مقاله انگلیسی رایگان در مورد کنترل بیولوژیکی خاکهای انتقال دهنده سرمی در پارک باغی – الزویر 2018

Toxascaris leonina and Trichuris sp. are soil-transmitted helminths (STHs) infecting domestic and wild mammals. The antagonistic effect of the saprophytic filamentous fungi Mucor circinelloides and Verticillium sp. was examined on eggs of T. leonina passed in the feces of captive lynxes (Lynx lynx) kept in a zoological park. The activity of M. circinelloides and Trichoderma atrobrunneum was tested on eggs of Trichuris sp. shed by captive dromedaries (Camelus dromedarius). The parasiticide activity was assessed by measuring the ovistatic (delayed development) and ovicidal (non-viability) effects on eggs placed in Petri plates, and by spraying spores directly onto fecal samples. Based on the observation of that hyphae of M. circinelloides, Verticillium sp. and T. atrobrunneum adhered to the eggshells, penetrated and destroyed the inner embryo, an ovicidal type 3 effect was concluded. Development of eggs of T. leonina and Trichuris sp. in the feces was delayed in the presence of all fungi, and one third remained at the stage of zygote. A significant reduction of T. leonina viable eggs was recorded in the feces sprayed spores of M. circinelloides (58%) or Verticillium sp. (67%). Fifty percent of the eggs of Trichuris sp. became into non-viable by 30 days after the exposure to either M. circinelloides or T. atrobrunneum. It is concluded that distribution of the filamentous fungi M. circinelloides, Verticillium sp. and T. atrobrunneum constitutes a novel approach to conduct the biological control of the STHs (T. leonina and Trichuris sp.) affecting wild animals captive in a zoological park.

Introduction

Soil-transmitted helminths (STHs) are parasites involving roundworms (ascarids), hookworms and whipworms which can affect animals and humans. Infection occurs through the accidental ingestion of infective eggs in contaminated soil or food (Vandemark et al., 2010; Elsheika, 2011), which develop in the feces from unembryonated eggs shed by adult female worms localized in the intestine (Mateus et al., 2014; Hoopes et al., 2015). Embryonation happens in the feces or ground after several weeks, resulting in that a second stage larva (L2) originates inside the eggs of ascarids, which becomes into infective (Hendrix, 2014), whereas in the case of whipworms the eggs are infective when a L1 larva develops inside (Felsmann et al., 2017). The role of rodents as paratenic hosts has been indicated in the transmission of Toxocara and Toxascaris (Okulewicz et al., 2012), and thus it has been pointed that the cycles of these nematodes could be considered as non-strictly monoxenous (Reperant et al., 2007). Some ascarid species have zoonotic potential, as Toxocara canis, T. cati, Baylisascaris procyonis, Ascaris suum or Toxascaris leonina, frequently detected in domestic (cats, dogs, pigs) and wild mammals (foxes, wolves, lynxes, raccoons) (Okulewicz and Buńkowska, 2009; Dado et al., 2012; Carver et al., 2012; Beiromvand et al., 2013; Neves et al., 2014; Figueiredo et al., 2016). The zoonotic role of Trichuris spp. has been also reported (Gałęcki et al., 2015; Felsmann et al., 2017; Gawor and Borecka, 2017). As indicated for other STHs, control of ascarids regularly comprises the administration of anthelmintics together with adequate hygiene (Alemu et al., 2011). Despite successful deworming is frequently administered among captive wild carnivores in zoo gardens (lions, lynxes, foxes, wolves), they infected again by helminths because their maintenance in the same parcels enhances that ground is permanently contaminated by eggs passed in the feces (Fagiolini et al., 2010; Maesano et al., 2014). In the same way, frequent infection by Trichuris sp. in dromedaries has been also described (Gurler et al., 2010; Eo et al., 2014). The eggs of ascarids and whipworms are very resistant to chemical and climatic factors, thus can remain infective in the soil for several years (Gavin et al., 2005; Overgaauw and van Knapen, 2013; Gałęcki et al., 2015; Gawor and Borecka, 2017). Nevertheless, there is insufficient information regarding measures to reduce the presence of infective stages in the ground. Prior investigations reported that certain saprophytic soil fungi perform an antagonistic activity on eggs of T. canis and A. suum, based on their ability to adhere to the eggshell, penetrate and destroy the embryo inside (Carvalho et al., 2010; Cortiñas et al., 2015).