Gotoh, T., T. Kamoto and H. Oku, 1994. Effects of physical and chemical stimuli on termination of embryonic diapause in the spider mite, Panonychus bambusicola Ehara et Gotoh(Acari: Tetranychidae). J. Acarol. Soc. Jpn., 3(2): 53-58. Physical and chemical stimuli were effective in breaking diapause in eggs of the spider mite, Panonychus bambusicola Ehara et Gotoh. A 60-day or longer exposure to 5°C promoted hatching in some diapause eggs. However, more eggs terminated diapause when stimulated with a needle or exposed to ammonia-gas after chilling, although such artificial stimuli were not effective in terminating diapause if the eggs had not been chilled. Eggs stimulated with a needle or ammoniagas after chilling hatched more rapidly at 25°C than did those experienced chilling alone. Because such physical and chemical treatments were effective in terminating diapause only when they were applied to pre-chilled eggs, these stimuli seemed to influence the final phase of diapause development.

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The incidence of diapause at 15-20°C/9L15D was determined in 6 populations of the phytoseiid mite, Amblyseius womersleyi Schicha, collected from south-central and southern Japan. Diapause in phytoseiid mites is characterized by reproductive arrest in females, however, some females induced by short daylength and low temperature exhibited incomplete diapause as follows: 1)oviposition ceased after they laid a few eggs (“ switching” into diapause) ; and 2) the pre-oviposition period was much longer than that of females reared under a long-day photoperiod (“ reproductive delay” ) . In the populations from south-central Honshu and northern Kyushu, temperature greatly affected the diapause expression: almost 100% of the individuals entered diapause at 15° C and the percentages of diapause decreased with increasing temperature to 45-75% at 18°C and 10-40% at 20°C On the other hand, in the populations from Okinawa the percentages of diapause remained low (0-25%) over the temperature range tested, and temperature only slightly affected the expression of diapause. In particular, the percentage observed in the Tokashiki population was only 10.3%, even at 15° C. These results show that the diapause in A. womersleyi is a quantitative threshold trait and that variation in the diapause capacity exists within populations, as well as among populations from different localities. In some phytoseiid species, the importance of a thermoperiod for diapause induction has been shown, but in A. womersleyi a thermoperiod in combination with a short daylength (scotophase coincided with cool phase) held no stimulation for diapause induction.

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Based on the previous data (Uchikawa et al., 1994), we presumed that Leptotrombidium scutellare larvae were distributed widely in man-made environments around densely populated areas inwestern Kanagawa Prefecture, Japan. Employing modified Suzuki's visual sampling method (Uchikawa et al., 1993), this assumption was examined during the period between November 4 and 6, 1993, in Yamakita Town and Minamiashigara City, Kanagawa Prefecture. The above assumption was verified, indicating at the same time that the method was appropriate for our purpose. Many L. scutellare larvae were frequently found on shaded and humid places but not on dry soil surface. Very heavily infested places were encountered in mandarin orange groves and, unexpectedly, in a young kiwi fruit orchard surrounding the center of Yamakita Town with crowded dwellings, and in mandarin orange groves on gently rolling hills of Minamiashigara City. As many as 9, 658 unfed larvae to use in other analyses were taken on sampling and collecting pieces of black cloth during the survey. These larvae were observed to have stayed still in clusters on the cloths sealed in plastic bags that had been kept in a container since the previous day.

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Infestation of ixodid female ticks were found on African ball python(Python regius), which had been imported into Asahiyama Zoo, Hokkaido, Japan by way of the United States. These ticks were identified as Aponomma latum (Koch, 1844) . Spirochete-like bacteria were detected from unfed one of two females associated with the ball python. The subculture of the organisms resulted in failure. This is the first detection of the bacteria from the tick.

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