Abstract: In order to screen the preferred color of Trichogrammatoidea bactrae Nagaraja, the behaviour responses of T. bactrae to seven colors, i.e., red, yellow, black, purple, green, white and blue, were investigated with petri dishes pasted underside with color papers in the laboratory. The results revealed that the retention duration of female wasps was significantly longer on red, yellow, purple, green and blue papers than on transparent ones (control) (P< 0.01), but not on black and white ones. The percentage of first choice by female wasps to yellow was extremely significantly higher than to transparent color (P< 0.01), and that to red, purple, green or blue was significant higher than to transparent color (P＜0.05), but that to black and white was not significantly different from the control. In selection tests of two colors, the retention duration of female wasps on the yellow paper was significantly longer than those on other four colors when compared on yellow paper with red, purple, green and blue paper, respectively. However, in selection tests of multiple colors with red, purple, green, blue and yellow, no obvious differences were detected in percentage of the first choice and retention time of the wasps to five colors; while the retention duration of wasps on red and blue papers was significantly longer than on purple one, but no significant differences were detected between on these three color papers and on both yellow and green papers. The number of parasitized eggs on yellow paper was extremely significant higher than on the transparent paper (P＜0.01), while the number of parasitized eggs on black paper was extremely significant less than that on the transparent paper （P＜0.01). The number of parasitized eggs on the other five color papers, i.e., red, blue, purple, green and white, was not significantly different from that on the transparent paper. In conclusion, T. bactrae has the highest preference to yellow, less preference to red, purple, green and blue, but the least preference to white and black.

Key words: Trichogrammatoidea bactrae, behavior, taxis, color preference, RGB values