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R Garms

Publications and source records attributed to R Garms.

At least 37 records · Page 2Linked to original sources
PubMed1987

Cytotaxonomy of the Simulium sanctipauli sub-complex in Liberia.

Larvae of the Simulium sanctipauli sub-complex from three of the main rivers of Liberia, the Lofa, the St. Paul and the Farmington were examined. All larvae were identified as S. sanctipauli (sensu Vajime and Dunbar, 1975) but as S. soubrense using the new definition of Post (1986). It therefore appears that S. soubrense (sensu Post) and not S. sanctipauli is the main man-biting species of the S. sanctipauli sub-complex in Liberia. Larval populations from the three rivers were genetically distinct. Those from the Lofa and St. Paul were most closely related, but the double inversion 1L-B.C. which was in Hardy-Weinberg equilibrium in the Lofa at a frequency of 0.578 was absent in the St. Paul. An abrupt genetical change was observed between the populations of the St. Paul and Farmington, which are only about 30 to 40 km away from each other. The inversion 2L-D, which was fixed and present in more than 90% of specimens from the Lofa and St. Paul respectively, was practically absent in the Farmington. Of further interest was the sex-linkage of inversion 3L-5 in the Lofa and the St. Paul. This inversion was autosomal and rare in the Farmington.

Animals↗
PubMed1987

Failure of Onchocerca gutturosa to develop in Simulium soubrense and Simulium yahense from Liberia.

Laboratory reared female S. soubrense and S. yahense from Liberia were intrathoracically inoculated with bovine skin dwelling microfilariae of Onchocerca gutturosa. Of a total of 174 flies, each injected with 50 fresh microfilariae, the maximum development was to late first-stage larvae. One S. soubrense also contained two second-stage larvae and a maldeveloped third-stage larvae. No development to normal third-stage larvae was observed in any fly despite maintenance at 28 degrees C for up to 10 days following infection. This contrasts with complete development of O. volvulus in both blackfly species under similar conditions.

Animals↗
PubMed1985

Identification of adults of the Simulium damnosum complex using hydrocarbon analysis.

Using advanced gas liquid chromatography in association with multivariate statistical analysis, a study of four members of the S. damnosum complex - S. sirbanum, S. damnosum s.str., S. yahense and S. sanctipauli, revealed that both adult male and female flies could be distinguished by quantitative analysis of the cuticular hydrocarbon peaks. Adult flies were obtained from sites which were known to contain a very high proportion of pure cytospecies. The females of the complex were more readily separated from each other than were the males. On the basis of preliminary results, the technique provides for the first time, a reliable method for distinguishing S. sirbanum and S. damnosum s.str., the most important vectors of onchocerciasis in the savanna areas of West Africa, as well as an additional method for identification of adult S. sanctipauli and S. yahense. Analysis of the hydrocarbons by GC/MS showed them to be straight chain and branched saturated hydrocarbons ranging from C22-C35. The technique is simple in respect of field methods of collection, and thus holds considerable promise as a means of identifying S. damnosum complex flies throughout the area of onchocerciasis transmission in Africa.

Africa, Western↗
PubMed1984

Morphological identification of simulium sanctipauli and S. yahense in Liberia and comparison of results with those of enzyme electrophoresis.

Simulium sanctipauli and S. yahense have been incriminated as the main vectors of Onchocerca volvulus in the rain-forest zone of Liberia. An accurate identification of the females of the two species which breed in different types of water-courses but are morphologically similar is essential for a proper study of their epidemiological importance and the planning of control measures. Various external characters were examined for their diagnostic value by the comparison of identifications using these characters and those based on enzyme electrophoresis (phosphoglucomutase, trehalase). It was shown that the females of the two species can be separated reliably by the use of external morphological characters. The occasional finding in the same fly of phosphoglucomutase variants typical for each species indicated the possible occurrence of natural hybridization between S. sanctipauli and S. yahense.

Animals↗
PubMed1983

Identification of a laboratory mating form of the Simulium damnosum Theobald complex in West Africa.

