Spring fest for bees

Pollinators in Japan: Their importance and needs

Japanese cuisine is characterized by healthy, seasonal and vibrant foodstuffs, its visual presentation an art form with great attention to every little detail. This article introduces the artists behind the scene when it comes to fruits and vegetables, showing the key role honey bees and other bees play in pollination, the challenges they face and ways to ensure bee health. Regarding the latter, Bayer is working on a ‘Japanese cuisine for bees’: a seed mixture as a source of nectar and pollen with flower species native to Japan – to create flowering areas on unused land.

Spring fest for bees


// In Japan there are two different species of honey bee, the Japanese honey bee (Apis cerana japonica) and the European honey bee (Apis mellifera).

// Problems due to pests and diseases are the major cause of reduced bee health, and this applies to both species.

// The few bee research institutions in Japan mainly focus on honey bees, developing general studies to look at honey bee biology and health.

// In Japan, there are about 390 native bee species. Although data is limited, it is clear that many wild bees are effective pollinators for wild plants and crops.

// Good nutrition has been identified as a key factor for good health of both managed honey bee colonies and wild bees alike.

// Bayer is working on a seed mixture as a source of nectar and pollen with native Japanese flower species – which are already part of the existing ecological balance – to create flowering areas on unused land.

Every year, when the first days of spring trigger the buds of plum, peach and cherry trees to open up as flowers, people in Japan celebrate a spring fest named Hanami. The colorful cherry blossoms - known as Sakura - not only draw in the Japanese and tourists with their beauty; they also attract honey bees, butterflies and other insects, who visit the blossoms for their nectar and pollen.

Professor Jun Nakamura

Professor Jun Nakamura
Bee scientist at the Honeybee Science Research Center, Tamagawa University in Machida since 1993.

Although thousands of people marvel at the natural spectacle at the Hanami, many may not be so aware of the important insect activity going on in the background and how this plays a crucial role for food production. For many of those agricultural crops which are pollinated by insects, bees play an important role, and their visit to the blossoms is vital for the development of fruit. Yet it was exactly the significance of these pollination services which triggered one of the pioneering bee academics in the country, Professor Okada at Tamagawa University in Machida near Tokyo, to intensify bee research. He led one of the first honey bee research teams in Japan in the early 1950s and in 1979 the university's Honeybee Science Research Center was opened. Professor Okada's initial aim was to increase agricultural food production through scientific knowledge.
"After the Second World War, we had a big food shortage here in Japan. As a consequence, many universities and research institutions were studying pests - among them insects - in their laboratories to help protect the crops," reflects Professor Jun Nakamura, a bee scientist at the Center since 1993. "Professor Okada recognized a significant research gap in terms of beekeeping and pollination studies and started to focus on honey bees, which play a key role for food security, as they increase the productivity of many crops through the pollination services they provide." Today, the main focus of the research group at Tamagawa is still the honey bee. "Our activities range from basic to applied research, both laboratory and field studies and the improvement of beekeeping practices and evaluation of bee health products," says Professor Nakamura. He wants to help local beekeepers to keep their colonies healthy.

Cherry blossom tree

When cherry trees bloom in Japan, honey bees will find nectar and pollen. However, the cherry blossoms only last for a few weeks. These polli­nators need varied nutrition through­out the year.



Dr Keiko Nakamura

"Problems due to pests and diseases are the major cause of reduced bee health and have increased with the rising number of hobby bee­keepers."

Dr Keiko Nakamura
Research Institute for Animal Science in Bio­chemistry and Toxicology (RIAS), Kanagawa, Japan.

Specific to East Asia is that there are two different species of honey bee; the Asian honey bee (Apis cerana), in Japan represented by the subspecies A. c. japonica, and the European honey bee (Apis mellifera). This situation makes bee research and beekeeper advice more complex. Professor Nakamura explains, "There are big problems with the high rate of transferred parasites between our two different honey bee species." While the Varroa mite (Varroa destructor) is the biggest problem for the European honey bees, the native Japanese honey bees are better adapted to this parasite.

