Comigration of the predatory bug Cyrtorhinus lividipennis (Hemiptera: Miridae) with two species of rice planthopper across the South China Sea

The mirid insect Cyrtorhinus lividipennis Reuter (Hemiptera: Miridae) is an economically and ecologically important enemy of insect pests of rice. Its comigration with its prey, two species of rice planthopper (RPH), is widely recognized, but has not been well characterized, especially in its year-round breeding region in Southeast Asia. In a 4-year trapping study of C. lividipennis and two types of RPH (Sogatella furcifera and Nilaparvata lugens) on an isolated island in the South China Sea, we obtained direct evidence that the mirid and its host RPHs were migrants and regularly comigrated across the sea from March to October every year; the peak period for the three species was from the late July to late August. Biomass of the mirid was significantly positively correlated with that of the two species of RPH in all migration periods. Moreover, the percentage of migrants was strongly female biased, and examination of ovaries indicated that almost all trapped females were virgins with little or no ovarian development, suggesting that most females that began the migration were sexually immature. Simulations of possible migration trajectories demonstrated that the three species mainly migrated between Indochina Penin-sula and China (or the Philippines) in both directions. Collectively, these findings improve our understanding of the occurrence of the mirid and RPH across Southeast Asia and of the comigration of natural predators with their prey insects and will aid in developing more effective management strategies against RPH.