Abstract
Developmental zeros and effective heat units of Eysarcoris aeneus (Scopoli) were calculated from its developmental periods at different constant temperatures. The developmental zeros were 13.7°C in the egg, 10.2°C in the egg and nymph, and 17.0°C during the preoviposition period. The effective heat units were 66.7 day-degrees in the egg, 500.0 day-degrees in the egg and nymph, and 73.5 day-degrees in the preoviposition period. The number of annual generations of E. aeneus was estimated based on these data and the meteorological data for 20 years recorded by an AMeDAS system with six observation points in Ishikawa Prefecture. The number of annual generations was estimated to be two or three, differing between years or areas. Analysis of overwintered adult density surveyed in 50 grassland fields for nine years showed a significant positive correlation (r=0.81) between the annual effective heat unit for E. aeneus in each year and the overwintered adult density in the following year.
