Microclimatic and Anthropogenic Drivers of Insect Biodiversity in Rubber-Based Agroforestry Systems

Rubber (Hevea brasiliensis) plantations constitute the largest artificial ecological forest systems in tropical regions of China, while long-term monoculture has significantly reduced biodiversity, particularly among insect communities. Rubber-based agroforestry systems are widely recognized as a promising approach to improving ecosystem functionality. However, the mechanisms by which different intercropping patterns affect insect community dynamics remain poorly understood. This study systematically evaluated the effects of eight rubber-based agroforestry systems on insect community diversity, functional group composition, and associated environmental drivers. Using rubber monoculture as a control, seven rubber-based agroforestry systems were investigated from April 2024 to March 2025. A total of 94,483 insect individuals belonging to 16 orders, 222 families, and 1560 species were recorded. The results indicate that the rubber-fig (Ficus hirta) and rubber-banana (Musa nana) agroforestry systems supported higher insect richness, diversity, and community stability than other systems, while the more complex rubber-coconut (Cocos nucifera)-fig (Ficus hirta) system exhibited a relatively lower value. Functionally, herbivores dominated the rubber monoculture system. The moderately grazed rubber-forage grass (Brachiaria eruciformis)-black goat agroforestry system promoted predators and detritivores, whereas the rubber-konjak (Amorphophallus bulbifer) agroforestry system attracted more omnivores. The permutational multivariate analysis of variance revealed that insect species composition was primarily negatively driven by canopy cover (R² = 14.65%) and management intensity (R² = 11.54%). The ecological benefits of rubber-based agroforestry systems depend not only on crop species diversity but also on vegetation structural complexity and management practices. It is recommended to promote the rubber-banana and rubber-fig agroforestry systems as optimized models and to enhance insect-mediated ecosystem services by maintaining understory vegetation structure, regulating canopy cover, and implementing low-intervention management practices.