Working with research partners around the world, Bayer is pulling together a leading-edge mosaic of information on pollinators in important crops. The aim is to safeguard their health in an agricultural setting. This study – carried out by Peru’s National Agrarian University La Molina – focuses on citrus.
// There are still considerable knowledge gaps as to the activity of different bee species in important crops.
// A study in Peru has investigated the bee community foraging on citrus blossoms in orchards.
Bayer Stewardship Manager, LATAM
“Our goal was to enhance our technical expertise on how to help farmers to protect the local pollinators. There were lots of open questions and we were looking for answers.”
Close your eyes and imagine pure citrus blossom bliss: mandarin, orange and tangelo groves as far as you can see. Overwhelming fragrances – sweet and spicy – fill the air as the fruit is warmed by the bright midday sun. Later in the year, an ever so light drizzle called “garúa” will act as a welcome moisturizer … the Peruvian coast with its natural greenhouse climate offers perfect cultivation conditions for citrus growers.
As a result, citrus has become an increasingly important generator of foreign currency for Peru in the past decade. In 2016, citrus exports amounted to about 125,000 tons which translated into a total of 130 million US dollars foreign exchange. By 2020, Peru plans to almost triple its fresh fruit and vegetable exports to 2.3 million tons, and citrus plays a major role in this ambition. Today, Peru’s citrus fruits are exported to 30 countries, among them the USA, the Netherlands, the UK, Canada and China. They are considered among the best in the world for their quality, flavor and fragrance.
While the fruits of the citrus trees are cherished by vitamin-hungry consumers all over the world, their blossoms are a popular foraging ground for the local bee populations. That is why Bayer decided to commission a study on the Peruvian bee community in citrus, says Mariela Reátegui, Bayer Stewardship Manager for the LATAM region. “Our goal was to enhance our technical expertise on how to help farmers to protect the local pollinators. There were lots of open questions and we were looking for answers: How attractive are the Peruvian citrus crops to different bee species? Are there wild bees in the groves? What are their visitation patterns? How does the local bee community differ from other geographies?” The kind of questions raised made it imperative to instigate basic research with an academic partner.
Native bee species appreciate a wide diversity of vegetation for foraging, including blossoms from cultivated citrus.
// Peru has a surface area of about 1.3 million km2 which makes it bigger than France and Spain combined. It is the third largest country in South America and one of the 20 largest countries in the world.
// Peru is an extremely diverse country with a large variety of climates: from the subtropical coasts and the temperate highlands of the Andes to the damp tropical equatorial climate in the Eastern lowlands.
// Spanish, Quechua and Aymara are the three main languages in Peru. Many people are bilingual.
// Citrus has become an increasingly important generator of foreign currency for Peru in the past decade.
// By 2020, Peru plans to almost triple its fresh fruit and vegetable exports to 2.3 million tons. Citrus plays a major role in this ambition.
The study team gathered representative bee species samples at six different locations in Peru, covering a distance of 12,400 km and braving higher than usual coastal temperatures and heavy rain in the rainforests.
Mariela Reátegui contacted Dr Alexander Rodríguez, Senior Entomologist at the renowned National Agrarian University La Molina, and asked him to coordinate and implement the study. The choice of university was logical to her: “We looked for technical expertise and La Molina is a top agricultural university with an important entomological institute. So we were very confident that the study would be carried out to high professional standards.”
The on-site investigations in the citrus groves took place throughout 2015. The study team gathered representative bee species samples at six different locations in Peru. And the results were a surprise to everyone: In the coastal citrus locations, the European honey bee turned out to be the almost exclusive bee species visiting the flowers; hardly any other species was found in the citrus plantations during the sampling period. “It’s amazing,” says Dr Rodríguez. “The wild bees have apparently been displaced almost completely by the European honey bee. We had not expected this dominance. We had thought we would see a much greater diversity, particularly of the native stingless bees belonging to the genus Melipona.”
Looking into possible reasons, Dr Rodríguez explains that European honey bee colonies were introduced centuries ago and have multiplied through beekeeping activities. Lately, they have been used for increased crop pollination of other commercial fruit crops, particularly avocados which cover ever larger areas as an increasing export item. Even though citrus production does not depend on bee pollination in most cases, the bees found neighboring citrus blossoms attractive and started to visit. When they found the huge monocultures of the groves very much to their liking, the honey bees just kept returning. Native species, on the other hand, appreciate a wider diversity of natural vegetation and seem to have moved on. Asked about the most exciting insight resulting from these findings, Dr Rodríguez points to the adaptability of Europe’s favorite pollinator: “The dominance of the honey bee suggests their good health and their adaption capabilities to changes in the agroecosystems.”
