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Deer, parasites and other small creatures on the pasture – a multifactorial, diverse biocenosis: Papers presented at the „Timely questions in grassland and game management” scientific conference (Hungarian Academy of Sciences – Kaposvár University, 18-19 May 2006)
34-38Views:101Red, roe and fallow deer have outstanding importance in game management and hunting in Hungary. They live in very diverse ecological circumstances affected by parasites and other ecological factors (Table1). Among the many parasites, lungworms are considered to be the most significant, at least for animals in captivity. Species differentiation in large lungworms (Dictyocaulidae) on the basis of their morphological features is difficult; therefore, the sequencing of ITS2 of rDNA has become a useful tool for their genetic characterization. In our study, in addition to the typical Dictyocaulus eckerti ITS2 sequence another sequence is derived, which is significantly different from the known D. eckerti and D. viviparus sequence characteristics. This indicates the real need for a large-scale molecular, systematic study of Dictyocaulus specimens from red, fallow and roe deer from an epidemiological point of view.
In the period of host to host (deer), lungworm larvae (L1) on the pasture face many different environmental factors, including enemies and helpers. Number of L1s can be strongly reduced by dung beetle imagos as small predators. At the same time Pilobolus fungi help L1s to be spread on the ground vegetation, and improve and equalize the chance to get into the final hosts (deer) in the case of large lungworms (direct development) or into the intermediate hosts (terrestrial snails) for the necessary larval development of the Protostrongylidae species. Dung-breeding flies (Diptera) complete the set of factors. This is the uniquely functioning „micro”-biocenosis on the deer pasture.
Deer herds, especially those kept intensively (eg. deer farm), are usually routinely treated with anti-parasitic chemicals, such as albendazol or ivermectin. A number of studies demonstrate that the later is toxic for the dung utilizing insects (dung beetles and flies) inhibiting the normal ecological processes: the decomposition of feces and reduction of lungworm larvae. The necessity of chemotherapy against lungworm is questionable. If we know that in sound ecological circumstances (healthy deer with good immune response on one side, and sound pasture as a well functioning biocenosis on the other), these parasites are harmless due to the long-term coevolution with their deer hosts, we may discontinue using anti-parasitics. Furthermore, because of the long food-hygienic waiting period (3-6 weeks), it is even contraindicated in terms of eco production of meat products, such as venison.