Start by preparing a temporary maintenance Petri dish with excised cruciferous leaves and water infiltrated filter paper at the bottom. Next place five aphids on the prepared Petri dish. When the aphids increase in number, cut the originally excised leaves into four to six smaller pieces.
Transfer each small leaf piece with the aphids into separate Petri dishes containing fresh leaves and wet filter paper. To collect the aphid genomic DNA, first homogenize the aphids using a pellet pestle. Next, extract the DNA using a Gene-Spin genomic DNA isolation kit as per the manufacturer's guidelines.
Finish the extraction process by eluting the genomic DNA with 50 microliters of preheated nuclease-free water. Perform PCR amplification and DNA sequencing by adding the DNA sample to the PCR master mix with primer pairs. Analyze the PCR product using 1%agarose gel electrophoresis to confirm the identity of the mustard aphid.
The field collected aphids were confirmed as mustard aphids using molecular markers, including the PCR amplicon size and Lipaphis erysimi CO1 sequencing.
