A mutation in chitin synthase I associated with etoxazole resistance in the citrus red mite Panonychus citri (Acari: Tetranychidae) and its uneven geographical distribution in Japan

• Published in: Pest management science Vol. 78; no. 10; pp. 4028 - 4036
• Main Authors: Tadatsu, Misono, Sakashita, Ryota, Panteleri, Rafaela, Douris, Vassilis, Vontas, John, Shimotsuma, Yushi, Ishida, Tatsuya, Sudo, Masaaki, Van Leeuwen, Thomas, Osakabe, Masahiro
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.10.2022; Wiley Subscription Services, Inc
• Subjects: acaricide resistance; Chitin; Chitin synthase; chitin synthesis inhibitor; CHS1; CRISPR; diagnostic qPCR; Dispersal; Dispersion; Frequency analysis; Gene flow; Geographical distribution; geographical variation; Hatchability; Heredity; Mutation; Panonychus citri; Polymerase chain reaction; Populations; Resistance factors; Substitution reactions; target site mutation; Japan
• ISSN: 1526-498X; 1526-4998
• DOI: 10.1002/ps.7021

BACKGROUND High‐levels of etoxazole resistance have not yet been frequently reported in Panonychus citri. Although a highly resistant strain was discovered in 2014, etoxazole resistance has not become a significant problem in areas of citrus production in Japan. A target site mutation in chitin synthase 1 (CHS1), I1017F, is a major etoxazole‐resistance factor in Tetranychus urticae. To investigate the mechanisms of etoxazole resistance and the dispersal of resistance genes, we analyzed target‐site mutations in a highly resistant strain and their geographical distribution in Japan. RESULTS High‐level etoxazole resistance was completely recessive. The I1017F mutation was detected in CHS1 of the highly resistant strain, and its frequency was correlated with the hatchability of eggs treated with etoxazole. Sequencing and variant frequency analyses of local populations by quantitative polymerase chain reaction revealed that I1017F is restricted to the Ariake Sea area of Kyushu Island. Although a new nonsynonymous substitution, S1016L, accompanied by I1017F was found in CHS1 of the highly resistant strain, CRISPR/Cas9 engineering of flies showed that S1016L had no effect on the etoxazole resistance conferred by I1017F. CONCLUSION I1017F is a major target site mutation that confers high‐level etoxazole resistance on P. citri. Dispersion of I1017F possibly was suppressed as a result of the completely recessive inheritance of resistance together with low gene flow between local populations. © 2022 Society of Chemical Industry. The I1017F in CHS1 is a major target‐site mutation that confers completely recessive high‐level etoxazole resistance in Panonychus citri. We found this mutation at a restricted area in Kyushu Island in Japan.