Predatory activity of nematophagous fungi on infective larvae of Ancylostoma sp.: evaluation in vitro and after passing through the gastrointestinal tract of dogs

Assessing the applications and efficacy of using helminthophagous fungi to control canine gastrointestinal parasites

Helminths are a major challenge in dog breeding, particularly affecting young animals and posing a significant zoonotic risk. The widespread use of anthelmintics to treat gastrointestinal helminth infections in companion animals is common. However, these chemical products generate residues that can have adverse effects on animal, human and environmental health. In addition to the challenge of parasite resistance to treatment, there is an urgent need to explore and discuss complementary and sustainable methods of controlling helminthiases in these animals. In this context, nematophagous or helminthophagous fungi have emerged as a potential tool for the control of environmental forms of helminths. The purpose of this review is to emphasize the importance of these fungi in the control of free-living forms of helminth parasites in companion animals by highlighting the research that has been conducted for this purpose. In vitro experiments demonstrated the efficacy of fungi like Pochonia chlamydosporia, Arthrobotrys robusta, and Monacrosporium thaumasium in trapping and reducing helminth infective forms. These findings, along with soil contamination studies, suggest the feasibility of using helminthophagous fungi as a sustainable and effective strategy for environmental control. The current literature supports the potential of these fungi as an environmentally friendly solution for managing helminthiasis in dogs, benefiting both animal health and public welfare.

It's a worm-eat-worm world: Consumption of parasite free-living stages protects hosts and benefits predators

Predation on parasites is a common interaction with multiple, concurrent outcomes. Free-living stages of parasites can comprise a large portion of some predators' diets and may be important resources for population growth. Predation can also reduce the density of infectious agents in an ecosystem, with resultant decreases in infection rates. While predator-parasite interactions likely vary with parasite transmission strategy, few studies have examined how variation in transmission mode influences contact rates with predators and the associated changes in consumption risk. To understand how transmission mode mediates predator-parasite interactions, we examined associations between an oligochaete predator Chaetogaster limnaei that lives commensally on freshwater snails and nine trematode taxa that infect snails. Chaetogaster is hypothesized to consume active (i.e. mobile), free-living stages of trematodes that infect snails (miracidia), but not the passive infectious stages (eggs); it could thus differentially affect transmission and infection prevalence of parasites, including those with medical or veterinary importance. Alternatively, when infection does occur, Chaetogaster can consume and respond numerically to free-living trematode stages released from infected snails (cercariae). These two processes lead to contrasting predictions about whether Chaetogaster and trematode infection of snails correlate negatively ('protective predation') or positively ('predator augmentation'). Here, we tested how parasite transmission mode affected Chaetogaster-trematode relationships using data from 20,759 snails collected across 4 years from natural ponds in California. Based on generalized linear mixed modelling, snails with more Chaetogaster were less likely to be infected by trematodes that rely on active transmission. Conversely, infections by trematodes with passive infectious stages were positively associated with per-snail Chaetogaster abundance. Our results suggest that trematode transmission mode mediates the net outcome of predation on parasites. For trematodes with active infectious stages, predatory Chaetogaster limited the risk of snail infection and its subsequent pathology (i.e. castration). For taxa with passive infectious stages, no such protective effect was observed. Rather, infected snails were associated with higher Chaetogaster abundance, likely owing to the resource subsidy provided by cercariae. These findings highlight the ecological and epidemiological importance of predation on free-living stages while underscoring the influence of parasite life history in shaping such interactions.

