Parasitic infections of amphibians in the Pendjari Biosphere Reserve, Benin
The parasitic infections of amphibians in the National Park (pristine savanna), Buffer Zone (slightly altered savanna closer to fields) and Agricultural Zone (agricultural land including cotton fields with intensive use of pesticides) of the Pendjari Biosphere Reserve, Benin, were investigated. A total of 145 amphibian specimens of 14 species were examined and parasites recovered included two monogenean parasites, an acanthocephalan, two cestode species, four trematode species and eight nematode species. Results obtained show the possible influence of land-use pattern on parasite distribution. For example, the encysted acanthocephalan had higher prevalence in Phrynobatrachus latifrons caught in the Agricultural Zone, but specimens from the Buffer Zone had a higher intensity of infection. Infection with trematodes occurred predominantly in hosts collected in the Agricultural Zone, indicating that landscape alteration, pesticide use and nutrient enrichment from fertilizers in this zone may be enhancing intermediate host populations and hence parasite prevalence. Furthermore, this infection pattern may be indicative of an immunosuppressive effect of pesticides on the frogs of the Agricultural Zone. Prevalence of Rhabdias sp. infecting P. latifrons caught in the Buffer Zone was almost 14 times higher than those caught in the Agricultural Zone. Similarly, the infection with Amplicaecum sp. was higher in Amietophrynus maculatus from the National Park (57.1%) than those from the Agricultural Zone (15%). It is possible that the pesticide-contaminated environment of the Agricultural Zone inhibits the development of the free-living stages of these nematodes.
Key words: amphibians, parasites, Pendjari Biosphere Reserve, Benin Republic.