Geometric morphometric wing analysis as a tool to discriminate female mosquitoes from different suburban areas of Chiang Mai province, Thailand

Abstract

Mosquitoes are hematophagous insects that transmit parasites and pathogens with devastating effects on humans, particularly in subtropical regions. Different mosquito species display various behaviors, breeding sites, and geographic distribution; however, they can be difficult to distinguish in the field due to morphological similarities between species and damage caused during trapping and transportation. Vector control methods for controlling mosquito-borne disease epidemics require an understanding of which vector species are present in the area as well as the epidemiological patterns of disease transmission. Although molecular techniques can accurately distinguish between mosquito species, they are costly and laborious, making them unsuitable for extensive use in the field. Thus, alternative techniques are required. Geometric morphometrics (GM) is a rapid and inexpensive technique that can be used to analyze the size, shape, and shape variation of individuals based on a range of traits. Here, we used GM to analyze the wings of 1,040 female mosquitoes from 12 different species in Thailand. The right wing of each specimen was removed, imaged microscopically, and digitized using 17 landmarks. Wing shape variation among genera and species was analyzed using canonical variate analysis (CVA), while discriminant function analysis was used to cross-validate classification reliability based on Mahalanobis distances. Phenetic relationships were constructed to illustrate the discrimination patterns for genera and species. CVA of the morphological variation among Aedes, Anopheles, Armigeres, Culex, and Mansonia mosquito genera revealed five clusters. In particular, we demonstrated a high percentage of correctly-distinguished samples among Aedes (97.48%), Armigeres (96.15%), Culex (90.07%), and Mansonia (91.67%), but not Anopheles (64.54%). Together, these findings suggest that wing landmark-based GM analysis is an efficient method for identifying mosquito species, particularly among the Aedes, Armigeres, Culex, and Mansonia genera.

Fig 1. Map of Thailand showing the collection sites of adult mosquitoes used for wing morphometric analysis.

Mosquitoes were collected from three subdistricts (Maehia, Sri Phum, and Sunpesua) in the Muang district of Chiang Mai province, northern Thailand.

Fig 2. Representative image of wing landmark pattern.

Right wing of female Ae. aegypti showing the 17 plotted landmarks based on Dujardin et al. (2017).

Fig 3. Scatter plot showing wing shape variation among five mosquito genera.

Wing shape variation in Aedes, Anopheles, Armigeres, Culex, and Mansonia mosquitoes is shown along the first two canonical variate (CV1 and CV2) axes with 90% confidence ellipses.

Fig 4. Scatter plot showing wing shape variation among 12 mosquito species.

Wing shape variation is shown along the first CV1 and CV2 axes with 90% confidence ellipses.

Fig 5. Neighbor-Joining tree showing phenetic wing morphology relationships among mosquito species.

The tree was constructed based on the Mahalanobis distances between species.