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In most organisms, various physiological and behavioral functions are expressed rhythmically. Previous studies have shown that thermoperiod is an important factor affecting circadian clock-related genes that regulate insect locomotor activity. Bradysia odoriphaga Yang & Zhang is an underground pest that attacks more than 30 crops but is especially damaging to Chinese chives. In this study, we analyzed the adult eclosion time and period (Boper) gene expression in B. odoriphaga as affected by temperature (cycling vs constant temperature), insect stage, and tissue specific. We found that the eclosion time and expression of the Boper gene changed during the temperature cycle but not under a constant temperature. Silencing of Boper expression significantly decreased the adult eclosion rate and significantly increased adult mortality and malformation. The findings indicate that thermoperiod alters Boper expression and regulates the eclosion rhythm.

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.

Plants protect themselves with a vast array of toxic secondary metabolites, yet most plants serve as food for insects. The evolutionary processes that allow herbivorous insects to resist plant defenses remain largely unknown. The whitefly Bemisia tabaci is a cosmopolitan, highly polyphagous agricultural pest that vectors several serious plant pathogenic viruses and is an excellent model to probe the molecular mechanisms involved in overcoming plant defenses. Here, we show that, through an exceptional horizontal gene transfer event, the whitefly has acquired the plant-derived phenolic glucoside malonyltransferase gene BtPMaT1. This gene enables whiteflies to neutralize phenolic glucosides. This was confirmed by genetically transforming tomato plants to produce small interfering RNAs that silence BtPMaT1, thus impairing the whiteflies' detoxification ability. These findings reveal an evolutionary scenario whereby herbivores harness the genetic toolkit of their host plants to develop resistance to plant defenses and how this can be exploited for crop protection.

Bradysia odoriphaga is frequently subjected to heat shock during the summer in China. Although the effects of heat shock on insect ecology and physiology have been widely explored, the effects of heat shock on the life history parameters of Bradysia odoriphaga are largely unknown. In the present study, we investigated the effects of heat shock on B. odoriphaga survival and reproduction as well as on offspring development and sex ratio. We exposed adult B. odoriphaga to 31, 33, 35, or 37 °C for different durations (from 0 to 120 min). The results showed that the survival of both sexes declined with the increase in temperature and exposure time, especially at 33, 35, and 37 °C. Longevity was markedly greater for males than females across all treatments. Fecundity generally declined as temperature and exposure time increased, and no eggs hatched when females were exposed to 37 °C for >75 min. The development of offspring larvae was significantly delayed when the parent female and male had been exposed to ≥31 °C for ≥30 min. In addition, the sex ratio of F1 progeny derived from heat-shocked parental adults was increasingly skewed to female as exposure time and temperature treatment increased. Overall, the results indicate that heat shock negatively influences B. odoriphaga.