Wing geometric morphometrics to distinguish and identify Haematobosca flies (Diptera: Muscidae) from Thailand

Abstract

The hematophagous flies of the genus Haematobosca Bezzi, 1907 (Diptera: Muscidae) are important ectoparasites in domestic animals and wildlife. Two species of this genus have been recorded in Thailand, viz., Haematobosca sanguinolenta (Austen, 1909) and Haematobosca aberrans (Pont, Duvallet & Changbunjong, 2020). They have a similar morphology and coexist in the same habitat. The correct species identification of these flies is extremely important for understanding disease epidemiology and developing effective control measures. Geometric morphometrics (GM) has been confirmed to be a useful tool for differentiating and identifying morphologically similar insect species. Therefore, GM was used to distinguish and identify H. sanguinolenta and H. aberrans in Thailand. Adult flies of both sexes were collected using Nzi traps, morphologically identified, and analyzed by landmark-based GM of the wing. Results showed that GM was highly effective in distinguishing the two Haematobosca species based on their wing shape, with an overall accuracy score of 99.3%. We also revealed that our study material could be used as reference data to identify new field specimens collected from other geographic locations. We propose that wing GM can be used as a supplement to conventional morphology identification, particularly for Haematobosca specimen that has been damaged or has lost its diagnostic characteristics due to specimen collection and processing in the field.

Keywords: Haematobosca aberrans; Haematobosca sanguinolenta; Landmark; Morphometry; Stomoxyinae; Vector.

Graphical abstract

Fig. 1

Heads in the lateral view and the pleura of Haematobosca sanguinolenta (A, B) and H. aberrans (C, D). The anterior and posterior katepisternal setae (arrow) were used to distinguish between both species. Photographs were prepared by the authors.

Fig. 2

The topographic map of the Haematobosca fly collection sites in Thailand: Chiang Mai (1), Kanchanaburi (2), and Nakhon Ratchasima (3) (A). The Nzi trap used for fly collection was placed near animal hosts at each collection site (B, C). This map was prepared from the United States Geological Survey (USGS) National Map Viewer available at http://viewer.nationalmap.gov/viewer/, accessed on February 10, 2023.

Fig. 3

The 10 landmarks on the wing of Haematobosca flies used in the wing geometric morphometric analysis.

Fig. 4

The boxplot of the centroid size variations in male and female Haematobosca sanguinolenta and H. aberrans. The median dividing the 25th and 75th quartiles is represented by the horizontal line crossing each box.

Fig. 5

Mean shape of male (A) and female (B) Haematobosca sanguinolenta and H. aberrans after Procrustes superimposition.

Fig. 6

Factor map of the first two principal components (PC1, 47% as horizontal axis and PC2, 33% as vertical axis) of wing shape variables (A) and factor map of the first two discriminant factors (DF1, 66.8% as horizontal axis and DF2, 31.8% as vertical axis, the two discriminant factors represent 98.6% of the total discriminant space) of wing shape variables (B). Each point represents the individuals of male and female Haematobosca sanguinolenta and H. aberrans, and each polygon corresponds to a different species and sex. Squares represent the mean values in each group.

Fig. 7

Hierarchical agglomerative clustering tree based on shape similarities of each individual for male and female Haematobosca sanguinolenta and H. aberrans. Euclidean distances were used for the construction of the tree.

Fig. 8

Linear regression between centroid size and the first shape-based principal component (PC) of Haematobosca sanguinolenta (A) and H. aberrans (B). Linear regression prediction is shown by the orange dots. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 9

Factor map of the principal components (PC1, 46% as horizontal axis and PC2, 22% as vertical axis) from wing shape variables of test specimens (male and female) and reference data of Haematobosca sanguinolenta and H. aberrans. Squares represent mean values in each group.

Fig. 10

Hierarchical agglomerative clustering tree based on shape similarities of test specimens (male as yellow and female as gray) and reference data of Haematobosca sanguinolenta and H. aberrans. Euclidean distances were used for the construction of the tree. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)