Descriptions of the adults and pupa of Culicoides hildae n.sp. from the Republic of South Africa (Diptera : Ceratopogonidae)

A new species of biting midge, Culicoides hildae, is described from males, females and pupal exuviae collected in the Orange Free State, Republic of South Africa.This article has been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-Format

A survey of the Culicoides (Diptera: Ceratopogonidae) of the Umlalazi Nature Reserve in Zululand, South Africa, with notes on two species biting man

Culicoides biting midges were intermittently collected between July 1988 and December 1992 in the Umlalazi Nature. Reserve on the subtropical eastern coastal margin of South Africa. Altogether 34 species were collected in a diversity of habitats that included a mangrove community, dune forest and mixed thornveld. Most Culicoides were collected with the aid of light traps and whilst biting man. The pupae of ten species were collected from substrata in an open salt marsh, as well as from fresh and stagnant groundwater situations. It was the first time that the pupae of six of these ten species were collected. Of the species collected in light traps, the two most abundant species, C. leucostictus Kieffer (49,1% of 16563 identified) and C. rhizophorensis Khamala & Kettle (22,3%) , were also the two species found biting man. The larval habitat of C. leucostictus was widespread except in the more saline, tidal areas, but that of C. rhizophorensis appeared to be restricted to the tidal salt-marsh area. Two of the species collected, C. fulvithorax Austen and C. moreli Clastrier, are new records for South Africa.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

The effect of arsenical dips on Parafilaria bovicola in artificially infected cattle in South Africa

The possible adverse effect of arsenical tick control dips on Parafilaria bovicola infections was investigated in 48 artificially infected cattle. A treatment group of 24 cattle was dipped in a plunge dip containing 1600 ppm arsenic trioxide. A control group of the same size was dipped in an organophosphate dip containing a mixture of chlorfenvinphos and dioxathion. Regular weekly to 3-weekly dipping had no effect initially on the prevalence of ovipositional blood spots of P. bovicola in either group. However, from 4 months after bleeding commenced there was a significant reduction in blood spots in the arsenic-dipped cattle and, on slaughter at 12-14 months after infection, the arsenic group had significantly fewer live worms and fewer carcass lesions. Arsenic residues in muscle samples of treated cattle were 11,6 times higher than in the controls. It is proposed that arsenic residues in the sub-cutaneous muscle layers increase with repeated dipping until a level toxic to P. bovicola is finally reached. Older cattle would therefore be refractory to infection and their carcasses at slaughter would not be affected.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Seasonal abundance and distribution of Parafilaria bovicola ovipositional blood spots on cattle in South Africa

More than 23 000 cattle of both sexes and different ages were examined for blood spots caused by egglaying females of P. bovicola. Although these studies extended over four years and involved 5 farms in different parts of the Transvaal Bushveld, the overall results were the same. Ovipositional bleeding was strongly seasonal with blood spots first appearing in winter (June), reaching a peak in spring (September-November) and thereafter declining rapidly as summer progressed. In a single year at Zoutpan Research Station up to 92,1 % of the 1st year heifers had already bled by November and this proportion increased only slightly to 95,1 % by the end of the bleeding season (May). The number of blood spots per animal showed a similar seasonal abundance except for a second peak of abundance in June for 1st year heifers and oxen. The prevalence of blood spots in cattle of different ages and sex varied markedly. At Mara Research Station half as many oxen bled in their 2nd year as in their 1st year, while at Zoutpan 19,2% fewer heifers bled in their 2nd year than in their 1st. Bulls bled the most, then 1st year oxen, 1st and 2nd year heifers and 2nd year oxen, with breeding cows bleeding the least. A high female hormone level appears to be associated with the development of immunity. The shortest period from birth to 1st blood spot (the apparent prepatent period) was 191 days, while 81,8% of oxen bled for the 1st time within 279 days after birth. Blood spots were equally distributed on the left and right sides, with 92,1 % on the dorsolateral regions and 59,9% on the shoulder and rib regions. The blood spot distribution more or less matched the carcass lesion distribution. This suggests that ovipositing females are largely responsible for carcass lesions in these areas.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.am201

The role of carbon dioxide as stimulant and attractant to the sand tampan, Ornithodoros savignyi (Audouin)

Sand tampans cause irritation and losses among cattle in the sand veld areas of the Kalahari and South West Africa. They appear above the ground in response to a stimulus. The nature of this stimulus was investigated in the laboratory and in the field, in the hope that the knowledge so gained would lead to a means of control. These studies showed carbon-dioxide to be the main factor which caused tampans to surface. In the laboratory concentrations of 5 per cent CO₂ and higher proved to be effective stimulants. In the field 100 per cent CO₂ was used, liberated from a cylinder and from dry-ice. It caused marked stimulation and attraction of tampans, so that large numbers could be collected at the source of liberation. In one instance 4553 tampans were collected in 2 hours when using a small piece of dry-ice as attractant. At Onderstepoort 5 per cent CO₂ was liberated in a tampan-infested open air enclosure covered with an 8 in. depth of sand to resemble Kalahari conditions. As little as 1 litre per minute of 5 per cent CO₂ caused tampans to surface and move towards the CO₂ source. Even a slight breeze did not prevent them from surfacing and eventually locating the CO₂ source. At low temperatures, e.g. 52° F, tampans were not attracted by CO₂ unless activated by disturbing the sand in which they occurred. Laboratory investigations into the role of heat and moisture as tampan attractants showed that CO₂ activation was necessary before tampans would react to heat and moisture. Moist objects alone were unattractive, warm objects attractive, but warm-moist objects were the most attractive. In all experiments in the laboratory only a proportion of the tampans present reacted to the stimuli tested. It seems at present impractical and uneconomical to attempt to control tampans over large areas with traps containing CO₂, but it will be of great use in sampling tampan populations.The articles have been scanned in colour with a HP scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to final presentation PDF-Format

