Biological control of infective larvae of Ancylostoma spp. in beach sand / Control biológico de las larvas infectantes de Ancylostoma spp. en arena de playa

Background. Geohelminths are parasites that stand out for their prevalence and wide distribution, depending on the soil for their transmission. Aims. The aim of this work was to evaluate the predatory capacity of the fungal isolate of the genus Duddingtonia (CG768) on third stage larvae (L3) of Ancylostoma spp. in beach sand under laboratory conditions. Methods. In the assay A five treatment groups and 1 control group were formed. The treatment groups contained 5000, 10,000, 15,000, 20,000 or 25,000 chlamydospores of the fungal isolate and 1000 Ancylostoma spp. L3 in pots containing 30 g of sand. The control group (without fungus) contained only 1000 Ancylostoma spp. L3 and distilled water in pots with 30 g of sand. Results. Evidence of predatory activity was observed at the end of 15 days, where we observed the following percentages of reduction of L3: Group 1 (4.5%); Group 2 (24.5%); Group 3 (59.2%); Group 4 (58.8%); Group 5 (63%). However, difference was noted (p < 0.01) only at concentrations 15,000, 20,000 and 25,000 in relation to control group. In the assay B two groups were formed in Petri dishes of 9 cm in diameter containing agar water 2% medium. In the treated group, each Petri dish contained 500 Ancylostoma spp. L3 and 5 g of sand containing the isolate CG 768 at a concentration of 25,000 chlamydospores/g of sand, and the control group (without fungus) contained only 500 L3. At the end of 7 days the non-predation L3 of Petri dishes using the method of Baermann were recovered. Difference (p < 0.01) between groups on reducing the average number of Ancylostoma spp. L3 (percent reduction of 84%) was observed. Conclusions. The results of this study confirm earlier work on the efficiency of the Duddingtonia genus in the control of Ancylostoma spp. infective larvae (AU)

Antecedentes. Los geohelmintos son parásitos que destacan por su prevalencia y amplia distribución, puesto que su transmisión depende del suelo. Objetivos. El objetivo del presente estudio fue evaluar la capacidad predatoria de aislamientos fúngicos del género Duddingtonia (CG768) sobre las larvas de estadio 3 (L3) de Ancylostoma spp. en arena de playa, en condiciones de laboratorio. Métodos. En el ensayo A se formaron 5 grupos de tratamiento y un grupo de control. Los grupos de tratamiento contenían 5000, 10.000, 15.000, 20.000 o 25.000 clamidosporas del aislamiento fúngico y 1000 larvas L3 de Ancylostoma spp. en recipientes con 30 g de arena. Los recipientes del grupo de control (sin clamidosporas) solo contenían 1000 larvas L3 de Ancylostoma spp. y agua destilada con 30 g de arena. Resultados. Al término de 15 días, fue evidente la actividad predatoria, con los porcentajes siguientes de reducción de larvas L3: grupo 1 (4.5%); grupo 2 (24.5%); grupo 3 (59.2%); grupo 4 (58.8%), y grupo 5 (63%). Sin embargo, en relación con el grupo control, solo se identificaron diferencias significativas (p < 0.01) a las concentraciones de 15.000, 20.000 y 25.000. En el ensayo B, en placas de Petri de 9 cm de diámetro, que contenían un medio de agar agua al 2%, se formaron 2 grupos. En el grupo tratado, cada placa de Petri contenía 500 larvas L3 de Ancylostoma spp. y 5 g de arena con el aislamiento CG768 a una concentración de 25.000 clamidosporas/g de arena, y el grupo de control (sin hongo) solo contenía 500 larvas L3. Al cabo de 7 días, utilizando el método de Baermann, a partir de las placas de Petri se obtuvieron larvas L3 no sometidas a predación por el hongo. Entre los grupos se observó una diferencia significativa (p < 0.01) en la reducción del número medio de larvas L3 de Ancylostoma spp. (porcentaje de reducción del 84%). Conclusiones. Los resultados del presente estudio confirman los datos de investigaciones previas sobre la eficiencia del género Duddingtonia en el control de las larvas infectantes de Ancylostoma spp (AU)

Mixed production of filamentous fungal spores for preventing soil-transmitted helminth zoonoses: a preliminary analysis.

