Determination of Coccinellidae (Coleoptera) species in Siirt pistachio trees using DNA barcoding method

Pistachio (Pistacia vera L.) is a crop of strategic economic and agricultural importance in Türkiye, particularly in the Southeastern Anatolia Region. However, the pest Agonoscena pistaciae causes extensive pesticide use in pistachio orchards, leading to negative consequences for both the environment and human health. Therefore, interest in biological control methods within the framework of integrated pest management has been increasing. Predator species belonging to the family Coccinellidae are among the natural enemies of this pest. In this study, it was aimed to determine the Coccinellidae species collected from pistachio orchards in Siirt Province and its districts during 2023–2024 using morphological and DNA barcoding methods. Sampling was conducted using a Steiner funnel and direct collection methods. The obtained specimens were first identified morphologically, and subsequently subjected to DNA barcoding analyses targeting the COI gene region. Morphological identification revealed a total of 14 species, among which common species such as Coccinella septempunctata, Hippodamia variegata, Adalia bipunctata, and Exochomus quadripustulatus were prominent. Molecular analyses successfully generated DNA sequences for some species, which were found to be consistent with morphological identifications. However, using entire individuals of small-bodied species for DNA isolation sometimes resulted in the amplification of DNA from parasitoids, nematodes, or other microorganisms. This led to failure in species identification or the misidentification of unintended organisms. These findings highlight certain limitations of the DNA barcoding method and demonstrate that morphological identification still plays a crucial role, particularly for rare species. This study not only emphasizes the potential of Coccinellidae species in biological control but also sheds light on the technical challenges that must be considered in molecular analyses.