Detection of bifenthrin, bifenazate, etoxazole resistance inTetranychus urticaecollected from mint fields and hop yards using targeted sequencing and TaqMan approaches

Tetranychus urticae (Koch) is an economically important pest of many agricultural commodities in the Pacific Northwest. Multiple miticides are currently registered for control including abamectin, bifenazate, bifenthrin, and extoxazole. However, populations of Tetranychus urticae have developed miticide resistance through multiple mechanisms, in many different growing regions. Producers of agricultural commodities where Tetranychus urticae infestations are problematic rely on integrated pest management tools to determine optimal control methods. Within this species multiple single nucleotide polymorphisms have been documented in different genes which are associated with miticide resistance phenotypes. The detection of these mutations through TaqMan qPCR has been suggested as a practical, quick, and reliable tool to inform agricultural producers of miticide resistance phenotypes present within their fields and have potential utility for making appropriate miticide application and integrated pest management decisions. Within this investigation we examined the use of a TaqMan qPCR-based approach to determine miticide resistance genotypes in field-collected populations of Tetranychus urticae from mint fields and hop yards in the Pacific Northwest of the United States and confirmed the results with a multiplex targeted sequencing. The results suggest the TaqMan approach accurately genotypes Tetranychus urticae populations collected from agricultural fields. The interpretation of the results, however, provide additional challenges for integrated pest management practitioners, including making miticide application recommendations where populations of Tetranychus urticae are a mix of resistant and wildtype individuals.