Original article
Effect of Paecilomyces lilacinus, Trichoderma harzianum and Trichoderma virens fungal extracts on the hatchability of Ancylostoma eggsEfecto de los extractos de los hongos Paecilomyces lilacinus, Trichoderma harzianum y Trichoderma virens en la eclosionabilidad de huevos de Ancylostoma

https://doi.org/10.1016/j.riam.2016.04.004Get rights and content

Abstract

Background

Ancylostoma species have demanded attention due to their zoonotic potential. The use of anthelmintics is the usual method to prevent environmental contamination by Ancylostoma eggs and larvae. Nematophagous fungi have been widely used in their biological control due to the fungus ability to capture and digest free nematode forms.

Aims

The aim of this study was to evaluate the effect of four different fungal extracts of Paecilomyces lilacinus (n = 2), Trichoderma harzianum (n = 1) and Trichoderma virens (n = 1) isolates on the hatchability of Ancylostoma eggs.

Methods

Fungal extracts consisted of fungal broth culture supernatant without filtration (crude extract) and filtered broth (filtered extract), macerated mycelium (crude macerate), and macerated mycelium submitted to filtration (filtered macerate). The Ancylostoma eggs were obtained from the feces of naturally infected dogs. In vitro assays were performed in five replicates and consisted of four treatments and one control group.

Results

The activity of the fungal extracts of each evaluated fungus differed (p < 0.05) from those of the control group, showing significant ovicidal activity. The hatching of the eggs suffered reduction percentages of 68.43% and 47.05% with P. lilacinus, and 56.43% with T. harzianum, when crude macerate extract was used. The reduction with the macerate extract of T. virens was slightly lower (52.25%) than that for the filtered macerate (53.64%).

Conclusions

The results showed that all extracts were effective in reducing the hatchability of Ancylostoma eggs. The ovicidal effect observed is likely to have been caused by the action of hydrolytic enzymes secreted by the fungi.

Resumen

Antecedentes

Las especies del género Ancylostoma son de gran importancia debido a su potencial zoonótico. El uso de antihelmínticos es el método habitual en la prevención de la contaminación ambiental por huevos y larvas del género Ancylostoma. Los hongos nematófagos se utilizan ampliamente en el control biológico de aquellos, debido a su capacidad de capturar y digerir nematodos libres.

Objetivo

El objetivo del estudio fue evaluar el efecto de cuatro extractos diferentes de hongos (Paecilomyces lilacinus [n = 2], Trichoderma harzianum [n = 1] y Trichoderma virens [n = 1]) en la eclosionabilidad de huevos de especies de Ancylostoma.

Métodos

Los extractos de hongos constaban del sobrenadante del cultivo en caldo fúngico sin filtración (extracto crudo) y caldo filtrado (extracto filtrado), micelio macerado (macerado crudo) y micelio macerado sometido a filtración (macerado filtrado). Los huevos de Ancylostoma se obtuvieron a partir de heces de perros infectados de manera natural. Se realizaron cinco repeticiones de los ensayos in vitro con cuatro tratamientos y un grupo control.

Resultados

La actividad de los extractos fúngicos de cada hongo evaluado difiere (p < 0,05) de la de aquellos del grupo control, lo que demuestra una actividad ovicida significativa. Con el extracto crudo macerado, la reducción de la eclosión mostró porcentajes del 68,43 y el 47,05% en el caso de P. lilacinus y del 56,43% para el caso de T. harzianum. El porcentaje de reducción en el uso del macerado crudo en T. virens fue del 52,25%, algo inferior respecto al macerado filtrado (53,64%).

Conclusiones

Los resultados mostraron que todos los extractos fueron eficaces en la reducción de la eclosionabilidad de huevos de Ancylostoma. Es probable que el efecto ovicida observado haya sido causado por la acción de enzimas hidrolíticas secretadas por los hongos.

Section snippets

Fungal cultures

Four fungal isolates were used – CG193 Paecilomyces lilacinus and CG502 Trichoderma harzianum provided by Cenargen (Embrapa Genetic Resources and Biotechnology), MICLAB009 Paecilomyces lilacinus and MICLAB008 Trichoderma virens obtained from the collection of fungi of the Mycology Laboratory, Biology Institute, Federal University of Pelotas, Brazil properly identified by DNA sequencing. The cultures kept in test tubes containing potato agar (PDA) at 4 °C were subcultured on Petri dishes with PDA

Results

After a 24-h-interaction period, the fungal extracts (CE, FE, CM and FM) evaluated were observed to reduce the Ancylostoma hatchability to some extent, as compared to control (Table 1). Statistical analysis showed differences (p < 0.05) in the number of larvae between the fungal extracts of each fungus and the control group. Moreover, it showed that CE, FE, CM and FM did not present the same pattern for each fungus tested (Table 1). However, when the hatchability reduction percentage of

Discussion

Nematophagous fungi have been widely used for biological control because of their ability to capture and infect nematodes through enzymatic action.11, 12

The results of this study show the ovicidal activity of the evaluated fungi on Ancylostoma eggs and suggest that the activity may be due to the action of hydrolytic enzymes. Furthermore, the use of enzymatic extracts of the fungi significantly reduced Ancylostoma eggs hatching after a 24-h-exposure period. This ovicidal activity could be an

Conclusion

The use of enzymatic extracts of the fungi P. lilacinus, T. harzianum and T. virens significantly reduces Ancylostoma eggs hatching after a 24-h-exposure period. Thus, these fungi are, together with other known nematophagous fungi, promising biocontrol agents of geohelminths in the environment. Yet, additional studies are needed so that the molecules responsible for the observed effects can be identified and characterized.

Funding

This study was supported by internal funding. CNPq (National Council for Scientific and Technological Development) of Brazil and CAPES (Coordination for the Improvement of Higher Education Personnel) of Brazil provided scholarship and research grants to the authors.

Conflict of interest

The authors declare that there is no conflict of interest.

References (20)

There are more references available in the full text version of this article.

Cited by (7)

View all citing articles on Scopus
View full text