Spider functional ecology in subtropical perennial orchards: Molecular diet profiling and microhabitat use in pomelo agroecosystems

Spiders are important generalist predators in agroecosystems, yet their trophic roles and habitat use in subtropical perennial orchards remain insufficiently understood. We investigated spider assemblages in eight pomelo orchards in eastern Taiwan over three years (2022–2024) as a case study of subtropical orchard systems in the Asia-Pacific region. Sweep-net sampling yielded 1206 spiders from 16 families, with 92 morphospecies identified among adults. Organic management did not significantly increase overall spider abundance but supported higher abundance of several dominant hunting spider families (Lycosidae, Oxyopidae, Salticidae, and Thomisidae), whereas Theridiidae was more abundant under conventional management. Total spider abundance remained similar between actively managed and unmanaged phases in both farming systems, suggesting that perennial orchard structure may buffer predator communities against periodic agricultural interventions. COI metabarcoding of 72 Oxyopidae and Tetragnathidae revealed broad prey spectra comprising other spiders, numerous insect families, and several citrus pest-associated taxa, although many dietary signals derived from non-pest organisms. Cardboard trunk refugia provided supplementary microhabitats and recovered 21 spiders from six families, including ground- and bark-associated taxa not commonly captured by sweeping. Refugia-collected spiders exhibited distinct dietary profiles, with ants, particularly Technomyrmex albipes , producing prominent sequencing signals. Overall, these results suggest that spider assemblages in subtropical perennial orchards are associated with management regime, trophic context, and microhabitat structure. While the direct suppression of target pests and its ultimate impact on economic fruit metrics such as peel appearance may be context-dependent, diverse spider communities and their associated trophic networks may contribute to ecological stability of orchard agroecosystems.