Insecticide Resistance in Indian Vegetable Ecosystems: A Critical Appraisal of Toxicological Mechanisms, Resistance Frequencies and Control Options

Abstract

Vegetable production in India depends heavily on repeated insecticide application, and the arthropod species that dominate these systems have responded with rapid and repeated adaptation. The result is a control problem that is simultaneously toxicological, ecological and institutional, yet the literature describing it remains fragmented across pest-specific and state-specific studies that are seldom read against one another. This critical narrative review examines what is currently known about the toxicology of insecticide resistance in Indian vegetable cropping systems, organised around three questions: which physiological and molecular mechanisms are actually demonstrated in Indian populations, how reliably resistance frequency can be estimated from the available monitoring data, and which control measures are supported by evidence rather than by plausibility alone. Literature was identified through structured searching of accessible scholarly indexes and citation networks, with every retained source verified against its bibliographic record. The synthesis indicates that mechanistic understanding in Indian material is dominated by indirect biochemical inference, principally synergist ratios and enzyme assays, while direct molecular confirmation of target-site alleles or specific detoxification genes remains confined to a small number of pests, chiefly the diamondback moth, the whitefly species complex and the eggplant fruit and shoot borer. Reported resistance ratios span several orders of magnitude for the same compound across studies, but much of this variation is attributable to inconsistent reference strains, differing bioassay formats and unstandardised sampling rather than to true biological difference, which makes national frequency estimates unreliable. Evidence for control tactics is similarly uneven: rotation by mode-of-action group and the deployment of transgenic eggplant rest on comparatively strong reasoning and, in the latter case, on field data from the wider region, whereas insecticide mixtures, synergist-based tactics and many biopesticide recommendations remain supported mainly by short-term efficacy trials that cannot demonstrate durability. Residue monitoring shows widespread but generally sub-threshold contamination of vegetables, indicating that dietary risk and resistance are related but not interchangeable concerns. Priorities identified include a harmonised national bioassay and reference-strain framework, molecular diagnostics deployed at population scale, and management trials designed with resistance durability rather than seasonal yield as the primary outcome.