[Low-count and base populations of the warble fly, Hypoderma ovis (Hypodermatidae), and their significance in the...

During control measures taken against hypodermyiases a rapid drop of cattle infestation follows, but low warble fly populations persist, the extensity of invasion being up to 2--5%. In order to study these low populations experimentally isolated populations were established under conditions of Central Europe. Fundamental populations initiated by one gravid female H. bovis in a herd of young cattle consisted of 17, 25, 42 and 83 larvae, the extensity of infection being 11 to 52% and intensity of it 1.1 to 1.6 larvae per host. The persistence of low warble fly populations is due to an internal regulatory system limiting the population density of parasites in the host populations.