Bioaccumulation and Trophic Transfer of Heavy Metals in Terrestrial Soil–Plant–Insect Food Chains Within Agricultural Systems: Patterns, Mechanisms, and Ecological Implications

Heavy metal contamination is a persistent environmental problem in terrestrial ecosystems, where metals present in soils can enter food chains and affect organisms across multiple trophic levels. In terrestrial systems, heavy metals are transferred from soils to plants and subsequently to phytophagous insects and their predators, yet these pathways have received less integrated attention than aquatic food webs. This issue is especially relevant in naturally metal‐rich environments such as serpentine ecosystems, where elevated concentrations of metals, particularly nickel, strongly shape plant–insect interactions. This review synthesizes current knowledge on the bioaccumulation, trophic transfer, and elimination of heavy metals in terrestrial soil–plant–insect food chains, drawing on evidence from natural ecosystems as well as laboratory and field studies. We examine the behavior of key essential and non‐essential metals (Cd, Zn, Pb, Hg, Cu, and Ni) and highlight how soil properties, plant uptake mechanisms, insect feeding strategies, and detoxification processes regulate metal movement across trophic levels. Particular attention is given to bioaccumulation and biomagnification patterns, as well as to excretion and elimination pathways such as honeydew production and molting that can limit metal transfer to higher consumers. Overall, the review shows that metal transfer is highly species and metal‐specific, leading to changes in trophic interactions, community structure, and ecosystem functioning. Most available studies were conducted in agricultural systems, highlighting the need for more field‐based ecological investigations across natural ecosystems. We conclude by identifying key knowledge gaps and outlining future research directions needed to better predict ecological risks under increasing metal contamination.