Ecological Scenarios and Parasite Diversity in Anurans of West Africa: A Review

Abstract

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.

Parasitic helminths of alien invasive anurans in Butuan City, Northeastern Mindanao, Philippines

“…In the urban areas of the Philippines, high prevalence of gastrointestinal parasites was reported in anurans ( Ybanez et al ., 2018 ). The process of urbanization also reduces the number of hosts and increases the vector population of anurans ( Aisen et al ., 2021 ).…”

“…Agroforestry helps to maintain bio-diversity by creating diverse habitats and reducing environmental disruptions caused by agricultural activities ( Rosenstock et al ., 2019 ). However, agricultural practices that involve pesticides and herbicides can alter the environment and contribute to the development of free-living parasite forms due to their immunosuppressive and inhibitory effects ( Aisien et al ., 2021 ). In the Philippines, farm areas in Luzon have recorded a prevalence of 40 % to 72 % soil-transmitted parasites.…”

Inclusive Environmental Decision-making in a Developing Nation: Insights from the Ogoni Remediation Project, Niger Delta, Nigeria

“…The arable crops include cassava, yams, maize, pineapple, pepper, rice and leafy vegetables (Bodo and Gimah 2019 ; Ganabel et al 2021 ). The tree and fruit crops include the oil palm, rubber, cocoa, plantain, pawpaw, mango, guava and citrus (Aisien et al 2021 ). Thus, the traditional livelihood of the local population in the region is farming and fishing.…”

Nematodes of Amphibians from the South American Chaco: Distribution, Host Specificity and Ecological Aspects

“…In addition, knowledge on the geographic distributions of parasites and host species are the empirical basis for future research using amphibians as models of parasite-host interaction patterns [2][3][4]. In this sense, there are investigations that contribute to the knowledge of the distribution and diversity of helminths in amphibians of different biogeographic regions such as Afrotropical [5][6][7], Australasian [8][9][10], Indomalayan [11][12][13], Nearctic [14][15][16] and Palearctic [17][18][19][20][21].…”