First report on the application of the near-infrared spectroscopy to predict the age of Aedes albopictus Skuse

Authors: SIKULU-LORD, MAGGY - Queensland Institute Of Medical Research; DEVINE, GREGOR - Queensland Institute Of Medical Research; HUGO, LEON - Queensland Institute Of Medical Research; Dowell, Floyd

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/12/2018
Publication Date: 6/25/2018
Citation: Sikulu-Lord, M.T., Devine, G.J., Hugo, L.E., Dowell, F.E. 2018. First report on the application of the near-infrared spectroscopy to predict the age of Aedes albopictus Skuse. Scientific Reports. 8:9590. doi: 10.1038/s41598-018-27998-7.
DOI: https://doi.org/10.1038/s41598-018-27998-7

Interpretive Summary: Characterising the age of Aedes albopictus particularly in newly invaded regions is a crucial determinant of the efficacy of interventions designed against this mosquito. Knowing their survival is also critical as it determines their infectiousness. In this study we tested the capability of a near infrared spectroscopy technique to characterise samples of Ae albopictus mosquitoes reared in the laboratory at various age groups. We used the cross validation technique to develop prediction models and tested the accuracy of the model on a subset of samples. We show that NIRS can predict the age of females with an accuracy of >93% into two age groups that define their infectiousness. We conclude that the use of NIRS for age prediction for Ae. Albopictus is consistent with predictive accuracies previously reported for other mosquito species including Ae. Aegypti and Anophels gambiae. This study provides a platform for the development of this technique for future application to investigate survival characteristics of Ae. albopictus particularly following invasion in exotic areas.

Technical Abstract: To date there is no single technique described for predicting the age of Aedes albopictus commonly known as the Asian tiger mosquito. In this study we report the potential of a near infrared spectroscopy (NIRS) technique for characterizing the age of female laboratory reared Ae. albopictus. Using leave one out cross validation, laboratory reared mosquitoes at 1, 3, 7, 9, 13, 16, 20 and 25 days post emergence preserved in RNAlater for up to a month were assessed. Mosquitoes (N=322) were differentiated into two age classes (<7 or = 7 days old) with a predictive accuracy of 93%., into 3 age classes (>7, 7-13 and >13 days old) with a predictive accuracy of 76% accuracy and on a continuous age scale to within ±3 days of the actual average age. Similarly, models developed predicted mosquitoes (N=146) excluded from the model with 94% and 71% predictive accuracy to the two and the three age groups, respectively. We show for the first time that NIRS could be applied to predict the age of female Ae. Albopictus reared in the laboratory. Rapid characterisation of the survival of Ae. albopictus is crucial in determining its invasion capability in various regions of the world with downstream effects of designing appropriate interventions targeting their survival.