Population dynamics of predatory mites and citrus red mites on three different citrus varieties

Author of the article:SONG Zi-Wei, ZHENG Yuan, ZHANG Bao-Xin, LI Dun-Song

Author's Workplace：Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China

Key Words：Phytoseiidae mites; Panonchus citri; citron-lemon; Ehime Kashi No. 28; Shatangju

Abstract：[Objectives]  To investigate the population dynamics of predatory mites and citrus red mites in orchards with different citrus varieties, quantify the diversity of predatory mites, and assess the ability of the latter to control citrus red mites under natural conditions. [Methods]  Field surveys were conducted in citron-lemon orchards in 2019, and in Ehime Kashi No. 28 and Shatangju orchards, in 2020. The abundance of predatory mites and citrus red mites were measured using five-point sampling and the shaking-off the plate method at fixed sites from April to December each year. Samples of predatory mites were obtained using the plant-flapping plate method, after which species were identified under a microscope. [Results]  There were significant differences in the species of dominant predatory mites found in the three orchard types. Three species of phytoseiid mites were found in citron-lemon orchards of which the dominant species was Scapulaseius newsami. Five species of phytoseiid mites were found in Ehime Kashi No. 28 orchards of which the dominant species was Euseius nicholsi. Two species of phytoseiid mite were found in Shatangju orchards of which Neoseiulus californicus was the dominant species. Predatory mite populations fluctuated significantly over the duration of the study. The population of predatory mites in citron-lemon orchards had two peaks, one on May 13th and another on October 24th, whereas three distinct peaks were apparent in Ehime Kashi No. 28 and Shatangju orchards, the biggest of which occurred on May 9th. In citron-lemon orchards, the population dynamics of the predatory mites S. okinawanus and A. obtuserellus were relatively stable, whereas numbers of S. newsami fluctuated. In Ehime Kashi No. 28 orchards, the population dynamics of A. obtuserellus was more stable than that of E. nicholsi. In Shatangju orchards, the population dynamics of N. californicus and A. obtuserellus had an inverse relationship. [Conclusion]  There appear to be certain correlations between the population structure of predatory mites and citrus varieties. Citrus pollen may affect the sustainability of predatory mite populations. Because different predatory mite species may differ in their tolerance to pesticides, different pesticides may alter predatory mite community composition in different ways. Under natural conditions, predatory mites clearly controlled citrus red mites in orchards.