Field Assessment of Floral Resources and Pollinator Abundance Across Six Vegetable Crops

Pollinators play a crucial role in global biodiversity, providing essential ecosystem services such as crop pollination. However, their abundance and diversity have been gradually decreasing in recent years. Despite increasing interest in sustainable agriculture, information on vegetable crops that attract insect pollinators remains limited. We hypothesize that variation in floral traits among vegetable crop cultivars, especially nectar volume, nectar sugar concentration, and pollen characteristics, significantly influences visitation patterns and species composition. To test this, we evaluated multiple cultivars of six vegetable crops (cowpea, sweet potato, eggplant, green bean, mustard, and chickpea) over two years, focusing on five key pollinator groups (honey bees, bumble bees, carpenter bees, sweat bees, and wasps). Cowpea and sweet potato consistently attracted the most pollinators, whereas chickpea attracted the fewest. In 2022, nectar volume was highest in sweet potato (16.45 ± 0.37 µL) and lowest in chickpea (1.18 ± 0.75 µL). Similarly, in 2023, sweet potato recorded the highest nectar volume (8.33 ± 2.95 µL), and chickpea the lowest (0.02 ± 0.01 µL). However, chickpea (31.00 ± 1.58 °Bx) and mustard (30.10 ± 1.12 °Bx) recorded the highest nectar sugar concentration in both years, and chickpea and eggplant produced significantly more pollen grains. A significant positive correlation was observed between nectar volume and pollinator abundance. Comprehensively, this two-year study demonstrates the complex relationship between floral traits and pollinator preferences. These findings offer growers practical guidance on selecting vegetable intercrops that attract specific pollinators, thereby enhancing pollination services, supporting biodiversity, and improving the yield of pollinator-dependent crops.