[Corythucha marmorata affects growth and quality of Artemisia argyi].

This study aims to investigate the impact of the invasive pest Corythucha marmorata on the growth and quality of Artemi-sia argyi. The signs of insect damage at the cultivation base of A. argyi in Huanggang, Hubei were observed. The pests were identified based on morphological and molecular evidence. The pest occurrence pattern and damage mechanism were investigated. Electron microscopy, gas chromatography-mass spectrometry(GC-MS), and high performance liquid chromatography(HPLC) were employed to analyze the microstructure, volatile oils, and flavonoid content of the pest-infested leaves. C. marmorata can cause destructive damage to A. argyi. Small decoloring spots appeared on the leaf surface at the initial stage of infestation. As the damage progressed, the spots spread along the leaf veins and aggregated into patches, causing yellowish leaves and even brownish yellow in the severely affected areas. The insect frequently appeared in summer because it thrives in hot dry conditions. After occurrence on the leaves, microscopic examination revealed that the front of the leaves gradually developed decoloring spots, with black oily stains formed by the black excrement attaching to the glandular hairs. The leaf flesh was also severely damaged, and the non-glandular hairs were broken, disor-ganized, and sticky. The content of neochlorogenic acid, cryptochlorogenic acid, isochlorogenic acids A and B, hispidulin, jaceosidin, and eupatilin at the early stage of infestation was significantly higher than that at the middle stage, and the content decreased at the last stage of infestation. The content of eucalyptol, borneol, terpinyl, and caryophyllin decreased in the moderately damaged leaves and increased in the severely damaged leaves. C. marmorata was discovered for the first time on A. argyi leaves in this study, and its prevention and control deserves special attention. The germplasm materials resistant to this pest can be used to breed C. marmorata-resis-tant A. argyi varieties.

Parallel environmental factors drive variation in insect density and plant resistance in the native and invaded ranges.

Geographic variation in the traits of a species is shaped by variation in abiotic conditions, biotic interactions, and evolutionary history of its interactions with other species. We studied the geographic variation in the density of the lace bug, Corythucha marmorata, and the resistance of tall goldenrod Solidago altissima to the lace bug herbivory in their native range in the United States and invaded range in Japan. We conducted field surveys and reciprocal transplant experiments to examine what abiotic and biotic factors influence variation in lace bug density, and what ecological and evolutionary factors predict the resistance of the host plant between and within the native and invaded ranges. Lace bug density was higher throughout the invaded range than in the native range, higher in populations with warmer climates, and negatively affected by foliage damage by other insects in both ranges. The higher lace bug density in warmer climates was explained by the shorter developmental time of the lace bugs at higher temperatures. The resistance of S. altissima to lace bugs was higher in populations with lace bugs compared to populations without lace bugs in both native and invaded ranges, indicating that the evolutionary history of the interaction with the lace bugs was responsible for the variation in S. altissima resistance in both ranges. The present study revealed that abiotic and biotic factors, including temperature and other herbivorous insects, can drive the geographic variation in lace bug density, which in turn selects for variation in plant resistance in both in the native and invaded ranges. We conclude that the novel combination of factors such as higher temperature and lower number of other herbivorous insects is responsible for the higher lace bug density in the invaded range than in the native range.

[Life table and biological characteristics of an exotic lace bug, Corythucha marmorata (Uhler).] / å¤–æ¥å ¥ä¾µèŠæ–¹ç¿ ç½‘è½ç”Ÿç‰©å­¦ç‰¹æ€§åŠå®žéªŒç§ç¾¤ç”Ÿå‘½è¡¨.

The lace bug, Corythucha marmorata (Uhler) is a newly introduced species in China. The biological characteristics, such as the life table, fecundity, population dynamics were studied under laboratory conditions, i.e., temperature (25±2) ℃, humidity (80±5) %, photoperiod L:D=14:10. The lace bugs were reared on the host plant Solidago canadensis. The morphological characteristics at different life stages, the longevity and adult fecundity were recorded and used to construct the life table. Results showed that the average length of immature stages was (14.88±1.45) d and the adult average life-span was (59.88±5.85) d, and the progeny per female was (87.2±17.8). The intrinsic rate of increase of C. marmorata (rm) was 0.05 per female per day, the finite rate of increase (d) was 1.06, and the net reproductive rate (R0) was 11.88. The mean generation time (T) was 46.11 d, and the double population time was (t) 12.91 d. The population on reaching a stable age distribution comprised approximately 59.3% of immature stages, and 40.7% of the adult stage. It was suggested that C. marmorata might disperse quickly and pose a potential threat to agricultural production.