ATTEMPTS TO INTRODUCE STINGLESS BEES FOR THE POLLINATION OF CROPS UNDER GREENHOUSE CONDITIONS IN JAPAN

Kazuhiro Amano Laboratory of Apiculture National Institute of Livestock and Grassland Science Tsukuba, Ibaraki 305-0901, Japan

ABSTRACT

In Japan, a growing number of greenhouses for crops are now in use, where no wild pollinators are available. Although a large number of colonies of honeybees, Apis mellifera, and bumblebees, Bombus terrestris, are used for pollination, farmers face difficulty because of the absolute shortage of pollinators. Consequently, many of them are obliged to perform artificial pollination or apply hormones to their crops. To respond to these situations, the author has been trying to introduce the use of new efficient pollinators in recent years. Stingless bees, Meliponinae, and honeybees, Apinae, are the only highly social bees living in permanent colonies, and both share many biological characteristics. Many advantages could be expected from the use of stingless bees as pollinators. They are harmless to beekeepers and farmers, are active throughout the year, visit a wide range of crops (polylecty), and do not pose any environmental risks by escaping into natural habits because they cannot tolerate cold weather, especially in the winter. Consequently, among the stingless bees kept in their indigenous habitats, some promising species have been chosen and introduced from tropical and subtropical habitats overseas. These are Meripona beecheii, M. quadrifasciata, Trigona carbonaria, Tetragonula fuscobalteata, Scaptotorigona bipunctata, and Tetragonisca angustula. This paper shows the process of introducing stingless bees and the facilities involved, together with the pollination results obtained by using these bees.

Keywords: Meliponinae, Apinae, stingless bees, crop pollination under greenhouse conditions, Japan

INTRODUCTION Stingless bees are generally characterized by their stingers being atrophied and of little There are two groups of highly eusocial harm to beekeepers as opposed to those of insects in the world: Apinae bees and honeybees. They are also known as good Meliponinae bees. Some species of both pollinators of various crops. Since 1997, the groups have been used in the beekeeping author has been trying to screen promising industry, apiculture and meliponiculture, owing stingless bees as pollinators out of the species to the specific characteristics of eusocial being kept in their native areas, and to insects. The former group (Apinae) consists of introduce them to Japan with the practical aim less than 10 species including the Western of pollinating crops. honeybee, Apis mellifera, and the Oriental In Japan, more than 700,000 greenhouses honeybee, A. cerana, both of which are well- are used to grow crops, where no wind, rain, known as beekeeping species. The other or wild pollinators are available. Around group (Meliponinae) constitutes the stingless 120,000 colonies of Apis mellifera are used for bees, and contains more than 400 species in pollination annually, but farmers would rather tropical and subtropical areas, some of which not manage the colonies by themselves have been used just like honeybees in these because of the danger that their handling areas, especially in the Yucatan. poses. Professional beekeepers do the job

