The spatio-temporal distribution of honey bees and floral resources in Australia

© 2015 Dr. Jonathan Paul ArundelThe Western honey bee, Apis mellifera, is the most economically important pollinator worldwide. In Australia today there are more than half a million hives managed by beekeepers around the country. In addition, there is a large population of feral A. mellifera providing free pollination services to native and disturbed environments. The sustainability of pollinator populations globally, including both managed and feral A. mellifera, is under considerable pressure from four key threats; pests and pathogens, alien species, land-use intensification and climate change. Understanding what impact these threats will have on pollination in Australia requires better knowledge of the spatio-temporal distribution of honey bee colonies (both managed and feral) and the resources on which these colonies depend. In Australia, the life of honey bees is inextricably linked to the flowering of eucalypts. The majority of honey in Australia is produced from eucalypts, and beekeepers frequently move their hives across distances of hundreds of kilometres in pursuit of flowering events. Little is known about how this erratic flowering effects the distribution and abundance of feral colonies. This thesis demonstrates how agent-based models can be used in conjunction with genetics-based field survey methods to make inferences about the density of feral honey bee colonies in south eastern Australia. Colony densities vary with number of colonies observed in the sample in a log-linear relationship, rather than a linear relationship as previously thought. As a consequence, previous field surveys have overestimated densities by an order of magnitude. The surveys described in this thesis have shown that densities of feral honey bees are remarkably uniform across different types of environments, with some evidence that densities are marginally higher in undisturbed environments. Regardless of the type of environment, densities of feral honey bees are not high enough to provide pollination of most horticultural or agricultural crops. The spatial-temporal distribution of managed honey bees is determined by the aggregate behaviour of individual beekeepers. This thesis shows that in planning the movement of their hives from one set of flowering events to the next beekeepers need to solve complex optimisation problems. Where a beekeeper is able to use foresight to predict the location of future flowering events, the routes they choose can be up to 2-6% shorter than those obtained from using current flowering information only. To better understand the spatio-temporal distribution of floral resources, this thesis outlines the development of a new software application that processes remote-sensing data and makes the output available to beekeepers and researchers. This application is used to highlight agreement between patterns of eucalypt growth, flowering, and honey production at landscape scale. Further work is still needed to fully understand the relationships between climate, growth, eucalypt flowering, and the effects of flowering on feral colony densities and beekeeper movements. An agenda for future research outlines how threats to pollination security in the future can be better managed