce, 2003 and Culicoides sp. # 107) harvested from a variety of large herbivore dung types and from decaying fruits, are described and illustrated in detail. It is shown that they can be differentiated clearly on a number of morphological characters and, furthermore, are separable into two distinct groups based (principally) on the shape of the respiratory organ. A key for identifying and differentiating these five pupae is provided. Also, the pupa of the Oriental-Australasian C. brevitarsis was compared with its allopatric sister taxon, C. bolitinos. Because they share a common larval habitat (cattle and buffalo dung) and are almost inseparable in the adult phenotype, the question of their possible synonymy is raised. However, their respective pupae could not be differentiated on gross morphology and so it is argued that this unresolved problem requires a molecular solution.     

Seasonal abundance of carrion-frequenting blow-flies (Diptera: Calliphoridae) in the Kruger National Park

Monthly population fluctuations of carrion-frequenting blow-flies over a 24-month period were monitored using 2 carrion-baited traps in the southern Kruger National Park (KNP) and 3 in the northern KNP. All species displayed a clear seasonality. Chrysomyia marginalis and Chrysomyia albiceps were by far the most abundant. C. marginalis attained maximum abundance between November and March, with relatively low numbers present between May and September. C. albiceps maintained high population numbers between January and March in the northern KNP, with minimum numbers between May and August. In the southern KNP, C. albiceps became abundant from November to February, with low population levels between April and September. Although present only in relative low numbers, populations of Lucilia cuprina showed a clear increase in winter. Chrysomyia chloropyga, Chrysomyia putoria and Chrysomyia bezziana were trapped in significant numbers in the southern KNP, the latter 2 species reaching relative abundance in the warmer months, whereas C. chloropyga increased in cooler months from June to September. Graphic illustrations of monthly abundance are provided for all species.     

The prevalence of Cryptosporidium spp. oocysts in wild mammals in the Kruger National Park, South Africa

This study determined the prevalence of Cryptosporidium spp. oocysts in faecal samples from elephant (Loxodonta africana), buffalo (Syncerus caffer) and impala (Aepyceros melampus) in the Kruger National Park (KNP) and an adjacent game reserve in South Africa. Two of the study areas were in close proximity to rural communities on the western KNP boundary and the third study area was located in the centre of the KNP. Fresh stool samples (n=445) were collected and tested using an immunofluorescent antibody test (IFA) for Cryptosporidium parvum. A total of 278 of these were randomly selected (approximately 90 samples per wildlife species) and tested with the modified Ziehl Neelsen staining technique (ZN) for Cryptosporidium spp. The prevalence of Cryptosporidium spp. was highest in elephants (25.8% [95% confidence interval: 17.3, 35.9]), compared to buffalo (5.5% [1.8, 12.4]) and impala (4.3% [1.2, 10.5]). C. parvum showed similar patterns, being most prevalent in elephants (4.2% [1.5, 8.8]), compared to buffalo (1.4% [0.2, 5.1]) and impala (1.9% [0.4, 5.3]). 29 samples, including ZN positive and IFA positive samples, were retested using a real time PCR (rtPCR) technique. Of the 28 ZN-positive samples, 14 (50%) were positive with rtPCR and of the 9 IFA-positive samples 6 (67%) were confirmed positive by rtPCR. The prevalence of Cryptosporidium oocysts was significantly higher in both of the two study areas adjacent to the western KNP boundary compared to the area in the centre of the KNP (OR=3.2 [1.2, 9.0]; P=0.024). Our study demonstrates for the first time the presence of Cryptosporidium spp. in wildlife in South Africa. The transmission of this parasite between wildlife, domestic animals and humans is a plausible hypothesis and represents a potential risk for immunodeficient human populations.     

Culicoides spp. (Diptera: Ceratopogonidae) Associated with Farmed Ostriches (Struthio camelus) in Botswana

Veterinary Research Communications -     

Evaluation of Culicoides insignis (Diptera: Ceratopogonidae) as a vector of bluetongue virus.

