Study of the possibility of differentiating species of the Bactrocera tryoni complex based on regions of the mitochondrial genes COI and 16S

The Queensland fruit fly Bactrocera (Bactrocera) tryoni (Froggatt, 1897) is a member of the Tephritidae family and is a serious pest of a wide range of fruit and vegetable crops in Australia.
The object of this study, Bactrocera tryoni, belongs to the complex of B. tryoni species, which, in addition to it, includes the species Bactrocera aquilonis (May, 1965), Bactrocera neohumeralis (Hardy, 1951), and Bactrocera melas (Perkins & May, 1949). Since these species are morphologically very similar and some may infect similar products, there is a need for molecular genetic diagnostic methods that will reliably distinguish these species from other species and among themselves.
According to the obtained data on the COI gene generally in the sample matrix, there is a hiatus - a gap between intra- and interspecific distances. However, the species B. tryoni, B. aquilonis, and B. neohumeralis on the dendrogram form clades corresponding to the same species, therefore, it is impossible to distinguish them using the sequences of the COI gene region. However, based on this sequence, it is possible to narrow down the identification by molecular genetic methods to these three species, since they are well separated from other studied species.
According to the graph of the distribution of pairwise genetic distances for the 16S gene, there is a lower variability than for the COI gene. On the dendrogram, the species B. tryoni, B. aquilonis, and B. neohumeralis form the one clade, but other species formed separate clades. It is necessary to increase the number of 16S gene sequences in the sample for each species.
Thus, based on the COI gene sequence, it is possible to separate the species B. tryoni, B. aquilonis, and B. neohumeralis from other species of the genus Bactrocera studied by us. To study the relationships within the complex of B. tryoni species and search for a gene sequence by which it will be possible to reliably differentiate the B. tryoni species, another, possibly more rapidly evolving gene is required.