Abstract: The effects of different high temperatures on the biological characteristics such as the duration of nymphal stadia, egg laying, preoviposition period and longevity, were studied. Developing periods of nymphs prolonged when temperature reached above 34℃. The numbers of egg deposited by female adults reduced when the 4th-instar nymphs were treated with higher temperatures, while egg deposition was reduced as female adults were treated with high temperatures at different day, especially one day after the emergence of the brachypterous form and three days after emergence of macropterous form. The life span of BPH was shortened when treated with high tempertures. A little effect of constant high temperature on the period of preoviposition of brachypterous form female adults was perceived but the period of preoviposition of macropterous form females was obviously prolonged when the 4th instar nymphs were reared under constant high temperatures. When treated with changing high temperatures, the preoviposition periods of both brachypterous and macropterous female adults were prolonged. Changing high temperatures have greater effect on the reproduction than constant high temperatures. Greater effect of high temperature treatment on themating of female adults than that of male adults was also observed. In conclusion, 34℃ was the critical temperature in both development and reproduction of BPH.

Key words: brown planthopper, hith temperature, development, reproduction