Control of Bradysia odoriphaga (Diptera: Sciaridae) by soil solarization

The subterranean insect Bradysia odoriphaga (Diptera: Sciaridae) is an important pest in China and is especially damaging to Chinese chive. This study determined the exposure temperatures and times required to kill various stages of B. odoriphaga in vitro, the optimal plastic film for soil solarization, and the effects of soil solarization on control of B. odoriphaga. In vitro mortality was 100% when adults, eggs, larvae, or pupae were exposed to a constant temperature of 40 °C for 1.3, 1.8, 2.8, or 3.7 h. Among four kinds of plastic film (white common plastic film, light blue anti-dropping film [LBADF], white anti-dropping film, and black-white film), soil temperature increased fastest and remained over 40 °C for the longest time with 0.12-mm-thick LBADF located 30 cm above the soil surface. Favorable soil solarization with 0.12-mm-thick LBADF located at 30 cm above the soil surface or on the soil surface just 1 d after treatment provided 100% control of B. odoriphaga. The growth of Chinese chive was slower in solarized plots than in control plots for about 10 days but subsequently was faster in the solarized plots. At 20 days after treatment, the differences in yields between solarized plots and control plots were not statistically significant. This is the first report that soil solarization can be used to control B. odoriphaga in Chinese chive fields. This approach needs to be investigated for management of other plant diseases and insect pests.