Plant-parasitic Nematodes in Indian Agriculture: Risks, Dissemination Pathways and Mitigation Strategies

Abstract

Plant-parasitic nematodes are a persistent yet inconsistently quantified biotic constraint in Indian cropping systems. A small number of national loss estimates circulate widely in the Indian literature, shape research priorities and are reproduced in the introductions of a large proportion of subsequent papers, yet the evidential structure of those estimates has rarely been examined. This review evaluates the strength, internal consistency and methodological adequacy of the published evidence on plant-parasitic nematodes in Indian agriculture, concentrating on four interlinked problems: the derivation and reliability of crop loss estimates; the changing composition of damaging species assemblages; diagnostic capacity; and the quality of evidence supporting management recommendations. Literature published between 2001 and May 2026 was identified through openly accessible bibliographic indexes and metadata registries, supplemented by backward citation tracking from recent reviews and by verification of bibliographic identity against publisher and registry records. The synthesis indicates that the most frequently cited national loss figure rests on aggregation of long-accumulated coordinated project data rather than on contemporaneous nationally representative sampling, and that the field-level studies which contribute to such aggregates typically rely on nematicide-based paired-plot designs whose treatment effects cannot be attributed to nematode suppression alone. The species assemblage causing economic damage appears to be shifting, with the rice root-knot nematode expanding in irrigated and aerobic rice systems and a virulent root-knot species recorded on an increasing range of hosts, although the underlying evidence consists largely of localised surveys and first reports that cannot establish rate of spread. Diagnostic capacity emerges as a rate-limiting constraint: morphological identification shows only moderate inter-observer agreement, and molecular and community-profiling methods remain concentrated in a small number of laboratories and are sensitive to methodological choices. Management evidence is strongly weighted towards short-duration pot and single-season trials, with limited multi-season field replication. Priorities include standardised loss assessment, distributed diagnostic capacity and durable field validation of biological and integrated approaches.