Gathering local information on bees is vital to gain insights into the bee communities and the prevalence of certain pollinator species in different crops.
Surprising results: In coastal citrus locations, native wild bees have apparently been displaced almost completely by the European honey bee.
Dr Alexander Rodríguez, Study Leader and Senior Entomologist at the National Agrarian University La Molina, Peru“The dominance of the honey bee suggests their good health and their adaption capabilities to changes in the agroecosystems.”
It was generic basic research into the behavior of our pollinator communities in Peru. That is exactly our expertise at the Department of Entomology of the National Agrarian University. It was pure science, no products or brands involved. So we were keen to carry it out.
We decided to study farms in two of our country’s climate zones: the arid coast with its huge, highly mechanized export plantations, and the tropical rainforest with lots of smaller medium-tech businesses. The sampling sites at the coast covered satsumas, navel oranges and tangelos. In the rainforest, we selected three farms with Valencia juice oranges. For all six sites it was important that there were no beehives within a 500-meter distance so as not to distort our results.
The sampling took place in 2015 depending on when the different citrus varieties flowered. We spent a period of two months in each of the locations to gather representative species samples.
The qualitative results were the same: The European honey bee had apparently displaced our native bees. The difference was in degree: In the high-productivity groves at the coast, the local bees had vanished almost completely, while in the rainforest, there was still a small degree of pollinator species variety. This is due to the fact that there is a certain amount of weeds and shrubs in the rainforest sites so the bees have other sources of pollen and nectar than the citrus blossoms.
Identifying sampling sites which meet our strict scientific requirements was the first challenge. Once we had found them, the big task was to organize the human logistics. The sites were at considerable distance from each other, so that all in all, the assessors covered a distance of 12,400 km, braving higher-than-usual pre-Niño temperatures at the coast, and heavy rain in the rainforest. But scientists love a proper challenge, so everyone took it in good humor.
The scientific team also studied the daily foraging schedule of the honey bees and established two activity peaks: Peruvian honey bees are out in the citrus groves in early morning and late afternoon, enjoying a long siesta at midday. This is another surprising study result which shows how the European honey bee has adapted to its new environment. In Central Europe, honey bees prefer to stay in the hive until the sun has warmed the air. They leave the hives in the morning to forage throughout the day until they return home in early evening.
In Europe, farmers and gardeners are therefore requested to apply certain insecticide sprays preferably in the evening, when there are no bees about. The new findings from Peru will make it possible to adapt Peruvian crop protection strategies accordingly, asking farmers to spray at lunchtime, when honey bees are taking their long siesta.
As Bayer’s local Stewardship Manager, Mariela Reátegui will consider the study’s findings in the risk assessment and application recommendations for insecticide use in citrus groves. “We can now prove to the regulatory authorities that honey bees are dominant in citrus in Peru,” she says. “As a result, the risk assessment can focus on the honey bee, because native bees are not found in the groves to a significant extent.”
The new study shows again how vital it is to gather local information on bees. Bayer is committed to helping provide these data. The company is pulling together a mosaic of local studies to gain insights into the bee communities and the prevalence of certain pollinator species in different crops. “Our goal is to make science work for bees,” says Mariela Reátegui. “We want to contribute to pollinator health an safety by cooperating with other stakeholders to address pollinator topics which are emerging in countries and regions around the globe.”
// Traditional crops in Peru are corn, potatoes, rice and sugar cane.
// The country’s exporting origins were in vegetables – largely asparagus and grapes.
// Over the years, Peru has become more specialized in supplying fresh fruit. Today, this represents the lion’s share of Peruvia produce exports, accounting for some 4.6 billion US dollars in 2016. Export fruit includes citrus, table grapes, mangos, pomegranates, avocados and blueberries.
// Peru produces fruit and vegetables all year round and can take advantage of seasonal shortages elsewhere.
// The citrus harvest begins at the start of the year with varieties such as satsumas, followed by clementines, tangelos, novas, W. Murcott, tango, honey tangerines, navel oranges and others. Lime fruit is harvested throughout the year.
The European honey bee dominates in Peruvian citrus groves. It has apparently largely displaced native bees in some coastal regions.
Activity peaks of bees in citrus groves are early morning and late afternoon. They spend the hot midday hours resting in the hive.