1 instead. Since 1991, the bumblebee, Bombus The first one is Osmia cornifrons, a terrestris, has been used, and now up to species of solitary bees which is now essential about 40,000 colonies are consumed annually in the pollination of crops, especially apples. despite their cost [25,000 yen (=US$200)/ Its pollination ability on apples is considered colony]. Bumblebees are regarded as easy and much higher than that of the honeybee. Its life safe enough for farmers to manage partly cycle is very simple, and the foraging period because of their short lifespan, which is far coincides with the flowering of apple. Since the less than one year. However, many more bee readily accepts artificial nests just like its pollinators are needed to match the scale of native nests such as bamboo or reed, farmers greenhouses. manage it with minimal skills. At present, the Stingless bees are promising pollinators bees are used as apple pollinators in more for the following reasons: they are harmless to than 18,000 ha of orchards in the northern part beekeepers and greenhouse workers, visit a of Japan. Furthermore, the bees are expected to wide range of crops (polylecty), are tolerant of be applied to other crops by shifting the adult high temperatures, are active throughout the emerging time through controlling the year, can be transported easily, and hardly hibernation temperature. pose any environmental risks by escaping into The second one is the European and invading natural habitats as they would bumblebee, Bombus terrestris, which is a social not survive the Japanese winter. On the other insect. Unlike that of the honeybee or the hand, many issues need to be resolved before stingless bee, its colony is annual, so the using stingless bees, one of which is how to colony could be used for crop pollination for improve methods for propagating and about two months around the climax of its maintaining colonies throughout the year. To development. The bumblebee is considered an address this issue, a specific glasshouse with efficient pollinator of some crops such as attached laboratories has been completed in the solanaceous plants, which require the buzz- National Institute of Livestock and Grassland pollination done by bumblebees. Buzzing bees Science, Japan solely for stingless bee cling to the ends of the anthers and vibrate researches. their indirect flight muscles, leading to pollen Many authors have studied and release. These bees are now popular because described various aspects of the biology of farmers can manage them by themselves. stingless bees. Most of these studies have The third one is the honeybee, or been conducted in the native areas where the European honeybee, Apis mellifera. This well- species live. This paper hopes to present an known social insect is an important pollinator outline of the stingless bee researches of the of orchards, crop fields, and glasshouses, but author as well as the facilities where these are the number of colonies used as pollinators in conducted. Japan is not as many as expected. Most farmers who need pollinators do not want to Status of pollinator utilization in Japan keep the honeybees by themselves, and, if necessary, have professional beekeepers Where no pollinators are available, many crops manage the colonies. There are less than 5,000 need hand or mechanical pollination, unless professional or semiprofessional beekeepers in useful pollinators should be released artificially. Japan, the small number of which limits the The multiple use of insecticides and the use of honeybees as pollinators. expansion of single cropping, both of which Consequently, farmers in Japan expect easily have been conducive to the development of manageable and efficient pollinators which can modern agriculture, have also led to the be used over the long term. decrease of natural pollinator populations. In addition, cultivation under structures such as MATERIALS AND METHODS glasshouses and vinyl houses has been increasing in Japan. These agricultural Stingless bee colonies introduced conditions have stimulated the demand for efficient and manageable pollinators for crops. The important genera for stingless beekeeping, Three species of bees have had a great impact or meliponiculture, are Melipona and Trigona. on crop pollination in Japan. Crane (1992) listed 14 species of Melipona and

2 21 of Trigona that have been used in the RESULTS AND DISCUSSION traditional way. Melipona species are restricted to Central and South America, and Nest structure are of historical significance because of their long-time culture for the production of honey A few species of stingless bees build their and wax. Trigona species are present in the nests in underground cavities such as termite entire tropical continental area, and their use in mounds, most of them belonging to primitive traditional hive beekeeping has been reported groups. Some other species build an exposed in tropical America and occasionally in Asia. nest surrounded by hard and sometimes brittle The author chose the species to be introduced layers hanging on tree branches. Those species based on his study of traditional stingless do not seem to have ever been considered for beekeeping. The principal species introduced to beekeeping. The most common type of nest is Japan were Trigona carbonaria (Australia), T. found in a tree cavity, and the species fuscobalteata (Thailand), Melipona beecheii introduced belongs to this type. The nest is (Mexico), M. quadrifasciata, Tetragona usually made of five parts: brood comb, angustula, Plebeia droryana, and involucrum, store pots, batumen, and an Scaptotrigona bipunctata (Paraguay). entrance. The comb consists of brood cells, in each of which a single young is reared, Facilities for stingless bee research surrounded by a sheath of cerumen, or involucrum. Therefore, the cavity where the Glasshouses equipped with a thermo-control brood cells are present is called a brood system were built to keep introduced stingless chamber. Cerumen is made of a mixture of wax bee colonies throughout the year, multiply the secreted from the glands on the abdomen of colonies, and check their foraging activities. workers and propolis. The propolis is derived The honeybee queen flies whenever swarming from resins collected from plants. Honey and occurs, whereas, the stingless bee queen flies pollen are stored in pots quite different from only once in its life, that is, for mating. Being the brood cells. These storage pots are usually different from the honeybee queen, the placed above and below the involucrum, and stingless bee queen usually mates in a low made of cerumen. The extra space in the tree place, at a maximum of 5 m. Thus, the cavity is sealed by batumen plates, usually glasshouse was designed to be 10 m high. made of cerumen and other materials like mud. Two environmentally controlled chambers were The entrance of the nest is a simple hole. attached to the glasshouse, where various These observations apply to all of the species aspects of the biology of stingless bees can included in the study (Fig. 1). be observed.

