Abstract: To investigate the relationship of locomotor activity and dopamine levels in the head in fruit fly Drosophila melanogaster affected by rotenone, the effects of rotenone on locomotor activity and gene expression related to dopamine biosynthesis and dopamine levels in heads of fruit flies were determined. The results showed that locomotor activity was significantly reduced in male and female adult flies fed on Drosophila instant food containing 0.2-0.8 mmol/L rotenone for 6 d. The dopamine levels were reduced to 79.3%, 66.8% and 53.2% of that of the male control in heads of male adult flies and 83.2%, 72.3% and 59.8% of that of the female control in heads of female adult flies after feeding on instant food containing 0.8 mmol/L rotenone for continuous 6, 12 and 21 d, respectively. Under the above same conditions the expression levels of pale gene were reduced to 76.3%, 51.4% and 37.3% of that of the control, and Ddc gene to 87.1%, 78.2% and 63.5% of that of the control, respectively. The results suggest that rotenone can significantly interfere with pale and Ddc gene expression and reduce dopamine levels in heads of adult flies, and correspondingly affect the adult fly locomotor activity.

Key words: Drosophila melanogaster, rotenone, locomotor activity, dopamine level, gene expression, quantitative RT-PCR amplification