Based upon epidemiological evidence, Culicoides insignis Lutz is a probable biological vector of bluetongue viruses (BTV) in South Florida, the Caribbean Region and Central America. The vector potential of this species for BTV was evaluated in the laboratory in a series of experiments using insects caught in the field. Although there was great variation in the percentage of flies that fed from any one catch, it was demonstrated that C. insignis became infected after membrane feeding on a mixture of blood and virus. The infection rates ranged from 20 to 62.5%. Following intrathoracic inoculation, BTV replicated to high titres in C. insignis. Such flies were also shown to be capable of transmitting BTV to susceptible sheep and embryonated chicken eggs. This series of experiments provides the first conclusive evidence that C. insignis is a biological vector of bluetongue virus. This is the first proven vector of BTV in the neotropics.     

The use of a membrane feeding technique to determine the infection rate of Culicoides imicola (Diptera, Ceratopogonidae) for 2 bluetongue virus serotypes in South Africa.

Culicoides spp. in the Lowveld of the northern Transvaal, Republic of South Africa, were fed bluetongue virus serotypes 3 and 6 and African horsesickness virus serotype 1 through latex and chicken skin membranes. After an incubation period of 10 days at 25-27 degrees C, the infection rate of C. imicola for bluetongue virus serotypes 3 and 6 was established at 31% and 24% respectively. No African horsesickness virus could be recovered. The membrane feeding technique and handling procedures proved to be suitable for field studies.     

Tuberculosis in kudus (Tragelaphus strepsiceros) in the Kruger National Park.

Five kudus (Tragelaphus strepsiceros), three bulls and two cows, within the Greater Kruger National Park complex, were diagnosed with generalized tuberculosis caused by Mycobacterium bovis. The lesions seen in these animals were similar to those previously reported in kudus and included severe tuberculous lymphadenitis of the nodes of the head and neck (that resulted in noticeable uni- or bilateral swelling beneath the ear), thorax, and the mesentery. All the animals also suffered from severe granulomatous pneumonia. The lesions in the lungs were more severe cranially and had a miliary distribution elsewhere in the lungs. Based on the DNA patterns of the M. bovis isolates, at least some of these kudus were infected with strains commonly present in tuberculous buffaloes, lions, cheetahs, and baboons in the Park whereas other strains from these kudus were quite different and may reflect another source of infection. The presence of tuberculous kudus in the Park is expected to complicate control measures that may be instituted to contain or eradicate the disease in the Park.     

Seasonal abundance of four Culicoides spp. (Diptera: Ceratopogonidae) at Al-Ahsa oasis,Eastern Province,Saudi Arabia

This report constitutes the first study of Culicoides spp. and their seasonal abundance at Al-Ahsa, the largest oasis in the Eastern Province of Saudi Arabia. New Jersey light traps were used to collect the midges at Mastock farm and Al-Mansura village. The mean monthly abundance was determined from October 1993 to October 1994. The mean monthly number per trap reached its minimum value during January 1994, increasing gradually from February to reach its maximum value during September 1994. During the study period, the following species were collected: Culicoides schultzei group (September), non-spotted group of Culicoides (September), Culicoides imicola (May) and Culicoides newstaedi (March). The potential importance of the Culicoides spp. in relation to arboviral activity in Saudi Arabia is discussed.     

Bluetongue virus isolations from midges belonging to the Obsoletus complex (Culicoides, Diptera: Ceratopogonidae) in Italy

Between July and September 2002 there were outbreaks of bluetongue on three sheep holdings in the communities of San Gregorio Magno (Salerno, Campania), Laviano (Salerno, Campania) and Carpino (Foggia, Puglia), and the involvement of bluetongue virus (btv) was confirmed serologically and virologically. The mortality rate was at least 11 per cent and involved btv serotype 2 (btv-2) and serotype 9 (btv-9). These holdings were also surveyed for the Culicoides (Diptera: Ceratopogonidae) vectors; approximately 10,000 midges belonging to 15 species were captured, but they did not include a single specimen of the classical Afro-Asiatic bluetongue vector, Culicoides imicola. Species belonging to the Obsoletus complex dominated the light-trap collections, and Culicoides obsoletus Meigen, Culicoides scoticus Downes and Kettle and Culicoides dewulfi Goetghebuer constituted 90 per cent of all the Culicoides species captured. Fifty-six pools of the Obsoletus complex (excluding C dewulfi), each containing 100 individual midges and containing only parous and gravid females, were assayed for virus. btv-2 was isolated from three pools from San Gregorio Magno and Carpino, and btv-9 was isolated from one pool from Laviano. These results indicate that a species other than C imicola is involved in the current re-emergence of bluetongue in the Mediterranean Basin, but whether it is C obsoletus sensu stricto or C scoticus, or both, is uncertain.     