Fig. 1. Nest of Melipona beecheii Brood comb of Melipona beecheii. in an observation box. The arrow shows a queen.

3 Thermoregulation stingless bees to tropical and subtropical areas. Studies by the author show that T. carbonaria It is believed that the leading reason why cannot easily control the temperature in the stingless bees have not spread into the hive (Fig. 3). temperate zone is because of their lack of tolerance to low temperatures. However, Hive boxes for stingless bees research by the author shows that, for adult workers, the tolerance of T. carbonaria to low Since stingless bees do not tolerate low temperature is not as poor as that of other temperatures, hive boxes should be devised for Apis honeybees, in addition to the fact that it use in temperate countries like Japan. The tolerates much higher temperatures than Apis author designed the hive box by using the species (Fig. 2). introduced stingless bees. Two points were Considering the colonies as a whole, Apis considered in designing: the first was spp. do have a system of thermoregulation. temperature control, and the second was They are able to maintain the temperature convenience in splitting or multiplying the around the brood at 34o-36oC year-round. The colony. temperature is raised with their own body heat, To address the problem of temperature, generated by shivering the wing muscles, and the hive was constructed of two boxes, an lowered, if necessary, by fanning their wings at inner hive box and an outer box. The outer the nest entrance to draw cooler air into the box was equipped with a heater system to nest or by gathering water into the nest to keep the hive at a fixed temperature even in spread over the comb. winter (Fig. 4). The hive boxes made it Generally, stingless bees are not as possible for T. carbonaria and S. bipunctata efficient as honeybees in controlling the nest colonies to survive for years in the outdoor temperature, especially when the temperature is field. low. When the temperature is too high for The inner hive box was designed to split them, they have been observed to lower the the colony. Researchers in Australia have temperature by fanning their wings at the nest developed various types of hives for T. entrance partly for ventilation as honeybees carbonaria. The design of the inner hive box, do, but they are inefficient in raising the which consists of three-storied spaces to temperature. This may be a factor that limits contain a brood space, a food storage space,

B C A D Effective temperature A. mellifera

B C A D Effective temperature A. cerana japonica

B C A D Effective temperature T. carbonaria

515354555 0 10204050(oC)

Fig. 2. Thermo-responses of adult workers in three species A: Lethal low temperature, B: Effective low temperature, C: Effective high temperature, D: Lethal high temperature

4 (oC)

40 Brood area Food storage area 30

20 Inner space near entrance

Ambient 10 temperature

40

30

Brood area 20 Food storage area Inner space of hive edge 10 Ambient temperature 0:00 0:00 0:00 (Time) Fig. 3. Temperature in and out of the nest of honey bee, Apis mellifera (above), and the stingless bee, Trigona carbonaria (below)

