Opportunities and challenges of entomopathogenic nematodes as biocontrol agents in their tripartite interactions (original) (raw)
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ENTOMOPATHOGENIC NEMATODES : A HIDDEN ENEMY OF INSECT PESTS
Entomopathogenic nematodes (EPN's) are attractive, organic alternatives for controlling a wide range of insect pests and they are utilized in classical, conservation and augmentative biological control programs. The history of entomopathogenic nematology is briefly reviewed. In general, EPN's are soil borne and generally gets mutually associated with a bacterium which is responsible for pesticidal actions and its life cycle of consist of five developmental stages. The two most studied species of EPN's are Steinernematidae and Heterorhabditidae families which has mutualistic association with bacteria of genus Xenorhabdus and Photorhabdus, respectively. The virulence mechanisms of the symbiotic bacteria were depending upon antibiotic properties, phase variants and impeding host defense responses. In the laboratory use and small scale field experiments, in vivo production of EPNs appears to be the appropriate method. In vitro technology is used when large scale production is needed at reasonable quality and cost. The efficacy of EPNs can be enhanced through proper production technology, storage mechanism, application technology etc. The scientific community, academician and industrialist are interest to development of new bio-insecticides, which are environmentally friendly. The concerns for the environment and human health and to reducing the risks connected with chemicals, the present review article focused on importance of EPN's in insect pests management, its life cycle, virulence mechanism, mass production technology, commercial product and storage, application technology, guideline for field application and its ccompatibility with insecticide and fertilizers are briefly reviewed.
Mass Production of Entomopathogenic Nematodes or Plant Protection-A Review
Chemical pesticides may cause secondary pest outbreaks, accelerate the development of resistance, destroy natural enemies and create hazards for human's poisonings and approximately twenty thousand deaths occurring annually due to pesticides. As a result, regulatory agencies in different countries have imposed restrictions on chemical pesticide usage. Biological control using predators, parasitoids or pathogens can be an effective measure in insect pest management. Research and development on biological control and insect pests has increased manifold during the past two decades and entomopathogenic nematodes (EPN's) have been developed as one of the tool in insect management. Already, the EPN based biopesticides occupy the major share in the biopesticide world, being second only to Bacillus thuringiensis. EPN's of the families Steinernematidae and Heterorhabditidae (Order: Rhabditida) are lethal parasites associated with symbiotic bacteria of the family Enterobacteriaceae. Steinernematids are associated with Xenorhabdus spp. and Heterorhabditids with Photorhabdus spp. EPN's can be mass produced by in vivo or in vitro methods. The use of EPN is safe for both the user and the environment.
Entomopathogenic Nematodes: Integrated Pest Management and New Vistas
Egyptian Journal of Agronematology
Despite the current use of entomopathogenic nematodes (EPNs) commercially, there are still new prospects for expanding their applications to occupy a prominent market position. Scientists, extension specialists and stakeholders need to identify and widely disseminate conditions under which EPN application can offer a cost-effective, value-added approach to integrated pest management. Moreover, EPN use should not be limited to plant pests. There are other pests that EPNs can effectively and safely control such as those that significantly affect health and production of farm animals and honey bees. Examples of such pests against which nematodes can be reliably applied and general precautions to be taken to optimize EPN operation are given. The wide host range of EPN and their mutualistic bacteria against arthropods and pathogens are promising for advantageous industrial products for boosting pest/disease management. Therefore, a full useful spectrum of the EPN-bacterium complex or the symbiotic bacterium individually should be harnessed for useful usage in current and emerging agricultural systems. Fitting symbiont-obtained insecticidal, acaricidal, nematicidal, pharmaceutical, fungicidal, antimicrobial, and toxic compounds into current or emerging strategies, for controlling many pests/pathogens should be earnestly sought.
