Annual Variability of Wing Morphology in Culex sitiens Wiedemann (Diptera, Culicidae) Mosquito Vectors fromthe Coastal Area of Samut Songkhram Province, Thailand

摘要

Culex sitiens Wiedemann (Diptera, Culicidae) is a mosquito vector that is found in coastal areas. Effective control of mosquitoesrequires knowledge of the biology, ecology, and behavior of the vector as well as of various other aspects, including its morphology.Currently, variations in the wing size and shape of coastal Cx. sitiens have not been described. Here, morphological changes werestudied in the wings of Cx. sitiens from a coastal area of Samut Songkhram Province, Thailand. Samples were collected at night(6:00 pm–6:00 am) during single weeks of September in the years 2015–2017 using Center for Disease Control light traps withdry ice as bait. Eighteen landmarks of each individual were selected and digitized for landmark-based geometric morphometricanalyses. Wing size variability was estimated using the isometric estimator of centroid size. Wing-shape variables were computedas Procrustes superimposition with residual coordinates of the 18 landmarks following a Generalized Procrustes Analysis andthe principal components of residual coordinates. Degrees of wing-shape dissimilarity among individuals were analyzed usingdiscriminant analysis or canonical variate analysis, which was illustrated in a discriminant space of canonical variables. Differencesin wing size and shape among populations were calculated using nonparametric permutations based on 1000 runs with Bonferronicorrection tests at a p-value of <0.05.The wing sizes and shapes of the mosquitoes differed significantly between observation yearsin all population groups, as indicated by nonparametric tests (1000 runs) with the Bonferroni correction. Differing rainfall betweenobservation years was related to morphological changes inmosquito populations, presumably reflecting environmental adaptation.Differences in the wing morphology of Cx. sitiens between annual populations reflect adaptation to environmental variables suchas rainfall and may affect the potential to act as insect vectors of human disease.These observations may facilitate the developmentof tools for managing mosquito-borne disease.