Larvae and pupae of Simulium damnosum s.l. were collected from the Begba rapids on the Mono river. Emerging adults were induced to mate, blood feed and oviposit. Six out of 13 discrete egg batches counted were fertile. The F1 females did not blood feed and thus no F2 eggs were obtained. Larvae from the breeding site and the F1 generation were identified as being the Beffa form of the S. sanctipauli/S. soubrense group. This form appears to be the only member of the S. damnosum complex in West Africa which mates in the laboratory and is almost certainly the same form as that colonized by Simmons and Edman (1982). The mating behaviour of West African S. damnosum s.l. described by several authors is similar to that observed in the Beffa form, and the possibility that earlier reports referred to the Beffa form is discussed.

Africa, Western↗
PubMed1983

Variation and distribution of forms of Simulium soubrense and S. sanctipauli in West Africa.

Examination of specimens from savanna areas of Togo and Benin attributable to Simulium soubrense and S. sanctipauli according to the criteria of Vajime and Dunbar (1975) revealed hitherto undescribed features. Cytological examination showed many larvae with the arrangement IIL- 4.6/4.6.7, heterozygous for the 'diagnostic' inversion and 86% of the males possessed a previously undescribed inversion IIS-6b. The occurrence of such larvae in Togo and Benin was associated in adult males with records of a type of scutal pattern which is described and termed Type IV. This pattern is one extreme of a range of scutal pattern variation in the males of the S. soubrense/S. sanctipauli sub-group, which was separated into four arbitrary classes and specimens were scored as Type I, II, III or IV. The distribution of these different types of male scutal pattern, based on collections made in West Africa between 1963 and 1981, is presented. Type I and II patterns predominated in forest areas and Type IV in savanna. Many female flies which occurred together with the latter possessed pale wing tufts. In the light of the above and additional evidence, derived from the progeny of individual females, and because the 'diagnostic' inversion for S. soubrense and S. sanctipauli together with a previously undescribed sequence IIL-6 occurred in Hardy-Weinberg equilibrium, it was concluded that the populations in Togo and Benin are a single interbreeding group. This group is described as a new form, named the Beffa form, of the S. soubrense/S. sanctipauli subgroup of the S. damnosum s.l. complex and its possible taxonomic status is discussed.

Africa, Western↗
PubMed1982

Anthropophily of Simulium damnosum s.l. and its rôle as a vector of human onchocerciasis in the Yemen Arab Republic.

Immature stages of Simulium damnosum s.l. were collected in four of the main wadis (Surdud, Zabid, Rasyan, Ghayl) which drain westward to the Red Sea. The species was absent from the Wadi Tuban which flows to the south-east, but other black-fly species were found herein. For the first time it was shown that S. damnosum s.l. in the Yemen bites man, may ingest microfilariae of Onchocerca volvulus and can harbour filarial infections. Out of 303 flies which were caught on human bait in the Wadi Rasyan 33% were parous, four contained developing and three third-stage larvae (two of the flies had larvae in the head) indistinguishable from those of Onchocerca volvulus. The significance of these findings for the epidemiology of onchocerciasis and the possibility of vector control measures are discussed.

Animals↗
PubMed1981

Histochemical differentiation of filarial larvae found in Simulium damnosum s.l. in West Africa.

The azo-dye method for the histochemical demonstration of acid phosphatase activity was used to differentiate filarial larvae within and outside th area of the Onchocerciasis Control Programme (OCP) in natural infections of female S. damnosum s.l. caught in West Africa. The histochemical patterns of 1263 larvae (all stages) dissected from 556 positive files caught at 35 catching sites during the period of reinvasion in 1978 and 1979 were determined and compared with those of O. volvulus known from experimental infections. In Mali, Ivory Coast and Upper Volta, about 16% of 3rd-stage larvae in 17.3% of invading female S. damnosum s.l. (savanna cytospecies) could be separated from those of O. volvulus-like larvae, on account of their different enzyme staining patterns. The percentage of larvae enzymatically distinguishable from O. volvulus and the flies carrying them showed a distinct geographical distribution; the highest percentages (36.4/38.4) were found in the north-west (Mali) and the lowest percentages (4.4/8.2%) were found in the interior (east-central) of the Programme area (Upper Volta). By contrast, all larvae found in S. damnosum s.l. females caught in Ghana and in Togo were morphologically as well as enzymatically similar to those of O. volvulus. Third-stage larvae of the enzymatically distinguishable "species" were found to be somewhat longer than those of O. volvulus-like larvae. Morphologically, the larvae concerned probably belong to the genus Onchocerca, but their specific identity and vertebrate host remain unknown.

