Using REIMS to dig into resistance phenotypes

organ J, Salcedo-Sora JE, Wagner I, Beynon RJ, Triana-Chavez O, Strode C. (2022) Rapid Evaporative Ionization Mass Spectrometry (REIMS): a Potential and Rapid Tool for the Identification of Insecticide Resistance in Mosquito Larvae. J Insect Sci. 2022 Sep 1;22(5):5. doi: 10.1093/jisesa/ieac05

Insecticide resistance is a significant challenge facing the successful control
of mosquito vectors globally. Bioassays are currently the only method for
phenotyping resistance. They require large numbers of mosquitoes for testing,
the availability of a susceptible comparator strain, and often insectary
facilities. This study aimed to trial the novel use of rapid evaporative
ionization mass spectrometry (REIMS) for the identification of insecticide
resistance in mosquitoes. No sample preparation is required for REIMS and
analysis can be rapidly conducted within hours. Temephos resistant Aedes aegypti
(Linnaeus) larvae from Cúcuta, Colombia and temephos susceptible larvae from two
origins (Bello, Colombia, and the lab reference strain New Orleans) were
analyzed using REIMS. We tested the ability of REIMS to differentiate three
relevant variants: population source, lab versus field origin, and response to
insecticide. The classification of these data was undertaken using linear
discriminant analysis (LDA) and random forest. Classification models built using
REIMS data were able to differentiate between Ae. aegypti larvae from different
populations with 82% (±0.01) accuracy, between mosquitoes of field and lab
origin with 89% (±0.01) accuracy and between susceptible and resistant larvae
with 85% (±0.01) accuracy. LDA classifiers had higher efficiency than random
forest with this data set. The high accuracy observed here identifies REIMS as a
potential new tool for rapid identification of resistance in mosquitoes. We
argue that REIMS and similar modern phenotyping alternatives should complement
existing insecticide resistance management tools.