Phytoseiulus persimilis (Acari: Phytoseiidae) is a specialist predator on tetranychid mites, especially on the twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). The foraging environment of the predatory mites consists of prey colonies distributed in patches within and among plants. Previous studies have found that several behavior related to foraging are governed by genetic factor(s), therefore we are using quantitative and molecular techniques to investigate the genes related to variation in these behaviors.  We are particularly interested in the resource (i.e., prey)-dependent dispersal behavior of the predator.  In the course of developing molecular markers to study the foraging behaviors, we isolated a partial sequence that is presumed to be the orthologue of the foraging (for) gene, which we have named Ppfor (Phytoseiulus persimilis foraging gene). The for gene is associated with the rover-sitter phenotypes in fruit flies and is known for its role in foraging behaviors in other arthropods like honeybee and ant.  We studied the use of the Ppfor gene to develop molecular markers for and understand behavioral phenotypes.