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Amblyseius orientalis (Ehara) (Acari: Phytoseiidae) is an effective predatory mite for spider mite control on fruit trees in China. In recent decades, it has been produced massively at a commercial natural enemy producer, feeding on the storage mite Carpoglyphus lactis (L.). In the predator production process, the ratio of predatory mites to their prey was found to be critical for the population increase of A. orientalis in large-scale rearings. In this study, we investigated the predatory capacity of A. orientalis on various developmental stages of the prey C. lactis, and the effect of prey numbers on predator reproduction. The maximum predation rate of A. orientalis adults on C. lactis adults was 2.21 per day at the lowest density of five prey adults, and on C. lactis eggs it was 45.07 at the highest density of 60 prey eggs. The preference index Ci of A. orientalis on C. lactis eggs and adults was 0.4312 and − 0.9249, respectively, suggesting that A. orientalis preferred eggs to adults. Amblyseius orientalis could reproduce when it preyed on either eggs or deutonymphs of C. lactis. However, the fecundity of the predatory mites is not always proportional to the provided prey number. Higher density of prey deutonymphs resulted in lower fecundity, whereas more prey eggs resulted in higher fecundity of A. orientalis. Therefore, our study indicated that the choice of suitable density and developmental stage of prey can significantly improve A. orientalis production on a large scale. [ABSTRACT FROM AUTHOR]

The carmine spider mite (CSM) Tetranychus cinnabarinus has become a serious pest in China and has developed resistance to acaricide propargite as it is used to control mites worldwide including T. cinnabarinus . In this study, a resistant colony of T. cinnabarinus , PRR34 (37.78-fold resistant ratio), was established after 34 generations of propargite selection, and cross-resistance patterns of 7 other acaricides were determined in comparison with a susceptible strain (SS). The contribution of detoxification enzymes to propargite tolerance were investigated using biological, biochemical and molecular approaches. Enzyme inhibitor synergist tests suggested glutathione S -transferases (GST) involvement in propargite-resistance of PRR34, and GST activity against 1-chloro-2,4-dinitrobenzene (CDNB) was correlated with the development of resistance. Eight novel GST genes ( TcGSTd1, TcGSTd2, TcGSTm1, TcGSTm2, TcGSTm3, TcGSTm4 and TcGSTm5 ) were cloned, and phylogenetic analysis showed that the eight GST genes were most closely related to GST family delta and mu from Tetranychus urticae . Quantitative RT-PCR revealed that the expression level of GSTs in PPR34 strain increased in larvae, nymphs and adults, while decreased in eggs compared with that of SS. Collectively, these results support a role of GSTs in mediating resistance to propargite in the PRR34 strain. TcGSTd1,TcGSTd2 and TcGSTm2 genes might play significant roles in propargite resistance of CSM, especially at adult stage. This is the first attempt to define specific genes involved in GST mediated propargite resistance of T. cinnabarinus at the transcriptional level. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the resistance citrus red mite Panonychus citri which are considered to be the most important pesticide-resistant pests in China. The study collected six populations of the mite from Chinese citrus orchards to monitor their resistance to spirodiclofen and other five acaricides. Conclusion shows that there are essential difference in resistance to the evaluated acaricides among the examined populations of mite.

Natural pesticides are potential alternatives to conventional chemical pesticides. Recently, studies on pesticide–pest interactions have combined empirical biochemical measurements and practical field experiments. In this study, we performed laboratory and field efficacy analysis and biochemical characterization of two phytochemicals (2,4-di-tertbutylphenol (DTBP) and ethyl oleate (EO)) for carmine spider mite Tetranychus cinnabarinus control. DTBP and EO controlled mites by inhibiting egg hatchability and showed significant residual toxicity in laboratory tests. The control efficacy was confirmed in eggplant and cucumber field trials in three provinces in China. Oxidative stress induced by antioxidant enzymes (superoxide dismutase and peroxidase) and detoxification metabolism (involving carboxylesterase and/or mixed-function oxidase) may be involved in the response of mites to DTBP and EO. This study demonstrates the potential of DTBP and EO as effective acaricides for the control of spider mites and provides researchers a better understanding of acaricide–mite interactions. • DTBP and EO effectively controlled T. cinnabarinus under laboratory and field conditions. • Oxidative damage is the most likely causative mechanism in T. cinnabarinus response to the toxicity of DTBP and EO. • The ovicidal activities of DTBP and EO were strongly affected by egg age. • These findings provide a crucial theoretical basis for future commercialization of DTBP and EO as natural acaricides. [ABSTRACT FROM AUTHOR]