Entomopathogenic nematode as a biocontrol agent – Recent trends – A Review
International Journal of Advanced Research in Biological Sciences (IJARBS), 2017
Safety and environmentalcal insecticide issues surrounding the use of chemical insecticides has led to an emphasis on developing alternative control measures such as entomopathogens and their products. Entomopathogenic nematodeare effective biopesticide which can be incorporated in IPM programs because they are considered non-toxic to humans, relatively specific to their target pests and can be applied with standard pesticide equipment. Entomopthogenic nematodes have proven to be the most effective as biological control organisms. Entomopathogenic nematodes have been released extensively in crop fields with negligible effects on non target insects and are regarded as exceptionally safe to the environment. Our focus in this paper was to review mechanism and pathogencity of nematode, phylogeny of nematode for Steinernematidae and Heterorhabditidae. Steinernematidae is represented by the genera Steinernema and Neosteinernema and Heterorhabditidae is represented by the genus Heterorhabditis. They are associated with mutualistic bacteria in the genus Xenorhabdus for Steinernema and Photorhabdus for Heterorhabditis. Thus, it is a nematode bacterium complex that works together as a biological control unit to kill an insect host by penetrating the host through natural opening and there by releasing the bacterial symbiont which spread and multiply in the haemolymph of the insect pest and kill them by septicemia. Infective juvenile entomopathogenic nematode locate their hosts in soil by means of two strategies-ambusing and crusing. Nematode employs different foraging strategies to locate and infect hosts. Genetic diversity may be lost, or genetic variation may have been limited during collection or lost during importation and rearing. A serious problem for EPNs is founder effect because only a limited number of insect cadavers are collected at single geographical sites, resulting in reduced genetic variance. EPNs have been most efficacious in habitats that provide protection from environmental extremes, especially in soil, which is their natural habitat and in cryptic habitats. Excellent control has been archived against plantboring insects because their cryptic habitats are favorable for nematode survival and infectivity. In developing biocontrol programs using EPNs, one mechanism to increase the chance of success is to screen novel nematode species or strains for potential efficacy against particular target pests.
TURKISH JOURNAL OF AGRICULTURE AND FORESTRY, 2015
Introduction Entomopathogenic nematodes (EPNs) (Steinernematidae and Heterorhabditidae) are mutualistically associated with insect-pathogenic bacteria and together they kill their insect hosts. The steinernematids are associated with the bacterial genus Xenorhabdus, whereas the heterorhabditids are associated with the genus Photorhabdus. These EPNs have adapted specific mechanisms to transmit the bacteria to their insect hosts (Dillman et al., 2012) and are considered good candidates for integrated pest management of soil insect pests (Lacey and Georgis, 2012). In fact, several nematode species are produced commercially and applied in a variety of cropping systems in many different countries (Alves, 1986; Garcia et al., 2008). These biological control agents must be delivered in a way that enables the infective juveniles (IJs) of the nematodes to survive and infect their hosts (Shapiro-Ilan et al., 2006; Brusselman et al., 2012). EPNs can be applied with nearly all agronomic or horticultural ground equipment including pressurized tank sprayers, mist blowers, electrostatic sprayers, drip irrigation systems, or even aerial sprayers (Georgis, 1990;
A REVIEW ON ROLE OF ENTOMOPATHOGENIC NEMATODES IN INTEGRATED PEST MANAGEMENT
International Journal of Zoology and Applied Biosciences, 2022
Entomopathogenic nematodes (EPNs), which are microbial pathogens cum insect pest's biocontrol agents, have been used successfully in agricultural systems. They may be easily cultivated in vivo or in vitro and are extremely pathogenic, quickly killing their hosts. Due to their widespread production in liquid media, their production costs have recently decreased dramatically, while still being safe for the environment and non-target vertebrates. Additionally, there are no challenges in using EPNs because they can be coupled with practically all chemical control chemicals and are simple to spray using ordinary equipment. EPNs are frequently used to control economically significant insect pests in a variety of farming systems, including nurseries, greenhouses, turf grass, and fruit orchards. Only in the early 1980's did EPNs start to be used for biocontrol, and this needed a gradual advancement of both science and technology. The commercialization of nematode-based insect pest management was greatly aided by the nematode's mass production. This review paper discusses different species of EPNs, its Mass production and utilization in Integrated Pest Management program.
