Mechanisms of resistance to three mite growth inhibitors ofTetranychus urticaein hops

Abstract

Mite growth inhibitors (MGIs), such as etoxazole and hexythiazox, are valuable IPM tools for Tetranychus urticae control in hops due to their unique mode of action and selectivity. Hence, it is necessary to standardize bioassay methods to evaluate the efficacy of MGIs, monitor resistance, and identify mechanisms underlying MGI resistance in the field. Here, we developed a three-tiered approach for evaluating ovicidal toxicity of MGIs to T. urticae, which simulated different MGI exposure scenarios in the field. The most effective bioassay method was direct exposure of T. urticae eggs to MGIs. With this method, four field-collected T. urticae populations showed low-to-moderate resistance to MGIs. Cross-resistance among MGIs and from MGIs to bifenazate and bifenthrin was detected. Besides target site insensitivity, enhanced cytochrome P450 and esterase activities also contribute to the MGI resistance in hop yard-collected T. urticae populations. Low-to-moderate MGI resistance in T. urticae populations may be mediated by multiple mechanisms. Positive selection pressure on the I1017F mutation is moderate in field-collected T. urticae populations. Further studies are required to identify metabolic detoxification genes that confer resistance to MGIs for precise resistance monitoring.

Laboratory selection, resistance risk assessment, multi‐resistance, and management of Tetranychus urticae Koch to bifenthrin, bifenazate and cyflumetofen on cowpea

“…Due to its short life cycle, abundant progeny and arrhenotokous reproduction, it develops resistance to various acaricides very rapidly. A large number of studies have presented the resistance of T. urticae to different acaricides …”

“…A large number of studies have presented the resistance of T. urticae to different acaricides. [20][21][22][23] In this paper, we reported the resistance selection of bifenthrin, bifenazate and cyflumetofen conducted for one and half years under lab conditions. As bifenthrin was mainly effective on the adult mites, while bifenazate and cyflumetofen were effective on each stage of mite, the population treated with bifenthrin could recover comparatively faster than those treated with bifenazate or cyflumetofen, which was indicated by different selection generation numbers (16 for bifenthrin, 12 for bifenazate or cyflumetofen).…”

RNA interference of NADPH-Cytochrome P450 reductase increases susceptibilities to multiple acaricides inTetranychus urticae

“…The two-spotted spider mite, Tetranychus urticae (Koch), is a global agricultural and 44 horticultural pest with significant economic importance due to its quantitative and qualitative 45 damage to food, fiber and specialty crops, including corn [1], soybean [2], rose [3], cotton [4], and 46 hops [5]. In fact, T. urticae is regarded as the most successful generalist arthropod herbivore, with the capability of utilizing over 1,100 plant species as hosts [6].…”

Physiological resistance alters behavioral response of Tetranychus urticae to acaricides

“…The two-spotted spidermite, Tetranychus urticae Koch, is a highly polyphagous pest of global distribution with a host range of over 1100 plant species. Among the host plants of T. urticae are highly valued economic crops of agricultural and horticultural importance [28][29][30][31][32] . The control of T. urticae is largely dependent on the use of multiple acaricides with different modes of action.…”

“…However, behavioral components of resistance of T. urticae to acaricides have received little attention 5,6 . Moreover, the consequence of acaricide resistance development in T. urticae and other species has been based on fitness related traits including population growth 9,34,35 and cross resistance to other acaricides 28 , but not on the sensory perception of acaricides by T. urticae. It is unknown whether acaricide resistant T. urticae populations may have developed an acaricide-aversive behavior or become desensitized to the presence of an acaricide since they have developed physiological mechanisms to cope with its acute toxicity.…”