Chem. Senses 26: 223-230,
2001
© Oxford University Press 2001
SYMPOSIUM: AChemS XXII Symposium |
Foraging Behaviour in Drosophila Larvae: Mushroom Body Ablation
1 Department of Biological Sciences, University of Nevada, Las Vegas, NV 89154, USA and 2 Department of Zoology, University of Toronto, Mississauga, Ontario, Canada L5L 1C6 3 Present address: National Institute of Mental Health, Laboratory of Molecular Biology, Bethesda, MD 20892, USA
Correspondence should be sent to: Marla B. Sokolowski, Department of Zoology, University of Toronto, 3359 Mississauga Rd, Mississauga, Ontario, Canada L5L 1C6. e-mail: msokolow{at}credit.erin.utoronto.ca
Abstract
Drosophila larvae and adults exhibit a naturally occurring genetically based behavioural polymorphism in locomotor activity while foraging. Larvae of the rover morph exhibit longer foraging trails than sitters and forage between food patches, while sitters have shorter foraging trails and forage within patches. This behaviour is influenced by levels of cGMP-dependent protein kinase (PKG) encoded by the foraging (for) gene. Rover larvae have higher expression levels and higher PKG activities than do sitters. Here we discuss the importance of the for gene for studies of the mechanistic and evolutionary significance of individual differences in behaviour. We also show how structure–function analysis can be used to investigate a role for mushroom bodies in larval behaviour both in the presence and in the absence of food. Hydroxyurea fed to newly hatched larvae prevents the development of all post-embryonically derived mushroom body (MB) neuropil. This method was used to ablate MBs in rover and sitter genetic variants of foraging to test whether these structures mediate expression of the foraging behavioural polymorphism. We found that locomotor activity levels during foraging of both the rover and sitter larval morphs were not significantly influenced by MB ablation. Alternative hypotheses that may explain how variation in foraging behaviour is generated are discussed.