Heterogeneity In Flight Ability Of The Diamondback Moth Plutella Xylostella(Lepidoptera: Plutellidae)and Its Molecular Mechanisms

The diamondback moth(DBM),Plutella xylostella(Lepidoptera: Plutellidae),is a major pest of cruciferous plants in the world.It is one of the most difficult pests on cruciferous vegetables and oilseeds due to its strong pesticide resistance,serious generation overlapping,rapid development.Many studies found that the DBM can perform long-distance migration.In China,a large number of DBM migrate every year from the south areas,where they can overwinter,to the northern areas,where they cannot survive the cold winter,causing serious damage in northern China.Under the climate warming and the adjustment of crop planting pattern in northern China,damages by the DBM in northern China is increasing.Flight ability of population is the precondition of long-distance spread.In addition,research has showed that some individuals of migration insect will remaining in the original living area while others spreading,which might be caused by the variation of flight ability among individuals.At present,the difference in flight ability among individuals of the DBM and the molecular mechanism of flight ability remains unclear.In this study,the flight ability of different populations of DBM was measured by flight mill,and populations with different flight abilities were selected.The transcriptome sequencing technology and reduced representation genome sequencing technology were used to study the flight ability mechanism of the DBM.The main results are as follows:1.Variation in flight ability in the DBM.Seven DBM populations were collected from three areas of Guangdong,Sichuan,and Beijing.Flight ability of these populations was tested by flight mill.Significant differences in flight ability among those seven populations and among individuals within a population was found.There are significant differences in flight ability among the four populations collected in Huizhou,Guangdong Province,and among the three populations feeding on the same host,cabbage.The results showed that there were significant differences in the flight ability of different populations of DBM.2.Laboratory selection of high and low flight ability populations.High and low flight populations were selected by flight ability test for four generations.The selection process affected the flight ability of the DBM.The flight ability of high flight ability population is always stronger than the low flight ability population during the whole testing.The results showed that the flight ability of the DBM could be inheritable,and the strong selection pressure may lead to population depression.but the selection process might cause population decline.3.Genetic diversity between high and low flight ability populations.Genetic diversity between the high and low flight ability populations was examined by using the dd RAD(double-digest RAD)method to explore the variation of genetic diversity after flight ability selection and the related genes and SNPs.The result showed that the high flight ability population had lower genetic diversity than the low flight ability population.Genes related to flight ability selection are enriched to developmental regulation and neural information processing.4.Differentially expressed genes among high and low flight ability individuals.Male and female individuals with high and low flight ability were selected by flight ability test.Transcriptomes of individuals with high and low flight ability were sequenced and analyzed for function and pathway.The results showed that differentially expressed genes between different flight ability of laboratory and field populations,and male and female are different.In summary,this study found that the flight ability of the DBM varied among individuals and populations.Inheritability of flight ability was found.Genes involved in flight ability regulation were mostly related to developmental regulation and neural information processing.It provides some reference and guidance for the controlling of Plutella xylostella in northern China and the further study of flight behavior mechanism of Plutella xylostella and other insects.