Agriculture and pollinators: sustainable interaction that promotes economic growth

Agriculture and agribusiness play an important role in the socioeconomic development of most Brazilian states by generating employment and income for thousands of families in rural and urban areas. Agricultural performance is influenced by several factors: climate, cultivated area, size of livestock, technologies used, production costs, demand for products in domestic and foreign markets, exchange rate, general behavior of the economy, among others. In 2020, the value of agricultural production in the state of Santa Catarina alone (which has just 1% of Brazil's territorial extension) was R$40,9 billion, with part of this production dependent on pollination by bees in greater or lesser need.

In global terms, the contribution of pollinators to the main crops dependent on these agents reaches US$ 54 billion per year, and could reach 200 billion dollars. In the United States, the contribution of pollinators to increasing the fertilization of flowers of various crops brings estimated yields between 20 and 40 billion dollars per year and, in apple cultivation alone, the annual value attributed is estimated at US$ 1,58 billion. to pollination by Apis mellifera bees and native bees.

In Brazil, just eight pollinator-dependent crops are responsible for US$9,3 billion in exports. In the South region, apple cultivation produces around 1,1 million tons of apples annually on approximately 35 thousand hectares, moving an average of R$7 billion per year from the field to sales in the markets. Around 100.000 colonies of Apis mellifera bees are used in this culture each year, generating more than R$5 million from hive rental alone.

Despite the importance of pollinators in agriculture, it is observed that they are still underused in Brazil. Deficit pollination is recognized as one of the biggest problems in fruit growing, with apple and melon crops having the most intensive use of directed pollination. To give you an idea, in South Korea around 500.000 Apis mellifera hives and more than 64.000 bumble bee hives (Bombus spp.) are used annually for the pollination of the most varied crops.

The need for cross-pollination varies greatly depending on the cultivated species, which can be classified as dependent, benefited or non-dependent. In the specific case of apple cultivation, a species dependent on pollination by bees, the plants have self-incompatible flowers, that is, they do not self-pollinate, which is why they require the presence of two or more cultivars for the fruits to be formed, thus , cross-pollination (transfer of pollen between cultivars) is of fundamental importance and that there are pollinating agents capable of transferring pollen between flowers. Good pollination is not only reflected in an increase in productivity, but also in quality, since poorly pollinated fruits become deformed and lose commercial value.

In the conditions of southern Brazil, in the main fruit-producing regions with a temperate climate, it is not uncommon for adverse conditions to occur for adequate pollination. Climatic factors such as rain, winds above 25 km/h, low temperatures during the flowering period, as well as crops with a low percentage of pollinating plants or low pollinator flowering density and problems with flowering coincidence between cultivars directly affect pollination. . Due to this, the management of pollination in orchards must be carefully planned, from the implementation of the orchard with the choice of cultivars and their planting arrangement, through the correct management of the plants and, during their flowering, the fruit grower must pay attention mainly in the quality and correct management of the hives, as well as paying attention to the weather conditions.

In Brazil, technical recommendations for hive density per hectare of planted area in apple orchards are based on studies conducted in the 1970s on crops of the cultivars ‘Golden Delicious’ and ‘Starkrinson’. The recommendation for that time and still used today is between 0,5 and 3,0 hives/ha, with the old plantings having densities of around 600 plants per hectare and plants with an average of 330 flowers. Currently, most crops have high density plantings (>2.500 plants/ha) and plants often with more than 1000 flowers, that is, the number of flowers per area has increased significantly, while the recommendation for the number of bees per area remained the same as in the 1970s.

In countries such as Canada, Chile and Argentina, fruit growers have increasingly used more hives per area so that more bees can visit the flowers during periods favorable for foraging. Currently, in apple cultivation in Canada, 7 hives/ha are used in optimal foraging conditions and 12 hives/ha when adverse weather conditions and/or floral competition occur. In Argentina, several producers use a density of 4-6 hives/ha on apple trees. In Chile, in kiwi cultivation, it is common to use up to 20 colonies per planted hectare.

In the main temperate fruit production regions of Brazil, it is common for species of beekeeping interest to flourish during the same flowering period as apple trees, causing strong competition that ends up “stealing” bees from orchards. Because of this, the way in which beehives are introduced into crops is fundamental to increasing the efficiency of pollination. The introduction of six hives per hectare sequentially, twice (half with 10-20% of flowers open and the other half in full bloom), presents much better fruit setting results compared to the introduction of only three hives per hectare at the beginning of flowering, since in newly migrated colonies the bees gradually increase their flight range, remaining in the orchard until they find another, more interesting source of nectar.

Another decisive factor is the quality of the hives used to pollinate the target crop. When a hive is rented to pollinate a crop, it must meet some requirements regarding the size and development of the brood, and for pollination of fruit species, four to five combs with brood are acceptable, at least 2 combs with larvae, two combs with honey and pollen and eight to ten combs covered with adult bees. Since bees collect pollen from flowers as food for the larvae, the number of combs with larvae in the hive is considered a determining factor for the collection of this resource and, the greater the number of larvae, the greater the efficiency of this hive as a pollinator. Therefore, it is necessary to carry out a careful evaluation of the hives, classifying them according to their population potential at the time of introduction into the planting area, preferably opting for colonies with queens up to two years of age and with a high laying capacity.

Recent studies have demonstrated that the introduction of native bee hives (Mandaçaia, Manduri, Tubuna, Jataí, Mirins and Guaraipo) in orchard areas covered with anti-hail screen significantly increases effective fruiting, production per plant, number of seeds per fruit and the average weight of the fruits, showing that meliponines have great potential as pollinators complementary to Apis mellifera bees.

Due to inadequate pollination, fruiting in orchards of some temperate fruit plants is being achieved through extensive use of growth regulators. Among the substances that act on fruiting, we can mention gibberellic acid (GA3), Thidhiazurom (TDZ) and Proexadione calcium (PCa), which stimulate different metabolic and physiological processes in plants, being able to promote an increase in effective fruiting, being tools useful in inducing the formation of parthenocarpic fruits when conditions for pollination by bees are unfavorable, but they will never be able to fully replace the effects of good pollination.

Pollination management as a whole is complex and requires a set of prior care that begins with planning the implementation of the orchard and ends with the management of bees in each production cycle. Just as there is Integrated Pest Management (IPM), which consists of the use of various management methods and measures that aim to keep pests always below the level at which they cause economic damage, we must also think about Integrated Pollination Management (MIPol), which should bring together several rationally designed actions to optimize cross-pollination in each specific crop and, thus, promote increased productivity, quality and profitability for everyone involved in the production chain.

This path must involve the professionalization of this important stage of food production, starting with professional migratory beekeeping in the provision of this service with the rental of bee colonies suitable for pollinating specific crops, as well as the responsibility of farmers in maintaining bee health. taking due care in applications and always informing the beekeeper when using pesticides on crops.