Mosquito chronological age determination using mid-infrared spectroscopy and chemometrics

WCU Author/Contributor (non-WCU co-authors, if there are any, appear on document)
Bradley Forrest Guilliams (Creator)
Western Carolina University (WCU )
Web Site:
Scott Huffman

Abstract: Determining a mosquito population’s species composition and age is crucial for estimating the risk of pathogen transmission. At present, age-grading methods are chiefly physiologic and classify the mosquitoes in terms of parity (e.g., nulliparous or parous). Less commonly used chronologic methods (e.g., qPCR or near infrared spectroscopy [NIR]) have limited temporal resolution (NIR) or require consumable reagents and technological expertise with molecular methods. The current lack of robust methods to rapidly evaluate a population’s chronologic age limits our ability to assess pathogen transmission risk in the context of vectorial capacity estimations (i.e., daily survivability). Our current research seeks to develop methods of mosquito age determination utilizing mid-infrared spectroscopy and advanced numerical analysis(chemometrics). Infrared (IR) spectroscopy is a type of vibrational spectroscopy that is both sensitive and information rich. Subtle changes in IR spectra correlate with changes in the biochemistry of mosquitoes as they age. It has been shown that mosquito species can be identified using mid infrared spectroscopy and chemometrics. Using mid-infrared spectroscopy and chemometrics, the chronologic age of Aedes triseriatus mosquitoes were predicted using PLSR and ANN models. Aedes triseriatus were successfully reared into groups of different ages with low uncertainty in the age. Aedes triseriatus spectra were used to create a training dataset and fit models for prediction using PLSR and ANN. PLSR and ANN models were used to predict the age of samples using a validation dataset with SEPsv of 4.3 and 3.3 days respectively. Mean spectra for each age group were used to try and discern a specific chemical underpinning for the performance of these models and to explain why mosquito age could be predicted using PLSR and ANN models. Peaks between 1200 – 1000 cm-1 typically associated with chitin were investigated and the second derivative of mean absorbance by age at 1032 cm-1increased linearly with age.

Additional Information

Language: English
Date: 2020
Chemometrics, Infrared, Mosquito, Spectroscopy
Infrared spectroscopy
Spectrum analysis

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