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Controlling parasites in zoo animals is a significant challenge, making practical infection prevention methods essential. This study evaluated a novel solution using parasitophagous fungi-treated forage seeds to reduce soil parasite persistence. We conducted two experiments to assess the soil distribution of the fungi Mucor circinelloides (ovicidal) and Duddingtonia flagrans (larvicidal). Forage seeds were immersed in a submerged culture containing 106 spores/mL and subsequently sown in plastic trays (trial 1) and demarcated ground plots (40 × 30 cm) framed with wood (trial 2). Fifteen days later, Ascaris suum and cyathostomin eggs were placed above the germinated vegetation. After a 25–30-day period, the viability of roundworm eggs reduced by 62%, and half of them remained undeveloped; a 64% reduction in the counts of L3 cyathostomins was recorded. In trial 2, viability decreased by 55% in roundworm eggs, with an infectivity rate of 30%, while L3 counts lessened by 57%. It has been concluded that the risk of infection by ascarids and cyathostomins can be reduced by at least half by sowing the soil with forage seeds pre-treated with fungi, providing a practical solution for parasite control in zoos.

In recent decades, important modifications have been introduced in zoos in order to guarantee the welfare of captive wild animals. Thus, many of these species are housed in enclosures with access to vegetation, where they can enjoy habitats close to those in their natural surroundings, interact with the environment, etc. These habitats present beneficial conditions for some species of parasites to survive and spread. This is a very similar problem to that affecting livestock, and the same solution, based on deworming, is currently being applied. However, the free-living stages of certain parasites that develop in the soil are responsible for high rates of ground contamination throughout the year, so that animals become infected soon after successful deworming, resulting in chemical parasiticides being frequently administered. Preventive measures are seldom considered, which worsens the situation. This entry summarizes the usefulness of the dissemination of certain saprophytic filamentous fungi with proven antagonism against some of the parasites.

Nematophagous fungi are a biological control tool used against gastrointestinal nematodes in livestock. These fungi prey on free-living larvae in faeces and could be affected by active drugs excreted post-treatment. This study aimed to determine in vitro and under environmental conditions the effect of the following anthelmintics on the fungus Duddingtonia flagrans: ivermectin, levamisole, albendazole, fenbendazole and ricobendazole. The in vitro effect of anthelmintics on fungal growth and predatory capacity was assessed in corn meal agar and coprocultures, respectively. Ivermectin (1, 2 and 10 ppm), fenbendazole (0.027, 0.054 and 1 ppm) and albendazole (1 ppm) significantly affected fungal development. The fungal efficacy against L3 was high in the control and levamisole coprocultures but decreased significantly in the presence of albendazole, fenbendazole, ricobendazole and ivermectin. The impact of levamisole on D. flagrans was further assessed under environmental conditions in autumn and winter; the fungal efficacy measured in faecal pats and the surrounding herbage was not affected by levamisole at any time. This study shows that using albendazole, fenbendazole, ricobendazole or ivermectin may compromise fungal activity, as these drugs affect the free-living stages of nematodes in faeces, but levamisole can be safely considered in parasite control strategies involving D. flagrans and anthelmintic treatments.

The filtrate of the nematophagous fungus Duddingtonia flagrans produces silver nanoparticles (AgNPs) with nematicidal potential. However, there are currently no reports of its activity against Toxocara canis eggs. The aim of this study was to investigate the potential ovicidal activity of AgNPs–D. flagrans on T. canis eggs. T. canis eggs were obtained from the dissection of the uterus of adult female nematodes. After the biosynthesis of AgNPs, two experimental assays (A and B) were performed. In assay A, the ovicidal activity of AgNPs on eggs was evaluated after 15 and 30 days of interaction. In assay B, the inhibition (development) of the eggs was measured after 30 days of interaction. The results of assay A showed that the AgNPs destroyed an average of 47% of the eggs tested by the end of the experiment, causing significant structural damage. In assay B, an inhibition rate of 88% was observed at the end of 30 days. The results of the ovicidal activity of AgNP–D. flagrans were promising and indicate the potential for future studies on these biomolecules with ovicidal properties.

Control of infection by gastrointestinal nematodes remains a big problem in ruminants under continuous grazing. For the purpose of decreasing the risk of infection by Trichuris sp. in captive bison (Bison bison) always maintained in the same plot, dried gelatins having ≥106 chlamydospores of both Mucor circinelloides and Duddingtonia flagrans were given to them for one week, and at the end, fecal samples (FF) collected each week for four weeks were analyzed immediately. Feces taken one week prior to gelatin administration served as controls (CF). Eggs of Trichuris sp. were sorted into non-viable and viable, then classified into viable undeveloped (VU), viable with cellular development (VCD), or viable infective (VI). Ovistatic and ovicidal effects were determined throughout the study. In FF, viability of Trichuris eggs decreased between 9% (first week) and 57% (fourth week), egg development was delayed during the first two weeks, and VI percentages were significantly lower than in CF (p = 0.001). It is concluded that the preparation of gelatins with chlamydospores of parasiticidal fungi and their subsequent dehydration offer an edible formulation that is ready to use, stress-free to supply, and easy to store, as well as being well-accepted by ruminants and highly efficient to reduce the risk of Trichuris sp. infection among animals under continuous grazing regimes.

