Abstract:
1. As cropland increases, fields become progressively isolated from pollinators, leading to
declines in pollinator-dependent crop productivity. With the rise in demand for pollinatordependent
foods, such productivity losses may accelerate conversion of natural areas to cropland.
Pollination–compensation measures involving managed pollinators or hand pollination
are not always optimal or are too costly. Introducing areas of native vegetation within cropland
has been proposed as a way to supplement crop pollinators, but this measure is
perceived by farmers to carry costs outweighing benefits to agricultural production. Studies
quantifying benefits of small patches of native flowers to crop pollination are therefore necessary
to encourage such practices.
2. To ascertain whether provision of floral resources within farmlands can facilitate pollination,
and hence, crop yields, small experimental patches of perennial native plants (native
flower compensation areas, NFCAs) were created in nonproductive areas of large commercial
fields of several cultivars of mango Mangifera indica.
3. Pesticide use and isolation from natural habitat were associated with declines in flying visitors
and in mango production (kg of marketable fresh fruit), but presence of NFCAs ameliorated
these declines, and NFCAs did not harbour any mango pests. In areas far from natural
vegetation, orchards near NFCAs had significantly higher diversity and abundance of mango
flying visitors, as well as mango production, than orchards far from NFCAs, although these
measures were still lower than in orchards close to natural areas.
4. Neither the most abundant flower visitors to mango (ants) nor initial fruit set was significantly
affected by distance, pesticides or NFCAs, suggesting that although fertilization is
associated with factors unaffected by isolation from natural habitat and pesticide use (i.e. selfand
ant-pollination), viable fruit set (and ultimately, production) requires cross-pollination,
for which flying visitors are essential.
5. Synthesis and applications. Our results show that the presence of small patches of native
flowers within large farms can increase pollinator-dependent crop production if combined with
preservation of remaining fragments of natural habitat and judicious use of pesticides. Native
flower compensation areas represent a profitable management measure for farmers, increasing
cost-effectiveness of cropland while indirectly contributing to preservation of natural habitat.
