The European honeybee, Apis mellifera, is important economically not just for honey production but also as a pollinator. Bee pollinated plants contribute towards one third of the food eaten worldwide. However, honeybee numbers in some areas are declining. A range of interacting factors are thought to be involved, including pathogens and parasites, loss of forage, pesticide use, bad weather, and limited genetic variability. Pathogens are also known to cause changes in the behaviour of their hosts and these premortality and sublethal effects of disease may well play a role in colony declines and are the focus of this thesis. For individual bees the fungus Metarhizium anisopliae was used as a model pathogen and RT-Q-PCR was used to detect and quantify naturally occurring pathogens. In field colonies the level of infestation of the parasitic mite Varroa destructor was modified as a surrogate for disease load as the amounts of many viruses correlate with mite levels. Survival experiments showed that both disease load and forage availability had an effect on honeybee longevity and feeding the bees pollen increased their survival. Learning experiments showed that both the fungus and some of the bees’ naturally occurring pathogens caused changes in the learning ability of young adult and older forager bees. Young adult bees were better able to learn when infected with the fungus, possibly because it made them more responsive to the sucrose stimulus, whilst older forager bees where less able to learn when infected with the fungus. Harmonic radar was used to show that honeybee flight ability was affected by naturally occurring pathogens, especially deformed wing virus which caused bees to fly shorter distances and for shorter amounts of time than uninfected bees. Observation hives were used to study in-hive behaviour showing that bees with more pathogens were likely to start foraging earlier than healthier bees.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:582373 |
| Date | January 2013 |
| Creators | Wright, Emma |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/57266/ |
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