Nocturnal insect communities altered by land-use change contribute little to coffee pollination in the Western Ghats, India

Narayanan, H. R., Krishnan, S., & Osuri, A. M. (2026) Nocturnal insect communities altered by land-use change contribute little to coffee pollination in the Western Ghats, India. Agriculture, Ecosystems & Environment 396: 109966. DOI: https://doi.org/10.1016/j.agee.2025.109966.

Wild insects pollinate numerous agricultural crops, but the role of nocturnal pollinators, while increasingly acknowledged, remains poorly understood. We examined nocturnal insect communities and pollination in agroforests of robusta coffee (Coffea canephora) – a crop that exhibits floral traits suggestive of nocturnal pollination – in India’s Western Ghats mountains. Specifically, we (1) compared nocturnal insect communities of a shaded robusta coffee agroforest and a nearby secondary tropical rainforest using light screens, and (2) assessed nocturnal and diurnal pollination of coffee using floral exclosure experiments in the agroforest and in a former coffee agroforest located within the secondary rainforest. Nocturnal pollinators visiting light screens were 21 % fewer in the agroforest than the rainforest, mainly due to reduced numbers of Lepidoptera, Coleoptera, and Diptera in the former. Lepidoptera and Coleoptera differed in genus richness and composition between habitats, with the agroforest having fewer Lepidoptera and more Coleoptera genera than the rainforest. Coffee pollination success was largely attributable to diurnal pollinators in both the agroforest and rainforest. While nocturnal pollination effects were absent in the agroforest, we found some evidence of nocturnal pollination in the secondary rainforest, where coffee flowers accessible to diurnal and nocturnal pollinators had higher pollination success (60 %) than flowers accessible to diurnal pollinators alone (46 %). In summary, the nocturnal insect community of coffee agroforestry, which is distinct from the rainforest community, contributes little to coffee pollination. However, a greater contribution of nocturnal pollination under less intensive coffee cultivation is a possibility that warrants further exploration.