Abstract: Intensive research of the influences of environmental temperature variation on flight and locomotory searching abilities of Harmonia axyridis would be significant for its application in biological control. Three constant temperature conditions (15, 25 and 35℃), and two temperature variations (i.e. continuously linear temperature variation from 15℃ to 35℃ and continuously jumping alternation temperature variation among 15℃-25℃-35℃) were set up as different treatments. We utilized flight mill and insect behavior recording device to evaluate the behavior responses of H. axyridis in flight and searching to the treatments. The flight frequency (14.2±1.9), total flight distance (1089.6±112.3) m, accumulative flight duration (98.3±11.6) min and average flight speed (11.2±1.1) m/min of H. axyridis at 15℃ were significantly higher than those at other constant temperatures, respectively. While the walking frequency (26.1±2.1), total walking distance (719.6±73.2) cm, average walking speed (2.6±0.7) cm/s and direction change frequency (101.3±11.2) of H. axyridis at 35℃ were all higher than those at other temperatures. H. axyridis showed significantly higher flight and searching ability under the treatment of continuously jumping alternation temperature variation, than the treatments of continuously linear temperature variation and constant temperature (25℃). Our results demonstrate that H. axyridis tend to flight more at lower temperature and show superb walking/searching ability at higher temperature. Furthermore, high disturbing temperatures may stimulate H. axyridis to higher flight/walking abilities.

Key words: Harmonia axyridis, flight behavior, searching behavior, flight mill, continuous temperature variation