Presence of <i>Neoseiulus californicus</i> (Acari: Phytoseiidae) and suppression of citrus red mite <i>Panonychus citri</i> (Acari: Tetranychidae) density in mandarin orange orchards with rat’s tail fescue ground cover

Abstract

Presence of Neoseiulus californicus (Acari: Phytoseiidae) and suppression of citrus red mite Panonychus citri (Acari: Tetranychidae) density in mandarin orange orchards with rat's tail fescue ground cover Abstract A investigation revealed that Neoseiulus californicus is the dominant species among the natural enemies of citrus red mite Panonychus citri in mandarin orange orchards in Shizuoka prefecture. In conventionally managed orchards, routine herbicide spraying suppresses habitats of phytoseiids. It has indicated that habitat management in orchards is important to conserve Phytoseiid mites for control of spider mites. Then, we compared the occurrence of N. californicus in orchards covered with rat's tail fescue Vulpia myuros with that in orchards with bare soil in 2004 and 2005. We collected N. californicus from spikes of rat's tail fescue in late April and from citrus trees after death of the fescue in May, but 1 to 5 weeks later in the bare-soil orchards. The peak density of the citrus red mite during the summer in the fescue orchards was 11% to 59% of that in the bare-soil orchards.In autumn and winter, we collected a few female adults of N. californicus from rat's tail fescue. The provision of additional rat's tail fescue may stabilize the occurrence of N. californicus in mandarin orange orchards in spring.