Frequency of occurrence and distribution of entomopathogenic nematodes (EPNS) under varied ecosystems of Southern Rajasthan

Entomopathogenic nematodes (EPNs) are obligate or facultative insect-parasitic nematodes that play a significant role as biological control agents in sustainable and future agriculture. The current investigation aims at minimization of indiscriminate use of harmful pesticides by using EPNs. For this, the native isolates of EPNs should be isolated, identified and mass produce for their vast use. So, by conducting surveys for varied ecosystem in southern Rajasthan, we have collected total of 64 soil samples from Udaipur, Chittorgarh, Pratapgarh and Rajsamand districts. Collected samples were processed for isolation of EPNs by using insect baiting technique with Galleria mellonella larvae. The frequency of occurrence and distribution was calculated based on the parameters analyzed. Out of 64 samples, seven were found positive for EPNs, showing an overall recovery rate of 10.93 percent of EPNs. The highest EPNs frequency was observed in Udaipur district (17.14%), followed by Chittorgarh (11.11%) while no EPNs were recorded in the sample collected from Pratapgarh and Rajsamand. Among ecosystems, fig orchard showed the highest EPN occurrence (42.85%). Among seven isolates, two isolates were selected for their identification based on their virulency against Galleria mellonella. These both isolates were collected from Madar village, Udaipur (Lat. 24.67041°N; Long. 73.62292°E) and RCA, Udaipur (Lat. 24.571270°N; Long. 73.691544 °E). Upon morphological and molecular identification, these isolates were diagnosed as Heterorhabditis indica M-1 and Oscheius tipulae M-2. The findings highlighted the significance of isolating native EPNs adapted to local Agro-climatic conditions for effective and efficient use in integrated pest management (IPM) programs.