Page 37 - VHSA - Onderstepoort 100 Years - Part 3

E.M. (Errol) Nevill, obtained an MSc in Entomology from the University of Natal in Pietermaritzburg. He joined the Section of Entomology at the Institute in 1962 and remained there until his retirement in 2003. Early on
in his research life at the Institute he was
able to demonstrate that, by grazing cattle
close to sheep, Culicoides midges preferred
to feed on the cattle rather than on the
sheep. As these midges are the vectors
of bluetongue in sheep, the proximity of
the cattle reduced the risk of the sheep
becoming infected with this virus.
Bovine parafilariosis or ‘false bruising’, caused by the filarial worm Parafilaria bovi- cola that is transmitted by various Musca spp. flies, has severe economic implica- tions for cattle ranching in the tropical and subtropical regions of South Africa. This prompted several investigations into the host-parasite interactions and epidemio- logy of this condition. Not only did Nevill identify the fly vectors of this nematode, namely Musca lusoria and Musca xantho- melas, but he also described the life cycle of the worm in the fly. Furthermore he noted that the female worms, that live in the subcutaneous tissues on the shoulders and flanks of their cattle hosts, only caused bleeding points in the skin of their hosts on sunny days when the intermediate fly hosts of the worms are active. The worms lay their eggs in the blood trickling from these points and the eggs are then ingested with the blood by the flies. He was awarded
Insecticides being loaded onto a helicopter to combat black flies (Simulium)
a doctoral degree for the thesis he produced on this research. Nevill was also active in researching black flies or Simulium spp. along the Vaal and Orange Rivers and in developing methods for the control of these flies, whose bites and swarming cause intolerable ‘fly worry’ to humans and animals within their considerable flight range. One of these methods involved the application of insecticides to the rivers to kill off the fly larvae. Another was aimed at the pupae of the flies. These pupae are attached to rocks below the water surface in fast-flowing rapids, and by manipulating the water level through closing the sluice gates of the large dams on these rivers the pupae could be exposed to the sun and dry out. In later years Nevill became involved with R.J. (Rob) Bagnall, state veterinarian for the district of Hluhluwe, and F.R. (Richard) Emslie, state veterinarian for the district of Jozini, in research on the distribution and control of the two tsetse fly species responsible for the resurgence of trypanosomosis in cattle in north-eastern KwaZulu-Natal. He was also involved in the establishment of breeding colonies of tsetse flies at the Institute. J.H. (Hugo) Viljoen, who had joined the staff of the Section of Entomology, worked on the life cycle of P. bovicola in its final cattle host and was also awarded a doctoral degree for
this research.
Colonies of tsetse flies bred in the laboratory for sterilization research
ONDERSTEPOORT 100
“Early on in his research life at the Institute he was able to demonstrate that, by grazing cattle close to sheep, Culicoides midges preferred to feed on the cattle rather than on the sheep.”
127
Parasitology
1908-2008
Years