An experimental analysis on the autumn activity of the new generation of Haemaphysalis longicornis nymphs (Acari: Ixodidae) : The autumn activities of the nymphs that developed outdoors in August and September

In order to clarify the existence of the autumn activity of the new generation of Haemaphysalis longicornis nymphs on floor vegetation, the seasonal activities of the nymphs, which developed outdoors in August 1999 and September 2004, were observed for a period of one year in plastic cylinders which were placed outdoors. The nymphs that developed in August 1999 showed high activity until August 2000 when they were introduced to the plastic cylinders (August 26), although activity was scarcely observed from December to March. After introduction on September 28, the activity of the nymphs that developed in September 2004 was barely observed until mid March 2005. However, the activity abruptly began in late March, and showed high activity from April to September. These results suggest that the new generation nymphs of H. longicornis that developed in summer are found on floor vegetation in the autumn, but the nymphs that developed in autumn are not. The inactivity of the new generation of the nymphs in the autumn appears to be due to behavioral diapause induced by the short days.