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

## TL;DR

This study shows that combining rubber trees with banana or fig plants boosts insect diversity and ecosystem health more than monoculture rubber plantations.

## Contribution

The study identifies specific agroforestry systems (rubber–banana and rubber–fig) that enhance insect biodiversity and stability in tropical rubber plantations.

## Key findings

- Rubber–fig and rubber–banana systems supported higher insect diversity and stability compared to other systems.
- Canopy cover and management intensity negatively impacted insect diversity, while flowering intensity and vegetation cover had positive effects.
- Different agroforestry systems favored distinct insect functional groups, such as predators and detritivores.

## Abstract

Insect diversity is vital for ecosystem health but declines significantly in tropical monoculture rubber plantations. Agroforestry systems that combine rubber with other plants offer a promising alternative, yet the influence of varying planting configurations on insect communities remains poorly understood. This year-long study conducted in Hainan, China, compared insect assemblages across multiple rubber-based agroforestry systems and a conventional rubber monoculture. The results indicate that the type of agroforestry system significantly influences insect community composition. Systems like the rubber–fig (Ficus hirta) and rubber–banana (Musa nana) supported higher levels of insect diversity and stability, while a more complex rubber–coconut (Cocos nucifera)–fig (Ficus hirta) system exhibited relatively lower performance. Furthermore, different systems also favored distinct functional groups: monoculture attracted more herbivores, while other diversified systems supported more predators, detritivores, and omnivores. Canopy cover and management intensity were identified as the primary negative drivers of insect diversity, whereas flowering intensity and vegetation cover emerged as the main positive factors. We recommend promoting the rubber–banana and rubber–fig systems as optimized models and enhancing insect ecosystem services through maintaining understory vegetation structure, regulating canopy cover, and adopting low-intervention management practices.

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.