Aedes species (Diptera: Culicidae) ecological and host feeding patterns in the north-eastern parts of South Africa, 2014-2018.

BACKGROUND: There is a paucity of recent data and knowledge on mosquito diversity and potential vectors of arboviruses in South Africa, with most of the available data dating back to the 1950s-1970s. Aedes and Culex species are the major vectors of some of the principal arboviruses which have emerged and re-emerged in the past few decades. METHODS: In this study we used entomological surveillance in selected areas in the north-eastern parts of South Africa from 2014 to 2018 to assess mosquito diversity, with special emphasis on the Aedes species. The impact of trap types and environmental conditions was also investigated. Identification of the blood meal sources of engorged females collected during the study period was carried out, and DNA barcodes were generated for selected species. RESULTS: Overall, 18.5% of the total Culicidae mosquitoes collected belonged to the genus Aedes, with 14 species recognised or suspected vectors of arboviruses. Species belonging to the Neomelaniconion subgenus were commonly collected in the Bushveld savanna at conservation areas, especially Aedes mcintoshi and Aedes circumluteolus. Aedes aegypti was present in all sites, albeit in low numbers. Temperature was a limiting factor for the Aedes population, and they were almost exclusively collected at temperatures between 18 °C and 27 °C. The cytochrome oxidase subunit I (COI) barcode fragment was amplified for 21 Aedes species, and for nine of these species it was the first sequence information uploaded on GenBank. CONCLUSION: This study provides a better understanding of the diversity and relative abundance of Aedes species in the north-east of South Africa. The information provided here will contribute to future arboviral research and implementation of efficient vector control and prevention strategies.

Patterns of mitochondrial variation within and between African malaria vectors, Anopheles gambiae and An. arabiensis, suggest extensive gene flow.

Anopheles gambiae and An. arabiensis are mosquito species responsible for most malaria transmission in sub-Saharan Africa. They are also closely related sibling species that share chromosomal and molecular polymorphisms as a consequence of incomplete lineage sorting or introgressive hybridization. To help resolve these processes, this study examined the partitioning of mtDNA sequence variation within and between species across Africa, from both population genetic and phylogeographic perspectives. Based on partial gene sequences from the cytochrome b, ND1 and ND5 genes, haplotype diversity was high but sequences were very closely related. Within species, little or no population subdivision was detected, and there was no evidence for isolation by distance. Between species, there were no fixed nucleotide differences, a high proportion of shared polymorphisms, and eight haplotypes in common over distances as great as 6000 km. Only one of 16 shared polymorphisms led to an amino acid difference, and there was no compelling evidence for nonneutral variation. Parsimony networks constructed of haplotypes from both species revealed no correspondence of haplotype with either geography or taxonomy. This trend of low intraspecific genetic divergence is consistent with evidence from allozyme and microsatellite data and is interpreted in terms of both extensive gene flow and recent range expansion from relatively large, stable populations. We argue that retention of ancestral polymorphisms is a plausible but insufficient explanation for low interspecific genetic divergence, and that extensive hybridization is a contributing factor.

Small mammals as hosts of immature ixodid ticks.

Two hundred and twenty-five small mammals belonging to 16 species were examined for ticks in Free State, Mpumalanga and Limpopo Provinces, South Africa, and 18 ixodid tick species, of which two could only be identified to genus level, were recovered. Scrub hares, Lepus saxatilis, and Cape hares, Lepus capensis, harboured the largest number of tick species. In Free State Province Namaqua rock mice, Aethomys namaquensis, and four-striped grass mice, Rhabdomys pumilio, were good hosts of the immature stages of Haemaphysalis leachi and Rhipicephalus gertrudae, while in Mpumalanga and Limpopo Provinces red veld rats, Aethomys chrysophilus, Namaqua rock mice and Natal multimammate mice, Mastomys natalensis were good hosts of H. leachi and Rhipicephalus simus. Haemaphysalis leachi was the only tick recovered from animals in all three provinces.

Community dynamics of carrion-attendant arthropods in tropical african woodland.

