Use of REIMS for profiling of wild mosquitoes

Wagner I, Grigoraki L, Enevoldson P, Clarkson M, Jones S, Hurst JL, Beynon RJ, Ranson H. (2023) Rapid identification of mosquito species and age by mass spectrometric analysis. BMC Biol. 2023 Jan 24;21(1):10. doi: 10.1186/s12915-022-01508-8.

BACKGROUND: A rapid, accurate method to identify and to age-grade mosquito
populations would be a major advance in predicting the risk of pathogen
transmission and evaluating the public health impact of vector control
interventions. Whilst other spectrometric or transcriptomic methods show
promise, current approaches rely on challenging morphological techniques or
simple binary classifications that cannot identify the subset of the population
old enough to be infectious. In this study, the ability of rapid evaporative
ionisation mass spectrometry (REIMS) to identify the species and age of
mosquitoes reared in the laboratory and derived from the wild was investigated.
RESULTS: The accuracy of REIMS in identifying morphologically identical species
of the Anopheles gambiae complex exceeded 97% using principal component/linear
discriminant analysis (PC-LDA) and 84% based on random forest analysis. Age
separation into 3 different age categories (1 day, 5-6 days, 14-15 days) was
achieved with 99% (PC-LDA) and 91% (random forest) accuracy. When tested on wild
mosquitoes from the UK, REIMS data could determine the species and age of the
specimens with accuracies of 91 and 90% respectively.
CONCLUSIONS: The accuracy of REIMS to resolve the species and age of Anopheles
mosquitoes is comparable to that achieved by infrared spectroscopy approaches.
The processing time and ease of use represent significant advantages over
current, dissection-based methods. Importantly, the accuracy was maintained when
using wild mosquitoes reared under differing environmental conditions, and when
mosquitoes were stored frozen or desiccated. This high throughput approach thus
has potential to conduct rapid, real-time monitoring of vector populations,
providing entomological evidence of the impact of alternative interventions.