The experimental establishment of ruminant nematodes in European hares (Lepus europaeus)

Abstract

The factors that control the demography of European hare Lepus europaeus populations are poorly understood, but it has been recognized that the decline of hares in Europe is associated with an increasing intensity of agricultural activity. Many mechanisms have been suggested. We propose another mechanism; a negative impact arising from ingestion of the infective larvae of ruminant livestock. We dosed juvenile hares from a worm-free colony with a conservative dose from a mixed culture of infective larvae of the nematode parasites of sheep and cattle. We examined the hares post-mortem for the establishment of those ruminant nematodes, differences in weight changes, and the shedding of eggs. We found that under the circumstances of our trial, Trichostrongylus colubriformis and to a lesser extent T. rugatus, T. vitrinus, and Teladorsagia circumcincta were able to establish as adults in the dosed animals. We found strongyle eggs in the faeces of the dosed hares, and were able to culture larvae from those eggs. However, the ecological significance of our findings, if any, remains to be elucidated. Because of their mobility, hares may transmit resistant strains of parasites between grazing properties.