30

25 Inside of inner box 20

Inside of outer box 15

10 Ambient temperature 5

0 0:00 0:00 0:00 0:00 0:00 0:00

Fig. 4. Temperature in and out of the hive box

and a feeding space, was inspired by their advancing edges of the spiral comb are a ideas. The brood space can be divided for growing portion where new cells are propagating the colony when it matures. constructed and added along them. When the summit reaches the ceiling of the brood Splitting the colony chamber, the growing portion appears again at the bottom to repeat its rise. To split a mature To multiply the colony, the nest, especially the nest, the inner box is prised open, while the brood, should be split. The layers of T. brood in a brood space is cut in half. The top carbonaria's brood cells form a single spiral, part and mid-part of the inner box are kept that is, a single comb. The summit and the together, and a new bottom part is added. The 5 bottom part is given a new top part and a somewhat poor results, contrary to what was new mid-part. Then, two new nests are expected (Fig. 5). As the control, bagged formed. There is no problem with the new nest flower heads produced almost no seed. The containing the original queen, but the other average weights of flower heads produced by one does not contain any mature queens. T. carbonaria, S. bipunctata, B. terrestris, and However, in this species, there are usually A. mellifera were 4.7 g, 7.1 g, 16.6 g, and several large cells containing developing queen 14.2 g, respectively, while the weights of yield bees scattered throughout the brood comb. per 0.75 m2 were 4.0 g, 7.9 g, 19.4 g, and One of these cells will grow to be a new 17.0 g. Several reasons were advanced for the queen. It is going to fly for mating return to poor performance of stingless bees. Perhaps its new colony, which subsequently becomes the main one was that 0.2 ha of one independent. For success in multiplying the greenhouse compartment was too spacious for colony, plural colonies of the same species one colony of the stingless bees to pollinate, should be kept in the same place for mating. and the second was that the colonies were When provided with the thermo-equipped hive tested too soon after introduction from boxes, colonies of the two species, T. overseas, and they had not adjusted to their carbonaria and S. bipunctata, can survive for new habitat yet. Actually, many individuals of years even in the winter season. Mature both species gathered around the ceiling facing colonies of the bees can also be multiplied in the sun and stayed there, causing wear and a glasshouse along with other colonies of the tear to the colonies. species. Pollination of tomato plants. The flowers of tomatoes, Lycopersicon esculentum, do not Pollination efficiency produce nectar, and the specific shape of their anthers favors the bumblebee, which does Although there are limited data on the buzzing-pollination. The effect of bumblebees, influence of pollination by stingless bees on B. terrestris, and stingless bees, T. carbonaria, crop yield, many species are considered useful on producing fruit were compared. One for the pollination of crops. Pollination tests compartment of a greenhouse contained a comparing stingless bees with honeybees and/ colony of B. terrestris and another of T. or bumblebees were performed. carbonaria. It is well known that when B. Pollination of white clover. Two species terrestris visits tomato flowers, it leaves a each of stingless bees, honeybees, and bite-mark on the flower. T. carbonaria was bumblebees were placed in greenhouses of found to visit the flowers very often and leave white clover, Trifolium repens. White clover a similar bite-mark. Based on calculations of must be pollinated to produce seed. The the number of bite-marked flowers, B. terrestris results of tests comparing bumblebees, visited the flowers at 82% of the time, T. honeybees, and stingless bees showed carbonaria more than 95%. However, T.

20 T. carbonaria

15 S. bipunctata B. terrestris 10 A. mellifera 5

0 Weightweight of of NNo. o o of f flflowerower WeiWeightght of ofseeds flflowerower heads heads (g) headsheads (x20) (x20) seedsper 0.75 perm2 (g ) 0.75m 2

Fig. 5. Pollination efficiency for white clovers by four species

6 100 90 80 70 60 50 40 T. carbonaria 30 20 10 B. terrestris 0 Flowersflowers visited fruitsFruits per per flower fruitsFruits per per flower visited visted flowers flowers visited

Fig. 6. Differences between T. carbonaria and B. terrestris in visited and fruiting tomatoes

1.5

1 stingless honeybees 0.5 honey 0 cucumber egg plant paprika red bees pepper

Fig. 7. Relative incidence in fruiting crops by two kinds of pollinators

carbonaria yielded about 8% fruits from grown crops need to be pollinated to produce visited flowers, whereas B. terrestris had over satisfactory fruits with commercially high value. 90% from visited flowers, corresponding to The presence of both bees, honeybees and about 80% from all flowers (Fig. 5). stingless bees, was frequent enough during the Pollination of other crops. Using his entire flowering season of the crops, during glasshouse and apiary area, the author which time they were observed to visit the conducted a pollination efficiency test of flowers. Stingless bees foraged mainly in the stingless bees, T. carbonaria and C. morning, compared with all day for honeybees, bipunctata, and of honeybees, A. mellifera which may be due to the difference in their (Fig. 6). During the experiment period, 10 field situations. colonies of each stingless bee were kept inside Generally, the results show that stingless the glasshouse with some fluctuation in the bees pollinate as well as honeybees, factoring colony number, while about 30 colonies of in the difference among the crops (Fig. 7). The honeybees were kept in the apiary. Four kinds stingless bees in the glasshouse had settled of crops, namely, cucumbers, eggplants, long enough to adjust themselves to field paprikas, and red peppers, were settled in the conditions, implying that once stingless bees glasshouse as well as in the apiary for are accustomed to conditions in the field, they comparison. In Japan, these four commercially show their efficiency in pollination.

