Effect of Paecilomyces lilacinus, Trichoderma harzianum and Trichoderma virens fungal extracts on the hatchability of Ancylostoma eggs

Lecanicillium psalliotae (Hypocreales: Cordycipitaceae) Exerts Ovicidal and Larvicidal Effects against the Sheep Blood-Feeding Nematode Haemonchus contortus through Its Liquid Culture Filtrates

Nematophagous fungi (NF) form part of the soil microbiota and are natural enemies of nematodes, helping to regulate nematode populations. A verticillate NF isolated from soil from Tepalcingo, Mexico, was morphologically and molecularly characterised. This fungus was cultured in two different liquid media-Czapek-Dox broth (CzDoxB) and sweet potato dextrose broth (SPDB)-for 21 days. The ovicidal (OA) and larvicidal (LA) activities of fungal liquid culture filtrates (LCFs) were assessed in 96-well microtitre plates at different concentrations against Haemonchus contortus after 48 h. The morphological and molecular identification revealed the presence of Lecanicillium psalliotae. Additionally, the groups of compounds associated with nematocidal activity were determined from a qualitative chemical profile (QCP) using different reagents. The highest OA of the LCFs was obtained at 25 mg/mL from SPDB and CzDoxB and amounted to 97.2 and 99.06%, respectively. Meanwhile, the highest LA recorded with these LCFs at 100 mg/mL was 54.27% and 96.8%, respectively. The QCP revealed the presence of alkaloids and tannins in both LCFs that have previously been associated with nematocidal activity. Lecanicillium psalliotae exerted an important effect on H. contortus and could be of significance in future studies focused on the control and prevention of haemonchosis in small ruminants.

A systematic review on products derived from nematophagous fungi in the biological control of parasitic helminths of animals

Nematophagous fungi have been widely evaluated in the biological control of parasitic helminths in animals, both through their direct use and the use of their derived products. Fungal bioproducts can include extracellular enzymes, silver nanoparticles (AgNPs), as well as secondary metabolites. The aim of this study was to conduct a systematic review covering the evaluation of products derived from nematophagous fungi in the biological control of parasitic helminths in animals. In total, 33 studies met the inclusion criteria and were included in this review. The majority of the studies were conducted in Brazil (72.7%, 24/33), and bioproducts derived from the fungus Duddingtonia flagrans were the most commonly evaluated (36.3%, 12/33). The studies involved the production of extracellular enzymes (48.4%, 16/33), followed by crude enzymatic extract (27.2%, 9/33), secondary metabolites (15.1%, 5/33) and biosynthesis of AgNPs (9.1%, 3/33). The most researched extracellular enzymes were serine proteases (37.5%, 6/16), with efficacies ranging from 23.9 to 85%; proteases (31.2%, 5/16), with efficacies from 41.4 to 95.4%; proteases + chitinases (18.7%, 3/16), with efficacies from 20.5 to 43.4%; and chitinases (12.5%, 2/16), with efficacies ranging from 12 to 100%. In conclusion, extracellular enzymes are the most investigated derivatives of nematophagous fungi, with proteases being promising strategies in the biological control of animal helminths. Further studies under in vivo and field conditions are needed to explore the applicability of these bioproducts as tools for biological control.

A Nematode Crude Extract Acts as an Elicitor of the Nematocidal Activity of Nematophagous Fungi Liquid Culture Filtrates Against Haemonchus contortus (Nematoda: Trichostrongylidae)

AIM

This study was designed to investigate if culturing nematophagous fungi (NF) in the presence of a Haemonchus contortus larva crude extract (HcCE) enhances the nematocidal activity of nematophagous fungi liquid culture filtrates (NFCF).

MATERIALS AND METHODS

Four NF Arthrobotrys oligospora, A. musiformis, Duddingtonia flagrans and Clonostachys rosea were cultured in flasks (n = 5) containing Czapek-Dox broth medium (CDB) in the presence or absence of HcCE. NFCF recovered by filtration of each fungus (200 mg/mL) were assessed on H. contortus infective larvae (L3) using 96-well micro-titer plates (n = 4). Additionally, CDB and water were considered negative controls, while Ivermectin acted as a positive control. After 48 h confrontation, ten 10-μL aliquots of each well were deposited on slides and observed under the microscope (40 ×). Dead and alive larvae in the aliquots were quantified, and a mortality rate (MR) was estimated.

RESULTS

The MR of the different NFCF was greatly enhanced by the presence of HcCE. The four NF incubated in the absence of HcCE showed low mortality percentages from 8.2 to 25.8%; in contrast, when the assessed NF growth in the presence of HcCE showed a lethal activity ranging from 66.8 to 80.5%. Only C. rosea showed a moderate increase in the presence of the elicitor (42.7%).

CONCLUSION

This study shows evidence about the HcCE enhances the production of nematocidal activity in NFCF. Future studies should be performed to elucidate the compounds responsible of the nematocidal activity that could have important implications in the control of sheep haemonchosis.