Preliminary report on the transmission of Parafilaria bovicola in South Africa

The filarial worm Parafilaria bovicola causes streaks of blood on the skins of live cattle and slimy bruise-like lesions on the subcutaneous surfaces of their carcases. To determine the vectors of this worm a field survey was conducted in November 1972 and during the summer of 1973/74 on 6 farms in the Transvaal. A total of 10 093 flies was collected off cattle and examined for the infective 3rd stage Parafilaria larvae. Of the 12 fly species collected, Muscalusoria, Musca domesrica, Musca xanthomelas, Musca n. sp., Musca sorbens and Musca fasciata were the commonest. Third stage larvae were found in 3 species all belonging to the subgenus Eumusca, viz. M. fusaria, M. xanthomelas and a new Musca species. The infection rate in these flies was usually less than 1% and most of the worms were recovered from the heads of female flies. The same 3 species were successfully infected artificially in the laboratory, the infection rate ranging from 40, 0%-53, 8%. The measurements of larvae from these flies agreed closely with those of larvae recovered from field-collected flies. Female P. bovicola worms perforate the skin of cattle and deposit their eggs and/or microfilariae into the blood which trickles down from the holes. Most of these bleeding marks were noticed between July and December 1973. As 3rd stage larvae were recovered from flies from August 1973 to February 1974 the main period for transmission is likely to be between July and February. Since the 3 flies suspected of being vectors feed mainly on eye secretions it is believed that most transmission takes place via the orbital route. Thereafter development of the worms in cattle to the adult stage will take approximately 7-10 months.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acroabt XI was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

The epidemiology of Parafilaria bovicola in the Transvaal Bushveld of South Africa

A total of 20 375 flies collected off cattle on 12 farms over 36 months were identified and examined for 3rd stage P. bovicola. The 3 vector species accounted for 64,1 % of the flies collected and were the only fly species found to be infected. Musca lusoria was clearly the dominant vector fly, although large numbers of Musca sp. A appeared regularly between February and April each year. This phenomenon, coupled with high numbers of M. lusoria throughout most of the year, led to an increase in the numbers of vector flies from their lowest level in June to a peak in February-April. Of the 13 070 vector flies examined for 3rd stage larvae only 64 (0,52 %) were positive; of these 41 were M. lusoria and 17 Musca sp. A. No positive male flies were found. Incubation of wild-caught flies for up to 13 days at 27 °C noticeably increased the larval recovery rate. Flies were found to be infected mainly from August-March. Infected M. lusoria were recorded from July-March and infected Musca sp. A from January-May. Only 6 infected M. xanthomelas were collected and this was during the period August-December, when most ovipositional blood spots occur on cattle. It is concluded that P. bovicola transmission in the Bushveld is not correlated with peak periods of bleeding but rather with high numbers of vector flies, the various species augmenting each other so that transmission may take place almost throughout the year.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

The experimental transmission of Parafilaria bovicola to cattle in South Africa using Musca species (subgenus Eumusca) as intermediate hosts

In controlled experiments in an insect-free stable, cattle became infected with Parafilaria bovicola when Musca lusoria, infected with the larvae of this worm, were allowed to feed on a fresh skin incision, and when infective larvae were placed on fresh skin incisions, injected subcutaneously or into the jugular vein, or instilled into the eyes. The sites of blood spots caused by ovipositing P. bovicola females and the sites of carcass lesions were seldom close to the site of infection, an indication that the worms had migrated. The prepatent period of P. bovicola in 4 cattle which developed blood spots ranged from 242-319 days. Neither of the infected cattle that were kept continuously in a shady stable showed blood spots, but 4 out of 7 infected cattle which spent some time in the sun bled. However, carcass lesions on shaded cattle were similar in appearance to those on cattle kept outdoors. Infective larvae were stimulated to escape from the mouth-parts of infected M. lusoria and Musca xanthomelas s.s. when these were fed citrated ox blood warmed to 38-40 °C. No escape took place when the flies were fed warmed saline or warmed 15% sucrose solution.This article has been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-Format

The development of Parafilaria bovicola in Musca xanthomelas and Musca lusoria

Artificially infected adult flies were used in this study. In both Musca species, P. bovicola developed in the fat-body cells, mainly of the abdomen. Escape from the midgut and penetration of the fatbody cell was possibly achieved by use of the cephalic hook of the microfilaria. At 27 °C, development to the 3rd larval stage took 9 days, but maximum length was only reached after 11 days. Sharp increases in larval length took place on Days 6-7 and on Day 9. These sudden increases possibly indicate moults to the 2nd and 3rd larval stages respectively. During larval development the fat-body cell increased markedly in size to form a thin-walled capsule around the larva. On reaching the 3rd stage, larvae escaped from the capsules and migrated to the head cavity and proboscis.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format