A review of the use of Duddingtonia flagrans as a biological controller of strongylid nematodes in horses

In horses, the nematodes of the Strongylidae family are the most important due to their prevalence and pathogenicity. Sanitary plans include parasite control based on chemical anthelmintics. Among these, the benzimidazole compounds have been used since the 1960s to control the nematode Strongylus vulgaris. Its inappropriate use resulted in the development of resistance in parasites with a shorter biological cycle, such as the small strongyles. Currently, the genera that make up this group show widespread resistance to all chemical treatments available in veterinary medicine, except for macrocyclic lactones, where less effective action has been detected. The need to find alternative routes for its control is recognized. International organizations and markets are increasingly restrictive in the allowed levels of drugs in products of animal origin, so one of the drawbacks is the permanence of chemical compounds in tissues. Therefore, other tools not chemically based are proposed, such as the biological control of gastrointestinal nematodes. Various research groups around the world have carried out tests on the control capacity of the nematophagous fungus Duddingtonia flagrans against this group of parasites. The objective of this review is to compile the different tests that are available on biological control in this species, in in vivo and in vitro tests, and the possible incorporation of this tool as an alternative method of antiparasitic control in an integrated control scheme of parasites.

Eficacia antiparasitaria in vitro del extracto de quebracho (Schinopsis balansae) sobre larvas infectantes de Haemonchus contortus de ovinos

El objetivo fue evaluar in vitro la eficacia del extracto de quebracho (Bioquina®), rico en taninos condensados, en el control de H. contortus de ovinos, dadas las evidencias de que los taninos condensados provenientes del extracto de quebracho (Schinopsis spp.) pueden reducir la excreción de huevos, la fecundidad de las hembras parásitas y la carga de parásitos nematodos gastrointestinales adultos en rumiantes. Se utilizó el test de inhibición de migración larval (IML) a 3 concentraciones diferentes (5 mg/ml, 15 mg/ml y 30 mg/ml) sobre larvas infectantes de H. contortus susceptibles a todos los grupos químicos. El efecto se analizó mediante un análisis de varianza y para la estimación de las diferencias entre grupos (a posteriori) se usó la prueba LSD Fisher. El test in vitro demostró que el extracto de quebracho evaluado redujo aproximadamente entre un 74% y un 80% la migración larval a las concentraciones de entre 5 mg/ml y 30 mg/ml. Del análisis de varianza surgen diferencias significativas entre tratamientos (p = 0,0494). Al realizar la prueba de comparación de medias se evidenciaron diferencias significativas (p < 0,05) entre los promedios de migración a las diluciones de 5 mg/ml y 15 mg/ml y de 5 mg/ml y 30 mg/ml, mientras que no se detectaron diferencias significativas entre la dilución de 15 mg/ml y 30 mg/ml. Estos resultados señalaron que el extracto de quebracho, a las diluciones evaluadas, presentó actividad antihelmíntica sobre larvas L3 susceptibles de H. contortus; sin embargo, se requiere ampliar los estudios in vivo en ovinos.

Ivermectin dissipation and movement from feces to soil under field conditions

The aim of this work was to evaluate the fate of ivermectin (IVM) at two concentrations in cattle feces and its movement to the nearby soil and plants. Feces were spiked with IVM at two levels: 3000 ng g^-1 (high group, HG) and 300 ng g^-1 (low group, LG). Artificial dung pats were prepared and deposited in an experimental field area. Feces and underlying soil were sampled up to 60 days post-deposition (dpd). As an additional analysis, grasses growing around the pats were sampled at 30 and 60 dpd. Ivermectin concentrations in all matrices were determined by HPLC. Mean IVM fecal concentrations were in the range between 3901.9 ng g^-1 and 2419.2 ng g^-1 (high group) and 375.3 ng g^-1 and 177.49 ng g^-1 (low group). Mean times for 50% and 90% dissipation were 88.23 and 293.03 days (HG) and 39.1 and 129.9 days (LG). Soil concentrations ranged from 26.1 ng g^-1 to 71.1 ng g^-1 (HG) and 3.4 to 5.9 ng g^-1 (LG); in plants, concentrations were between 71.4 and 380.8 ng g^-1 and 5.40 and 51.8 ng g^-1 in HG and LG, respectively. These results confirm that IVM moves from feces to the underlying soil as well as to nearby plants. The potential risk of detrimental effects on soil organisms and the impact on herbivorous animals should be further evaluated.