Purpureocillium lilacinum and Trichoderma virens for biological control of trichostrongylid parasites of sheep: an in vitro evaluation

The study evaluated the ovicidal activity of enzymatic extracts of Purpureocillium lilacinum and Trichoderma virens against trichostrongylid eggs from sheep. Filtered extract (FE) and macerated crude extract (MCE) were prepared from fungal cultures in minimal broth. In the experiment, 100 trichostrongylid eggs, obtained from the feces of naturally infected sheep, were exposed to fungal extracts for 24 and 48 hours/25°C. In the control group, eggs were incubated in minimal broth. The number of L1 larvae was ascertained. Each treatment consisted of four repetitions and the experiment was repeated five times. It was observed that the effect of FE and MCE of P. lilacinum and T. virens on egg hatchability differed from that of the control group. MCE of T. virens and P. lilacinum showed higher ovicidal activity than FE over both periods and at 48 hours of exposure, respectively. From the percentage reductions in hatchability of the eggs, MCE was shown to be superior to FE for both fungi. This study demonstrated the ovicidal potential of these fungi against trichostrongylid eggs. However, further studies are needed in order to identify the molecules responsible for the ovicidal effects, and to evaluate the behavior of fungal extracts in biotic and abiotic interactions.

The efficacy of predatory fungi on the control of gastrointestinal parasites in domestic and wild animals-A systematic review

BACKGROUND

Gastrointestinal parasites like nematodes are associated with significant impacts on animal health, causing poor growth rates, diseases and even death. Traditional parasite control includes the use of anthelmintic drugs, albeit being associated with drug resistance and ecotoxicity. In the last decade, biological control of parasites using nematophagous or predatory fungi has been increasingly studied, although systematic evidence of its efficacy is still lacking. The aim of this work was to assess the evidence of efficacy of nematophagous fungi in the control of nematodes and other gastrointestinal parasites in different animal species.

METHODS

Using the PICO method (Population, Intervention, Comparison and Outcomes), we performed a systematic review on the subject to search for original papers published between January 2006 and October 2019, written in English, and indexed in PubMed/Medline. Medical Subject Headings (MeSH) terms were used in the syntax. Papers were selected for detailed review based on title and abstract. Inclusion and exclusion criteria were applied, and relevant data were collected from the remaining papers.

RESULTS

The literature search retrieved 616 papers. Eighty-nine were submitted to a detailed review. In the end, 53 papers were included in the analysis. The studies were very heterogeneous, using different fungi, doses, frequency of administration, duration of treatment, host animals, and target parasites. Considering the 53 papers, 44 studies (83 % of the interventions) showed efficacy, with only 9 studies (17 %) showing no significant differences when compared to control.

CONCLUSION

With the increasing hazards of drug resistance and ecotoxicity, biological control with predatory fungi stands out as a good tool for future parasite management, whether as a complementary treatment or as an alternative to standard parasite control.

Effect of Paecilomyces lilacinus, Trichoderma harzianum and Trichoderma virens fungal extracts on the hatchability of Ancylostoma eggs

BACKGROUND

Ancylostoma species have demanded attention due to their zoonotic potential. The use of anthelmintics is the usual method to prevent environmental contamination by Ancylostoma eggs and larvae. Nematophagous fungi have been widely used in their biological control due to the fungus ability to capture and digest free nematode forms.

AIMS

The aim of this study was to evaluate the effect of four different fungal extracts of Paecilomyces lilacinus (n=2), Trichoderma harzianum (n=1) and Trichoderma virens (n=1) isolates on the hatchability of Ancylostoma eggs.

METHODS

Fungal extracts consisted of fungal broth culture supernatant without filtration (crude extract) and filtered broth (filtered extract), macerated mycelium (crude macerate), and macerated mycelium submitted to filtration (filtered macerate). The Ancylostoma eggs were obtained from the feces of naturally infected dogs. In vitro assays were performed in five replicates and consisted of four treatments and one control group.

RESULTS

The activity of the fungal extracts of each evaluated fungus differed (p<0.05) from those of the control group, showing significant ovicidal activity. The hatching of the eggs suffered reduction percentages of 68.43% and 47.05% with P. lilacinus, and 56.43% with T. harzianum, when crude macerate extract was used. The reduction with the macerate extract of T. virens was slightly lower (52.25%) than that for the filtered macerate (53.64%).

