Investigating population and genetic structure in giant honey bee Apis dorsata Fabricius in Thailand

Abstract

The giant honey bee (Apis dorsata) is an important pollinator of Asian lowland forests. Across its range, the species is impacted by heavy hunting and habitat disturbance. In this thesis, it was investigated how these pressures impact the connectivity and viability of the A. dorsata population of Thailand. In Chapter III, a morphometric analysis of forewing shape that can accurately identify any of the four species of honey bee present in Thailand was described, regardless of sex. Thus, geometric morphometry of the wing alone can be used to identify Asian honey bee species in most circumstances. In Chapter IV, the procedure to characterize 73 A. dorsata colonies collected from 31 different localities in Thailand was applied. Multivariate analysis of variance (MANOVA) demonstrated no significant differences between the bees sampled from five geographic regions. Therefore, this suggests that the A. dorsata populations of mainland Thailand are a single population. In Chapter VI, the genetic structure and colony relatedness of A. dorsata populations based on microsatellite analysis of 54 nests in 3 aggregations was examined. Also, it was shown that the population has high levels of heterozygosity and that FST values between aggregations were not significantly different from zero (P > 0.05). The analysis also showed that no colonies were related as mother-daughter. Thus, if reproduction occurred at the study site, daughter colonies dispersed. This suggests that rapid increases in A. dorsata colony numbers during general flowering events most likely occur by swarms arriving from other areas rather than by in situ reproduction. In Chapter VII, queen mating frequency and allelic diversity between colonies sampled in disturbed and undisturbed areas in Thailand was compared. Microsatellite analysis of 18 colonies in 6 aggregations showed no significant difference in queen mating frequency at disturbed and undisturbed habitats. This suggests that the mating behaviour of A. dorsata is robust to anthropogenic changes to the landscape. It could be concluded that despite the formidable anthropogenic pressures that the A. dorsata population endures in Thailand, the species continues to enjoy a large effective population size and has high connectedness. Furthermore, this finding suggests that habitat disturbance has no effect on mating frequency or genetic diversity. It was concluded that A. dorsata is currently able to tolerate habitat fragmentation and annual harvesting.