Development of Species-Specific Markers and Molecular Differences in Mitochondrial and Nuclear Dna Sequences of Aphis Gossypii and Myzus Persicae (Hemiptera: Aphididae)

Aphids are one of the major challenges in the agricultural pest management programmes. A reliable, quick, accurate and life stage-independent method of identification of vectors such as Aphis gossypii Glover and Myzus persicae (Sulzer) is important with respect to virus transmission, insecticide resistance and biological control. The complex life cycles, significant polymorphism, immature taxonomy and absence of trained manpower make the identification of these pests difficult. On the other hand, molecular identification is not limited by the above factors and can be easily executed by a non-specialist with a little training. Since the mitochondrial cytochrome oxidase-1 (COI) exhibits maternal inherited characteristics and reliable inter-specific variation as compared to other molecular markers, species-specific markers have been developed using existing nucleotide differences in the COI partial sequences of both A. gossypii and M. persicae. These species-specific markers have proved to be adequate for the molecular identification of these species, and to corroborate their morphological identification. Molecular diversity analyses using both mitochondrial and nuclear markers showed that neither A. gossypii nor M. persicae has as much genetic variability as expected. An outcome of this investigation is the development of a technique that is useful for the quick identification of A. gossypii and M. persicae, a critical factor in understanding the epidemiology and management of the potyviruses, and also in facilitating quarantines of these 2 pests.