CONCLUSIONS

The results showed that all extracts were effective in reducing the hatchability of Ancylostoma eggs. The ovicidal effect observed is likely to have been caused by the action of hydrolytic enzymes secreted by the fungi.

Comparative study of cultivation of feces in vermiculite or charcoal to obtain larvae of Strongyloides venezuelensis

INTRODUCTION

We compared feces culturing in charcoal or vermiculite to obtain Strongyloides venezuelensis larvae.

METHODS

Feces (5 g) from infected rats was mixed with vermiculite (10 g) or coal (10 g) in plastic cups and incubated at 28°C for 48 h. Larvae were recovered using Baermann-Moraes method.

RESULTS

Significantly higher number of positive larval cultures were recovered from vermiculite than from charcoal (15/17 and 4/17, respectively; p < 0.001; 990.6 ± 307.5 and 215 ± 78.1 larvae, p = 0.027).

CONCLUSIONS

Vermiculite yields more larvae and provides cleaner pellets, improving larvae identification and facilitating their use for other purposes.

Fungi predatory activity on embryonated Toxocara canis eggs inoculated in domestic chickens (Gallus gallus domesticus) and destruction of second stage larvae

The objective of this study was to evaluate the infectivity of Toxocara canis eggs after interacting with isolated nematophagous fungi of the species Duddingtonia flagrans (AC001) and Pochonia chlamydosporia (VC4), and test the predatory activity of the isolated AC001 on T. canis second stage larvae after 7 days of interaction. In assay A, 5000 embryonated T. canis eggs previously in contact with the AC001 and VC4 isolated for 10 days were inoculated into domestic chickens (Gallus gallus domesticus), and then these animals were necropsied to collect material (digested liver, intestine, muscles and lungs) at 3-, 7-, 14-, and 21-day intervals after inoculation. In assay A, the results demonstrated that the prior interaction of the eggs with isolated AC001 and VC4 decreases the amount of larvae found in the collected organs. Difference (p < 0.01) was observed in the medium larvae counts recovered from liver, lung, intestine, and muscle of animals in the treated groups when compared to the animals in the control group. At the end of assay A, a percentage reduction of 87.1 % (AC001) and 84.5 % (VC4) respectively was recorded. In the result of assay B, the isolated AC001 showed differences (p < 0.01) compared to the control group, with a reduction of 53.4 % in the recovery of L2. Through these results, it is justified to mention that prior interaction of embryonated T. canis eggs with the tested fungal isolates were efficient in reducing the development and migration of this parasite, in addition to the first report of proven predatory activity on L2.

First report of the activity of predatory fungi on Angiostrongylus cantonensis (Nematoda: Angiostrongylidae) first-stage larvae

The nematode Angiostrongylus cantonensis causes eosinophilic meningoencephalitis in humans and thus alternative methods of control should be studied. The objective of this work was to evaluate the predatory capacity of eight fungal isolates of the species Duddingtonia flagrans (AC001, CG768 and CG722), Monacrosporium thaumasium (NF34), M. sinense (SF53) and Arthrobotrys robusta (I31), A. cladodes (CG719) and A. conoides (I40) on first-stage larvae (L₁) of A. cantonensis under laboratory conditions. The treated groups contained 1000 conidia of the fungal isolates and 1000 A. cantonensis L₁ in Petri dishes containing 2% water-agar medium (2% WA). The control group (without fungi) contained only 1000 A. cantonensis L₁ in 2% WA. Evidence of predation was observed at the end of 7 days. Percentage reductions in L₁ were: AC001, 82.8%; CG768, 71.0%; CG722, 72.8%; NF34, 86.7%; SF53, 89.7%; I40, 48.3%; CG719, 84.7%; and I31, 80.4%. No significant difference was observed (p>0.01) between the actions of the isolates used; however, a difference was noted (p<0.01) in relation to the control group. The results of the present work, confirm previous reports of the effectiveness of the fungi D. flagrans, M. thaumasium, M. sinense and A. robusta in controlling larvae of potentially zoonotic nematodes, this being the first report on A. cantonensis L₁.