However, the Japanese honey bees have been faced with another big challenge for the last five years: "Today around 40 percent of Japanese honey bee colonies are infected with tracheal mites (Acarapis woodi), which produce their offspring inside the trachea of honey bees," he explains. Many beekeepers are concerned about this because the mites, which likewise are parasites of the European honey bee, might also transfer viruses to the bees. In recent years, tracheal mites have caused significant losses in bee colonies. "Problems due to pests and diseases are the major cause of reduced bee health and have increased with the rising number of hobby beekeepers. Unfortunately, many of them do not have enough experience to successfully fight these various pests," explains Dr Keiko Nakamura from the Research Institute for Animal Science in Biochemistry and Toxicology (RIAS) in Kanagawa, Japan.

Honey bee colony numbers in Japan

In recent years, worldwide discussions about bee health have increased - and thus also received media attention in Japan. At times, this has led to an overreaction: "Many people were concerned, relying on misinformation regarding alleged honey bee colony decline," says Dr Keiko Nakamura. "Similar to the situation in Europe and North America, the managed honey bee population has declined in Japan over the past decades but during the last ten years the population has stabilized," she explains.

Source: J-MAFF, Situation On Beekeeping, Wo Meguru Jousei, 2015 (Japanese)

Fluency Agent

The few bee research institutions in Japan today mainly focus on honey bees, developing general honey bee studies to look at the bees' biology and health. Yet Dr Tomoyuki Yokoi, an assistant professor at University of Tsukuba, Japan highlights the importance of wild bee species in agriculture.

Dr Tomoyuki Yokoi

"Although many people do not notice their presence, most wild bees are effective polli­nators for wild plants and crops."

Dr Tomoyuki Yokoi
Assistant professor at Tsukuba University in Japan, specializes in research on wild bees.

His research ranges from elucidating the interactions of insects and their environment (basic ecology), to the agricultural relevance of these insect visits, studying the interaction between visiting flower insects and plants in satoyama woodland environments. This is the border zone or area between mountain foothills and arable flat land. Literally, 'sato' means arable and livable land or homeland, and 'yama' means hill or mountain. Another focus area in his research is the evolution of feeding strategies and reproductive strategies of native bees, for instance bumblebees and Japanese honey bees. "In Japan, we have about 390 native species including solitary and social bees," he indicates. As he explains: "From spring to autumn, many wild bees visit flowers in the field. Although most people do not notice their presence, most wild bees are effective pollinators for wild plants and crops. For example, farmers, in some areas of Japan, use Osmia bees for the pollination of apple and cherry trees." The data on wild bees and other pollinators is limited, although their contribution to crop production is estimated to be 330 billion Yen (which equals 2.7 billion Euro) - accounting for 70 percent of total insect pollination services.

Good nutrition has been identified as a key factor for good health of managed honey bee colonies and wild bees alike. Honey bees need varied diet, and they need forage throughout the season, whereas most plants just have a limited flowering window. "Take the Sakura: the spring blossom in Japan only lasts for a few weeks and the nectar and pollen sources in the summer are too short for bees," explain Professor Jun Nakamura. Wild bees frequently depend on one of a few plant species, but they are many in number, and they all have different needs, so in sum they also depend on floral diversity. Professor Nakamura is now tackling this issue in Japan by planting bee-attractive flowers in the agricultural landscape in areas where crop production has been abandoned. He is aware that nutrition is critically important to keep bees fit.

Wild carpenter bee

Wild carpenter bees are one of the important pollinators. This bee species has strong mandibles, which help them make holes in dead wood in which to nest.

European honey bee

Locust acacia with European honey bee.

Halictus aerarius bee

Female Halictus bee visits creeping smartweed.

Plasterer bee

Plasterer bee (Colletidae) collects pollen from wild flower.

Yasuo Araki

Yasuo Araki
Biologist and expert for pollinator health at Bayer in Tokyo, Japan.

Inspired by Professor Nakamura's idea and as part of the Bayer Feed a Bee Program, Yasuo Araki, biologist and expert for pollinator health at Bayer in Tokyo, Japan started his project to develop a suitable flower-mix specifically for Japan. "Blooming strips with bee-attractive flowers, specifically designed for the conditions in Japan, which supply a sufficient amount of nectar and pollen for a long period, can contribute to improved health of honey bees and other bees by offering additional nutritional sources," says Araki. To develop a suitable flower-mix (not limited to annual plants) specifically for Japan, he is searching for useful flower species including native ones which are already part of the existing ecological balance for bees as a source of nectar and pollen.