Helminth zoonoses are parasitic infections shared by humans and animals, being the soil-transmitted helminths (STHs) mainly caused by roundworms (ascarids) and hookworms. This study was aimed to assess the individual and/or mixed production of two helminth-antagonistic fungi, one ovicide (Mucor circinelloides) and other predator (Duddingtonia flagrans). Fungi were grown both in Petri plates and in a submerged culture (composed by water, NaCl, Na2HPO4 · 12 H2O, and wheat (Triticum aestivum)). A Fasciola hepatica recombinant protein (FhrAPS) was incorporated to the cultures to improve fungal production. All the cultured plates showed fungal growth, without difference in the development of the fungi when grown alone or mixed. High counts of Mucor spores were produced in liquid media cultures, and no significant differences were achieved regarding single or mixed cultures, or the incorporation of the FhrAPS. A significantly higher production of Duddingtonia spores after the incorporation of the FhrAPS was observed. When analyzing the parasiticide efficacy of the fungal mixture, viability of T. canis eggs reduced to 51%, and the numbers of third stage cyathostomin larvae reduced to 4%. It is concluded, the capability of a fungal mixture containing an ovicide (Mucor) and a predator species (Duddingtonia) for growing together in a submerged medium containing the FhrAPS offers a very interesting tool for preventing STHs.

Predatory activity of the fungus Duddingtonia flagrans in equine strongyle infective larvae on natural pasture in the Southern Region of Brazil.

Biological control is an alternative method to reduce the population of parasites through natural predators. A promising option of biological control in the reduction of infective larvae on pasture is the use of nematophagous fungi. In this study, the efficacy of the nematophagous fungus Duddingtonia flagrans in controlling gastrointestinal nematode parasites in field-raised horses was tested. Ten foals with an average age of 12 months were divided in two groups: five males constituted the treated group and five females constituted the control group. Each group was introduced in a field of mixed pasture with approximately 5 ha. The treated group received the fungus D. flagrans at a concentration of 10(6) chlamydospores per kilogramme of animal body weight daily, mixed with horse food for 5 months. The control group did not receive the fungus. Samples were collected to perform eggs per gramme (EPG) counts weekly. Coproculture and collection of pasture were done monthly for larvae counting. No significant difference was observed in the EPG counting and in the number of larvae recovered from coprocultures, where cyathostomines, Strongylus and Trichostrongylus spp. were found after monthly larvae counting. No significant difference was observed in the EPG counts, and Trichostrongylus sp. was identified. The number of recovered larvae on pasture was significantly lower in the treated group in the last month of treatment, showing a reduction of 73.5% (p < 0.05). As such, the fungus was able to reduce the number of infective larvae in the pasture. Nevertheless, this did not reflect in a decrease of parasitic infection during the 5-month study period.

Kinetics of capture and infection of infective larvae of trichostrongylides and free-living nematodes Panagrellus sp. by Duddingtonia flagrans.

Duddingtonia flagrans, a nematode-trapping fungus, has been investigated as an agent for biological control against infective larvae of gastrointestinal nematode parasites of production animals. The initial process of nematode-trapping fungi infection is based on an interaction between the trap structure of the fungus and the surface of the nematode cuticle. This report investigates by light and scanning electron microscopy the kinetics of capture and infection during the interaction of D. flagrans with the infective larvae (L(3)) of trichostrongylides and the free-living nematode Panagrellus sp. D. flagrans was cultivated for 7 days in a Petri dish containing agar-water. L(3) and Panagrellus sp. were inoculated in the Petri dishes and the samples consisting of agar-L(3)-fungi and agar-Panagrellus sp.-fungi were collected after 10, 20, 30, 40, 50, 60, and 70 min and 3, 4, 5, 10, 15, 20, and 25 h of interaction. All samples were observed by light microscopy. The samples with 1, 5, 15, and 25 h of interaction were also analyzed by scanning electron microscopy. The interaction was monitored up to 25 h. An initial differentiation of predation structures was observed after 30 min of interaction. The presence of traps and of captured L(3) or Panagrellus sp. occurred after 70 min. The live captured nematodes were observed up to 3 h of interaction. However, after 4 h, all Panagrellus sp. were dead. It took 15 h of interaction for the fungus to invade the L(3), and the presence of hyphae inside the nematode near the region of penetration was evident. At this time, the hyphae had filled the whole body of Panagrellus sp. The complete occupation of the body of L(3) occurred at 20 h of interaction and with 25 h the nematode was completely damaged except for the cuticle. Although the double cuticle of L(3) slows the penetration of D. flagrans, it was possible to verify that the process of trap formation and capture occurs quickly when both nematodes were tested, suggesting that the organisms would eventually be killed once in contact with the fungi encouraging the use of the fungus as a biological control agent.