D3256: Transcriptome analysis unveils molecular mechanisms of acaricide resistance in two-spotted spider mite populations on hop

Hop, Humulus lupulus is a specialty crop, cultivated mainly for its resins and oils in flavoring of craft beer. The US hop industry is estimated to be worth over $500 million each year, with 99% of overall production from the Pacific Northwest. Two-spotted spider mite (TSSM) (Tetranychus urticae) is the most important arthropod pest on hop in hot and dry climates. TSSM management heavily relies on the use of acaricides including abamectin, bifenazate, bifenthrin, and mite growth regulators. Unfortunately, TSSM has been documented to quickly develop resistance to these acaricides which directly cause control failures. To understand mechanisms of acaricide resistance in hop TSSM populations, two acaricide-resistant TSSM populations were collected from hop fields and selected in the lab with increasing doses of abamectin and bifenthrin to develop resistance. A transcriptomic study was carried out using four populations (susceptible, abamectin resistant and two bifenthrin resistant populations). Differential gene expression analysis uncovered a notable disparity, with a significantly higher number of downregulated genes observed compared to upregulated genes. Gene ontology enrichment analysis revealed a striking consistency among all three resistant populations with downregulated genes predominately associated with chitin metabolism. While upregulated genes in the resistant populations were found to be associated with cellular lipid metabolism. These findings offer valuable insights into the molecular mechanisms underlying acaricide resistance in TSSM. This knowledge can be leveraged to develop innovative pesticides and molecular diagnostic tools that aid in monitoring and managing resistant TSSM populations effectively.