Carcasses are temporary resources which are unbredictable and inconsistent in their availability and locality. A recognisable community of interacting user arthrocods comprising sarcophages, coprophages, dermatophages, keratophages, detritivores, predators and parasites has evolved to exploit the carcass habitat. The large number of arthropods, close confinement, and limited duration of resources necessitates aggressive utilisation. The trophic relations, competition and successionary pattern of these arthropods is discussed. Several pathways to reduce competitive conflict are described. Succession at carcasses is viewed as being inherently different from the traditional concept as the habitat is non-replenishing and does not lead to a climax community.

Enzyme variation at the aspartate aminotransferase locus in members of the Anopheles gambiae complex (Diptera: Culicidae).

The enzyme aspartate aminotransferase (AAT) currently is used to identify Anopheles quadriannulatus Theobald, the animal-biting, nonmalaria vector species of the Anopheles gambiae complex. Samples of An. quadriannulatus from South Africa and An. gambiae Giles s.str. from the island of Grand Comoros and the People's Republic of Congo have shown variation in electromorph frequencies that indicate that AAT has five alleles. The three slowest alleles are found in An. quadriannulatus and the three fastest in An. gambiae, An. arabiensis Patton and An. merus Dönitz. One of these is common to both An. quadriannulatus and An. gambiae. This overlap indicates a potential misidentification of 0.3% of unknown females with a further 2.1% being unidentifiable. However, all of the specimens in the overlap area were classified correctly using octanol dehydrogenase (ODH). Variation at the ODH locus in An. quadriannulatus is recorded for the first time, with four of 157 specimens being heterozygous for the fast allele. The probability of both AAT and ODH giving an incorrect or indecisive identification is 0.0005. The slowest AAT alleles were present in samples from a single locality, indicating the lack of gene flow between subpopulations of An. quadriannulatus in close geographic proximity in the Shingwedzi area, South Africa. A modified method for multiple gel casting is given.

Biting pattern and host-seeking behavior of Anopheles arabiensis (Diptera: Culicidae) in northeastern South Africa.

Biting rhythm as well as vertical and horizontal distribution of host-seeking Anopheles arabiensis Patton was studied at a remote warm-water spring in the Kruger National Park, South Africa, which usually is devoid of human presence. An. arabiensis seeking hosts were collected throughout the night with several peaks, often with greatest biting activity during the predawn period. Abundance did not decline linearly as a function of distance from the breeding area, but was related to vegetation patterns. Most bites occurred on the ankles or feet and decreased rapidly above that height. Wearing closed shoes or raising feet off the ground could reduce vector contact and therefore the risk of malaria infection.

Risk of malaria in visitors to the Kruger National Park, South Africa.

BACKGROUND: The risk of malaria to visitors to South Africa's nature reserves is unknown. Current recommendations for travelers are based on malaria incidence rates in local communities. These rates may well overestimate travelers' malaria risk and lead to unnecessary use of antimalarial prophylaxis with associated drug-related adverse events. This study investigated the incidence of malaria in visitors to South Africa's Kruger National Park (KNP). METHODS: Postal questionnaires were sent to the cohort of visitors staying in the KNP during April 1996, 6 to 8 weeks after they returned to their homes. Nonrespondents received duplicate questionnaires 8 weeks later. Responses from 3267 groups, representing 11,107 visitors (56. 8%) allowed determination of the malaria attack rate in this group of travelers and assessment of associations between malaria risk and a number of factors, including type of accommodation used during the visit; duration of stay; use of chemoprophylaxis; and use of personal protection measures. All travelers indicating that they had suffered an episode of malaria following their visit were telephonically contacted and their health providers traced to determine the basis of diagnosis and clinical outcome. RESULTS: One clinically suspected and four confirmed cases of Plasmodium falciparum malaria among the visitors suggest a low attack rate of 4. 5 cases per 10,000 visitors during April, the highest risk month for malaria in South Africa. No association was found between malaria risk and accommodation type, duration of stay, use and type of chemoprophylaxis, and use and number of personal protection measures. CONCLUSIONS: These findings confirm the importance of careful assessment of local malaria risk before individualized advice is provided to travelers.

Malaria protection measures used by in-flight travelers to South African game parks.

