ホウレンソウケナガコナダニの高温耐性ならびにオンシツケナガコナダニ，ケナガコナダニ，ロビンネダニとの種間比較

The high-temperature tolerance of Tyrophagus similis (Acari: Acaridae) was investigated to explore the possibility of controlling T. similis in agricultural soil by heat treatment. The tolerance of two congeners, T. neiswanderi and T. putrescentiae, and Rhizoglyphus robini was also examined for comparison. No eggs and adults of T. similis survived treatments at 40°C for 24 h, 45°C for 3 h, or 50°C for 1 h, although the heat tolerance of eggs was relatively higher than that of adults. These findings indicate that hot-water soil sterilization or steam soil sterilization have a great potential for the control of T. similis, and that these methods should be effective for T. similis even though a lower amount of hot-water or steam are used for treatment than in the case for plant pathogens. The tolerance of T. similis to high temperature was lower than that of T. neiswanderi and T. putrescentiae, and was similar to that of R. robini. T. similis and R. robini may not have developed high-temperature tolerance because, in contrast to the other two, these species dwell in the soil where temperature fluctuation is not severe.