Diptera↗
PubMed1981

Further studies on the reinvasion of the onchocerciasis control programme by Simulium damnosum s.l.: the effects of an extension of control activities into southern Ivory Coast during 1979.

During 1979 the aerial larviciding operations of the Onchocerciasis Control Programme were extended southwestwards to cover those areas with Ivory Coast where the savanna cytospecies of the Simulium damnosum complex were known to breed. This resulted in a marked reduction of the reinvasion which threatened the Programme in Ivory Coast and Upper Volta in earlier years. Previous conclusions concerning the location of sources of invading populations and consequently the direction and distance of the movements of flies were substantiated. It was confirmed that S. damnosum s. str. and S. sirbanum were the main migrant species. In this area S. Squamosum was shown to be of much less importance as a migratory vector.

Cote d'Ivoire↗
PubMed1979

Displacements of Simulium damnosum and strategy of control against onchocerciasis.

Regular aerial treatment of 14 000 km of watercourses has achieved and maintained, over an area of 700 000 km2 of West African savannah, a very high degree of control of the larvae of Simulium damnosum sensu stricto and S. sirbanum, the vectors of onchocerciasis in this area. However, particular and relatively restricted parts of this area, mainly in northern Ivory Coast and neighbouring parts of Upper Volta, experience regular and prolonged reinvasions by parous female vectors, which have already taken bloodmeals (and many of them carrying the parasites) and arrive from unknown sources probably hundreds of kilometres away, from directions probably between southwest and north. This reinvasion, now experienced in three successive years, represents the outstanding scientific, epidemiological and logistic problem still facing the WHO Onchocerciasis Control Programme. An outline is presented of the multidisciplinary investigations being undertaken to find a solution.

Africa, Western↗
PubMed1979

Studies on the reinvasion of the Onchocerciasis Control Programme in the Volta River Basin by Simulium damnosum s.I. with emphasis on the south-western areas.

The aerial larvicidng operation of the Onchocerciasis Control Programme of the World Health Organization which began in February 1975 resulted in a sharp reduction in Simulium damnosum numbers. However, at the onset of the rainy season the fly population increased in certain areas. Detailed surveys both on the ground and by helicopter did not reveal any significant failures of treatments that could account for the fly densities observed, and it was concluded that the flies must originate from sources outside the controlled zone. This reinvasion proved to be an annual occurrence which has been studied in detail between 1975 and 1978 in the south-western parts of the control zone. The methods used included full day catches by vector collectors carried out every day throughout the season, cytotaxonomic determination of larvae, detailed morphological examination of reared and biting adults and treatment of suspected source rivers with insecticide. The results indicate that the invasion takes place in a SW-NE direction across country for distances of 300 km or more along the track of the monsoon winds. It involves mainly the savanna cytospecies S. damnosum s. str. and S. sirbanum. The invading populations are composed of older parous flies, many of which carry infective 3rd stage larvae indistinguishable from those of Onchocerca volvulus. These females tend to bite close to the rivers and do not disperse as far as normal populations with a higher proportion of younger flies.

Animals↗
PubMed1978

Use of morphological characters in the study of Simulium damnosum s.l. populations in West Africa.

Morphological characters were tested which could be used to compare and to associate Stimulium damnosum s.l. populations reinvading the area of the Onchocerciasis Control Programme in the Volta River basin with those of potential source areas. The savanna cytospecies S. damnosum s.str. and S. sirbanum could be distinguished from the forest species S. sanctipauli, S. soubrense and S. yahense by the size and shape of the antennae and the colour of the basal wing tufts. Wing tufts of S. squamosum were of variable colour. Results did not confirm morphological keys for the complex which used counts of maxiillary teeth to separate S. damnosum s.str. and S. sirbanum, and numbers of spinules on the radial vein of the wings to separate S. yahense and S. squamosum. Populations of the S. damnosum complex could be characterised by morphometric methods. Measurements of the length of the thorax provided a rapid and easy means to distinguish different populations. The length of the thorax was positively correlated with the length of the wings. By using several measurements in combination populations could be more clearly characterised.

Africa, Western↗