Nematophagous Fungi: A Biological Agent for Regulation of Plant Parasitic Nematodes
Abstract
The occurrence of plant-parasitic nematodes amongst farmers around the globe is a major concern. Farmers also turn to organic pesticides as an additional method to combat pests and diseases. Nematicides are widely available and of significant toxicity in the natural environment, for example, Aldicarb (Temik). Meanwhile, one of the major components of Integrated Pest Management (IPM) is the biological control using other organisms. Many microorganisms predate nematodes, but only handfuls are used for commercial purposes. In addition, the success of a nematode check is strengthened by a combination of two or more biocontrol agents. Fungi can be an efficacious biocontrol agent in particular, and can be feasibly obtained on a large scale. This review would include an outline of the different biomonitoring processes of technological development, but more on the morphological and biochemical dimensions and interactions of nematophagous fungi must be made available. This analysis will contribute to more nematodes and fungal biodiversity resources.
Keywords
Download Options
Introduction
The nematodes under the phylum Nematoda (Britannica) are often referred to as roundworms or eelworms. They are the most extensive taxon of the helminth group (Schouteden, De Waele, Panis & Vos, 2015) and all plant and animal groups including aquatic habitats are prone to nematodes (Blouin, Liu, and Berry, 1999). Furthermore, its high fertility rate and reduced lifespan characterize it and survive at varying ambient temperatures, e.g. daily average temperature between < 0 and > 25 ° C,on land and in water. (Moens & Vincx, 2000, p. 2).
Plant-parasitic nematodes are peculiar in terms of feeding behavior by using a stylet to penetrate the feeding host (Jones et al., 2013). The tube known as a stylet begins with the digestive tract. Collagen protein was the precursor to nematode elasticity (Bird and Bird, 1991). Typically, nematodes moult four times during their lifespan before entering an adult stage. In the case of root-knot and cyst nematodes, the most destructive is second-stage juveniles J2 (DACKMAN & JANsson 1991). Besides they are classified into two classes of destructive nematodes, ectoparasite, and endoparasite. Ectoparasitic nematodes feed on the outer layer and causeless damage, while endoparasitic nematodes penetrate the roots and remain destructive for along time (Agrios, 1997). Other nematodes such as Dagger nematode (Xiphinema spp.,) Needle nematode (Longidorus spp.,) and stubby-root (Trichodorus spp.,) transmit the virus and main mode of ingestion by sucking root sap (Wyss, 1981).
Some plant-parasitic nematodes (PPN) had an impact and ongoing depletion of yield on important agricultural crops. In addition, sedentary endoparasites have a complex structure and are considered to be an important nematode group, e.g. root-node nematodes (Meloidogyne spp.) and cyst nematodes (Globodera and heterodera spp.) (Janson & Lopez-Llorca, 2004). Root-knot nematode (Meloidogyne spp) with a huge array of hosts for all communities and the capacity to disperse quickly being the most economically disastrous genera of the plant-parasitic nematode. They are sedentaries and plunge towards the roots for the so-called "root-knot" for nourishment (Elling, 2013). Some root-knot species are Meloidogyne javanica, M.incognita and M.arenaria. Nevertheless, the infestation is probably due to the formation of gall and depletion of water and food. That it would eventually cause the shootings to bolt, wilt, and chlorosis (Crow & Dunn, 2009).
It also poses a serious threat to horticulture crops such as vegetables and cereals and an estimated loss of yield of approximately 50-80 percent (Mukhtar & Kayani, 2019) of nematodes in particular. So far, about one hundred species of nematodes have been recorded. The amount of nematode losses is 20.6 percent in crops reported by Jain et al., 2007 (SHARMA & TRIVEDI). Heterodera avenae, a cereal cyst nematode called CCN, causes about 15-20% of wheat and 20% of barley due to "Molya" disease (Nicol, Rivoal, Taylor and Zaharieva, 2003). Annual plant-parasitic nematode damages are projected to increase to about $100 billion (Degenkolb & Vilcinskas, 2016).
The most common way in the previous decade of the eradication of Plant-parasitic nematodes by using nematicides. They are inexpensive, and they effectively control nematodes. There are two groups of nematicides, for example, fumigants (1,3 dichloropropene (TeloneII)) and non-fumigants (granules and liquid), e.g. fenamiphos (Nemacur) and aldicarb (Temik). Fumigants became popular because they reduced nematode populations rapidly. (Whitehead, 1986) The predominant toxic compound found in nematicides is Methyl bromide, a multi-purpose fumigant recognized as an ozone-depleting substance (Jansson &Lopez-Llorca, 2004). In addition, nematodes developed resistance to nematicides (Resurgence) and were no longer destroyed by chemical substances (Yang, Tian, Liang, & Zhang 2007). Alternative nematode control measures are less prevalent, such as crop rotation or biological control, an important strategic approach to plant defense (Moosavi & Zare2012). Such problems may be overcome with the use of biological control solutions. This review article focuses on one of these approaches, the nematophagous fungi.
Conclusion
The Biological control of plant-parasitic nematodes is well defined, and we need to be much more informed of their physiological and molecular levels (Jansson & Lopez-Llorca, 2004). Molecular techniques have specifically been developed to examine the characteristics of the nematophagous fungi and their control capacity involving DNA sequences and analysis of markers. This results in a more comprehensive development. Developing commercial products for its effectiveness is therefore significant. Such products also reflect the technical improvements that nematology has made in the progress of biological control technology. Biocontrol products are not extensively used as nematicides, owing to the higher manufacturing costs and the need to establish better control of nematodes on crops. In addition, further research is required to perform field experiments such as seed testing with fungal inoculum and pellet processing of a biological agent, as well as a liquid formulation to check its effectiveness. Farmers gain knowledge of recent technology for better understanding by extension service.
VI. FUTURE PROSPECTS In the previous study, the majority of nematophagous fungi focused upon the involvement of fungi and nematodes in controlled systems. Although the issue of how to use fungus in biological control has been the driving factor, it is the context. There are top priority questions pertaining to the function of nematodes and nematophagous fungi and signals involved in interactions. In order to understand the biological control capacity of these fungi, input from both field and laboratory investigations should be compiled and incorporated in the future. Biological control of nematodes is a simple and feasible task, but it was indeed an inadequate method for management. Combined prospective efforts will concentrate on current knowledge of fungi and in-depth studies of the following characteristics. 1. Development of detailed but simple methods. 2. Population dynamics studies of both nematodes and fungi. 3. Studies of soil fungi and its survival strategies. 4. Continued work on basic interaction mechanisms.
In some experiments, the nature and the actions of nematodes and nematophagous fungi are already clarified by attracting nematodes to various sources. More thorough studies are expected of the adhesive bind of predatory fungi and endoparasitic spores and the adhesive mechanism in soil. The ability to manipulate nematode attraction behaviors or fungal adhesion processes have provided more ways of designing experiments in a competitive environment to explain the factors influencing the fung
