Rural shoulders play a key role in pollination

An academic study in the Pampean region has determined the role these areas play in supporting key biodiversity when it comes to increasing yields of certain crops. On this basis, agronomic management is proposed to preserve these environments.

When Mariano Devoto, Professor of General Botany at the UBA Faculty of Agronomy (FAUBA), speaks of “edges” of plots or rural roads, he is referring to areas not occupied by crops. Sometimes they are narrow like the bands attached to fences; others, wider, associated with shoulders or railway tracks. These environments are generally subject to agronomic management that harms the beneficial flora and fauna. In particular, pollination is affected, a key process in the generation of seeds or fruits that we will eventually harvest. In a recent study in the Pampean Region, Devoto et al., determined how essential these edges are for the ecosystem service of pollination, and proposed management to preserve them.

“Pollinating insects need a habitat where they can build their nests, reproduce and feed. Their food, precisely, is provided by the flowers, often in the form of nectar – which is a sweet juice – or even pollen. Therefore, certain practices such as the application of insecticides and herbicides, or the reduction of the size of borders in general, can be very harmful to pollinators and their habitat.said Devoto, also a CONICET researcher.

“Applying these agrochemicals to edges and shoulders reduces both the number of insects and the plants that provide them with the resources they need to live. But this same negative impact also occurs when the machinery very often cuts the plants on the shoulders either by reducing the width of these edges, or directly by removing the vegetated strips. In our study we were able to assess the impact of these managements on pollination“, underlined the teacher.

In this sense, Devoto has compared this process to a service of delivery in which insects carry pollen grains from the male parts of flowers to the female parts. “You can measure the quality of delivery. For example, if insects “mix orders”, that is to say transport pollen from one plant species to another, fertilization goes wrong. Or how long they take, since the pollen can arrive dead. Or if they eat some of the pollen from the original flower, which would be like ordering a pizza and fewer portions arrive… We were able to assess all of this in the field”.

Shoulders deserve more care

“In the work we publish in the journal Agriculture, Ecosystems & Environment we evaluate the importance of the shoulders for pollinationcommented Marcos Monasterolo, doctoral student at the FAUBA Graduate School under the supervision of Devoto and Santiago Poggio, professor at FAUBA. “We do this in the vicinity of the Ea. San Claudio, from UBA, in the center of the province of Buenos Aires. In it, we study the shoulders of dirt roads with light to medium traffic and analyze the landscape around these shoulders, including nearby cultivated or grazed fields.”. Marcos is the main author of the study along with Mariano Devoto, Santiago Poggio and Diego Medan, also a professor at this faculty.

“Among the main results we obtained, we found that the pollination ecosystem service received by the plants within the verges is better when these spaces have a large number of flowers. This increase benefits plants with more attractive flowers more than other plants with less attractive flowers. These can see their pollination reduced by up to 30%“, Detained.

Another key finding from Monasterolo and colleagues’ work was that when roadsides had many plant species and many flowers – a very favorable habitat – insects preferred not to fly very far, pollinating there and in grazed fields. near. According to Marcos, the pollinators had everything “at their fingertips”.

“Additionally, we found that pollinators did not find nearby corn or soybean crops as attractive, visiting them only 25% of the time. It was mainly because in these immense terrains the distances to be covered are very long.said Monasterolo, adding that the two crops would function as barriers to the pollination service.

When shoulders are home to many species of plants and flowers, pollinators prefer to transfer pollen to these environments and also to nearby grazed fields.

For his part, Devoto pointed out that they carried out the research with funds from the UBA, the National Agency for Scientific and Technological Promotion, the Banco Galicia Foundation and the Multifunctional Landscapes program of Syngenta. “This reflects the growing interest in these environments and the ecosystem services they provide to the agricultural system.”.

What about the edges?

“Our work has shown that in the extensive agricultural systems of the Pampean region, it would be essential to preserve the edges, because they constitute one of the rare natural or semi-natural environments existing in this landscape so altered by man. Even some shoulders of rural roads are even cultivated…“, underlined Monasterolo.

Devoto and Monasterolo agreed on the need to change the view of crop edges and rural roads as sources of crop adversity. Photo: Ignacio Marchi

Should we renew the vision of the edges of land and roads? According to the researcher, they are often considered sources of weeds or pests. The idea behind his recent publication is to promote agronomic management that preserves borders. “The results indicate that these environments need to be adequately addressed, managing characteristics such as plant numbers and the diversity of flowers and plant species.”.

“We offer two agronomic practices available to growers. One is to manage the number of plant and flower species in the shoulders. For this, cut and uncut strips of plants with a high density of flowers attractive to pollinators could be alternated. This would benefit plant species with low flower densities and increase pollination efficiency.“, he said.

“The other management aims to ensure that pollination does not concentrate on the edges and that it improves within the crops. Our proposal is to plant and maintain linear strips of plants attractive to insects in the plots. If possible, from the region or from the shoulders, although they can also be grown, such as clover or chicory, which are very attractive. We believe that soy, rapeseed and sunflower would benefit from increased pollinator activityMonasterolo concluded.

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