Identification of attractants from plant essential oils for Cyrtorhinus lividipennis , an important predator of rice planthoppers

The brown planthopper (BPH), Nilaparvata lugens , is a serious insect pest in rice cultivation, while Cyrtorhinus lividipennis, its main predator, feeds on BPH eggs and nymphs. The artificial release of C. lividipennis could significantly suppress the increase in BPH and prevent hopper burn in the open field. How to attract the artificially released C. lividipennis to the precise location of the target rice field is key for successful biological control. However, there have been few reports related to C. lividipennis . In the current study, we identified two attractant compounds for C. lividipennis from plant essential oils. Using olfactometer assays, we found that Coriandrum sativum and Nerium indicum essential oils were highly attractant to both adults and nymphs of C. lividipennis . The petroleum ether fractions of C. sativum , N. indicum , and Alpinia officinarum essential oils were analyzed with GC-MS. According to previous reports and the results of the GC-MS analysis, we selected ten compounds to screen their attractancy to C. lividipennis . After the olfactometer assays, we identified isocaryophyllene and trans-2-dodecenol, which were the most effective attractants to C. lividipennis under laboratory conditions. Our experiments under greenhouse and field conditions showed that isocaryophyllene and trans-2-dodecenol presented significant attractancy to C. lividipennis . These results highlight the potential of isocaryophyllene and trans-2-dodecenol as effective attractants to aid C. lividipennis in locating target rice fields during their artificial release. Further studies are required to develop a formulation that would increase efficacy with lower costs.