INVESTIGATION OF DORSATA MIGRATION ON BELITUNG ISLAND, INDONESIA WITH WING VENATION ANALYSIS

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1 INVESTIGATION OF DORSATA MIGRATION ON BELITUNG ISLAND, INDONESIA WITH WING VENATION ANALYSIS D. B. Purwanto 1, S.Fuchs 2 and N. Koeniger 2 1. Perum Perhutani, Ministry of Forestry and Estate Crops of Indonesia P O Box 19/JKWB Jakarta 10270, Indonesia, Fax , dpurwan@hotmail.com, dpurwan@gwdg.de 2. Institut für Bienenkunde, Karl-von-Frisch-Weg 2, Oberursel, Germany Introduction The giant honeybees are large, as their name implies. They are known as Apis dorsata. A. dorsata can be found in almost all of the Indo-Malayan region from Indus river in the west to the Philippines islands in the east and in parts of the Indonesian islands through the Kai island below Irian Jaya. They build a single comb in the open sky beneath the large branch of a tall tree or often under roofs, bridges, or walls of buildings. The trees that often nested by dorsata are called bee tree. One bee tree can be nested by more than a hundred colonies. In some places it was practice to use a rafter (artificial branch). The dorsata honey production is in the high proportion, about 60 % in Indonesia. In Sumatra, it is reported that the bees are present in a rain forest area. Even some colonies nested in nearby villages as in rubber and coffee plantations. The migration of dorsata colonies is important, because their flight could be long distance. They migrated from mangrove area to the mountain area in Riau province. It depends on the blooming season of the trees in the forest. It is more important to a small island such as Belitung where it was reported as a potential honey source in Sumatra. When their migration is by flight over the sea, the colonies on certain islands can be preserved for a long time. Dyer and Seeley, 1994, reported that in Thailand A. dorsata migrates seasonally. Colonies arrive in the area during the end of the dry season, reproduce, and then depart early in the rainy season. During the immigration phase, early arriving colonies stayed only temporarily, as if assessing habitat quality. Colonies departing after a long stay always left a barren comb behind. Koeniger and Koeniger (1980) reported that in Sri Langka long distance migrations take place two to four times a year, ranging about km, with several stops about every 4-6 weeks. In the east coast of Sumatra two commutation cycles were present with a stay of only 2-3 months at the nesting site (Hadorn (1948) in Ruttner, 1988). While preparing for migration the rearing of brood is stopped. The swarm settles generally close to the ground, no comb are constructed, but nectar gathering takes place. The distance between stops ranges from 200 m to 5 km that could have covered within 5-10 hours of direct flight for about 1 month. It is still unsolved, is the seasonal migration similar to bird migration. Dyer and Seely (1994) discussed the possibilities incoming and out going colonies, one of them reported that many immigrating colonies stay only temporarily at nesting sites which nevertheless are proven to be acceptable nesting sites, because they have been used for many generations, and are eventually accepted by later arriving colonies. But it is not clear enough have full knowledge of the behavior of seasonal migration. Objectives To find out how high the population size is and about the migratory behaviour of A. dorsata. Analysis and comparison of Apis dorsata population from Belitung with Sumatra s population in order to draw conclusions on the migration behaviour of A. dorsata. Proceedings of the 37 th International Apicultural Congress, 28 October 1 November 2001, Durban, South Africa APIMONDIA 2001 To be referenced as: Proc. 37 th Int. Apic. Congr., 28 Oct 1 Nov 2001, Durban, South Africa ISBN: Produced by: Document Transformation Technologies Organised by: Conference Planners

