No abstract

The parasitofauna of ground-dwelling anurans from pesticide-treated cocoa plantations (CP) in Ojo Camp, Ugboke, Edo State of Nigeria were investigated and compared with those recovered from host specimens collected from the village settlement (VS). The anurans were caught by hand following visual or acoustic location. The anurans encountered in both the VS and the CP included Aubria subsigillata, Hylarana spp. (H. albolabris and H. galamensis), Sclerophrys spp. (S. maculata and S. regularis), Ptychadena spp. (P. aequiplicata, P. longirostris, P. mascareniensis, P. oxyrhynchus and P. pumilio) and Hoplobatrachus occipitalis. Hylarana galamensis, Ptychadena spp. and Sclerophrys spp. were encountered in the VS and the CP while Aubria subsigillata, H. albolabris and H. occipitalis occurred only in the CP. The helminth parasites recovered included four cestode species (adult of Cylindrotaenia jaegerskioeldi and three encysted  proteocephalid larvae), five Polystoma spp. 11 species of digeneans and 19 nematode species. More parasite species were recovered from toads collected from the VS; parasite prevalence was generally low in both habitats but the intensity of infection was higher in the specimens collected from the VS. Although cip A. subsigillata and H. ocitalis both occurred in the CP, A. subsigillata was the more susceptible host of the two, harbouring 16 helminth parasites as against four from H. occipitalis. Polystomes were recovered from H. albolabris and H. galamensis in addition to Diplodiscus fischthalicus and Mesocoelium spp. Infections occurred  mostly among the Ptychadeniidae collected from the CP, with prevalence ranging from 12.5% to 100% and infection intensity from 1.0 to 13.0. The generally low parasite burden in anurans from the CP can possibly be attributed to the pesticide contamination of this habitat which may have hindered the development of the free-living stages of parasites in this milieu. Keywords: Anurans; cocoa plantation; pesticides; parasitofauna; prevalence; intensity.

The endohelminths parasitizing leaf litter frogs (LLFs) at Ojo Camp, Ugboke, Ovia South West Local Government Area of Edo State, Nigeria were investigated. The frogs were collected from cocoa plantations (CPs) exposed to pesticides and from the village settlement (VS) located outside the pesticide use environment, for 15 months, using the Visual Acoustic Encounter Surveys method and disturbance searches. Two genera of LLFs were encountered: Arthroleptis (A. poecilonotus, A. variabilis, and six other undetermined Arthroleptis spp.) and Phrynobatrachus (P. auritus, P. plicatus, P. natalensis and Phrynobatrachus sp.). The overall prevalence of infection in LLFs from the CPs and VS were 37.4% and 50.0%, respectively but thedifference was not significant (p>0.05). The most parasitized LLF in the CPs was the unidentified Phrynobatrachus sp. (64.7%); in the VS infections were only recorded in A. poecilonotus (50%, n=4) and the single specimens of Arthroleptis sp. 2 collected from this habitat. The helminth parasites recovered included four cestodes (two adults: Cylindrotaenia jaegerskioeldi and Ophiotaenia sp.) and two larvae (two unidentified Proteocephalus spp.), three digenetic trematodes (two unidentified Mesocoelium spp. and a strigeoid larva) and eight nematode species (Amplicaecum sp.,  Aplectana sp., Cosmocerca ornata, Cosmocerca sp., Foleyellides sp., Physaloptera sp., Rhabdias sp. and an Ascaridida sp.). Although the cocoa plantations had very high species richness and diversity of parasites (15 parasite species), the intensity of infection was low. This generally low infection intensity reflects the inhibitory effects of the pesticide-contaminated environment of the CPs on parasite larval development and  transmission. Keywords: Leaf litter frogs; helminth parasites; prevalence; intensity; cocoa plantations; pesticides.

The endoparasitic infections of anurans from Evbuabogun, a peri-urban community in Ikpoba-Okha Local Government Area of Edo State, southern Nigeria was investigated. The six anuran species encountered and the parasite prevalence recorded in them were Hoplobatrachus occipitalis (56.5%), Leptopelis spiritusnoctis (50%), Ptychadena oxyrhynchus (76.7%), P. pumilio (100%), Sclerophrys maculata (90.9%) and S. regularis (100%). Overall parasite prevalence and mean intensity were 75.6% and 52.4, respectively. The endoparasites recovered included pentastomids (Raillietiella sp.), acanthocephalan cystacanth, cestodes (Cylindrotaenia jaegerskioeldi and Nematotaenoides sp.), digeneans (Metahaematoloechus micrurus and Mesocoelium monodi) and nematodes (Camallanus dimitrovi, Chabaudus leberrei, Cosmocerca commutata, C. ornata, Oswaldocruzia hoepplii, Rhabdias africanus, Amplicaecum sp., Aplectana sp., Physaloptera sp., Ophidascaris sp. larva and an unidentified oxyurid nematode). The few anuran species recorded attests to the degraded nature of the study area. We presume that the high parasite prevalence in the anurans examined was due to intense exposure to parasite larvae in the few and crowded aggregation/breeding sites in the locality. Furthermore, exposure to herbicides used to suppress weeds in nearby farms, (which contaminate breeding ponds through run-offs), may have suppressed the immunity of the frogs, thus rendering them more susceptible to parasitic infections. Infections of P. pumilio with Raillietiella sp. and Nematotaenoides sp. are new

This paper is a survey of the parasite diversity, prevalence and infection intensity in anurans in diverse ecological settings in West Africa. The settings included natural habitats (rainforests, freshwater creeks, Guinea and Sudan savannas), monoculture plantations (cocoa, cotton and oil palm), urbanized and urbanizing rainforest biotopes and polluted environments due to oil industry activities. The natural habitats had higher amphibian species diversity, moderate parasite prevalence and low infection intensity, showing a balance in the host/parasite relationship. These habitats yielded most of the monogeneans, among which were new species. The freshwater creek biotope had low amphibian diversity, but hosts from this environment harbored several parasite taxa, a situation attributed to a prolonged wet season, high environmental humidity and persistent breeding pools for insect vectors in this area. The monoculture plantations were characterized by high parasite prevalence but lower infection intensity. For example, in the Pendjari Biosphere Reserve in Bénin Republic, the Agricultural Zone (AZ) had higher parasite prevalence values, while the National Park (NP) and Buffer Zone (BZ) had higher infection intensities. Higher prevalence was attributed to the single or combined effects of vector population explosion, immune-suppression by agrochemicals, nutrient enrichment and eutrophication from fertilizer use. The lower infection intensity was attributed to the inhibitory effect of the pesticide-contaminated environment on the free-living larval stages of parasites. The adverse effect of pesticide contamination was also evident in the lower infection intensity recorded in the anurans from the cocoa plantations at Ugboke in comparison to those from the pesticide-free village settlement. Urbanization reduced host diversity and numbers and increased the vector population, resulting in unusually high parasite prevalence and infection intensities at Diobu and Port Harcourt and high prevalence recorded for Ophidascaris larvae in the anurans of Evbuabogun. Oil pollution in the mangrove community reduced both host and parasite diversity; infection intensity was also low due to the adverse conditions confronting free-living stages of parasites in their development milieu. The high prevalence values obtained for monogeneans (Polystoma spp.) in Ptychadena spp. from Ogoniland was presumed to have resulted from host tadpole sequestration and exposure to high oncomiracidia burden in the few hospitable ponds. Also reviewed is the phenomenon of amphibian paratenism, a strategy on which many helminth parasites rely on for their trophic transmission to their definitive hosts.