Effects of Colored Plastic Film on the Occurrence of Bradysia odoriphaga in Garlic Field

The autumn garlic of Shandong was taken as the test material, with the field investigation and the laboratory test, the effect of different covering treatments（the silver gray, silver, black, blue, black and transparent） on the quantitative difference of Bradysia odoriphaga in garlic field was studied, and the reflection spectrum characteristics of different mulches was measured to explore its mechanism of insect control, in order to provide reference for green control of garlic pests.The results showed that the occurrence of B.odoriphaga was significantly reduced by covering silver gray and silver black mulch, with the occurrence of B.odoriphaga being 33.6 insects per 10 plants and 12.8 insects per 10 plants respectively, decrease by 63.8% and 86.2% compared with transparent mulch.The selection rate of silver gray and silver black mulching film by B.odoriphaga was significantly lower than that of transparent mulching film, which decreased by 26.2% and 27.4% respectively.The results of adult selection in laboratory were consistent with those in field.And the light reflectance and reflected light intensity of silver gray and silver black plastic films were significantly higher than that of other color plastic films, and their reflectance were the highest in ultraviolet（380-400 nm） and yellow-green（512-607 nm） wavelengths.In conclusion, the silver gray and silver black film mulching can significantly reduce the damage of B.odoriphaga in garlic field, the important factor is that the silver grey and silver black mulch exert repelling action on B.odoriphaga,which is related to specific spectral reflectivity on the light intensity and reflection of the silver grey and silver black mulch.