Life-stage niche partitioning and functional strategies promote predatory coccinellids' co-occurrence.

Species coexistence is shaped by how individuals share limiting resources such as space, food, and shelter. Theory predicts that niche differentiation promotes coexistence, depending on habitat characteristics, behavioral traits, and the intensity of competition. Niche use may vary across life stages, as ontogenetic shifts alter habitat use and species interactions. We investigated habitat segregation, niche overlap, and the role of non-crop vegetation in affecting coccinellid coexistence across life stages through semi-controlled experiments and field sampling at 42 sites. Species showed consistent differences in habitat and microhabitat use across developmental stages, influenced by innate behaviors and plastic responses to interspecific interactions. Superior competitors (Hippodamia convergens and Harmonia axyridis) generally dominated prey-rich crop areas during egg, larval, and adult stages, but shifted to sheltered sites outside the plants during pupation. In contrast, Eriopis connexa used soil microhabitats throughout its life cycle, reducing niche overlap with other species. Cycloneda sanguinea, a competitively inferior species, persisted by exploiting non-crop plants, which increased spatial heterogeneity and resource availability. Non-crop vegetation thus promoted coexistence by enabling spatial segregation and reducing presumed competitive asymmetries across life stages. These patterns highlight how the strength of species interactions and spatial partitioning changes ontogenetically, reflecting both behavioral flexibility and the influence of habitat features. We propose a plastic functional classification of species based on their behavioral responses to potential competition-risk scenarios across life stages, ranging from risk-tolerant generalists to conditional risk-avoiders and niche-fidelity strategists, that could be broadened and adapted to other study systems.