African Entomology, 2014
Entomopathogenic nematodes (EPNs) have been identified as being promising biological control agents of key insect pests. The two EPN genera that have shown potential for use as biological control agents within an integrated pest management programme are Steinernema and Heterorhabditis. Large numbers of EPNs can be produced through either in vivo or in vitro culturing practices. Commercialization and the successful use of EPNs to control pests in North America, Australia, Europe and Asia have confirmed the effectiveness of these organisms as biological control agents. Two endemic EPN isolates to South Africa, Heterorhabditis zealandica (SF41) and H. bacteriophora (SF351) have been shown to be effective control agents of codling moth, Cydia pomonella, false codling moth, Thaumatotibia leucotreta, obscure mealybug, Pseudococcus viburni, and the banded fruit weevil, Phlyctinus callosus. Unfortunately, EPNs in large enough numbers for commercial field applications are not yet available on the South African market.
Role of entomopathogenic nematodes in the management of insect pests
2014
Entomopathogenic nematodes (EPNs) of the genera Heterorhabditis and Steinernema are obligate and lethal insect parasites. They have the greater potential to be developed as a microbial agent for the management of various insect pests of orchard, vegetables, ornamental plants and turf grasses. The third stage juvenile i.e. the infective juvenile along with symbiotic bacteria (Xenorhabdus spp. in Steinernema spp. and Photorhabdus spp. in Heterorhabditis spp.) enters into the insect body through natural openings or sometimes by penetration through intersegmental membrane. The relationship between nematode and bacteria is an example of true mutualism and from this relation both the organisms are benefited. This nematode-bacterium complex causes the death of insect pests within 24–72 hours. Mass rearing of Steinernematid and Heterorhabditid nematodes can be done in vivo in insect hosts and in vitro in solid medium or in liquid medium. For in vivo production Galleria mellonella larvae are...
2014
Entomopathogenic nematodes of the genera Heterorhabditis and Steinernema are commercially used to control pest insects. They are symbiotically associated with bacteria of the genera Photorhabdus and Xenorhabdus, respectively, which are the major source for the nematodes. The biology of the nematode-bacterium complex is described, a historical review of the development of in vitro cultivation techniques is given and the current use in agriculture is summarised. Media development is mainly directed towards cost reduction, as the bacteria are able to metabolise a variety of protein sources to provide optimal conditions for nematode reproduction. The process technology is described, discussing the influence of bioreactor design and process parameters required to obtain high nematode yields. As two organisms are grown in one vessel and one of them is a multicellular organism, the population dynamics and symbiotic interactions need to be understood in order to improve process management. ...
African Entomology, 2014
The compatibility of two endemic entomopathogenic nematodes (EPNs) with biological control agents and agro-chemicals, likely to be used in an integrated pest management programme for citrus in South Africa was investigated. This is the first report on the possible negative effect of EPNs against Cryptolaemus montrouzieri, a commercially produced biocontrol predatory insect, used against mealybugs. Bioassays were conducted to determine the susceptibility of the mealybug predatory coccinellid beetle, C. montrouzieri, to both nematode species. Results showed the beetle larvae to be highly susceptible to a concentration of 80 IJ/insect of H. zealandica and S. yirgalemense, obtaining 80 % and 92 % mortality, respectively. Adult beetles were found to be twice as susceptible to S. yirgalemense with 64 % mortality, as to H. zealandica with 30 % mortality recorded. Tolerance of both species of infective juveniles to aqueous solutions of Cyperfos 500 EC ® , Cryptogran™, Helicovir™, Nu-Film-P ® and Zeba ® , for infectivity and survival was evaluated. Heterorhabditis zealandica proved to be highly compatible to all products tested, with no significant increase in nematode mortality. The formulations also did not affect the ability of H. zealandica to infect Tenebrio molitor, after exposure to products over a 24-h period. Significant increase in mortality of S. yirgalemense was recorded after 12 hours of exposure to Nu-Film-P ® and Cyperfos 500 EC ® , and after 6 hours of exposure to Nu-Film-P ® . However, results for S. yirgalemense infectivity showed no decrease in the ability of the nematodes to infect insect hosts. Results indicated that nematodes should possibly be applied before the release of C. montrouzieri in citrus orchards.