Enhancing chlamydospore production in Duddingtonia flagrans on solid substrate: The impact of mannitol and varied cultivation conditions.

Duddingtonia flagrans is a nematophagous fungus which has shown promising results as a non-chemical parasitic control tool. The fungus disrupts the parasite's life cycle by trapping larvae in the environment through the networks generated from chlamydospores, thus preventing the reinfection of animals. One barrier to the development of a commercial product using this tool is the need to increase chlamydospore production in the laboratory for its administration to livestock. The purpose of this study was to evaluate the addition of mannitol to an enriched culture medium and the effect of adverse cultivation conditions on chlamydospore production. D. flagrans was cultivated on Petri dishes with corn agar for 4 weeks at 27 °C and 70% relative humidity (RH). Four groups were then formed, all with Sabouraud agar as a base, to which different growth inducers were added: GSA (glucose Sabouraud agar), GSA-MI (glucose Sabouraud agar + meso inositol), GSA-E (enriched glucose Sabouraud agar), and AE-M (enriched agar + mannitol). After 4 weeks, chlamydospores were recovered by washing the surface of each plate with distilled water and then quantified. The medium that yielded the highest amount of chlamydospores was subjected to different cultivation conditions: NC (normal conditions): 70% RH and 27 °C, AC (adverse conditions) 1: 20% RH and 40 °C, CA2: 60% RH and 27 °C, and CA3: 55% RH and 24 °C. It was determined that mannitol increases chlamydospore production (65x106 chlamydospores/plate), and when reducing humidity by 10% under cultivation conditions it resulted in an approximately 10% increase in chlamydospore production compared to the control group. These results suggest that the addition of polyols, as well as its cultivation under certain environmental conditions, can improve chlamydospore production on a laboratory scale.

Effect of macrocyclic lactones on nontarget coprophilic organisms: a review.

Macrocyclic lactones are frequently used dewormers in livestock farms around the world. Due to their wide spectrum of action against nematodes and arthropods and their practicality of application at very low doses, their use has become massive since their discovery. These compounds are eliminated in a large percentage in the feces of animals, causing adverse effects on coprophilic fauna. Several research groups around the world have been devoted to evaluating these effects on this fauna. The aim of this review is to register the adverse effects of the concentrations in which macrocyclic lactones are eliminated in the feces of domestic animals and the importance of the coprophilic and edaphilous fauna on the degradation of the feces of the animals. The documented data shows that the use of macrocyclic lactones has a high toxicological risk for the different species that colonize the dung, thus causing an adverse effect on its disintegration and its subsequent incorporation into the soil. Even so, more studies at the regional level and their standardization are necessary to make the comparison between different areas possible.

Lack of negative effects of the biological control agent Duddingtonia flagrans on soil nematodes and other nematophagous fungi.

The possible environmental effects of the massive use of Duddingtonia flagrans for controlling sheep nematodes were evaluated in two regions. Non-supplemented faeces and faeces from sheep supplemented with D. flagrans were deposited three times on pasture plots and samples were collected 7 and 14 days post-deposition. Samples were cultured in agar-water (2%) with Panagrellus spp. to recover D. flagrans and other nematophagous fungi, and soil nematodes were extracted using Baermann funnels and counted. No significant differences in the populations of soil nematodes and fungi colonizing sheep faeces (P > 0.05) were observed between supplemented and non-supplemented groups, except in one sample. The topsoil in contact with the faeces was sampled 1-4 months post-deposition, revealing that, with one exception, D. flagrans did not persist in soil beyond 2 months post-deposition. Duddingtonia flagrans does not affect faecal colonization by other fungi and soil nematodes and, once deployed on pasture, does not survive for long periods in the environment.

The use of soy protein polymers as a release device for nematophagous fungi in the control of parasitic nematodes in ruminants.

This trial was conducted to evaluate the predatory activity of Duddingtonia flagrans incorporated into soy protein-based polymers as a controlled-release device (CRD). The rate of fungal release from the polymers and time of residence of the CRD in the rumen of a cannulated sheep was also determined. After administration to the sheep, the CRD was extracted at weekly intervals over a month for observation of its physical structure and faeces were collected to observe the subsequent predatory activity of the fungus in Petri dishes with water-agar 2% and Panagrellus spp. as bait. The CRD slowly degraded in the rumen over 4 weeks and liberated D. flagrans into the faeces. The formulation of the soy protein-based polymers did not affect the predatory activity of the fungus. The study demonstrates that biodegradable soy protein polymers could potentially improve the use of nematophagous fungi for controlling nematode parasites of ruminants.