Behavioral response of Panonychus citri (McGregor) (Acari: Tetranychidae) to synthetic chemicals and oils

Background: Panonychus citri (McGregor) (Acari: Tetranychidae) population outbreaks after the citrus plantation's chemical application is a common observation. Dispersal behavior is an essential tool to understand the secondary outbreak of P. citri population. Therefore, in the current study, the dispersal activity of P. citri was observed on the leaf surfaces of Citrus reticulata (Rutaceae) treated with SYP-9625, abamectin, vegetable oil, and EnSpray 99. Method: Mites were released on the first (apex) leaf of the plant (adaxial surface) and data were recorded after 24 h. The treated, untreated, and half-treated data were analyzed by combining the leaf surfaces (adaxial right, adaxial left, abaxial right, and abaxial left). All experiments were performed in open-air environmental conditions. Results: The maximum number of mites was captured on the un-treated or half-treated surfaces due to chemicals repellency. Chemical bioassays of the free-choice test showed that all treatments significantly increased the mortality of P. citri depending on application method and concentration. A significant number of mites repelled away from treated surfaces and within treated surfaces except adaxial left and abaxial right surfaces at LC30. In the no-choice test, SYP-9625 gave maximum mortality and dispersal by oils than others. No significant differences were observed within the adaxial and abaxial except abaxial surface at LC30. Therefore, the presence of tested acaricides interferes with P. citri dispersal within leaf surfaces of plantations depending on the mites released point and a preferred site for feeding.

Automated summary

The study observed the dispersal activity of Panonychus citri on chemically treated citrus leaf surfaces, finding that treated surfaces can significantly affect mite dispersal and certain treatment methods can increase the mortality rate of P. citri.