Life-history traits of the six Panonychus species from Japan (Acari: Tetranychidae).

Six species of the genus Panonychus are known from Japan. Life-history parameters of all six species were investigated at 25 degrees C, and for three species two strains of different geographical origin were included. The intrinsic rate of natural increase (r(m)) ranged from 0.172/day for the P. osmanthi albino strain to 0.209/day for P. citri, while the net reproductive rate (R0) varied from 23.98 in the thelytokous species P. thelytokus to 46.61 in P. citri. Both values were higher in the polyphagous species (P. ulmi, P mori and P. citri), which are considered crop pests, than those in the oligophagous species (P. thelytokus and P. osmanthi), considered non-pests. The only exception was P. bambusicola, an oligophagous non-pest species with R0- and r(m)-values closely resembling those of the three polyphagous species.