Honeybee health: from landscapes to behaviour

Abstract

Honeybees (Apis. spp) provide vital pollination services to plants and crops but are under assault from several interacting stressors including infectious diseases. Parasites and pathogens have not only been implicated in colony losses but may also alter the foraging behaviour of honeybees, with knock on consequences to colony health and pollination services. This thesis takes a multidisciplinary approach to examine the health of honeybees from the viral ecology across honeybee species down to the individual behaviour of immune stimulated bees. In Chapter 2 I used high-throughput sequencing techniques to characterise and then compare the viral communities of managed honeybees in an understudied region in South India. I found that there was a highly diverse and specious community of novel viruses, with 45 putative novel species discovered. While viruses were shared between species, Apis mellifera and Apis cerana had distinct viruses despite being kept at the same apiaries. For Chapter 3, I studied the effect of immune stimulation on trophallaxis, a key social behaviour in honeybees. Immune stimulation of bees was found to decrease the time bees spent performing trophallaxis, and reduced the occurrence and mass of trophallactic fluid transferred, likely as a mechanism to reduce disease transmission within the colony. Chapter 4 examined the impact of immune stimulation on feeding and gustation of forager honeybees. Immune stimulation was found to alter gustation by decreasing sucrose sensitivity and increasing aversion to a distasteful compound, quinine. Feeding on artificial nectars of varying concentration and on nectars with different secondary plant compounds was not altered by immune stimulation.