Habitat heterogeneity and alternative hosts enhance the stability and effectiveness of egg parasitoid-mediated...

Egg parasitoids are key natural enemies of insect pests and provide essential biological control services in forest and agricultural ecosystems. However, the mechanisms by which habitat heterogeneity and seasonal dynamics drive parasitoid communities remain poorly understood. We examined egg parasitoid diversity, abundance, parasitism rates, and interaction network structure across seminatural Masson pine forests and 3 crop habitats (tea plantations, plum orchards, tobacco fields). Sentinel egg cards of Antheraea pernyi (Guérin-Méneville) and Samia ricini (Jones) were deployed monthly from April to November over 2 consecutive years. Parasitoid diversity was strongly determined by habitat type, with seminatural habitats supporting higher species richness and diversity. Parasitoid abundance and parasitism rates were shaped by habitat type, season, and host egg type. Species-habitat network analyses revealed a highly modular structure dominated by peripheral species, with few connector species, indicating strong habitat-filtering and functional specialization. Complex seminatural habitats sustained stable modular networks and higher parasitoid activity, while intensively managed crop habitats exhibited weaker connectivity and greater temporal variability. Our findings demonstrate that parasitoid community dynamics and biocontrol efficacy are closely linked to habitat heterogeneity, seasonal resource availability, and network structure. Alternative hosts sustain parasitoid activity and enhance network stability, supporting biological control. Maintaining a mosaic of crop and seminatural habitats is critical for preserving parasitoid network integrity and improving the stability and effectiveness of biological control services.