Fig. 1
Discrimination of laboratory reared Anopheles gambiae mosquitoes by age. Anopheles gambiae mosquitoes were raised in the laboratory, fed sugar solution and/or blood meals before being killed by freezing and subsequent storage at room temperature. Specimens of seven age classes (2 days, 4–5 days, 8–10 days, 11–12 days, 15–17 days, 18–19 days and 20–21 days) were collected, with 175 females in each category. To explore the differences between the age groups the REIMS data was analysed using a combination of principal component and linear discriminant analysis (PC-LDA) and visualised through the Offline Model builder (OMB) software (a) and in the R environment (b) in form of 3D models and a kernel density plot. The PC-LDA separation was tested using cross-validation in OMB (using the option ‘Leave 20% out’ and a standard deviation of 5), resulting in an accuracy of 70% (c). Additionally, the data was analysed through random forest using a training/test data set split of 70 and 30%, leading to a total accuracy of 58% (d).
