Ashok K. Chaubey

By Himani Sharma, Aasha Rana, Aashaq H. Bhat and Ashok K. Chaubey

The insect parasitoid nematodes are a means boon to agronomy and serve as important bio-pesticides for controlling crop damaging insect pests. These nematodes inhabit moist soils and have been to exist in all the continents excluding Polar Regions. These nematodes have 3rd larval stage infective which is the only free living stage existing outside the host. These infective stages are mutually associated with bacteria which reside in their alimentary canal and duo are responsible for mortality of the insect host. These nematodes are currently given great attention by scientific community because of their insect killing properties and can be used to replace hazardous pesticides. These nematodes include various species belonging to genus Heterorhabditis and Steinernema, and members of insectivorous group of genus Oscheius. Before their use as bio-control agents, these nematodes need to be properly identified. Currently, these nematodes are characterized by using morphological and morphometrical parameters and advanced molecular tools including cross hybridization and scanning electron microscope studies. Their associated bacterial partners are studied through advanced molecular and biochemical techniques. The properly characterized nematodes having more entomopathogenic properties can be easily mass produced through in vitro and in vivo methods. They can be formulated in various carrier materials and supplied to farmers for effective control of damaging insect pests. Several countries have formulated various useful products of entomopathogenic nematodes which are available in markets for use by the farmer community and some have given very effective results. India is still at the early stage in the use of these nematodes for bio-control of insects in agronomy. More research in this field needs to be carried, especially in India to produce effective indigenous nematode products which may prove a boon for agriculture.

Part of the book: Nematodes

By Kajol Yadav, Lovely Bharti and Ashok Kumar Chaubey

Chemical fertilizers and pesticides are presently accumulating in the environment harming the ecosystem, causing pollution, and spreading some of the diseases. Nematodes can be considered as entomopathogenic (EPN) if they fulfill criteria for entomo-pathogenicity when they bearing a pathogenic bacterium within a dauer juveniles juvenile, releasing the bacterium inside the host, actively seeking out and penetrating the host, rapid insect death, nematode and bacterial reproduction, reassociation of the pathogenic bacteria with new generations of dauer juveniles, and emergence of IJs from the cadaver so that the cycle can be repeated. Synthetic chemical pesticides have various disadvantages which include crop and soil contamination; killing of beneficial fauna and flora; resistance development in insects and adverse effects due to contamination in food chain; and other environment-related issues. To minimize pesticides contamination, EPN were identified as biological control agents and most suitable natural enemies of problematic insects because they reduce risk to humans and other related vertebrates.

Part of the book: Organic Fertilizers

By Himani Sharma and Ashok Kumar Chaubey

Plant parasitic nematodes are major pests of the agricultural industry in developing countries. This group is associated with different parts viz., flower, leaves, buds, roots, trunk etc., of approximately all crucial crops of agronomy due to their omnipresent nature. They are categorized as endo, ecto and semi-endoparasite based on the feeding habits. PPNs possess remarkable characteristics especially, parasitic adaptations which help in combating adverse conditions. Furthermore, they interact with other microorganisms (pathogens) forming complex diseases in crops. For effective management of the PPNs through biological control, it is essential to understand their parasitic mechanism, adaptation of J2 stages, feeding mechanism, host-nematode relationship and identification of associated microbiota. This review focuses on the basic biology of PPN, feeding habits, parasitic potential, molecular insights for understanding host-nematode relationship and their management by exploiting the inherent abilities of biocontrol agents.

Part of the book: Nematodes