Abstract
Higher Vegetation Cover Promotes Wild Pollinators Abundance in Eggplant (Solanum melongena) Agroecosystems
Md Meftahul KARIM1*, Natsuki KOMADA2, Tomohiro WATAZU2 and Tetsuro HOSAKA1
1Graduate School of Innovation and Practice for Smart Society, Hiroshima University., 2Graduate School of Advanced Science and Engineering, Hiroshima University.
Abstract
Wild pollinators play a crucial role in providing pollination services in agroecosystems. Infield weeds can play a vital role in increasing wild pollinators’ abundance by providing shelter, continuous foraging opportunities, floral resources, and thus, promoting pollination of crops. However, the relative importance of some weed community metrics (e.g. weed coverage, species richness, and flower density) on pollinators and pollination services remains poorly understood. This study aimed to investigate how these weed community metrics, in addition to crop flower density and use of agrochemicals, influence abundance of wild pollinators and pollen number on the stigma of eggplants in farms in Hiroshima, Japan. Time lapse cameras were used to observe pollinators visiting eggplant flowers during 9:00 to 18:22. Weed coverage, weed flower density and weed species richness were quantified within a 5 x 5 m area around the camera. Pollen grains attached on the stigmas of eggplants were collected and counted under microscope. Our results showed that weed vegetation coverage was a key driver of some functional groups of pollinators such as solitary bees and hoverflies. This could reflect their reliance upon infield floral and nesting resources due to lower flying abilities compared to bumble bees and honeybees. In contrast, higher weed vegetation coverage was negatively associated with beetles’ abundance. On the other hand, high weed species richness reduced solitary bee abundance, possibly due to intensifying competition for pollinators between eggplants and weeds. Pollen deposition on the stigma of the eggplant increased with higher weed vegetation coverage. The increase in pollen deposition could be due to increased abundance of solitary bees and hoverflies. In conclusion, increase of weed vegetation coverage is beneficial for promoting pollinator abundance and pollination services in agroecosystems. Moreover, this approach represents a more cost-effective strategy by lowering weed-management costs.