Supplemental Material for Christesen et al., 2021

nAChRs are the most abundant excitatory receptors in the insect brain, yet relatively little is known about their roles in neurological pathways. Here, we describe the pleiotropic consequences associated with deletion of the <i>Db1</i> nAChR subunit. Using somatic CRISPR-Cas9 editing, we show that deletion of <i>Db1</i> specifically in CCAP neurons impairs wing expansion and this is associated with disruption of signalling by the hormone <i>bursicon</i>. <i>Db1</i> is a commercial insecticide target, and the fitness costs identified explain the scarcity of resistant mutants in field populations, whilst also providing insight into pathways potentially affected by chronic low-dose exposure in beneficial species.