Understory Vegetation Influences Insect Diversity in Rubber Plantations of Kanyakumari, India

Insects play a crucial role in maintaining ecological balance, and their decline has detrimental effects on various organisms. Globally, rubber plantations have been associated with a reduction in insect diversity. However, the impact of monoculture rubber plantations on biodiversity in India, particularly in Kanyakumari, is not well understood and has received little research attention. This study aimed to assess the status of insect diversity in rubber plantations in this region. Kanyakumari, Tamil Nadu, with its extensive monoculture rubber plantations, provides an ideal setting for this investigation. Three adjacent rubber plantations with varying topography and understory vegetation were selected for the study. Data was collected between July 2021 to January 2022 and analysis was done using biodiversity indices - Simpson and Shannon-Weiner indices. Results indicated that insect diversity was significantly higher in one plantation when compared to the other two plantations. Canopy and understory vegetation were identified as key factors influencing insect diversity. Plantations with dense understory vegetation consisting of diverse native plant species exhibited greater insect richness. The predominant insect orders across all plantations were Hymenoptera (29.70%) and Diptera (29.40 %). However, the impact of rubber plantations on individual insect species varied based on their habitat preferences. Seasonal fluctuations in diversity were particularly noticeable during the monsoon season. Further comparative studies are needed to understand the broader implications of rubber plantations on insect diversity across the district.