The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), is an important agricultural pest with a strong migratory ability.  While the species is native to the Americas, it has recently invaded China, ravaging crops in many provinces (autonomous regions, municipalities).  Its long-distance migration, which is critical to understand for pest management programs, has been well studied in its native region.  In other regions however, the moth’s migration patterns have not yet been characterized.  Here, the migratory behavior of FAW populations in China was studied on an isolated island located in the center of the Bohai Strait from spring to autumn 2019, the year in which FAW first reached this region, by using searchlight trapping, stable carbon isotopes and trajectory simulation.  The main results were summarized as follows: (i) The number of FAW moths caught by searchlight trapping provided direct evidence that the species migrated across the Bohai Sea.  (ii) Species identification was confirmed by both morphology and molecular methods, and only the “corn-strain” that preferentially infests maize and sorghum was found in the collections.  (iii) Stable carbon isotope measurements showed that up to 95.07% of captured moths displayed the C4 isotope signature, thus providing additional evidence that this species is a migrant as there are no major C4 plants at the trapping site.  (iv) Backward trajectory analysis indicated that the pest now threatens to expand its range into the agriculturally important region of Northeast China, and thus authorities in this region should be vigilant to the threat posed by this species.  Together, these findings add to our knowledge concerning the occurrence of FAW in northern China, and will help us to develop sustainable and effective monitoring, forecasting, and pest management strategies.

It is predicted that the current atmospheric CO2 concentration will be doubled and global mean temperature will increase by 1.5-6°C by the end of this century. Although a number of studies have addressed the separate effects of CO2 and temperature on plant-insect interactions, few have concerned with their combined impacts. In the current study, a factorial experiment was carried out to examine the effect of a doubling CO2 concentration and a 3°C temperature increase on a complete generation of the brown planthopper (Nilaparvata lugens) on rice (Oryza sativa). Both elevated CO2 and temperature increased rice stem height and biomass of stem parts. Leaf chlorophyll content increased under elevated CO2, but only in ambient temperature treatment. Water content of stem parts was reduced under elevated temperature, but only when coupled with elevated CO2. Elevated CO2 alone increased biomass of root and elevated temperature alone enhanced leaf area and reduced ratio of root to stem parts. Brown planthopper (BPH) nymphal development was accelerated, and weight of and honeydew excretion by the F1 adults was reduced under elevated temperature only. Longevity of brachypterous females was affected by a significant interaction between CO2 and temperature. At elevated temperature, CO2 had no effect on female longevity, but at ambient temperature, the females lived shorter under elevated CO2. Female fecundity was higher at elevated than at ambient temperature and higher at elevated CO2 than at ambient CO2. These results indicate that the combined effects of elevated temperature and CO2 may enhance the brown planthopper population size.