Malaria prevention in travelers depends upon dissemination of accurate information about malaria risk, prevention of mosquito bites, appropriate chemoprophylaxis use and knowledge of the symptoms of malaria. A study was undertaken of travelers to the Kruger National Park and private game parks in Mpumalanga Province, South Africa to investigate travelers knowledge, of malaria, chemoprophylaxis use, and experience of adverse events. In-flight self administered questionnaires were distributed and completed by travelers on flights returning to Johannesburg International Airport, from the malaria areas. The study was conducted during the highest malaria risk period during 1996. The Mpumalanga game parks are those most visited in South Africa and are found in the extreme northeast of the country, which adjoins Mozambique in the east and Zimbabwe in the north. This area is classified by the South African health authorities as being a high risk Malaria area.10 Chloroquine-resistant Plasmodium falciparum malaria has been described in this area.2,3 The Department of Health in South Africa recommends the use of mefloquine alone or the combination of chloroquine and proguanil, (doxycycline is prescribed for travelers in which the former antimalarials cannot be utilized), for visitors to this area during the high risk period for malaria, which extends from October to May.4 For the remainder of the year mosquito avoidance measures are recommended. Little is known about travelers' compliance with these recommendations and their knowledge of malaria. A study to explore these factors was undertaken as a joint initiative between the SAIMR travel clinic, Mpumalanga Department of Health, and the South African National Parks.

Spread in South Africa of the Oriental latrine fly Chrysomya megacephala. (Fabricius) (Diptera: Calliphoridae), an introduced species closely resembling Chrysomya bezziana Villeneuve.

Chrysomya megacephala, also known as the Oriental latrine fly, is indigenous to south-east Asia. During the 1970's it successfully invaded Africa and South America, and more recently during the 1980's also established itself in the United States of America. Although the first specimens from South Africa were collected from the south-western Cape Province in 1978, no published data appears to exist on its subsequent spread or status in southern Africa. During May 1991 a specimen of C. megacephala was incidentally captured near Beaufort West, Cape Province, South Africa, which prompted re-examination of blow-flies captured in the Kruger National Park during 1984. In this way it was found that C. megacephala was already well established in the south-eastern Transvaal by mid-1984. Adult C. megacephala can easily be confused with C. bezziana and medical/veterinary entomologists and veterinarians should take note of the existence of this species and the fact that it is probably widespread throughout southern Africa at this state.

African horsesickness epidemiology: five species of Culicoides (Diptera: Ceratopogonidae) collected live behind the ears and at the dung of the African elephant in the Kruger National Park, South Africa.

During the culling of elephants (Loxodonta africana) at five sites in the Kruger National Park, South Africa, a total of 682 Culicoides of five species of the subgenus Avaritia were found live either behind the ears of elephants or attracted to the freshly disembowelled intestinal dung of elephants. The species are Culicoides tororoensis Khamala & Kettle, 1971; C. kanagai Khamala & Kettle, 1971; C. loxodontis Meiswinkel, 1992, and two undescribed species, i.e. Culicoides sp. #50 and Culicoides sp. #54 pale form (p.f.). Of 511 female midges found behind ears, 39.9% were nulliparous, 57.3% empty parous, 2.5% freshly bloodfed and 0.2% gravid. The age composition of this subpopulation indicates that the Culicoides were behind the ears to suck blood and, furthermore, would do so in broad daylight. The age composition of 171 Culicoides of three species attracted to dung was entirely different: 1.8% nulliparous, 14.6% empty parous, and 83.0% gravid, indicating that the great majority of midges captured at dung were about to oviposit or had just oviposited. Immediately after culling, light-traps were operated at two of the sites. Of 4,023 Culicoides of 21 species captured, 93% were of the same five species found on the ears and at the dung of elephants. Using these and other unpublished data pertaining to the rearing of these five Avaritia species from elephant dung over the past seven years, we broadly sketch the life cycle of these Culicoides, the first for any Afrotropical species of the genus. We also discuss the implications the close association between elephant and midge has for the dispersal and geographic distribution of the latter, and how it may influence the involvement of midges in the transmission of diseases such as African horsesickness. Owing to difficulties in identifying species of the subgenus Avaritia in the Afrotropical Region, the taxonomy of each of the five above-mentioned species is briefly appraised. Of the remaining 16 species (7%) captured in light traps 15 (6%) belong to that sector of the genus Culicoides whose immature stages develop in groundwater habitats and include C. imicola, which comprised only 2% of the light-trap collections. The large disparity in the adult abundance patterns of the "dung" and "groundwater" species in the middle of dry bushveld, is probably the result of differences in host and larval habitat preferences, and is briefly discussed. Finally, the few reports extant on the wild-host preferences of Afrotropical Culicoides are reviewed. Five tables and five figures accompany the text.

