Resistance to fenazaquin in broad mite, Polyphagotarsonemus latus (Banks) (Acari: Tarsonemidae): Realized heritability, risk assessment and cross‐resistance

Abstract

AbstractThe broad mite, Polyphagotarsonemus latus (Banks), is an important phytophagous mite that causes extensive damage to a wide range of crop species across the world. Fenazaquin, a mitochondrial electron transport inhibitor (METI), is one of the commonly used acaricides for the management of P. latus. The response to fenazaquin selection over generations and the risk of development of resistance was estimated herein using a laboratory‐selected population of P. latus (FEN‐SEL). Repeated exposure to fenazaquin over generations resulted in decreased susceptibility (99.32 folds) as compared to the unselected counterpart. FEN‐SEL took 26 generations for a 10‐fold increase in resistance with a realized heritability (h2) of 0.12 which indicated a low genetic variation and high phenotypic variation. Over a selection intensity of 20%–80% mortality, the generations required for a 10‐fold increase in LC50 for fenazaquin were 14.21–55.75, 7.75–30.41 and 5.33–20.91 at h2 values of 0.12, 0.22 and 0.32, respectively, with a constant slope of 2.39. The FEN‐SEL population also exhibited moderate levels of cross‐resistance to diafenthiuron, dicofol and spiromesifen and low cross‐resistance to propargite. The findings suggest a rational and rotational application of fenazaquin in the field to delay the development of resistance and to prolong its efficacy against P. latus.