Summary of foot-and-mouth disease outbreaks reported in and around the Kruger National Park, South Africa, between 1970 and 2009

Information with regard to foot-and-mouth disease (FMD) outbreaks that occurred in the Kruger National Park (KNP) and adjacent areas of South Africa between 1970 and 2009 was collected from reports and files of various government departments and collated into one report. The collected data were summarised in a table and assessed for patterns. Fifty-one FMD outbreaks occurred during this period in the target area, of which 16 were SAT 1, 31 were SAT 2,4 were SAT 3 and 3 were not serotyped. No pattern could be discerned although SAT 1 outbreaks occurred more frequently in the summer months while more SAT 2 outbreaks occurred in winter.     

Rearing of Culicoides nubeculosus (Diptera: Ceratopogonidae) by natural or artificial feeding in the laboratory

A technique for the mass rearing of Culicoides nubeculosus in the laboratory is described. Female midges were fed either on fresh or deep-frozen, defibrinated cattle blood (-70 degrees C) through latex membranes, or on anesthetized white mice. Feeding rates of up to 90% were obtained on the latex membrane, whereas only 41% of the midges fed on mice. The best oviposition rates of greater than 50% were achieved after feeding either on the latex membrane with fresh cattle blood or on mice. An average of greater than 100 eggs per female were deposited. The highest larval hatching rate was observed after feeding with fresh blood; about half of the larvae developed to the adult stage. A reproduction index was defined for the colony based on the feeding rate, oviposition rate, larval hatching rate and development to the adult stage. The highest reproduction index was obtained when the midges were fed on fresh cattle blood through the membrane.     

Parasites of domestic and wild animals in South Africa. XLI. Arthropod parasites of impalas,Aepyceros melampus,in the Kruger National Park

Ectoparasites were collected from impalas, Aepyceros melampus, at four localities within the Kruger National Park, namely Skukuza, in the Biyamiti region, Crocodile Bridge and Pafuri. Animals were also examined at Skukuza during a severe drought and at Skukuza and Pafuri towards the end of a second drought. Parasite burdens were analysed in relation to locality, sex, age class, month and drought. The impalas were infested with 13 ixodid ticks species, including two that were identified only to genus level. Except for four animals at Pafuri, all were infested with Amblyomma hebraeum. The highest intensity of infestation with larvae of this tick occurred from April to June and during November and December at Skukuza and in the Biyamiti region. Infestation with nymphs was highest during late winter. All animals were infested with Boophilus decoloratus, and the intensity of infestation was highest during spring. The intensity of infestation with Rhipicephalus appendiculatus was highest at Crocodile Bridge and at Pafuri, and that of Rhipicephalus zambeziensis at Skukuza. With both the latter species the intensity of infestation of larvae was highest from April to August, of nymphs from July to September or October and of adults during February and March. Rhipicephalus kochi was present only at Pafuri. The impalas also harboured five louse species and two species of hippoboscid flies. The intensity of infestation with lice tended to be greater during late winter and spring than during other seasons and greater on lambs than on yearlings on which it was greater than on adult animals.     

Models for the dispersal in Australia of the arbovirus vector, Culicoides brevitarsis Kieffer (Diptera: Ceratopogonidae)

Culicoides brevitarsis is the main biting midge responsible for the transmission of bluetongue and Akabane viruses to livestock in Australia. Models are given for its dispersal after winter from endemic areas at the southern limit of its distribution in New South Wales (NSW); the models might also be applicable elsewhere. Model 1 shows that dispersal can be explained by distance from a key point just outside the endemic area in mid-northern/northern coastal NSW. The model provides probability data for times of first occurrence at sites within regions down the southern coastal plain or up the Hunter Valley towards (but rarely reaching) the western slopes and tablelands. Model 2 shows that the movement depends on temperature and wind speed from northerly and easterly directions. Preliminary data also are given to suggest a relationship between density in the endemic area and the maximum distance that C. brevitarsis can travel in a given year. The models can be linked to other information which in combination can provide probabilities for winter survival outside the endemic area, times of occurrence at sites where it cannot survive winter and times when activity ceases naturally at these sites at the end of the season. This information can be used to predict the potential for virus transmission and indicate zones of seasonal freedom from both vector and virus for the export of livestock.