The Research Of Development,Reproductive And Flight Activity Among Three Kinds Of Sibling Species Of Armyworm

Mythimna separata(Walker),Mythimna loreyi(Duponchel)and Mythimna roseilinea(Walker)were all wordwide pest.They have occurred around the year and caused huge economic loss to agricultural production in China.The morphology of larva and pupa were similar illegible bring great difficulties to our work of prediction.Therefore,understanding the biological characteristic of three kinds of armyworm is necessary to strengthen the population projection of armyworm.In addition,with the world's climate change and the change of planting structure in our country,understand the influence of temperature and host plant to population dynamics can provide the basis for the various armyworm control pollution.This research adopts the age-stage two sex life table technique to analyze the population growth and population projection of three armyworms under different temperatures and clarified the differences among armyworms in developmental duration and life table parameters: the longest immature stage and the lowest life table parameters are M.roseilinea;developmental duration was negatively related to the temperature,with the temperature increased the developmental duration decreased,both the intrinsic rate of increase(r)and finite rate increase(?)increased as temperature significantly increased,and mean generation time(T)decreased significantly with increasing temperature;the highest values for net reproductive rate(R0)of M.loreyi and M.separata was observed at 24°C,while net reproductive rate(R0)of M.roseilinea was observed at 21 and 24?,and the R0 of M..roseilinea was lowest among three kinds of armyworm.The M.separata effective accumulated temperaturs of one generation was largest and the lowest was M.roseilinea.The population projection at different temperatures showed the size of population growth was observed at 24?.The flight mill was adopted to test the flight capacity and difference of three kinds of armyworm: M.separata had the strongest flight capacity while M.roseilinea had the weakest flight capacity;moth age had significantly influence on flight capacity,M.separata had the strongest flight capacity in 4-old-days,M.roseilinea and M.loreyi had the strongest flight capacity in 3-old-days;rearing temperature also had significantly influence on flight capacity,the flight capacity of M.separata increased as temperature significantly increased,the flight capacity of M.loreyi was strongest at 24?,other temperattures were no difference,the flight capacity of M.roseilinea increased as temperature significantly increased at 27? then significantly decreased,between 18? and 30?.The results of free flight clarified the flight rhythm of armyworms and verified tethered flight.1-day-old and 6-day-old had poor flight activity.The flight activity of M.loreyi and M.roseilinea gradually improved after 24:00 am,while the flight activity of M.separata was stronger during dark period.The strongest flight activity was observed at 3:00-5:00 am.We tested and analyzed the cooling capacity of three kinds of armyworm: the supercooling point was lowest at pupal stage,which was optimum overwintering statge;the supercooling point of M.separata was no difference in larval and pupal;the super cooling point was no difference between M.separata and M.roseilinea but lower than M.loreyi,however the pupa survival rate of M.loreyi was highest at low temperature;the rearing temperature had significantly influence on cold resistance ability,high and low temperature can make the supercooling point of M.loreyi and M.roseilinea decrease while only low temperature can make the supercooling point of M.separata decrease.The pupa weight and sex were no difference in cold resistance ability.We explained the parental effects of host plant on growth and development,flight and frost resistance: different host plant in parental and offspring were significantly difference in immature stage of M.separata,the larval stage that parental and offspring with wheat as host plant was longer than that with maize as host plant,while the pupa stage was shorter;the host plant of parental and offspring interchangeable can increase pupal weight and decrease supercooling point;the supercooling point that parental and offspring with maize as host plant was significantly lower than that with wheat as host plant;the flight capacity that parental and offspring with maize as host plant was significantly stronger than that with wheat as host plant;however,the different host plants(maiz and wheat)were no difference in reproduction and longevity of parental and offspring adults.