Entomopathogenic nematodes (EPNs) in the families' Steinernematidae and Heterorhabditidae are obligate insect parasites. Their easy multiplication, broad host range, compatibility with chemical pesticides, and ease in application has grabbed interest among research practitioners to work on these beneficial microorganisms. Till date, around 100 valid species of Steinernema and 21 species of Heterorhabditis have been identified from different countries of the world. Extensive surveys have been conducted across the globe to isolate locally adapted EPN species and exploit them to suppress soil-dwelling and foliar insect pests in agricultural fields. Most of the new species have been described from Asia, whereas research in some Asian countries are still at infancy. Some new species have been recorded from Australia but very few surveys have been conducted in New Zealand. Likewise, less information about these tiny creatures is from Central America; however, in North America many new species have been described, some of which have been commercialized for insect pest control, whereas in South America, several native nematode species have been described and exploited as biological control agents. European countries have also been explored for EPN diversity and new species have been reported, exploited under field condition, and commercialized. Many new species and other previously described species have been reported from Africa. Despite frequent surveys in different continents of the world, number of sites touched are low and, therefore, further surveys are still needed to explore untouched geographic areas and climatic conditions, both in plantations and indigenous forests with an aim to identify and exploit additional EPN species.

Plant-parasitic nematodes (PPNs) pose a serious threat to quantitative and qualitative production of many economic crops worldwide. An average worldwide crop loss of 12.6% (equaled $215.77 billion) annually has been estimated due to these nematodes for only the top 20 life-sustaining crops. Due to the growing dissatisfaction with hazards of chemical nematicides, interest in microbial control of PPNs is increasing and biological nematicides are becoming an important component of environmentally friendly management systems. Fungal and bacterial nematicides rank high among other biocontrol agents. In order to maximize their benefits, such bio-nematicides can be included in integrated nematode management (INM) programs, and ways that make them complimentary or superior to chemical nematode management methods were highlighted. This is especially important where bio-nematicides can act synergistically or additively with other agricultural inputs in integrated pest management programs. Consolidated use of bio-nematicides and other pesticides should be practiced on a wider basis. This is especially important, since there are many bio-nematicides which are or are likely to become widely available soon. Identification of research priorities for harnessing fungal and bacterial nematicides in sustainable agriculture as well as understanding of their ecology, biology, mode of action, and interaction with other agricultural inputs is still needed. Therefore, accessible fungal and bacterial nematicides with their comprehensive references and relevant information, i.e., the active ingredient, product name, type of formulation, producer, targeted nematode species and crop, and country of origin, are summarized herein.

This chapter discusses the global impact of phytonematodes on crop production and presents a recent assessment of crop losses caused by these tiny creatures. The habitat, taxonomy, biology, parasitism, sampling, spatial distribution, contribution in the soil food web and management of plant parasitic nematodes are described. Progress in molecular and biochemical studies on these nematodes is highlighted. The economically important plant parasitic nematodes worldwide, as well as the economic thresholds for damage by these nematodes, are also described. Future prospects are mentioned.

This chapter aims to highlight the significance of nematophagous fungi, their efficacy as biological control agent as well as their possible role in future control strategies of nematodes, particularly those concerning the integrated nematode management programme. Information is given on their morphology, mode of action, ecology, distribution, and effect on plant parasitic nematodes.

Biological control agents (BCAs) are increasingly used against various plant-parasitic nematode (PPN) pests and offer a favorable alternative to hazardous chemical nematicides. Yet, their lack of efficacy, inconsistent field performance, and/or unfavorable economic factors have generally relegated them to a relatively small sector of pesticide market. Efficacy and biocontrol success can be boosted via holistic grasping of soil biological and ecological factors. Therefore, such factors were highlighted to give better directions for their use. Main points discussed currently are considered to affect the transmission success of these BCAs so that their use must be a way forward in crop protection/pest management. These included improved sampling, grasping BCAs interactions with soil biota and ecology, cost-effective use of BCAs, genetic manipulation for better PPN control, grower acceptance and awareness-raising of BCA techniques, and commercial application.

This chapter outlines the historical records of insect nematology before highlighting the major groups of beneficial nematodes. These include entomopathogenic nematodes to use against insect pests, slug nematodes to manage mollusc pests, entomophilic nematodes such as Thripinema to manage thrips, predatory nematodes to manage plant parasitic nematodes and fungal-feeding nematodes to manage soilborne plant pathogens. Research achievements related to these nematode groups, particularly in managing insect pests, mollusc pests and plant pathogens, are summarized. Major impediments that preclude beneficial nematodes from a significant share of the pesticide market are presented, and possible solutions for their effective utilization are discussed. To develop these nematodes as biopesticides, only those nematode groups that will be financially beneficial to the biological control market and that have had promising results published will be addressed. Future research priorities and goals are also identified.

Three strains of entomopathogenic nematodes, labelled P5, P6 and PH, were isolated during surveys of agricultural soils of Pir Panjal Range, using insect baiting technique. Morpho-taxometrical studies and molecular data confirmed that these isolates belong to Heterorhabditis bacteriophora, making this finding the first report of this species from Jammu and Kashmir, India. Their distribution using a meta-analysis of GenBank records was attempted to assess. The morphology, morphometric studies and molecular data were conspecific to original description with minor deviations. Data analysis of the distribution showed that H. bacteriophora was the most ubiquitous throughout the South Africa subcontinent, but it was rarely found in Indian subcontinent having been isolated from 3 states throughout the country. As these 3 strains of H. bacteriophora are native to the hilly region of Kashmir Valley, they can be exploited for the control of target crop insect pests of the region. However, further studies are required regarding their life cycle, host range, virulence potential and survival capacity under extreme environmental conditions.

Background The complex including entomopathogenic nematodes (EPNs) of the genera Steinernema and Heterorhabditis and their mutualistic partner, i.e., Xenorhabdus and Photorhabdus bacteria, respectively possesses many attributes of ideal biological control agents against numerous insect pests as a third partner. Despite authenic opportunities for their practical use as biocontrol agents globally, they are challenged by major impediments especially their cost and reliability. Main body This review article presents major attributes of EPNs to familiarize growers and stakeholders with their careful application. As relatively high EPN costs and frequently low efficacy are still hindering them from reaching broader biopesticide markets, this is to review the latest findings on EPN strain/species enhancement, improvement of production, formulation and application technology, and achieving biological control of insects from the standpoint of facing these challenges. The conditions and practices that affected the use of EPNs for integrated pest management (IPM) are identified. Besides, efforts have been made to address such practices in various ways that grasp their effective approaches, identify research priority areas, and allow refined techniques. Additionally, sampling factors responsible for obtaining more EPN isolates with differential pathogenicity and better adaptation to control specific pest(s) are discussed. Conclusion Specific improvements of EPN production, formulation, and application technology are reviewed which may help in their broader use. Other diverse factors that optimize EPNs to constitute a cost-effective, value-added approach to IPM are also demonstrated.