Dispersal, density and habitat preference of the blow-flies Chrysomyia albiceps (Wd.) and Chrysomyia marginalis (Wd.) (Diptera: Calliphoridae).

16 000 Chrysomyia albiceps and 52 000 C. marginalis adults were radioactively labelled with 32P-orthophosphate and released in the northern Kruger National Park, South Africa. After a 1-week dispersal period 69 baited blow-fly traps were placed in different habitat types and at varying distances around the release point. C. albiceps were subsequently found to have covered up to 37.5 km and C. marginalis 63.5 km, suggesting dispersal rates per day of 2.20 km and 2.35 km for the 2 species, respectively. Calculation of density using the Lincoln Index yielded estimates per hectare of 7.56 C. albiceps and 29.03 C. marginalis. Both species were trapped more numerously in forested environments than in open scrub, and both avoided arid scrubland.

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.

Feeding habits and flight range of blow-flies (Chrysomyia spp.) in relation to anthrax transmission in the Kruger National Park, South Africa.

Carrion-frequenting blow-flies (Chrysomyia albiceps and C. marginalis) were allowed 4 days of feeding on 32P-orthophosphate-labelled blood or an impala carcass (Aepyceros melampus) in the northern Kruger National Park, South Africa. The dispersal and density of fly faecal and discard droplets were then established using a Geiger-Counter, indicating that most droplets occurred between a height of 1 and 3 m on nearby leaves and twigs. This coincides with the preferred feeding height of kudu (Tragelaphus strepsiceros). During a previous anthrax epizootic kudu comprised 73.15% of a total medium to large mammal mortality figure of 1054. Further analysis of mortality shows browsers to have been most severely affected, and it is suggested that this is correlated with feeding habits of these animals. Trapping also yielded radioactively labelled C. albiceps up to 32.5 km and C. marginalis up to 25 km from the isotope source.

Parasites of South African wildlife. VII. Helminths of suni, Neotragus moschatus, in Natal.

The helminths of 4 suni, Neotragus moschatus, from the Tembe National Elephant Park, KwaZulu, Natal, were collected, counted and identified. Cooperia hungi, a race of Cooperia rotundispiculum, Haemonchus vegliai, Setaria cornuta, a Skrjabinema sp., Strongyloides papillosus, Trichostrongylus anomalus and Trichostrongylus deflexus are new parasite records for suni in Africa. Megacooperia woodfordi was recovered for the first time from South African antelope.

Fleas and lice on scrub hares (Lepus saxatilis) in South Africa.

A total of 380 scrub hares (Lepus saxatilis) from 5 localities, ranging from the north-eastern Transvaal to the eastern and the south-western Cape Province of South Africa, were examined for fleas and lice. Ctenocephalides felis damarensis was almost exclusively responsible for the flea infestations on hares at 4 of the 5 sites. At 4 localities the prevalence and abundance of this flea reached peaks between August and October and declined thereafter to their lowest levels between February and April. Its prevalence and abundance in the north-eastern Transvaal were not correlated with the breeding cycle of the hares in this region. The 2 louse species recovered, sometimes sympatrically, were Haemodipsus lyriocephalus and Haemodipsus setoni. Listrophorus leporicolus was the only mite species recovered.

Parasites of domestic and wild animals in South Africa. XLIV. Fleas (Insecta: Siphonaptera: Pulicidae) collected from 15 carnivore species.

Fleas were collected from 61 wild carnivores belonging to 13 species in various nature reserves and on farms, two feral domestic cats in a nature reserve and a domestic dog in the city of Johannesburg. Eleven flea species, including two subspecies of one of these, belonging to six genera were recovered. Amongst these only Ctenocephalides felis felis and Ctenocephalides felis strongylus are considered specific parasites of carnivores. The remaining ten species normally infest the prey animals of the various carnivores.

