Using comparative genomics to decode the genetics of acaricide resistance

Abstract

The availability of genome assemblies and other genomic resources is facilitating investigations of complex genetic traits for several species of ticks. Understanding the genetics of acaricide resistance is a priority for tick and tick-borne disease control. The synaptic enzyme acetylcholinesterase (ACE) is recognized as the target of organophosphates (OPs) and carbamates, and mutations in ACE have been tied to resistance. Multiple studies support three ACE (ace) loci in but the molecular basis of OP-resistance in this tick remains elusive. Here, we exploited the genome assembly of the black-legged tick and comparative genomic analyses to explore the complement of tick ACEs and their potential roles in OP resistance. We identified eight putative ace loci () in I. scapularis. Molecular analyses and homology modeling suggest ACE activity for IscaACE1a. Our analyses reveal the molecular complexity of the ace gene family, highlight the need for functional studies of ACEs in species of the Ixodidae, and reveal potential challenges to management of OP resistance in ticks.

A Roadmap for Tick-Borne Flavivirus Research in the “Omics” Era

“…Unfortunately, widespread resistance among pest populations represents a threat to continued disease control. The identification of pesticide chemistries that operate via novel modes of action (MoA) by binding at alternative sites on existing insecticide targets) or via disruption of novel molecular targets in the arthropod, is a high priority (Van Zee and Hill, 2017 ). Disease control is expected to rely on insecticides for the next several decades and new acaricides that operate via targets distinct from acetylcholinesterase (the main target of OPs and carbamates) and the voltage-gated sodium channel (the main target of SPs) are sought.…”

“…Future genome sequencing targets identified by the Tick and Mite Genomes Consortium are described in a white paper (Hill, 2010 ; Van Zee and Hill, 2017 ). This project, approved by the National Institutes of Health, is a community-ratified guide for genomic and genetic research on ticks and mites of medical and veterinary importance.…”