Influences of rearing temperature on flight and reproductive capacity of adult oriental armyworm, Mythimna separata (Walker)

The variation of flight and reproductive capacity of adult oriental armyworm, Mythimna separata (Walker)(OAW)reared at the constant temperature of 24,27,30,and 33℃ from egg to adult stage were investigated in the laboratory.The flight capacity,based on 20\|hours tethered\|flight test of the unfed newly emerged moths from the rearing temperatures,was the highest at 27℃.Flight distance and duration in average for the female and male were 31.1 km and 7.9h,30.9km and 7.7h,respectively.Proportions of the adults flying beyond 30km and 9h during the test period accounted for 42.4% and 39.4% of the total.Flight capacity in the moth rearing at 24℃ ranged second,then followed by that at 30℃ and 33℃.Reproductive capacity was also significantly affected by the temperature.Preoviposition period of the female from 27℃ was significantly shorter than that of the other treatments,even though it was insignificantly different in the remain treatments.Fecundity,mating rate and longevity of the adults were declined as the temperature increased from 24℃ to 33℃.Furthermore,all the adults rearing at 33℃ were not able to mate.Results obtained from this study presumably suggest that reproductive system is more sensitive than the flight system to the influences of high temperature and the 24℃ is suitable for the development of both reproduction and flight system in the OAW.The reproductive but not the flight system may be impaired by the temperature of 27℃.Reasons for the high flight capacity of the adults at 27℃ may be they want to escape from the harmful effect of this temperature on reproduction or their flight system develops faster.The significant decline of both flight and reproductive capacity at the temperature of 30 and 33℃ are resulted in the injured flight and reproductive systems.It is,therefore concluded that escape from the harmful effects of high temperature is one of the major reasons for the OAW migrate from south to north in spring.