Entomopathogenic Nematodes Survey, Persistence in Soil, Reproductive Potential and their Effects on Meloidogyne incognita

The increasing cost of nematicides and environmental deterioration are the great challenges to agriculture. Entomopathogenic nematodes (EPNs) could be a choice as biocontrol agent in suppressing the root knot nematode, Meloidogyne incognita on tomato and other crops. A total number of 75 soil samples were collected from different locations of Vehari and Faisalabad, Pakistan. In Vehari out of 14 sites, 13 sites were found positive for EPNs, Nematodes were recovered from 19 (54 %) of 35 soil samples obtained from ecologically diverse habitats. From University of Agriculture Faisalabad, EPNs were recovered from 6 (40 %) of 15 soil samples. While, out of 25 samples collected from Ayub Agriculture Research Institute 9(36%) were found positive for EPNs. Both Steinernema and Heterorhabditis species were found in these locations. The soil samples were also analyzed to indicate the effect of soil texture. Maximum EPNs (36 %) were recovered from sandy loam soil followed by loamy soil. A series of experiments was carried out to unearth EPNs’ soil persistence, reproductive potential and their effects on root knot nematodes. All species and strains of EPNs had potential to persist in almost all type of soils. Persistence was observed in sterilized soil sand and clay (1:1). Maximum persistence was found in S. glaseri (29.11 %) followed by S. pakistanese (28.41 %), H. indica (26.93 %), S. asiaticum (24.42 %), S. feltiae (21.52 %) and H. bacteriophora (21.11 %) which showed the least persistence in sterilized soil. All species of both the families Heterorhabditidae and Steinernematidae did not persist more than 30 % in sterilized soil. Reproductive potential of three EPNs was recorded using the greater wax moth Galleria mellonella larvae. H. indica showed very high reproductive potential within wax moth followed by S. asiaticum and S. pakistanese. On the other hand, maximum emerged infective juveniles per day were recovered from H. indica followed by S. pakistanese and S. asiaticum. Suppressive effect of EPNs against root knot nematodes was observed on susceptible tomato cultivars at different concentration. S. pakistanese suppress M. incognita population more efficiently than H. indica at all the levelsi.e. 1250, 2500 and 5000 nematodes pot-1 . After 35days egg masses (EM) recovered from S. pakistanese treated pots at level 1250 were 232/pot, at level 2500 were 207 and at level 5000 were 135 respectively. Similarly, egg masses recovered from H. indica treated plants at level 1250 were 276, at level 2500 were 212 and at level 5000 were 154 EM pot-1 respectively. No EM were recovered from clean plants on contrary328 EM were recovered from plants with root knot nematodes only.