First report of interaction of nematophagous fungi onLibyostrongylus douglassii (Nematoda: Trichostrongylidae)

Libyostrongylus douglassii is a gastrointestinal nematode parasite of ostriches that can cause up to 50% mortality in young birds. The objective of this study was to compare the predatory capacity of two isolates of the predatory fungi Duddingtonia flagrans(AC001 and CG722 isolates) and one of Arthrobotrys cladodes (CG719) on infective larvae (L3) of L. douglassii under laboratory conditions, in 2% water-agar medium. The results showed that the fungi tested were effective in preying upon the L3 of L. douglassii (P < 0.05), compared with the control group. However, there was no difference in predatory capacity between the fungi tested (P > 0.05) during the seven days of experimental testing. In comparison with the control, without fungus, there were significant decreases (P < 0.05) of 85.2% (AC001), 81.2% (CG722) and 89.2% (CG719) in the average numbers of L3 of L. douglassii recovered from treatments with the isolates tested. In the present study, the three isolates of the predatory fungi D. flagrans (AC001 and CG722) andA. cladodes (CG719) were efficient at in vitro destruction of the L3 of L. douglassii.

[Predatory activity of the nematophagous fungi Duddingtonia flagrans, Monacrosporium thaumasium and Arthrobotrys robusta on Strongyloides stercoralis infective larvae]

INTRODUCTION

Strongyloides stercoralis is a nematode that infects much of the population worldwide.

METHODS

This study aimed to compare the ability of predatory nematophagous fungi Duddingtonia flagrans (AC001), Monacrosporium thaumasium (NF34) and Arthrobotrys robusta (I-31) on infective larvae (L₃) of Strongyloides stercoralis in laboratory conditions on 2% water-agar.

RESULTS

At the end of the experiment, the percentage reductions in Strongyloides stercoralis L3 were 83.7% (AC001), 75.5% (NF34) and 73.2% (I-31).

CONCLUSIONS

The nematophagous fungi were able to capture and destroy the L3 in vitro and may be used as biological controls of Strongyloides stercoralis.

The effect of nematophagous fungus Duddingtonia flagrans on the gastrointestinal parasites in sheep

Sheep production has serious problems due to the spread of intestinal parasites. These parasites cause loss of appetite, maldigestion, slow growth in body weight and wool, all of which results in economic losses as well. The control measures of infestation with strongyloid parasites in ruminants have until now been based mainly on the organization of grazing and the use of antihelmintics. However, due to the occurrence of resistance, alternative methods of control have been introduced. The use of nematophagous fungus Duddingtonia flagrans, which is capable of decreasing the number of infectious larvae and eggs in feces, has been successful. The aim of this study was to determine whether Duddingtonia flagrans decreases the number of eggs of Trichostrongylus spp in sheep feces. Fecal samples of thirty-four sheep were examined and the parasites were found in twelve sheep, six of which were fed with the fungus, and six of which were used as the control. According to ?2 test, at the level of certainty of p<0,005, a statistically important difference in the number of eggs was observed between the sheep which were given the fungus and those which were not.

When parasites become prey: ecological and epidemiological significance of eating parasites

Recent efforts to include parasites in food webs have drawn attention to a previously ignored facet of foraging ecology: parasites commonly function as prey within ecosystems. Because of the high productivity of parasites, their unique nutritional composition and their pathogenicity in hosts, their consumption affects both food-web topology and disease risk in humans and wildlife. Here, we evaluate the ecological, evolutionary and epidemiological significance of feeding on parasites, including concomitant predation, grooming, predation on free-living stages and intraguild predation. Combining empirical data and theoretical models, we show that consumption of parasites is neither rare nor accidental, and that it can sharply affect parasite transmission and food web properties. Broader consideration of predation on parasites will enhance our understanding of disease control, food web structure and energy transfer, and the evolution of complex life cycles.