Fungal Antagonism Assessment of Predatory Species and Producers Metabolites and Their Effectiveness on Haemonchus contortus Infective Larvae

Biotic interactions in soil and dung shape parasite transmission in temperate ruminant systems: An integrative framework

Gastrointestinal helminth parasites undergo part of their life cycle outside their host, such that developmental stages interact with the soil and dung fauna. These interactions are capable of affecting parasite transmission on pastures yet are generally ignored in current models, empirical studies and practical management. Dominant methods of parasite control, which rely on anthelmintic medications for livestock, are becoming increasingly ineffective due to the emergence of drug-resistant parasite populations. Furthermore, consumer and regulatory pressure on decreased chemical use in agriculture and the consequential disruption of biological processes in the dung through nontarget effects exacerbates issues with anthelmintic reliance. This presents a need for the application and enhancement of nature-based solutions and biocontrol methods. However, successfully harnessing these options relies on advanced understanding of the ecological system and interacting effects among biotic factors and with immature parasite stages. Here, we develop a framework linking three key groups of dung and soil fauna-fungi, earthworms, and dung beetles-with each other and developmental stages of helminths parasitic in farmed cattle, sheep, and goats in temperate grazing systems. We populate this framework from existing published studies and highlight the interplay between faunal groups and documented ecological outcomes. Of 1756 papers addressing abiotic drivers of populations of these organisms and helminth parasites, only 112 considered interactions between taxa and 36 presented data on interactions between more than two taxonomic groups. Results suggest that fungi reduce parasite abundance and earthworms may enhance fungal communities, while competition between dung taxa may reduce their individual effect on parasite transmission. Dung beetles were found to impact fungal populations and parasite transmission variably, possibly tied to the prevailing climate within a specific ecological context. By exploring combinations of biotic factors, we consider how interactions between species may be fundamental to the ecological consequences of biocontrol strategies and nontarget impacts of anthelmintics on dung and soil fauna and how pasture management alterations to promote invertebrates might help limit parasite transmission. With further development and parameterization the framework could be applied quantitatively to guide, prioritize, and interpret hypothesis-driven experiments and integrate biotic factors into established models of parasite transmission dynamics.

Individual and Combined Application of Nematophagous Fungi as Biological Control Agents against Gastrointestinal Nematodes in Domestic Animals

Gastrointestinal nematodes (GINs) are a group of parasites that threaten livestock yields, and the consequent economic losses have led to major concern in the agricultural industry worldwide. The high frequency of anthelmintic resistance amongst GINs has prompted the search for sustainable alternatives. Recently, a substantial number of both in vitro and in vivo experiments have shown that biological controls based on predatory fungi and ovicidal fungi are the most promising alternatives to chemical controls. In this respect, the morphological characteristics of the most representative species of these two large groups of fungi, their nematicidal activity and mechanisms of action against GINs, have been increasingly studied. Given the limitation of the independent use of a single nematophagous fungus (NF), combined applications which combine multiple fungi, or fungi and chemical controls, have become increasingly popular, although these new strategies still have antagonistic effects on the candidates. In this review, we summarize both the advantages and disadvantages of the individual fungi and the combined applications identified to date to minimize recurring infections or to disrupt the life cycle of GINs. The need to discover novel and high-efficiency nematicidal isolates and the application of our understanding to the appropriate selection of associated applications are discussed.

Biological methods for the control of gastrointestinal nematodes

Gastrointestinal nematodes (GIN) are a cause of significant losses in animal production worldwide. In recent years, there have been important advances in the biological control of GIN of ruminants and horses. While these measures are still relatively under-utilised in practice, interest will undoubtedly grow due to the emergence of drug resistant parasite populations, the rise in demand for organically farmed products (which does not allow prophylactic use of drugs, including anthelmintics) and legislation, which regulates and restricts the use of anthelmintics. This review provides an overview of the most promising biocontrol agents of GIN of grazing animals including nematophagous fungi, dung beetles, earthworms, predacious nematodes and nematophagous mites. Recent advancements in these fields are evaluated, and the potential reasons for the delayed development and slow uptake of biocontrol agents are discussed. It is now widely believed that no method of GIN control is sustainable alone, and a combination of strategies (i.e. integrated pest management) is required for long term, effective parasite control. This review shows that, although their efficacies are lower than those of conventional anthelmintics, biological control agents are an important adjunct to traditional GIN control.

