Variation of nematode indices under contrasting pest management practices in a tomato growing agro-ecosystem

This study examined the variation of generic composition and nematode indices to evaluate the soil health status under differently treated tomato growing experimental plots. The study was conducted from 2016 to 2018 in summer and winter seasons on a traditionally tomato (Lycopersicon esculentum) growing farm in the Northern part of the Kathmandu valley, Nepal. Soil samples were taken from four types of replicating plots (each 5 × 5 m sq.) each using a different pest control method consisting of: cattle manure (MP), chemical pesticides (PP), botanical pesticides (BP), and a control plot (CP). The nematode communities were extracted, colonizer-persister (c-p) values assigned and ecological indices such as maturity index (MI), enrichment indexes (EI), structural index (SI) and channel index (CI) were calculated. The low abundance of all indices in pesticide applied plots during both seasons (winter and summer) was recorded. This result indicated pesticide application can be linked to the sensitivity of nematode genera. Nematode indices such as maturity index (MI), enrichment index (EI) and structural index (SI) were significantly affected with lower mean value especially in chemical pesticides applied plots during both the summer and winter seasons. The decomposition channel index (CI) did not exhibit significant variation in our analysis of treatment plots in either season. There was a positive response towards moisture content, soil temperature and nitrogen–carbon ratios for these indices. Nematode genera and indices showed significant variation for pest management practices in tomato grown plots.