The Flight Behavior And Interaction With Reproduction Of The Rice Leaf Roller, Cnaphalocrocis Medinalis (Guenée)

The rice leaf roller, Cnaphalocrocis medinalis (Guenée)(Lepidoptera: Pyralidae) is a seasonal andlong-distant migrant. It is also an economically-important migrant insect. The flight character andthe interrelationship between flight and reproductive of adult C. medinalis were investigated. Theresults we obtained provide practical information toward establishing effective population monitoringand forecasting projects for this species. The results were summarized as follows:(1) The character of flight in the rice leaf roller. Our results indicated that flight capacity ofadult C. medinalis moths in day1were obviously weaker than that on day2. On day4after emergence,flight distance and duration both decreased, but the difference was not significant. And we hypothesizedthat migratory flight of moth for one night was less than12h because flight capacity in18h tetheredgroup was not significantly higher than that in12h group. Different flight frequency experiment showsthat the flight capacity was significantly decreased when experienced4times successive flight test,while that experienced1to3times flight test shows no significant difference. Positive flight monitoringtest revealed that the flight diurnal rhythm and it directly proved that adult rice leaf roller flight duringdark period. The strongest flight willingness time of C. medinalis moth was day1after emergence.(2) Effects of flight on reproduction. The results indicated that preoviposition period weresignificantly shortened when experienced a6h or12h flight on day1or2after emergence. The periodof first oviposition (PFO) was also became significant shorter and lifetime fecundity had no significantdifferences compared to the unflown control. When moths flight less than3times, the lifetime fecundityand oviposition period had no significant differences with the unflown group. The effects of flight onreproduction depended on flight age, flight duration and flight frequency. There were on reproductivecost existed when the moths flight less than12h on day1or2, and flight less than3times from day1after emergenc. Mass number of eggs, shorted preoviposition period, synchronized oviposition triggeredby migratory flight intensifies larval outbreanks of the rice leaf roller.(5) Effects of reproduction on the flight capacity. Results of correlation analysis revealed thatmating, total number of eggs, oviposition days, ovarian grade, age have negative relationship with flightcapacity and dry flight muscle weight, respectively. For example, mating has great influence on flightdistance, flight duration and dry flight muscle weight in female C. medinalis. The flight distance ofmated females was significantly less than that of the unmated on the age of4,5and7. The flightcapacity and dry flight muscle weight were significantly decreased when the number of eggs producedreach to200, but still has relatively great flight capacity. These results indicated that flight capacity wasdecreased with the onset of reproduction, but the onset of reproduction may not mean the end thelong-distance migration.