Anthelmintic Activity of Extracts and Active Compounds From Diospyros anisandra on Ancylostoma caninum, Haemonchus placei and Cyathostomins

The present study aimed to evaluate the anthelmintic activity of leaf and bark extracts of Diospyros anisandra collected during different seasons and their major constituents on eggs of Ancylostoma caninum, Haemonchus placei, and cyathostomins. Specifically, the eclosion inhibition of the methanolic extracts of the leaves and bark of D. anisandra collected during the dry and rainy seasons (600–37.5 μg/ml) were evaluated in addition to the fractions, sub-fractions (300–37.5 μg/ml) and active major constituents (150–2.3 μg/ml). The rainy season bark extract had the highest percentage of eclosion inhibition (PEI) against the evaluated nematodes (≥ 90% at 75 μg/ml) along with high ovicidal activity (90.0 to 93.4% at 75 μg/ml). The purification of the rainy season bark extract showed that its biological activity came from the non-polar n-hexane fraction (≥ 93% at 75 μg/ml). The bioguided fractionation pointed to sub-fraction 5 as having the highest anthelmintic activity against the three evaluated genera of nematodes (PEI ≥ 93% at 37.5 μg/ml). Gas chromatography and mass spectrometry revealed that the major constituent in sub-fraction 5 was plumbagin. Upon evaluation, plumbagin was confirmed to be responsible for the anthelmintic activity of D. anisandra, with a PEI ≥ 90% at 2.3 μg/ml on the three evaluated nematodes. Additionally, the compounds betulin and lupeol in the bark of D. anisandra were evaluated but presented low anthelmintic activity (PEI ≤ 5.3% at 2.3 μg/ml). In conclusion, the rainy season bark extract of D. anisandra exerts a high ovicidal activity against the eggs of the three studied nematodes. Plumbagin is the active compound responsible for this activity and represents a potential alternative for the control of different genera of gastrointestinal nematodes given the current scenario of anthelmintic resistance.

Purpureocillium lilacinum and Trichoderma virens for biological control of trichostrongylid parasites of sheep: an in vitro evaluation

The study evaluated the ovicidal activity of enzymatic extracts of Purpureocillium lilacinum and Trichoderma virens against trichostrongylid eggs from sheep. Filtered extract (FE) and macerated crude extract (MCE) were prepared from fungal cultures in minimal broth. In the experiment, 100 trichostrongylid eggs, obtained from the feces of naturally infected sheep, were exposed to fungal extracts for 24 and 48 hours/25°C. In the control group, eggs were incubated in minimal broth. The number of L1 larvae was ascertained. Each treatment consisted of four repetitions and the experiment was repeated five times. It was observed that the effect of FE and MCE of P. lilacinum and T. virens on egg hatchability differed from that of the control group. MCE of T. virens and P. lilacinum showed higher ovicidal activity than FE over both periods and at 48 hours of exposure, respectively. From the percentage reductions in hatchability of the eggs, MCE was shown to be superior to FE for both fungi. This study demonstrated the ovicidal potential of these fungi against trichostrongylid eggs. However, further studies are needed in order to identify the molecules responsible for the ovicidal effects, and to evaluate the behavior of fungal extracts in biotic and abiotic interactions.

Exposure of Toxocara canis eggs to Purpureocillium lilacinum as a biocontrol strategy: an experimental model evaluation

Abstract Purpureocillium lilacinum is a nematophagous fungus used in biological control against some parasites, including Toxocara canis. This study researched the infectivity of embryonated T. canis eggs after exposure to the fungus P. lilacinum. T. canis eggs were exposed to P. lilacinum for 15 or 30 days and subsequently administered to Swiss mice (n=20). Control group consisted of mice who received T. canis embryonated eggs without fungal exposure. Forty-eight hours after infection, heart, lung, and liver from animals of each group were collected to assess larval recovery. The organs of mice that received embryonated eggs exposed to the fungus showed a lower average larval recovery (P<0.05) suggesting that exposure of T. canis eggs to P. lilacinum was able to reduce experimental infection. Under the evaluated conditions, the interaction time between the fungus and the parasite eggs was not a significant factor in larvae recovery. P. lilacinum may be considered a promising T. canis biological control agent. However, further studies are needed to determine a protocol for the use of this fungus as a biological control agent.

Control of Haemonchus contortus in sheep using basidiocarps of Agaricus blazei Murril

OBJECTIVE

This study evaluated the effects in vitro and in vivo of Agaricus blazei against Haemonchus contortus in sheep.

METHODS

The in vitro efficacy of aqueous extract on egg hatching inhibition (EHI) was investigated and after 72 h incubation with varying concentrations the effects on, blastomeres, embryonated eggs, and first stage larvae (L1) were evaluated. Larval development inhibition (LDI) for dry powder and the aqueous extract were evaluated in fecal cultures of sheep infected with H. contortus. In vivo efficacy was determined by reduction in fecal egg count (FEC). Lambs were treated with powder A. blazei (11.4 g/kg pc) or trichlorfon, or were untreated and the possible toxicity of this fungus was monitored by plasmatic enzyme analysis.

RESULTS

Concentrations equal to and higher than 3.62 mg/mL and of aqueous extract were 100% effective in the EHI test. In the LDI test, LC90 was estimated for 5.66 and 106.0 mg/g fecal culture for aqueous extract and powder, respectively. The mean FEC in lambs 14 days post-treatment with A. blazei powder was significantly lower than observed for the negative control, and the serum levels of aspartate transaminase and alanine transaminase were normal.

CONCLUSION

The fungi supplementation promotes, respectively, high and moderate anthelmintic efficacy with in vitro and in vivo tests, respectively, suggesting it as an alternative or complementary treatment for haemonchosis in sheep.