The red flour beetle, Tribolium castaneum , is an agricultural and storage pest with a global distribution. Studies have shown that eucalyptol has strong contact toxicity against larvae of this beetle, whereas odorant binding proteins (OBPs) are known to contribute to larval defenses against this phytochemical toxin. However, the mechanisms underlying the protective effect of insect OBP s against eucalyptol remain unclear. Here, TcOBPC02 from T . castaneum was cloned and characterized. Gene expression profile analysis showed that TcOBPC02 is highly expressed at early larval and early pupal stages. Additionally, tissue expression profiling revealed that, in the adult, TcOBPC02 was most highly expressed in the head, followed by the epidermis, whereas in larvae, TcOBPC02 was mainly expressed in hemolymph and the epidermis. These developmental stages and tissues that exhibit high TcOBPC02 expression are closely related to the detoxification of heterologous substances. Furthermore, the mRNA level of TcOBPC02 was significantly increased after exposure to eucalyptol, whereas TcOBPC02 -targeted RNA interference increased the susceptibility of T. castaneum to eucalyptol, indicating that TcOBPC02 participates in the tolerance of this beetle to eucalyptol. Additionally, recombinant TcOBPC02 was expressed in Escherichia coli and isolated, enabling a straightforward fluorescence competition binding assay. In combination, these results have demonstrated that TcOBPC02 is required for defenses against phytochemicals in T. castaneum . This study provides a theoretical basis for understanding the mechanisms underlying the degradation of exogenous toxicants in insects and adds to the repertoire of potential target genes for pest control.
Junyu Liang,Xiaohan Zhang,Qian Zhang,Yufei Tang,Weibao Kong,Ji Zhang,Yue An
The main objectives of the present study are to introduce a ecologically safe, and natural compound for controlling the red flour beetle , Tribolium castaneum . This study aims to thoroughly examine the effects of Elsholtzia ciliata essential oil ( E. ciliata EO) and its primary components, carvone , on Tribolium castaneum eggs, larvae, pupae, and adults. The study also includes a simulated warehouse test to assess the efficacy of these substances as contact agents, fumigants , repellents, and antifeedants. All of these anti-insect activities were positively correlated with the concentrations of E. ciliata EO and carvone. Firstly, in the contact activity assay, E. ciliata EO and carvone completely inhibited the hatching of eggs and pupae of the T. castaneum at a concentration of 2.5 μL/cm 2 . The LC 50 of E. ciliata EO and carvone were 7.62 and 4.33 μg/adult, respectively, against senior adults (5 weeks old). Secondly, in the fumigant activity assay, 60 mg/L of E. ciliata EO and carvone essentially completely inhibited pupae eclosion . On the other hand, the LD 50 of E. ciliata EO and carvone against senior adults (5 weeks old) were 8.72 and 5.02 mg/L, respectively. Thirdly, for T. castaneum adults, at the highest test concentration, the repellent rate of the E. ciliata EO was above 90%. Fourthly, the larvae and adults of the T. castaneum could reach complete antifeedant activity by E. ciliata EO and carvone at the highest test concentrations. Finally, 3000 ppm of carvone was sufficient to kill all the pests in the warehouse in the simulated warehouse test. In conclusion, the results of this study will contribute to the better control of the storage pest , T. castaneum , and the development of environmentally friendly insecticides based on E. ciliata EO and carvone.
危险品化学品经营许可证（带存储）