Pheromone-trapping the nun moth, Lymantria monacha (Lepidoptera: Lymantriidae) in Inner Mongolia, China

The nun moth, Lymantria monacha L., is one of the most important defoliators of Eurasian coniferous forests. Outbreaks during 2011-2015 in the natural/planted larch, and larch-birch mixed forests of the Greater Khingan Range in Inner Mongolia, China, caused tremendous timber losses from severe defoliation and tree mortality. A series of trapping experiments were conducted in these outbreak areas to evaluate the efficacy of a synthetic species-specific pheromone lure based on the female pheromone blend of European nun moth populations. Our results clearly show that the nun moth in Inner Mongolia is highly and specifically attracted to this synthetic pheromone, with few gypsy moths (Lymantria dispar) captured. Flight activity monitoring of L. monacha male moths using pheromone-baited Unitraps at 2 locations during the summer of 2015 indicated that the flight period started in mid-July, peaking in early August at both locations. Based on male moth captures, there was a strong diurnal rhythm of flight activity throughout the entire scotophase, peaking between 22:00 and 24:00. Unitraps and wing traps had significantly and surprisingly higher catches than the gypsy moth traps. Unitraps fastened to tree trunks 2 m above ground caught significantly more male moths than those at the ground level or at 5 m height. Male L. monacha moths can be attracted to pheromone-baited traps in open areas 150-200 m distant from the infested forest edge. Our data should allow improvement on the performance of pheromone-baited traps for monitoring or mass-trapping to combat outbreaks of this pest in northeastern China.