Agroecological cashew cultivation increases pollinator abundance, diversity and flower visitation rates, with potential yield benefits

Abstract

Agroecological approaches have the potential to reduce the adverse impacts of agriculture on the environment whilst sustaining productivity, yet rigorous assessments of associated policies’ ability to achieve these dual aims at farm scale remain scarce. Here, we evaluate the impacts of the Zero Budget Natural Farming (ZBNF) programme – a large-scale government-led agroecological strategy in South India – on the ecological and productivity performance of an emerging commodity crop associated with high deforestation-risk: cashew (Anacardium occidentale L.). ZBNF increased the abundance and species richness of insects visiting cashew flowers (including known cashew pollinators) by almost 400 % and 250 % respectively, with visitation rates to cashew flowers rising nearly fivefold compared to conventional, agrichemical-based systems. Whilst there was strong support for these positive effects, estimates of their magnitudes were imprecise. Around 40 % of all species were exclusively found at ZBNF orchards. ZBNF’s effect on cashew nut yield was uncertain due to high variability in the data, yet our results indicate a positive trend, with yields averaging over 70 % higher under ZBNF. Thus, ZBNF likely enhanced cashew pollination service provisioning and had insect conservation benefits, although more targeted actions may be needed for rare, specialist species. Whilst ZBNF can help shift cashew production towards sustainability, we stress that it must be paired with land-use planning and strengthened conservation efforts to prevent further cashew expansion into natural ecosystems.