About Project

Entomopathogenic nematodes (EPNs) have emerged as excellent candidates for managing a wide range of insect pests. It has also been established that these are safe for the human health and environment and hence exempted from registration in USA and some other countries. But, India is yet to exploit this area of high biological control potential. These nematodes belong to the families Steinernematidae and Heterorhabditidae, and they carry symbiotic bacteria (EPBs) belonging to the family Enterobacteriaceae in their gut. These nematodes along with their symbiotic bacteria (EPBs) kill the host within 24-48 hour and then emerge from the insect cadaver in millions to infect the other insect host. Nematode-bacterium relationship is not only species specific, but also exhibit variability in their host range and ecological characteristics. Therefore, there is need to devise models on nematode-bacterium-insect specificities in relation to major cropping-systems in different moisture regimes, for identifying the location-specific as well as target host-specific EPN-EPB species. The symbiotic bacteria associated with these nematodes undergo phase transition. Phase I and phase II of the bacteria can kill the insect host, but phase II does not support nematode reproduction. Nematodes can pick up and retain only phase I but not phase II. The phase transition of the bacteria Xenorhabdus carried by Steinernema, is reversible. While phase transition in Photorhabdus species carried by Heterorhabditis species, is irreversible. Therefore, there is an urgent need to understand the significance of phase transition and identify the factors responsible for supporting nematode reproduction and those supporting the virulence, in the indigenous strains of nematodes and their bacteria. The basic information on symbiosis and virulence mechanism will yield very useful information which can be exploited for in vitro mass production of these nematodes for commercialization.

Moreover, in EPN-EPB-insect trio-complex, the bacteria are known to produce a range of bioactive compounds having insecticidal, nematicidal, antifungal and antibacterial properties, which inhibit the growth of secondary microorganisms. Basic studies on mechanism involved in nematode-bacterium symbiosis and its virulence against insect host, can answer several subtle questions, and reveal important cues on the biotoxins produced by the bacteria, their chemical nature, which will be of immense value in developing novel broad spectrum biopesticidal compounds (effective in nano-doses) for managing several agricultural and veterinary pests. Keeping in view the socio-economic conditions of Indian farmers, use of these ecofriendly unified approaches will prove to be suitable for managing a wide range of insect pests and diseases prevailing in the country.