Species Discrimination of Stomoxys Flies S. bengalensis, S. calcitrans, and S. sitiens (Diptera: Muscidae) Using Wing Geometric Morphometrics

SIMPLE SUMMARY: Stomoxys flies (Diptera: Muscidae) are bloodsucking insects that feed on both animals and humans. They are a major vector of a variety of animal pathogens, including agents of trypanosomosis, anaplasmosis, bovine leucosis, African horse sickness, lumpy skin disease, etc. This study investigated the effectiveness of landmark-based geometric morphometrics of wings to discriminate among three morphologically similar species of Stomoxys in Thailand: Stomoxys bengalensis, Stomoxys calcitrans, and Stomoxys sitiens. Our study reveals that geometric morphometrics can accurately discriminate the three species of Stomoxys based on wing shape. Therefore, wing geometric morphometrics can be used in addition to traditional morphological methods to identify these flies as species. ABSTRACT: The flies of the genus Stomoxys Geoffroy, 1762 (Diptera: Muscidae), are regarded as pests of veterinary and medical importance. In Thailand, Stomoxys calcitrans (Linnaeus, 1758) is the most abundant species and is widely distributed throughout the country. This Stomoxys species can coexist with two other morphologically similar species: Stomoxys bengalensis Picard, 1908, and Stomoxys sitiens Rondani, 1873. Hence, discriminating using morphological characteristics is difficult, especially if the specimen is damaged or loses its diagnostic characteristics. In this study, we evaluated the effectiveness of the landmark-based geometric morphometric (GM) approach to discriminate among the three Stomoxys spp.: S. bengalensis, S. calcitrans, and S. sitiens. Left-wing images of S. bengalensis (n = 120), S. calcitrans (n = 150), and S. sitiens (n = 155) were used for the GM analyses. The results of the wing shape analyses revealed that the GM approach was highly effective for discriminating three Stomoxys, with high accuracy scores ranging from 93.75% to 100%. This study adds to the evidence that landmark-based GM is an excellent alternative approach for discriminating Stomoxys species.