A novel optical sensor system for the automatic classification of mosquitoes by genus and sex with high levels of accuracy

Abstract

Background Every year, more than 700,000 people die from vector-borne diseases, mainly transmitted by mosquitoes. Vector surveillance plays a major role in the control of these diseases and requires accurate and rapid taxonomical identification. New approaches to mosquito surveillance include the use of acoustic and optical sensors in combination with machine learning techniques to provide an automatic classification of mosquitoes based on their flight characteristics, including wingbeat frequency. The development and application of these methods could enable the remote monitoring of mosquito populations in the field, which could lead to significant improvements in vector surveillance. Methods A novel optical sensor prototype coupled to a commercial mosquito trap was tested in laboratory conditions for the automatic classification of mosquitoes by genus and sex. Recordings of > 4300 laboratory-reared mosquitoes of Aedes and Culex genera were made using the sensor. The chosen genera include mosquito species that have a major impact on public health in many parts of the world. Five features were extracted from each recording to form balanced datasets and used for the training and evaluation of five different machine learning algorithms to achieve the best model for mosquito classification. Results The best accuracy results achieved using machine learning were: 94.2% for genus classification, 99.4% for sex classification of Aedes, and 100% for sex classification of Culex. The best algorithms and features were deep neural network with spectrogram for genus classification and gradient boosting with Mel Frequency Cepstrum Coefficients among others for sex classification of either genus. Conclusions To our knowledge, this is the first time that a sensor coupled to a standard mosquito suction trap has provided automatic classification of mosquito genus and sex with high accuracy using a large number of unique samples with class balance. This system represents an improvement of the state of the art in mosquito surveillance and encourages future use of the sensor for remote, real-time characterization of mosquito populations. Graphical abstract

Automated differentiation of mixed populations of free-flying female mosquitoes under semi-field conditions

“…To our knowledge, we report findings from the first mixed-species test of a field-ready optoacoustic smart trap design under free-flight conditions. While others have achieved automatic classification of mosquito genera 46 , sex 47 , 48 , or both 49 , none have attempted point-of-capture classification of mixed-species populations of free-flying mosquitoes. The work presented highlights both the challenges and opportunities presented by optoacoustic surveillance.…”

Automated differentiation of mixed populations of free-flying mosquitoes under semi-field conditions

“…To our knowledge, we report ndings from the rst mixed-species test of a eld-ready optoacoustic smart trap design under free-ight conditions. While others have achieved automatic classi cation of mosquito genera 38 , sex 39,40 , or both 41 , none have attempted point-of-capture classi cation of mixed-species populations of free-ying mosquitoes. The work presented highlights both the challenges and opportunities presented by optoacoustic surveillance.…”

“…The study importantly introduces a novel optoacoustic smart trap design that improves the depth of acquired optoacoustic signals (signal length = 86-121 ms) relative to existing designs 41,43 . The success of the tested design is attributed to its above-trap sensor placement that allows for prolonged signal acquisition.…”

Automated detection of the yellow‐legged hornet (Vespa velutina) using an optical sensor with machine learning

“…Wingbeat fundamental frequency is the feature most used in works pertaining to insect species classification using audio recordings 25 , 39 with wingbeat harmonics used to a lesser extent. 55 , 56 In the present work, wingbeat fundamental frequency F1 (Hz) was found to be the most important single‐value feature.…”