In spring 2015, Bayer in Japan cultivated these flower species on test fields and positioned a colony of honey bees close to the blooming field. "From early July to late September, we studied the bees' visits to the flowers and analyzed if the bees collect pollen, nectar or both," explains Araki. "In the laboratory, we could assess the nectar in the bees' honey stomach and, based on the sugar content, define the nectar quality." From the 64 flower species planted in the test field, 34 species flowered during the screening period. Some of these plants have already been reported as attractive for bees in other countries. Not only the tested Western honey bees but various insects including social and solitary bees, butterflies, beetles and hoverflies visited all of these blooming flowers and some competition was seen. Honey bee visits could only be confirmed for nine of the tested flower species.

Japanese snow bell

Japanese snow bell

"This does not necessarily mean that the other flowers are not attractive to honey bees as this could very well be due to the small scale of the test plot and planted flowers," he says. "It may also be due to the abundance of flowers, and other factors." With this initial information, the researchers wanted to confirm the usefulness of cultured or wild flowering plants surrounding the test fields to provide nutrients for bees. "Since the spring of 2016, we began to document the quality and amount of bee pollen carried by the honey bees, in order to identify the visits of bees to blooming plants. The study confirmed bee visits to 71 kinds of plants including 15 of the test plants and 68 kinds of bee pollen were identified by November. In addition, Japanese honey bees visited 30 species of flowers including seven of the test plants, and other bees (at least 12 species) visited about 90 kinds of flowers including 35 of the test plants."

In Japan, the understanding of which flowers, trees and plant species are beneficial for the health of pollinators is still developing, yet the idea is to cultivate native flowers alongside agricultural fields. "In Japan, we have a lot of agricultural land that is not being used at the moment," states Professor Nakamura. "Both farmers and beekeepers could benefit from using this land for flowering strips. Honey bee colonies feeding on a mixture of pollen from different plants get a more diverse mix of nutrients, which makes them healthier than those fed on only one type of pollen. And healthy colonies can provide better pollination services."



Contributing to more flower resources is beneficial for the health of pollinators. Efforts to understand which flowers, trees and plant species are beneficial for the health of pollinators is instrumental. In Japan, as in many other countries, the idea is to cultivate native flowers alongside fields, on land which is not being used for agriculture.



The Japanese Pollination Journey:
Tenshi and Teishi

Japanese Pollination Journey infographic

Important nectar sources of honey bees in Japan are Satsuma Orange, Apple, Locust acacia (Robinia pseudoacacia), Japanese snowbell (Styrax Japonica), horse chestnut (Aesculus turbinata), Japanese linden (Tiliajaponica), Chinese milk vetch (Astragalus sinicus), Rapeseed and White clover, etc.

Most apiculture in Japan takes place with Western honey bees, which are used for both honey production and pollination services. The hives are moved to an equal extent, either over small (within a prefecture) or longer distances (outside of the prefecture) and the term used in Japan is 'Tenshi' [= moving apiaries]. Strict arrangements are made as to the location and positioning of the hives.

Colonies move from the south to the north from April to July, following the flowering seasons, for efficient honey production. The northern island of Hokkaido is the perfect place for the honey bees to spend the summer (July - September), offering a relatively cool climate, and consequently it can get quite crowded.

Colonies are restructured, i.e. consolidated or split, when necessary, after honey production and move mainly for pollination of greenhouse-cultivated crops from autumn to winter, from the north to the south.

The leasing and selling of colonies for pollination services can be quite a lucrative business. This brings the colonies to the warmer climate in the south of the country for overwintering.

Since professional beekeepers manage hundreds of colonies, it is impossible to feed them without moving under the conditions prevailing in Japan.

This is different for the Japanese honey bees; beekeeping is very minor and is carried out locally called 'Teishi' [= static apiaries]. The honey produced is often derived from various flowers within the area. This beekeeping practice works with colonies built from captured swarms. The Japanese honey bees are not used for managed pollination services.



Additional information


It’s not only Japan that is trying to improve the situation for bees and beekeepers in Asia: The article “Joining Hands in Asia” explores a similar project in China and India.

All over the world there is “A choice fruit bowl” depending to a certain level on insect pollination.

One of the areas we are working on under our Bee Care Program is our Feed A Bee activity in the USA and around the world. To find out more about what Bayer is doing to increase floral nectar and pollen resources for bees, read the story “Blossoms for Bees” and learn how to be part of Feed a Bee.

Complete Story

Spring fest for bees Pollinators in Japan: Their importance and needs
Back To Top