Native plants and pollinators in the city: the case of Abutilon grandifolium in Buenos Aires

Honey bee visiting Abutilon grandifolium

by Cáceres et al.

Urban green spaces can be important places for plants and insects. Parks, reserves and even small public squares can provide important spaces for plants, insects and the ecological interactions that connect them. In Buenos Aires, urban green spaces now include native plants but we still know relatively little about how these plants reproduce and which insects visit their flowers.

In this study, we worked with Abutilon grandifolium, a native shrub with orange-yellow flowers. We studied plants growing in two urban green spaces: an ecological reserve and a public square planted with native species to recreate local habitats. We studied its floral biology, reproductive system and flower visitors to understand how this plant reproduces and how it interacts with pollinators in the city.

We found that A. grandifolium can produce fruits and seeds by self-pollination, meaning that it does not strictly need pollinators to reproduce. Even so, its flowers attracted several insects, especially bees and native halictid bees.

Honey bees were the most frequent visitors, ut they did not always act as good pollinators: in many cases, they collected nectar without touching the reproductive parts of the flower. Native halictid bees, instead, moved inside the flower and touched both the pollen and the stigmas, making them particularly important pollinators. Other insects, such as large bees, hoverflies and beetles, also visited the flowers, although less frequently. By observing their behaviour and analysing where pollen was carried on their bodies, we were able to distinguish visitors that likely contributed to pollination from those that mainly collected floral rewards without effectively transferring pollen.

An interesting result was that the public square supported a community of floral visitors similar to that of the ecological reserve. In fact, visitor richness was even higher in the square. This suggests that small urban green spaces planted with native species can help maintain pollination processes and may act as stepping-stones for biodiversity within the city.

Our results show that bringing native plants back into urban landscapes is more than a matter of beauty or gardening. These plants can help create living networks between flowers and insects, supporting pollinators and ecological interactions even in the middle of a large city.

Read the scientific article in JPE here.