Research Highlights

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  • Neuroscience

Published online: 24 September 2008 | doi:10.1038/nchina.2008.222

Animal behaviour: What makes fruit flies fight?

Felix Cheung

Introduction

© (2008) Nature Neuroscience

Aggressive behaviour is not all bad. In the animal kingdom, aggression has been a major force in both natural and sexual selections. Yi Rao at the National Institute of Biological Sciences and Peking University, both in Beijing, and co-workers¹ have examined the chemistry and biology underlying this innate behaviour in the common fruit fly Drosophila.

Fruit flies of the same sex naturally brawl when they engage each other. The males tend to box with their forelegs, whereas female flies prefer headbutting. The researchers placed pairs of flies of the same sex into individual chambers with a food pad in the middle that provoked fighting (pictured). They counted the frequency of boxing or headbutting for the first ten minutes that the flies were in the chamber.

The researchers found that mutant flies lacking the ability to produce the neurotransmitter octapamine were less aggressive than wild flies. The mutant flies did not initiate fighting nor did they fight other flies. However, the mutant flies would still provoke wild flies to fight and were likely to lose in competing for copulation with females. The findings suggest that octapamine is responsible for driving fruit flies into aggression.

In the wild, fruit flies that are raised in groups tend to be less aggressive than those raised in isolation. The researchers found that increasing octopamine levels could restore aggressiveness in socially grouped flies, but did not promote aggression in socially isolated flies.

An insect's physiological processes are controlled by the central nervous system, which consists of the brain and the suboesophageal ganglion. Through further experiments, Rao and co-workers identified a small subset of octopaminergic neurons in the suboesophageal ganglion as being important for aggression.

The authors of this work are from:
National Institute of Biological Sciences, Beijing, China; Institute of Biophysics, Chinese Academy of Sciences, Beijing, China; School of Life Sciences and State Key Laboratory of Biomembrane, Peking University, Beijing, China.

Reference

1. Zhou, C., Rao, Y. & Rao, Y. A subset of octopaminergic neurons are important for Drosophila aggression. Nature Neurosci. 11, 1059–1067 (2008). | Article |