Abstract:

The migration process of the rice leaffolder, Cnaphalocrocis medinalis (Guenée), is composed of several successive long-distance nocturnal flights. It is the unpredictable re-migration ability that makes the outbreak forecasting of rice leaffolder extremely difficult. So it is important to understand the parameters of the flight behaviour of rice leaffolder for its prediction. In this study, the flight and re-migration capacity of the rice leaffolder moth were examined by tethered flight on a computerized flight mill. The results indicated that there were no significant differences in flight capacity of moths among different ages and sex, and the mean flight duration of males and females were 156.94±103.19 min and 147.71±111.38 min, respectively. Based on the accumulative flight duration (AFD) of the individuals on flight mill, the moths could be divided into three types: the residence type (AFD<40 min), the migratory type (40 min ≤AFD≤130 min) and the strong migratory type (AFD>130 min). The proportions of individuals and mean flight duration of the three types were 46.1% and 11 min, 27.3% and 82 min, and 26.6% and 232 min, respectively. Strong re-migration capacity of C. medinalis had been observed during the experiment. In all of the tested moths, the proportion of the one-off migration was higher than 90%, the twice re-migration above 70%, about half of the moths could fly for 4-5 successive nights, and the maximum re-migration was nine nights. There were no significant effects on re-migration capacity of the moths by foods, but feeding honey could enhance the flight capacity. These results will provide useful behavioral parameters for trajectory analysis and immigration forecasting of the rice leaffolder.

Key words: Cnaphalocrocis medinalis, flight capacity, re-migration capacity, tethered flight, food conditions