The purpose of using nematophagous fungi as biological control agents of gastrointestinal nematodes of livestock is to reduce the build-up of infective larvae on pasture and thus avoid clinical and subclinical disease. As the interaction of fungus-larval stages takes place in the environment, it is crucial to know how useful the fungal agents are throughout the seasons in areas where livestock graze all year-round. This study was designed to determine the predatory ability of the nematophagous fungus Duddingtonia flagrans against gastrointestinal nematodes of cattle during four experiments set up in different seasons. In each experiment, faeces containing eggs of gastrointestinal nematodes were mixed with 11,000 chlamydospores/g and deposited on pasture plots. A comparison between fungal-added faeces and control faeces without fungus were made with regard to pasture infectivity, larval presence in faecal pats, faecal cultures, faecal pat weight, and temperature inside the faecal mass. In three of the four experiments, Duddingtonia flagrans significantly reduced the population of infective larvae in cultures (68 to 97%), on herbage (80 to 100%), and inside the faecal pats (70 to 95%). The study demonstrated the possibility of counting on a biological control tool throughout most of the year in cattle regions with extensive grazing seasons.

Parasiticidal fungi have been used in several in vivo experiments in livestock farms worldwide, constituting an effective tool for the biocontrol of gastrointestinal parasites in grazing animals. In the first year of study, two groups of eight first-season pasturing ewe lambs infected by strongyles were dewormed with albendazole, and then, the test group received an oral dose of 106 chlamydospores of Mucor circinelloides and 106 Duddingtonia flagrans individually and thrice a week from mid-September to May (FS1), while the control group remained without fungi (CT1). In the second year, two new groups of first-season grazing ewe lambs were treated with ivermectin and subjected to the same experimental design (FS2 and CT2, respectively). The anthelmintic efficacy was 96.6% (CT1), 95.6% (FS1), 96.1% (CT2), and 95.1% (FS2). The counts of strongyle egg output increased in the control groups (CT1 and CT2) throughout the study and reached numbers higher than 600 eggs per gram of feces (EPG), while in FS1 and FS2, they were M. circinelloides and D. flagrans provides a helpful strategy for maintaining low levels of strongyle egg output in first-season grazing ewe lambs and improves their health status.

Plant parasitic nematodes, especially parasitic root-knot nematodes, are one of the most destructive plant pathogens worldwide. The control of plant root-knot nematodes is extremely challenging. Duddingtonia flagrans is a type of nematode-trapping fungi (NTF), which produces three-dimensional adhesive networks to trap nematodes. In this study, the pathogenicity and volatile organic compounds (VOCs) of the NTF D. flagrans against the plant root-knot nematode, Meloidogyne incognita, were investigated. The predatory process of D. flagrans trapping M. incognita was observed using scanning electron microscopy. Gas chromatography-mass spectrometry analysis of the VOCs from D. flagrans led to the identification of 52 metabolites, of which 11 main compounds were tested individually for their activity against M. incognita. Three compounds, cyclohexanamine, cyclohexanone, and cyclohexanol, were toxic to M. incognita. Furthermore, these three VOCs inhibited egg hatching of M. incognita. Cyclohexanamine showed the highest nematicidal activity, which can cause 97.93% mortality of M. incognita at 8.71 µM within 12 h. The number of hatched juveniles per egg mass after 3 days was just 8.44 when treated with 26.14 µM cyclohexanamine. This study is the first to demonstrate the nematicidal activity of VOCs produced by D. flagrans against M. incognita, which indicates that D. flagrans has the potential to biocontrol plant root-knot nematodes.

Cooperia, Haemonchus and Oesophagostomum are the genera of gastrointestinal parasitic nematodes most prevalent in cattle and constitute a serious problem in cattle breeding due to the impact they have on meat and milk production and the high costs of control measures. The objective of the present work was to evaluate the efficiency of Bioverm® (Duddingtonia flagrans) in the control of gastrointestinal parasitism of young cattle raised in the field, in the Central-West region of Brazil. The experiment was conducted on a farm located in the municipality of Jangada, MT, where 18 cattle, Nelore and Aberdeen Angus breeds, aged six to ten months, were randomly divided into two groups (treated group and control group) and distributed in paddocks of Brachiaria decumbens, naturally infested by larvae of gastrointestinal nematodes. The animals in the treated group received 1g of Bioverm® for each 10 kg of body weight, administered daily with commercial feed, throughout a period of six months. In the control group, each animal received 1 g of rice bran for each 10 kg of body weight, without Bioverm®, added to the feed. Stool and pasture samples were collected every two weeks. The treated group showed a significant reduction (p < 0.05) in values of eggs per gram of feces (EPG) and a significant gain of body weight (p < 0.05) when compared to the control group. The fungal formulation Bioverm® was effective in pasture decontamination and consequently in reducing the occurrence of reinfection by nematodes. The animals treated with Bioverm® showed a lower parasitic load and greater weight gain.