Quantifying Insecticide Response in Drosophila

The response of D. melanogaster larvae to imidacloprid was measured using the WI assay, which estimates the insecticidal effect by quantifying the reduction in motility during insecticide exposure^{32 (link)}. Third instar larvae of each genotype were picked, 25 per well, into a NUNC cell culture treated 24 well plate (Thermo-Scientific) preloaded with 200 µL 5% w/v sucrose (AR Grade; Chem Supply) in distilled H₂0. Larvae were filmed for 30 seconds at two time points, 0 min (before starting the exposure) and at 60 min after the addition of specific concentrations of imidacloprid (200 g L⁻¹ Confidor®; Bayer Crop Science). Subsequently, the WI ImageJ script was used to quantify the total motion in each well at each time point. The ratio between initial and final motility was used to calculate Relative Movement Ratios (RMRs), which were averaged to estimate imidacloprid response for each genotype tested in this study. 178 DGRP genotypes were considered at doses of 25 and 100 ppm as was RAL_517 and RAL_517-Cyp6g1KO. Other Cyp6g1 knockouts were tested at 5 ppm. UAS-Cyp6g1 and UAS-Cyp6g2 were tested at 20 and 40 ppm.