Crop pollination by native honey bees (Apis cerana) at risk due to agricultural intensification: Impact of farming systems

Agricultural intensification in Lao PDR has increased significantly each year, resulting in the conversion of vast natural habitats to various levels of agricultural intensification. However, there has been a longstanding knowledge gap regarding the impact of agricultural intensification on native fauna species in the country. The present study was conducted in two different agricultural systems (organic and conventional), which varied in land-use intensity, in central Lao PDR. Within each farming system, five sampling plots (30 x 50 m), spaced 100 m apart, and 900 m distance between organic and conventional farming systems were selected. The farming system had the greatest influence on native honey bee abundance. Although honey bee abundance was higher in the organic, the diversity of flowering plant resources did not differ significantly between the two farming systems. This suggests that the farming system has a more crucial impact on native honey bee populations than on the diversity of flowering plants. In organic farming, it was found that native honey bee populations could provide full pollination services, even for crops with high pollination demands without the need for other pollinators. All other sampling plots in the conventional farming system, however, showed a significant decline in native bee abundance, resulting in insufficient pollination services from native bees alone. This study found that diversity is crucial for sustaining these services, given the year-to-year variation in population levels. Additional measures are needed to conserve more specialized native honey bee species and other pollinators in both farming systems.