Simple method for monitoring dispersal of Heliothis (Lepidoptera: Noctuidae) backcross sterility genes

Release of sterile backcross males from [Heliothis subflexa (F.) X H. virescens (Guenée) females X H. virescens males] has been suggested as a means of reducing populations of H. virescens. A simple method is needed to measure the persistence or dispersal of the backcross sterility genetic factors. Backcross male sterility is transmitted via maternal inheritance. The mitochondrial DNA (mtDNA) also is inherited maternally; therefore, the mtDNA in the backcross is from H. subflexa. Several regions of the mtDNA were amplified using polymerase chain reaction (PCR), then were cut with restriction enzymes to generate restriction fragment length polymorphisms (RFLP). Differences between H. virescens and backcross mtDNA were observed for 16S (ribosomal DNA (rDNA)), 12S-16S rDNA, and the COI-COII (cytochrome oxidase) regions. This is attributed to species-specific differences between H. virescens mtDNA and H. subflexa mtDNA carried by the backcross. Therefore, mtDNA provides a convenient marker for tracking the progress of backcross sterility. Developmental stages from eggs through adults are suitable for use.