The essential oil ofStachys riederivar.japonica(Family: Lamiaceae) was extracted by hydrodistillation and determined by GC and GC-MS. A total of 40 components were identified, representing 96.01% of the total oil composition. The major compounds in the essential oil were acetanisole (15.43%), anisole (9.43%), 1,8-cineole (8.07%), geraniol (7.89%), eugenol (4.54%), caryophyllene oxide (4.47%), caryophyllene (4.21%) and linalool (4.07%). Five active constituents (acetanisole, anisole, 1,8-cineole, eugenol and geraniol) were identified by bioactivity-directed fractionation. The essential oil possessed fumigant toxicity against maize weevils (Sitophilus zeamais) and booklice (Liposcelis bostrychophila), with LC50values of 15.0 mg/L and 0.7 mg/L, respectively. Eugenol and anisole exhibited stronger fumigant toxicity than the oil against booklice. 1,8-Cineole showed stronger toxicity, and anisole as well as eugenol exhibited the same level of fumigant toxicity as the essential oil against maize weevils. The essential oil also exhibited contact toxicity againstS. zeamaisadults andL. bostrychophila, with LC50values of 21.8 µg/adult and 287.0 µg/cm2, respectively. The results indicated that the essential oil ofS. riederivar.japonicaand its isolates show potential as fumigants, and for their contact toxicity against grain storage insects.Keywords:Stachys riederivar.japonica;Sitophilus zeamais;Liposcelis bostrychophila;fumigant;contact toxicity;essential oil
Stored grain pests have developed widespread resistance to currently available grain protectants. Although symbiotic microbes played an important role in insecticide resistance of insect hosts, it has not been reported in stored grain pests. In this study, five gut bacteria were excised from adult Sitophilus oryzae (L.) (Coleoptera: Curculionidae), Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae), and Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae). These bacteria can degrade malathion , pirimiphos-methyl, and deltamethrin and utilize these insecticides as the carbon source in vitro . When treated with 0.5–10 mg/kg of malathion, pirimiphos-methyl and 0.3–0.75 mg/kg of deltamethrin, gnotobiotic reinoculation of a given bacterial strain significantly enhanced survival rates of its hosts. The significance of gut bacteria in host insecticide tolerance was insecticide dosage-dependent. Furthermore, the in vitro insecticide biodegradability of gut bacteria was not completely consistent with their in vivo performance in host insecticide resistance. This suggests that there may be other physiological processes responsible for host insecticide tolerance mediated by symbiotic bacteria except for direct degradation of insecticides. These results provide insight into insecticide resistance management of stored grain pests and further study of the association between gut bacteria and insecticide resistance.
危险品化学品经营许可证（带存储）