2 Methodology A. Location and time Field Research was conducted in the Belitung district, South Sumatra, Indonesia, from August to November of Morphometric analyses were done at the Institut für Bienenkunde (Polytechnische Gesellschaft), Fachbereich Biologie der J. W. Goethe-Universität, Frankfurt am Main, Germany. B. Equipment and material The equipment and material used in field work consisted of ethanol 70 %, K CN, bee packages, bee samples of A. dorsata from Belitung, Bangka, and Sumatra (each sample consisted of 40 bees from 1 colony), C. Data collection a) Raw material for laboratory analysis was collected such as bee samples from Muara Enim, South Sumatra Province (20 samples from 1 bee tree), Bangka (1 sample), and Belitung (Membalong subdistrict) (11 samples); b) Laboratory work was done for morphometric analysis of the bees (Uni Frankfurt) c) Collecting samples consisted of Bees samples were 40 bees, kept in 70 % ethanol. They were from 20 colonies from Muara Enim, 1 colony from Bangka, and 11 colonies from Belitung. D. Laboratory work 1. Morphometrics of bees A) Wing measurements were taken for the morphometric analysis based on Ruttner s Method. The fore left wing was taken from fifteen bees as samples separated by using tweezers. Fifteen wings were put on the slide glass and covered by another slide glass. The slide glasses were sealed to be ready for measurement. Wing dimension (length and width), cubital veins and 11 venation angels were measured. Due to the large wing of A. dorsata, the measurement for length and width had to be done using a ruler and a light glass desk with a magnification of 100 times. The results were added to the same program of venation and cubital veins dimension. The video was used for the other samples and connected to the soft ware and automatically counted by clicking the points. Its out-put is shown in the Table 1, having 17 characters. Due to the dark position in the clicking point of number I 7 and II 3 these measurements were unprecise and excluded for the angle of L13, J 16, and N23. The clicking point had to be put carefully due to the small path of wing venation. The wing must be in the right position, the inner part of the wing (folding place) has to be on top. Secondly the slide glass was placed under the video capture. While the analysis was run, the user has to follow the manual.

3 Table 1. Data set for morphometric analysis within 15 individual measurements Characters Belitung Bangka 6031 Sumatra Length (L) of forewing (mm) Width (W) of forewing (mm) Cubital 1 (mm) Cubital 2 (mm) Angle A4 Angle B4 Angle D7 Angle E9 Angle G18 Angle J10 Angle J16 Angle K19 Angle L13 Angle N23 Angle O26 Cubital index L/W forewing 2. Data analysis The data from interviewing was analysed by the statistic software with simple statistics, using the parameters honey hunters profile, their activities management, beekeeping activities management and its description, bee forages, economical value, and beekeeping problems. The data from observation of sunggau in the field was outlined by the qualitative measurement on construction and the site description. Qualitative description was taken by describing the sunggau site (landing mark, darkness of site, adjusting site). The morphometrics data was analysed by multivariate statistic with SPSS software. A comparison of the samples from Belitung and Sumatra was used by discriminate analysis and the t-test. Sample from Bangka was excluded from the comparison because there was only one. The samples were furthermore compared to other dorsata samples which are present in the data bank of the Institut für Bienenkunde, Universität Frankfurt am Main at Oberursel with factor score analysis and discriminant analysis. Result 1) Geographical setting and boundaries In its geographical boundaries, Belitung District lies between 107 o 35 l o 18 l East Longitude and 02 o South - 03 o 15 l South Latitude. Belitung is the archipelagic district which consists of about 189 islands in mostly uninhabited. Its district is surrounded by the China Sea in the North, Karimata Strait in the East, Java Sea in the South, and Gasfar Strait in the West. The island nearby is Bangka that is in between Sumatra Island and Kalimantan Island. The area is about Km2 with the cross diameter about 79 Km in West to East and 77 km in North to South.