Parasites of domestic and wild animals in South Africa. XXXVIII. Ixodid ticks collected from 23 wild carnivore species.

Ixodid ticks were collected from 104 wild carnivores belonging to 23 species in various nature reserves and on several farms in all nine provinces of South Africa. Seven feral cats in a nature reserve were also examined. Twenty-four tick species belonging to seven genera were recovered and identified. Amongst these ticks we consider the adults of Haemaphysalis leachi, Haemaphysalis spinulosa, Haemaphysalis zumpti, Ixodes rubicundus, Rhipicentor nuttalli, Rhipicephalus simus and Rhipicephalus turanicus to be true parasites of wild carnivores. Although numerous adult Rhipicephalus appendiculatus and Rhipicephalus zambeziensis were collected from some lions these were either sick or old animals. The immature stages of seven species regularly utilized wild carnivores as hosts on an opportunistic basis.

Fleas, lice and mites on scrub hares (Lepus saxatilis) in northern and eastern Transvaal and in KwaZulu-Natal, South Africa.

Fleas, lice and mites were collected from 24 and 120 scrub hares at Pafuri and Skukuza, Northern and Eastern Transvaal, respectively, in the Kruger National Park, and from 34 scrub hares in the Hluhluwe region, north-eastern KwaZulu-Natal. Ctenocephalides felis damarensis, the only flea recovered, reached peak burdens on the hares at each locality during late winter or spring. Juvenile hares harboured significantly fewer fleas than did adult animals. The lice Haemodipsus lyriocephalus and Haemodipsus setoni were collected from hares at each locality, with H. setoni generally being the most abundant. Listrophorus leporicolus was found on hares at Skukuza and Hluhluwe, and mites of the genus Cheyletiella were collected from hares at Skukuza.

Parasites of domestic and wild animals in South Africa. XXXII. Ixodid ticks on scrub hares in the Transvaal.

A total of 264 scrub hares (Lepus saxatilis) were examined for ixodid ticks at various localities in the Kruger National Park, eastern Transvaal Lowveld. Thirteen tick species were recovered from these hares. The seasonal abundances of the immature stages of Amblyomma hebraeum, Amblyomma marmoreum, Hyalomma truncatum, Rhipicephalus appendiculatus, Rhipicephalus evertsi evertsi, Rhipicephalus simus and Rhipicephalus zambeziensis and all stages of a Rhipicephalus sp. (near R. pravus) were determined. Three scrub hares, examined in the north-western Transvaal Bushveld, were infested with five ixodid tick species. Ten hares examined in the eastern Transvaal Highveld harboured three species. A total of 15 ixodid tick species were recovered from the scrub hares examined in the three regions of the Transvaal. No haematozoa were found in blood smears made from the hares examined in the southern region of the Kruger National Park.

Parasites of domestic and wild animals in South Africa. XXVII. Ticks on helmeted guineafowls in the eastern Cape Province and eastern Transvaal Lowveld.

Seventy-six helmeted guineafowls (Numida meleagris) were shot in the Andries Vosloo Kudu Reserve and on an adjacent farm in the eastern Cape Province during the period May 1985 to January 1987 and their tick burdens determined. A total of 10 ixodid tick species were recovered, of which Amblyomma hebraeum, Amblyomma marmoreum and Haemaphysalis silacea were the most abundant. The seasonal abundances of these 3 species and of Hyalomma marginatum rufipes were ascertained. A marked difference between the total number of A. hebraeum recovered from the birds in the reserve and those on the farm is ascribed to the treatment of domestic stock on the farm with an acaricide. The tick burdens of 118 helmeted guineafowls, shot in the southern part of the Kruger National Park, eastern Transvaal Lowveld, from August 1988 to August 1990, were also determined. Ten ixodid tick species and the larvae of an argasid species were recovered. A. hebraeum, A. marmoreum and the Argas sp. were the most abundant and their seasonal abundances and that of Rhipicephalus zambeziensis were determined. Only 2 of the 54,659 ixodid ticks recovered from the birds at the 3 localities were adults and the presence of these is ascribed to accidental infestations.