Host-related differences in diapause characteristics of different geographical populations of the Kanzawa spider mite, Tetranychus kanzawai Kishida (Acari : Tetranychidae), in Japan
A. Takafuji et al., Host-related differences in diapause characteristics of different geographical populations of the Kanzawa spider mite, Tetranychus kanzawai Kishida (Acari : Tetranychidae), in Japan, APPL ENT ZO, 36(1), 2001, pp. 177-184
The incidence of diapause in the polyphagous spider mite Tetranycnus kanzaw
ai was determined fur 65 populations derived from deciduous and herbaceous
hosts and for 33 populations from tea, at 3 temperatures under short-day co
nditions. Most populations on the four main islands of Japan, irrespective
of the host species on which they occurred expressed more than 90% diapause
at 15 degreesC, whereas populations on the Okinawa islands exhibited a ver
y low incidence or no diapause. The incidence of diapause decreased when te
mperature was increased from 18 to 20 degreesC in populations from warmer a
reas such as southern Kyushu and Honshu. This temperature-dependent decline
in diapause incidence was most conspicuous in populations from Tanegashima
and Yakushima Islands. The incidence of diapause at 20 degreesC tended to
be lower in populations derived from tea than those from deciduous hosts in
the same, warmer areas, showing that the former have a lower capacity for
diapause. The present results, together with previously published data for
T. urticae, showed that the lower temperature threshold for diapause induct
ion was higher in T: kanzawai than in T. urticae and thus the clinal decrea
se in diapause percentage occurred at much lower latitudes in the former at
20 degreesC.