Developing SCAR Makers And QRT-PCR To Study Predation On Tetranychus Urticae And Frankliniella Occidentalis By Neoseiulus Californicus

Tetranychus urticae and Frankliniella occidentalis are worldwide invasion pest,which have caused tremendous damage on agricultural crops all over the world.Because of their high resistance to insecticide,it is very difficult to control them using insecticides.Therefore,natural enemies such as predatory mites become the significant biological control candidates for them.In the field control experiment,it is not possible to directly study what kind of pests and quantities are preyed on.In this study,SCAR molecular markers and q RT-PCR techniques were used to establish a qualitative detection and quantitative evaluation system for the effects of the Neoseiulus californicus on the predation of Tetranychus urticae and Frankliniella occidentalis.According to the known sequence of Tetranychus urticae in Gen Bank,a pair of specific primer TU220 was designed,and the amplification fragment size was 180 bp.The results showed that the primers had amplification effect only on Tetranychus urticae.according to the known sequence of Frankliniella occidentalis was verified,the amplification fragment size was 434 bp.The results showed that it just had amplification effect on Frankliniella occidentalis.On the basis of multi-copy mitochondrial DNA,fluorescence quantitative PCR detection primers were designed according to the fragment specific to Tetranychus urticae and Frankliniella occidentalis,and plasmid DNA standard curve was used to measure the DNA copy numbers of different ages as 5.77×10~3eggs,27.45×10~3larvae,34.63×10~3nymphs and59.81×10~3of adults,respectively.To determine the relationship between the number of predation and digestion time and the quantitative detection of the predation effect of the predation mite on Tetranychus urticae and the zephyr,the correlation equations of predation were as follows:Y=0.3689X+4.002(R~2=0.9346),and the digestion time:Y=-0.21X+5.983(R~2=0.9713).The correlation of feeding on western flower thrips was Y=0.1827X+6.0405(R~2=0.9477),and the digestion time was Y=-0.0791X+7.2339(R~2=0.9011).In this study,the establishment of a qualitative and quantitative evaluation system for the predatory effect of the Neoseiulus californicus on Tetranychus urticae and the Frankliniella occidentalis provides a theoretical basis for the accurate evaluation of the control effect of the predatory mite on Tetranychus urticae and the Frankliniella occidentalis,which has important guiding significance for the full development and utilization of the natural enemies to control the occurrence and damage of Tetranychus urticae and Frankliniella occidentalis.