A complete genome sequence enables efficient genetic mapping of adaptive traits in a phytoseiid predatory mite...

Phytoseiid mites are important biological control agents in Integrated Pest Management (IPM), yet the genetic architecture underlying their adaptive traits remains largely unknown due to limited genomic and genetic resources. Here, we establish an integrated genetic framework for Amblyseius andersoni, generating a genome sequence and developing a high-resolution genetic mapping approach. The genome was assembled using long-read sequencing, yielding a highly contiguous assembly of approximately 202 Mb with 18,923 predicted protein-coding genes and high completeness. We then dissected resistance to two widely used insecticides, deltamethrin and spinosad, as exemplar adaptive traits. Genetic mapping via bulked segregant analysis (BSA) localized deltamethrin resistance to a major-effect QTL encompassing the voltage-gated sodium channel (VGSC). Next, F₂ linkage analysis demonstrated co-segregation of the M918L substitution in VGSC with the resistant phenotype, consistent with a target-site resistance mechanism. Spinosad resistance mapped to a region encompassing the nicotinic acetylcholine receptor (nAChR) α6 subunit. Altered splicing resulting in intron retention was consistent with a dysfunctional receptor in the resistant strain. Together, this framework establishes a powerful genetic tool for resolving genetic determinants of adaptive traits in predatory mites and provides genetic markers that can support breeding programs aimed at enhancing biological control strategies within IPM systems.