Abstract:
Research was conducted on two important groups of nematodes plant parasitic nematodes
(RKNs) and insect parasitic nematodes (entomopathogenic nematodes). Eggplants
(Solanum melongena L.) are the most seriously affected by Meloidogyne incognita.
Entomopathogenic nematodes i.e. Steinernema glaseri, S. asiaticum, Heterohabditis
indica and H. bacteriophora were evaluated at different time of application against M.
incognita for invasion, development and reproduction of M. incognita. In a life cycle
study, S. asiaticum and H. bacteriophora were proved more effective in influencing the
life cycle of RKNs at all application times than S. glaseri and H. indica. However
application of entomopathogenic nematodes before application of M. incognita proved
more effective than with and after the application of root knot nematodes. S. asiaticum
and H. bacteriophora delayed penetration of nematode juveniles (J2) into roots of brinjal.
Cells and toxins of and Xenorhabdus spp. and Photorhabdus spp. proved nematoxic to M.
incognita. Higher concentrations of bacterial cells suspensions and toxins were more
effective in suppression of hatching of eggs and immobilization of juveniles than the
lower concentrations. Percentage inhibition of eggs and juvenile’s immobilization of M.
incognita increased with increase in concentration. At concentration of 4x10 7 cells/ml,
Xenorhabdus spp. and Photorhabdus spp. cell suspensions completely prevented egg
hatching of M. incognita at 48 hrs exposure time. Bacterial cell suspensions and bacterial
toxins equally inhibited egg hatching and immobilized juveniles. Bacterial cell
suspensions and toxins of Xenorhabdus spp. and Photorhabdus spp. caused more than
90% immobilization of juveniles. The persistence effectiveness of bacterial cell
suspensions and toxins in soil were evaluated up to 7, 14 and 21 days against M.
incognita and determined that Xenorhabdus spp. and Photorhabdus spp. were effective in
suppressing number of galls, number of females, egg masses and reproduction factors
after 7 days of application followed by 14, 21 days of application. The efficacy of
bacteria and toxins decreased in the soil over long period of time. These bacteria and their
metabolites can be stored in vitro on room temperature up to the period of 5 months.
Protective and curative effects of Xenorhabdus spp. and Photorhabdus spp. and their
toxins on root-knot nematodes were also studied on nematode development parameter,
number of females and reproduction factors. All treatments proved effective as comparedto the control. Protective effect of Xenorhabdus spp. and Photorhabdus spp. and their
toxins at standard concentrations were more effective in controlling the number of females
and reproduction factor of root knot nematodes than their curative effect. Compatibility
and the combined action of bacteria (Xenorhabdus spp. and Photorhabdus spp.) and
toxins with bio-products (abamectin, emamectin and azadirachtin) against M. incognita
were also evaluated. The results of the study showed that the combined use of bacterial
cell suspensions and abamectin significantly reduced the population of M. incognita and
have synergistic effect with each other.