4 2) Migration of the bees One aim of this study is, to find out if the population in Belitung can be distinguished from the population in Sumatra. The locations of sampling were 370 km apart. The wing measurements of the bees from the two different origins were compared. The results are shown in below (Table 2, N : number of sample population, SD : standard deviation) Table 2. List of the measured characters of A. dorsata samples from Belitung (N = 11) and Sumatra (N = 20) (t-test, * p < 0.001, ** p < 0.05) Characters Belitung SD Sumatra SD Length of Forewing * mm 0.09 mm mm 0.05 mm Width of Forewing * 4.18 mm 0.06 mm 4.25 mm 0.04 mm Cubital 1 * 1.06 mm 0.03 mm 1.10 mm 0.02 mm Cubital 2 * 0.14 mm 0.01 mm 0.16 mm 0.01 mm Angle A4 * Angle B Angle D7 * Angle E Angle G Angle J10 * Angle K Angle O26 * Cubital index ** Forewing index It is shown in Table 2 that the length and width of forewing of the two groups differ (t-test, p < 0.001); they are smaller in the Belitung (12.78 mm in length and 4.18 mm in width) than in Sumatra population (12.97 mm in length and 4.5 mm in width). They do not differ in their proportion of length to width. The cubital 1 (c1) and cubital 2 (c2) veins differ, and are smaller in the Belitung population (1.06 mm in c1 and 0.14 in c2) than Sumatra population (1.10 mm in c1 and 0.16 in c2). The angles of J10, O26, A4 and D7 are shown to be different. Taking all the obtained results into account, the two groups can be considered as different. The Belitung and Sumatra populations are well within the range of other dorsata samples from Thailand, the Philippines, Pakistan, Nepal, Borneo, and India (taken from the data bank of Institut für Bienenkunde, Universität Main, at Oberursel ). A boxplot diagram for the values of forewing length. The difference between the populations from Sumatra and Belitung is not significant within the context of the entire dorsata population. However, with multivariate analysis, Belitung and Sumatra bees can be shown to differ significantly within the whole dorsata context. and to resemble one another more than any of the other groups. In discriminant analysis, all samples of Belitung and Sumatra were assigned to their correct group. Then the populations can thus be regarded as separated. Discussion Comparing the two different of populations from Muara Enim, Sumatra and Tanjungrusa, Belitung, we found that they are considered distinct. They are located 370 km apart. The distance from Muara Enim to the east coast of Sumatra is about 250 km and from the east coast of Sumatra to Belitung is about 120 km. It is still possible for the bees to leave Belitung to visit Bangka and Sumatra or vise versa. But it is quite impressive that width and length of the forewing are smaller for the Belitung population. This is also true for the cubital veins. These differences are probably caused by the co-adaptation process. If this proves to be true, the two dorsata populations are isolated on the islands. From the perspective of the food source, putting into consideration that the blooming season occurs 3-5 times a year (there might have been more in the past), the bees in Belitung only migrate from one place to the other on one island. There is no need for a long distance flight, so their wings are smaller. Sumatra colonies need to fly long distances to reach their forages, so their wings are bigger. More populations have to be compared to get a confidential conclusion.

5 is suggested to take more samples from other areas in Sumatra to look at the probable migration and the same should be done for the islands of Belitung and Bangka. It was difficult to do an interpolation of the distances because the samples were taken from the same place. Due to the mentioned factors this study cannot definitely exclude the over sea migration. Some reports showed that A. dorsata can migrate 50 km over the sea (Crane et al, 1993) and can fly further than 100 km (Koeniger and Koeniger 1989). If the colonies in Belitung are isolated on the island, they might disappear some day. This might have been the same case for Java populations that are present in smaller numbers today (personal experience). But if it could be concluded that the colonies can migrate over the sea, moving from Belitung to Bangka and to Sumatra, the number of colonies will decrease due to the scarcity of bee forage and move to Bangka and Sumatra. Reliable information on natural Apis dorsata populations is still scarce. Conclusion The colony of Apis dorsata in Belitung is considered to be different population than that in Sumatra (proved by morphometric analysis). The number of colonies are becoming smaller today. It might affect the habitat of Belitung in the future due to reduction of the pollination, thus reducing plants diversity. In particular, if bees from Belitung and Sumatra differed, It means reducing the habitat the result considering the other small islands? Were these the same and would you conclude they migrate over these small islands, crossing water? As you mention these islands qat the start - maybe you cannot decide yet from your data, but I feel you should say something about this question? REFERENCES 1. Chinch, Pung Huu, P.H. Thai, N.Q. Tan, N. H. Minh and N.Q. Tan Raftering, a traditional technique for honey and wax production from A. dorsata in Vietnam. Beekeeping and Development 36: De Vries, R The history of honey and wax production of the giant honey bee (A. dorsata) in Sumatra and Kalimantan, Indonesia. Proceedings of the first Nectar Seminar, pp Amsterdam. 3. Dyer, F. C., Th. D. Seeley Colony migration in the tropical honey bee A. dorsata F. (Hym. : Apidae). Insect Sociaux 41 : Kastberger, G., O. Wider, T. Hoetzl, G. Raspotnig Behavioral Features of a periodic form of massed flight activity in the giant honey bee A. dorsata. Apidologie 27 : Koeniger, N. and G. Koeniger Observations and experiments on migration and dance communication of A. dorsata in Srilanka. J. Apic. Res. 19 (1):21-34.