Study On The Migratory Behaviour Of Protoschinia Scutosa Denis & Schiffermüller (Lepidoptera:Noctuidae) Across The Bohai Strait

Migration is a “preemptive enemy” survival strategy evolved from long-term adaptation to habitat changes which usually leads to burstiness,regional and catastrophic outbreaks of crop pest and aggravates the difficulty of pest monitoring and also threatens food security.The spotted clover moth,SCM,Protoschinia scutosa(Lepidoptera: Noctuidae),is an important polyphagous pest of soybean(Glycine max),alfalfa(Medicago sativa),quinoa(Chenopodium quinoa Willd)and other economic crops.Whether it has migration habits or not has no scientific basis.Huang-Huai-Hai Plain and the Northeast Plain are important agricultural areas of staple crops,such as wheat,corn,and soybeans in China,and also the main distribution area of P.scutosa.Bohai Strait is not only the link between the two major agricultural areas,but also the migration route for many migratory insects.This study relied on the geographical advantages of the Changdao experiments station of IPP,CAAS to systematically monitor the migration behavior of P.scutosa from 2003 to 2015,and the main results are as follows:1)The flight-mill experiment showed that the P.scutosa has the potential to take a long distance migration.The average flight speed,flight duration and flight distance of 3days old moth was 3.57±0.07km/h,8.6±0.41 h,30.15±1.58 km respectively.There was a parabolic trend between flying ability and adult age,with the strongest flight ability at 3-4 days,and there was no significant difference between genders.The mating behavior significantly reduced the average flight speed and flight distance of SCM and had no significant difference on flight duration and maximum flight speed.2)Nutrient Supplement can significantly increase fertility and flight capacity of migrant populations,and SCM in backward period has the strongest ability of flight.Supplementation of 10% honey not only significantly increased flight speed,flight duration,and cumulative flight distance,but also significantly increased the amount of egg production and hatching,promoted females’ ovarian development and mating activities,shortened pre-oviposition period,oviposition period,extended egg laying duration and adult longevity.Feeding water also contributes to the improvement of flight ability and reproductive ability.There are significant differences in flight ability of SCM between different migration periods.Among them,in terms of flight speed,flight duration and accumulated flight distance,the north-forward period > transitional period > backward period.3)Migration scale of P.scutosa showed significant difference between years,and the female ratio was significantly higher than male,and ovarian development of females showed a significant downward trend with seasons.The largest migration occurred in 2009 with 1767 catches;the rare migration occurred in 2004 with a total catches of 127 individuals.The first capture of SCM in a year generally occurred in mid-May and the last was in late-September with the average migrant duration was 121.6±7.8 days.The first peak of migration was generally occurred from mid-May to mid-June,and the larger migratory insect peaks appear in mid-August.The percentage of female moths in the migratory population was 65.5±2.5%,which was significantly higher than that of males.There was no significant difference in the sex ratio of the migration population between the year and the month.The reproductive characteristics of female moths showed an obvious seasonal change.From May to October,the developmental level,mating rate,sexual maturation rate and mating frequency of SCM females showed a significant downward trend.In the spring and summer,the ovarian development level of SCM female was above level 3;the mating rate was above 60%,and the sexual maturation rate was about 70%.While mating and sexual maturation rates both were about 10% in the fall.P.scutosa migratory behavior is not inhibited by ovarian development,and this species does not exhibit an “oogenesis-flight syndrome” hypothesis.The seasonal changes of reproduction characteristics suggested that the relationship between migration and reproduction of P.scutosa is regulated by seasonal factors.In this study,the flight potential of SCM was studied,the relationship between nutrition and flight capacity and fertility was explored,and the interannual and seasonal dynamics of migration populations were analyzed,the results of this study provide a theoretical basis for monitoring,early warning and forecasting of P.scutosa.