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

Abstract

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.

Arthrobotrys musiformis (Orbiliales) Kills Haemonchus contortus Infective Larvae (Trichostronylidae) through Its Predatory Activity and Its Fungal Culture Filtrates

“…In this Table, we can observe A. musiformis has been assessed against different kinds of nematodes, including nematodes of importance for agriculture and the livestock industry, specifically against ruminant parasitic nematodes and against predatory nematodes and free-living nematodes. A predatory activity higher than 70% is a very good activity; if we consider that, using NF for the control of animal parasitic nematodes should be considered only as a tool of control together with other control measures, or even using a combined method with two or more fungal genera/species to achieve a more effective control [ 26 ]. It is important to consider that the use of nematode natural antagonists is only part of an integrated control system that can involve different strategies of control [ 27 ]; for example, the use of a high protein and energy-based diet, which promotes immune self-defence mechanisms [ 28 , 29 ], grazing management [ 30 , 31 ], vaccines [ 32 , 33 ] and the use of plants/plant metabolites [ 34 , 35 ].…”

Efficacy of a Fungal Formulation with the Nematophagous Fungus Pochonia chlamydosporia in the Biological Control of Bovine Nematodiosis

“…Despite the results found here, the enzymatic mechanisms of these fungi in egg adhesion and consequent destruction are suggested by several studies [11]. Additionally, in vitro and in vivo studies have been developed to decrease the number of recurrent gastrointestinal nematode infections in domestic animals using ovicidal fungi [7]. However, the factors that often impair the effectiveness of these fungi are strategies developed by the parasites themselves, such as the rapid passage from the egg to larval stage mentioned above, which makes interaction with the egg difficult [10].…”

“…In addition, environmental factors, such as temperature, can interfere with the dynamics of nematode predation by fungi since each species has a different ability to adapt to climatic conditions [17]. Additionally, such factors impact the action of these fungi also because each fungal species has a different adaptive capacity [7]. The data of average daily weight gain in kilograms (kg/day) are presented in Table 4.…”

“…Pochonia chlamydosporia is widely used as a biocontrol agent [7]. Its ovicidal action consists of the production of proteases (extracellular enzymes) that have ovicidal activity against helminth eggs in the feces environment.…”

“…In addition, this fungal species can produce enzyme extracts against solid substrates such as proteins, lipids, and polysaccharides [8]. Morphological changes are caused in the shell and internal content of nematode eggs [7]. In addition, this species also produces secondary metabolites [9].…”