7 From the three experiments on pollination Crane, E. 1992. The past and present status efficiency above and other surveys on of beekeeping with stingless bees. Bee stingless beekeeping techniques, T. carbonaria World 73: 29-42. and S. bipunctata can be expected to show Cruz-Landim, C. et al. 1968. Mandibular gland good potential as effective pollinators of crops development and communication in field in glasshouse conditions in temperate bees of Trigona (Scaptotrigona) postica. J. countries. Kans. Entomol. Soc. 41: 474-481. Dollin, A. and T. Heard. 1998. Keeping CONCLUSION Australian stingless bees in a log or box. In Native Bees of Australia Series Booklet The efficiency of insects as crop pollinators 5. By Australian Native Bee Research would depend on their biological characteristics Center: 1-14. in relation to the crop and the environment in Esch, H. et al. 1965. Sound: an element which they are needed. Each insect species common to communication of stingless which has been used as a pollinator so far bees and to dances of the honeybee. would have its specific characteristics, which Science 149: 320-321. might be favorable or unfavorable from the Heard, T.A. et al. 1993. Factors influencing standpoint of the user. The value of stingless flight activity of colonies of the stingless pollinators is obvious from the farmer's point bee Trigona carbonaria (Hymenoptera: of view. Due to their compact colonies and Apidae). Aust. J. Zool. 41: 343-353. safety for farmers and visitors, they can be Heard, T.A. 1999. The role of stingless bees used in areas where stinging insects are not (Meliponinae) in crop pollination. Annual desirable, as in greenhouses. However, very Review of Entomology, 44: 183-206. few surveys concerning pollination by stingless Heard, T.A. and A. Dollin. 1998. Crop bees have been conducted in the temperate pollination with Australian stingless bees. countries. The work of the author is still In Native Bees of Australia Series Booklet limited, and experiments to assess crop 6. By Australian Native Bee Research pollination efficiency by stingless bees and to Centre: 2-17. improve colony management techniques are Imperatriz-Fonseca, V.L. 1975. On swarming needed before they can be confidently used activity in Meliponinae. Proc. of the 25th for the pollination of crops in greenhouses. International Apicultural Congress: 298. Kerr, W.E. 1959. Bionomy of Meliponids - VI. REFERENCE Aspects of food gathering and processing in some stingless bees. In Food Gathering Amano, K., T. Nemoto and T. Heard. 2000. in Hymenoptera. Symp. Entomol. Soc. Am. Amano, K., Nemoto T. and Heard T. 2000. Detroit: 24-31. What are stingless bees, and why and Kerr, W.E. 1974. Sex determination in bees. how to use them as crop pollinators? A III. Caste determination and genetic control review . JARQ 34,3: 183-190. in Melipona. Insectes Soc. 21: 357-367. Amano, K. 1997. Successful breeding of non- Kleinert-Giovannini, A. et al. 1987. Aspects stinging honey bees farming Japan 31,5: of the trophic niche of Melipona marginata 36-42. marginata Lepeletier (Apidae, Meliponinae). Amano, K. and S. Boongird. 1997. Keeping Apidologie 18: 69-100. of the stingless bee, Trigona fuscobalteata Maeta, Y. et al. 1992. Utilization of the (Hymenoptera: Apidae) in an Brazilian stingless bee, Nannotrigona environmentally enclosed chamber. Ann. testaceicornis as a pollinator of Rept. Prot. North Japan 48: 210-212 (In strawberries. Honey bee Science 13: 71-78 Japanese with English summary). (In Japanese with English summary). Camargo, C. A. 1972. Mating of the social Michener, C.D. 1961. Observations on the bee Melipona quadrifasciata under nests and behavior of Trigona in Australia controlled conditions. J. Kansas Entomol. and New Guinea. American Museum Soc. 45: 520-523. Novitates 20261-46.

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