An approach to automatic classification of Culicoides species by learning the wing morphology

PLoS One. 2020 Nov 4;15(11):e0241798. doi: 10.1371/journal.pone.0241798. eCollection 2020.

Abstract

Fast and accurate identification of biting midges is crucial in the study of Culicoides-borne diseases. In this work, we propose a two-stage method for automatically analyzing Culicoides (Diptera: Ceratopogonidae) species. First, an image preprocessing task composed of median and Wiener filters followed by equalization and morphological operations is used to improve the quality of the wing image in order to allow an adequate segmentation of particles of interest. Then, the segmentation of the zones of interest inside the biting midge wing is made using the watershed transform. The proposed method is able to produce optimal feature vectors that help to identify Culicoides species. A database containing wing images of C. obsoletus, C. pusillus, C. foxi, and C. insignis species was used to test its performance. Feature relevance analysis indicated that the mean of hydraulic radius and eccentricity were relevant for the decision boundary between C. obsoletus and C. pusillus species. In contrast, the number of particles and the mean of the hydraulic radius was relevant for deciding between C. foxi and C. insignis species. Meanwhile, for distinguishing among the four species, the number of particles and zones, and the mean of circularity were the most relevant features. The linear discriminant analysis classifier was the best model for the three experimental classification scenarios previously described, achieving averaged areas under the receiver operating characteristic curve of 0.98, 0.90, and 0.96, respectively.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Area Under Curve
  • Automation
  • Bayes Theorem
  • Ceratopogonidae / classification*
  • Databases, Factual
  • Discriminant Analysis
  • Female
  • Image Processing, Computer-Assisted
  • ROC Curve
  • Support Vector Machine
  • Wings, Animal / anatomy & histology*

Grants and funding

DB. Collaboration Grants Program (Grant no. 12476), Universidad San Francisco de Quito (USFQ), https://www.usfq.edu.ec/ DB. Chancellor Grants Program (Grant no. 1114), Universidad San Francisco de Quito (USFQ), https://www.usfq.edu.ec/ Funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.