Tick control is a priority in order to prevent the transmission of vector-borne diseases. Industrial chemical acaricides and repellents have been the most efficient tools against hard ticks for a long time. However, the appearance of resistances has meant the declining effectiveness of the chemicals available on the market. The trend today is to develop alternative control methods using natural products to replace nonefficient pesticides and to preserve the efficient ones, hoping to delay resistance development. Traditional in vitro evaluation of acaricidal activity or resistance to synthetic pesticides have been reviewed and they mainly focus on just one species, the one host tick (Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)). Recent reports have called for the standardization of natural product components, extraction techniques, and experimental design to fully discover their acaricidal potential. This study reviews the main variables used in the bibliography about the efficiency of natural products against ticks, and it proposes a unification of variables relating to ticks, practical development of bioassays, and estimation of ixodicidal activity.

An approach to preventing strongyle infection in horses was tested, comprising rotational pasturing and the administration of spores of two parasiticidal fungi, Mucor circinelloides and Duddingtonia flagrans. Twenty-two adult Spanish Sport Horses were dewormed with ivermectin (1 mg pour-on/kg body weight) and then randomly divided into three groups. G-1 was maintained with continuous grazing, and G-2 and G-3 were kept on a four-paddock rotation system. Commercial pelleted feed (2.5 kg/horse) was supplied to G-1 and G-2 twice a week; horses in G-3 received pellets containing 2 × 106 spores/kg of each fungus. Fecal samples were analyzed by the flotation method to estimate the reduction in the fecal egg counts (FECR), the percentage of horses shedding eggs (PHR), and the egg reappearance period (ERP). Third-stage larvae were identified in fecal pats as Cyathostomum (sensu lato) types A, C and D, Gyalocephalus capitatus, Triodontophorus serratus, Poteriosthomum spp., Strongylus vulgaris and S. edentatus. Two weeks after treatment, the FECR values were 100% in G-1, 96% in G-2 and 99% in G-3; the PHR values were 100% in G-1, 75% in G-2 and 88% in G-3. A strongyle ERP of 6 weeks was observed in G-1, ERP of 10 weeks was observed in G-2, and ERP of 16 weeks was observed in G-3. The counts of eggs per gram of feces (EPG) were > 300 EPG in G-1 and G-2 but remained below 250 EPG in G-3 throughout the observation period of 12 months. These results suggest that horse strongyle infection could be decreased by combining rotational pasturing with feeding pellets containing the spores of parasiticidal fungi.

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 <250 EPG. The values of red blood cell parameters registered for CT1 and CT2 were lower than those of the reference standards, while a significant increment was recorded in FS1 and FS2, and values within the physiological range were attained. It is concluded that integrating efficient anthelminthic deworming with rotational pasturing and the regular intake of chlamydospores of 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.

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.

Free-ranging hens are at risk of infection by parasites characterized by certain stages that develop in the soil until attaining the infective phase. To analyze the usefulness of a biological control strategy of helminths affecting pasturing hens, fecal samples containing eggs of the helminths Ascaridia galli and Capillaria spp. were collected and then homogenized with an electric mixer. A total of 64 small areas were established by placing wooden frames (15 × 40 × 30 cm) on the ground and then adding approximately 100 g of a fecal mixture (per area). Four batches of 16 areas were considered: G1, sprayed with 2 × 10⁶ spores of the parasitophagous fungus Mucor circinelloides (day 0) at 0.5 L/m² (=600 mL/area); G2, sprayed with spores twice (every two weeks); G3, sprayed four times (every week); and Control, sprayed weekly with water. After a four-week period, the egg viability reduced for ascarids and capillarids (26% and 27%, respectively) in the control group; 64% and 79% in G1; 71% and 82% in G2; and 79% and 80% in G3. It was concluded that spraying with fungal spores provides a very useful tool for preventing infection by helminths on free-range poultry.

Several species of saprophytic filamentous fungi are able of disrupting the life cycle of certain soil-born parasites that are of veterinary and agronomy importance, offering a promising sustainable control alternative. This study consisted of designing an experimental model, using catnip (Nepeta cataria) trays to simulate a vegetated environment for evaluating the parasiticidal activity of Mucor circinelloides, Trichoderma atrobrunneum, and Duddingtonia flagrans. Fungal spores were added to treated trays before adding feces with protozoan (Eimeria spp.), and gastrointestinal nematodes (roundworms, strongyles), and untreated-control water. No differences in plant growth or vigor, regardless of fungal presence, were observed, confirming the safety of these biological agents for vegetation. In the control trays, the viability of parasites ranged from 50% to 85%. In the treated trays, the viability of Eimeria and roundworms decreased by 40–100%, and the strongyle egg counts were reduced by 74% within 15 days. It is concluded that the vegetated tray model effectively simulates field conditions and provides a reliable platform for evaluating fungal efficacy against the free-living stages of parasites, offering a versatile tool for future research on soil-borne pathogens affecting animals and plants.