Abstract: In order to study the predation capacity of tarantula to Drosophila melanogaster， the genomic DNA of tarantulas which had been fed with 1， 2， 3， 4， 5 and 6 Drosophila melanogasters were used as templates， and PCR amplifications were carried out by utilizing the universal primers for mitochondrial synthetic gene COI of Drosophila melanogaster as the specific primers. Results showed that the PCR amplifications were influenced by the content of templates， a linear positive correlation was found between feeding amount and PCR products， and the linear equation was E（y）=-29111+18212x， P=001， R2=095. Thus， DNA residues of Drosophila melanogaster in tarantula increased with the addiation of predation.

Key words:  tarantula, Drosophila melanogaster, PCR