In Vitro Nematophagous Activity of Predatory Fungi on Infective Nematodes Larval Stage of Strongyloidae Family

AIM

The main goal of the present research conducted to assess the in vitro activity of the nematophagous fungi Duddingtonia flagrans, Fusarium solani, Verticillium chlamidosporium, and Trichoderma harzianum.

MATERIAL AND METHODS

Four isolates of fungi including D. flagrans, F. solani, V. chlamidosporium and T. harzianum were used in this study. Horse faeces were used to provide the larvae stage of Strongyloidae family for the experiments.

RESULTS

D. flagrans was the most effective fungus to reduce the population of the larval nematodes. D. flagrans was able to kill 100% of larvae after 14 days of incubation. The significant effect was seen after 7 days of incubation, therefore, the live larvae was decreased to 9, 11, 19 and 25 for D. flagrans, V. chlamidosporium, F. solani and T. harzianum, respectively.

CONCLUSION

Our results illustrated that D. flagrans were most successful fungus for reducing the number of Strongylidae family larva stage from horse faeces. Follow D. flagrans, the live larvae was significantly reduced for V. chlamidosporium, F. solani and T. harzianum, respectively.

Nematicide activity of microfungi (Orbiliales, Orbiliaceae) after transit through gastrointenstinal tract of “Gallus gallus domesticus”

SUMMARY Parasites are common in intensive or organics systems destined for chickens, which is more conducive to the emergence of gastrointestinal parasites, favored by direct contact with soil and other organisms. The growing demand for animal protein stimulates an expansion of production systems, increasing the stocking density. Outdoor poultry breeding systems (organic or not) that enable lower population density and higher animal welfare does not exclude these animals the presence of environmental pathogens. The control of gastrointestinal helminthosis in non-organic intensive and extensive systems is accomplished by administering anthelmintics with high cost and results unsatisfactory due to the misuse of drugs with consequent selection parasite strains resistant to chemical bases. This problem stimulate research into alternative control measures. Nematophagous fungi are used by its enzymatic action in controlled conditions and how environmental biocontrolers of larvae of gastrointestinal nematodes of livestock. This study evaluated the capacity of conidia/chlamydospores of nematophagous fungi as Duddingtonia flagrans (AC001 and CG722) and Monacrosporium thaumasium (NF34A) for cross the gastrointestinal tract of domestic chickens (Gallus gallus domesticus), and yours germination after traffic and predatory activity “in vitro” on larvae of Panagrellus spp. Fungi conidia/chlamydospores was identified in feces of chickens at times of 6, 12 and 24 hours after administration and spores viability was found after observing the germination, mycelial growth, followed by production of traps, capture and death of Panagrellus spp larvae in feces. Fungi Nematophagous are alternative control measures, efficient and innovative technology for the biological control of helminth parasites of chickens.

Larvicidal activity of Bacillus thuringiensis var. israelensis Cry11Aa toxin against Haemonchus contortus

Effective control of gastrointestinal parasites is necessary in sheep production. The development of anthelmintics resistance is causing the available chemically based anthelmintics to become less effective. Biological control strategies present an alternative to this problem. In the current study, we tested the larvicidal effects of Bacillus thuringiensis var. israelensis Cry11Aa toxin against Haemonchus contortus larvae. Bacterial suspensions [2 × 108 colony-forming units (CFU) g-1 of the feces] of B. thuringiensis var. israelensis and recombinant Escherichia coli expressing Cry11Aa toxin were added to naturally H. contortus egg-contaminated feces. The larvae were quantified, and significant reductions of 62 and 81% (P < 0·001) were, respectively observed, compared with the control group. A 30 mL bacterial suspension (1 × 108 CFU mL-1) of B. thuringiensis var. israelensis and recombinant E. coli expressing Cry11Aa toxin were then orally administered to lambs naturally infected with H. contortus. Twelve hours after administration, feces were collected and submitted to coprocultures. Significant larvae reductions (P < 0·001) of 79 and 90% were observed respectively compared with the control group. The results suggest that the Cry11Aa toxin of B. thuringiensis var. israelensis is a promising new class of biological anthelmintics for treating sheep against H. contortus.