Migratory behaviour and colony aggregation in Giant honeybees

The Giant honeybees (Apis dorsata) are hornet-sized, live in huge single-comb nests in open air, measuring up to two meters in horizontal span. They are known as the most ferocious stinging insects on earth, and may nest in huge aggregations of up to 200 colonies at special sites. A. dorsata cannot be domesticated in particular because of their noticeable migratory behaviour. Seasonal migration and colony aggregation in the Giant honeybees are investigated; both behaviours have aroused great interest in contemporary literature, are characteristic only to Giant honeybees, unique in the world of insects. They are closely linked together and so far, in spite of various observations and assumptions, hardly understood. The project refers to the migratory pathways and obvious seasonal dependencies of colony status in Giant honeybees (A. dorsata) in Northeast India, a region which is the gateway to India`s richest biodiversity zone and not significantly touched by honeybee research before, The project investigates from the migrational pathways of the Giant honeybee colonies; the causes for migration and colony aggregation are found; whether aggregated colonies are members of one genetic family or unrelated, whether the colonies revisit certain aggregation sites in annual rhythm. The investigation proves a set of ecological, ethological and genetic hypotheses. The project aims are fulfilled by field work like collecting demographic, ecological and ethological data, as well as by sampling workerbee and brood from distinct colonies. Lab work (single-locus DNA-fingerprinting, PCR and sequencing) provides data of relationship between colonies and populations, The project is scheduled to be carried out with cooperating institutes in Bern, Berlin, New Delhi and Gauhati, as well as with Lunz and Graz.

The research project focused on two behaviours characteristic only for the giant honeybees of South East Asia (Apis dorsata und Apis laboriosa). These bees nest in the open, migrate in seasonal rhythm between different habitats, and form striking aggregrations of colonies on trees, rocks or buildings. We investigated the animals in Norteast-India (Assam) and in South Nepal (Chitwan). For the first time we gained evidence for an extraordinary orientational capacity that had been known so far only from vertebrates. By molecular genetic technique we proved that the same queen returns to the same nesting site, even after four years (Nature 406, 475 [2000]). Moreover we investigated the relationships between and within the colony aggregations, the drift (= verflug) rate between colonies in aggregations, and the polyandry of the queens of Apis laboriosa. Also in this animal we linked molecular genetic and morphometric analyses to measure the patrigenic descent on the wing patterning. We proved here for the first time that the wing patterns of super sisters are more similar than those of half sisters. Furthermore, the wing venation exhibits a high level of individuality which is 12 to 30fold more expressed than the patrigenic part of variance. By satellite imaging we tried to correlate the landuse pattern of nectar plants with the topographical distribution of the giant honeybee colonies in Chitwan during the winter season. We measured some adaptive aspects for the colony aggregation by studying the defence strategies of colonies. For this, we stimulated attacks and documented by infrared recordings the recruitment of soldier bees in the colonies. It takes some minute until colonies become "aggressive" enough to release groups of hundreds or thousands of soldier bees within parts of a second. This was impressively demonstrated by the interaction between the predatory bee eater and colonies. For the first time, we observed that non-threatened colonies or parts of it contribute in the defense response of the threatened colony. This chance for group defense is a selective advantage generated by the aggregation. Comparative investigations were performed in four races of Apis mellifera (Graz: carnica; South Africa: scutellata, capensis, Manaus: Africanized bee). We measured how much time it takes until guard bees are ready to attack, to quantify the so-called "aggressivity" of Western honeybees. Linked to these research topics we produced some highly awarded documentary films. "The magic trees in Assam" (Sir David Attenborough as narrator), "Defense strategies in Giant honeybees", the first has been aired world wide and was viewed by 50-70 million people. Additionally, we started to carry out pilot experiments concerning the biology of the African small hive beetle Athaena tumida and studied the extraordinary interspecific trophallaxis between bees and beetles. This beetle might become the most dangerous pest for European honeybees ever since. We are currently working on a documentary film about this problem. Moreover, we are about to produce, in April 2002, the final shooting in Arizona for a further documentary film about the Africanized bees ("killer bees").