Van der Linde, T. C. de K.Fourie, L. J.Brown, Leslie2017-06-152017-06-152000-05http://hdl.handle.net/11660/6368English: Biting lice are well known ecto-parasites of vertebrates. Most wild and domesticated animals have one or more louse species, living on them. Although lice are a source of irritation to the host, they are not generally considered as economically important because they do not cause much physical damage. The sheep biting louse (Damalinia avis) has, however, been shown to cause losses in wool production and quality. Damalinia limbata are ecto-parasites on Angora goats and can cause the same type of losses to the farmer as the sheep biting louse. Very little research has been done on these lice and their impact on mohair production can therefore not be objectively assessed. The objectives of the current study were to investigate aspects of the biology and distribution of D. limbata and to promote more effective and economical management of these lice on commercial farms. The following were investigated: (1) Aspects of the morphology of D. limbata and D. avis. (2) Environmental temperatures prevalent on the body of Angora goats. (3) The number of nymphal instars of D. limbata. (4) Seasonal changes in the populations of D. limbata. (5) The influence of D. limbata on the body mass of Angora goats and the production and quality of mohair, as well as the efficacy of different control methods. Field experiments were conducted on the farm Preezfontein (29°50'S, 25° 19'E), situated 10 km from the town Fauresmith, about 130 km southwest of Bloemfontein in the south-western Free State. The veld type of this area is defined as 'False Upper Karoo' and falls in the Karoo biorne. The Free State is a summer rainfall region with an average precipitation of 450-500 mm per annum, with hot summers and cold winters and droughts occurring regularly. D. limbata and D. avis were compared using general morphological characters, morphometric measurements of various body regions and placement of dorsal and ventral abdominal sclerites. D. limbata has a more robust appearance than D. avis. Females of both D. limbata and D. avis were on average 1.611 mm long and the males had average lengths of 1.378 mm and 1.255 mm, respectively. Male D. ovis had solid dorsal plates where as D. limbata males had dorsal plates, which were transversally split, on segments IV and V. Temperature studies, on the micro-habitat of D. limbata, showed that the temperature against the skin of an Angora goat is relatively constant at approximately 35°C. All attempts to establish a laboratory colony of D. limbata were unsuccessful. D. limbata was found to have three nymphal instars before reaching adulthood. Instar 1 had average head-capsule widths and lengths of 0.252 mm and 0.202 mm, respectively. The second and third instars had head-capsule widths of 0.364 mm and 0.467 mm and lengths of 0.305 mm and 0.425 mm respectively. The louse populations increased during spring and early summer, peaking in mid summer. Mid winter shearing seemed to have a greater impact on the louse populations than mid summer shearing. D. limbata moves around the body of Angora goats, being more abundant on the ventral areas of the body during summer and more evenly dispersed over the body during winter. It was found that D. limbata does not have an adverse influence on the body mass of Angora goats, but does adversely affect mohair production and quality. The average loss in mohair production was 12 % and individual losses of as much as 25 % were recorded, representing substantial financial losses to the farmer. D. limbata was effectively controlled by Deltamethrin when applied as either a backline treatment or as a lateral application with a Tikspray applicator.Afrikaans: Bytende luise is bekende ektoparasiete van vertebrate. Meeste wilde en mak- of huisdiere het een of meer luisspesie wat hulle parasiteer. Alhoewel die luise 'n bron van irritasie vir die gasheer is, word hulle nie normaalweg as ekonomies belangrik beskou nie, aangesien hulle min fisiese skade veroorsaak. Daar is wel aanduidings dat die bytende skaapluis (Damalinia ovis) verliese in wolproduksie en kwaliteit kan veroorsaak. Damalinia limbata, wat Angora bokke infesteer, kan moontlik dieselfde tipe verliese veroorsaak as D. ovis op skape. Min navorsing is egter nog gedoen op hierdie luise en gevolglik kan die invloed wat hulle moontlik op sybokhaar-produksie en -kwaliteit het nie objektief bepaal word nie. Die doelstellings van hierdie studie was om aspekte van die biologie en verspreiding van D. limbata te ondersoek sowel as die bevordering van effektiewe en ekonomiese bestuur van die luise op plase. Die volgende is ondersoek: (1) Aspekte van D. limbata en D. ovis se morfologie. (2) Die omgewings temperature op die lyf van Angora bokke. (3) Die aantal nimf instars van D. limbata. (4) Die seisoenale veranderings in D. limbata bevolkings. (5) Die invloed van D. limbata op die liggaamsmassa van Angora bokke en die invloed op bokhaarproduksie en - kwaliteit asook die doeltreffendheid van verskillende beheerrnetodes. Veldwerk is op die plaas Preezfontein (29°50'S, 25° 19'E) ongeveer 10 km buite Fauresmith in die suid-wes Vrystaat (ongeveer 130 km suid-wes van Bloemfontein) gedoen. Die veld tipe in hierdie area word beskryf as Skyn Hoër Karoo en val binne die Karoo bioom. Die Vrystaat is 'n somer-reënval gebied met jaarlikse neerslag van ongeveer 450-500 mm. Somers in die gebied is baie warm en die winters koud, met droogtes wat gereeld voorkom. Die algemene morfologiese kenmerke, morfometriese kenmerke en die plasing van dorsale en ventrale abdominale plate van D. limbata en D. ovis is vergelyk. D. limbata vertoon stewiger in vergelyking met D. ovis. Wyfies van beide D. limbata en D. ovis is ongeveer 1.611 mm lank en die mannetjies was onderskeidelik 1.378 mm en 1.255 mm lank. Manlike D. ovis het soliede dorsale plate vergeleke met D. limbata wat dorsale plate het wat op segmente IV en V transversaal gesplete is. Temperatuur studies op die mikro-habitat van D. limbata het getoon dat temperature teen die vel van Angora bokke relatief konstant bly teen ongeveer 35°C. Alle pogings om 'n laboratorium kolonie te begin, het misluk. D. limbata het drie nimf stadia. Instar 1 het 'n kopkapsule met 'n gemiddelde lengte en breedte van onderskeidelik 0.202 mm en 0.252 mm. Instar 2 se kopkapsule lengte en breedte was onderskeidelik 0.305 mm en 0.364 mm en die van instar 3 was onderskeidelik 0.467 mm en 0.425 mm. Luis bevolkings het gedurende lente en vroeg-somer toegeneem met 'n piek in die middel van die somer. Skeertyd in die winter het blykbaar 'n groter invloed op luis getalle as gedurende die somer. Die luise beweeg rond op die bokke en is meer volop op die ventrale gedeeltes van die liggaam gedurende die somer. Gedurende die winter is die luise meer eweredig oor die liggaam van die bokke versprei. D. limbata het nie 'n negatiewe invloed op die liggaamsmassa van Angora bokke nie. Daar is wel 'n negatiewe invloed in bokhaarproduksie en -gehalte waargeneem. Die gemiddelde verlies in bokhaarproduksie was 12 % en op sommige bokke was dit so hoog as 25 %, wat redelike ekonomiese verliese vir die produsent verteenwoordig. D. limbata word effektief deur Deltamethrin beheer wanneer dit as 'n dorsale behandeling toegedien word, of as 'n laterale toediening met 'n Tikspray toediener.enEctoparasitic infestationsGoat lice -- South Africa -- FauresmithAngora goat -- Diseases and pestsPhthirapteraDam alinia limbataLiceAngora goatsTemperatureInstarsMohairBody massMohair massChemical controlDissertation (M.Sc. (Zoology and Entomology))--University of the Free State, 2000DissertationUniversity of the Free State