Helminth parasitic infections of leaf litter frogs (Arthroleptis and Phrynobatrachus spp.) from cocoa plantations in southern Nigeria

Abstract

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 the
difference 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.