• Korean journal of applied entomology
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• v.48 no.2
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• pp.221-227
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• 2009

Temperature effects on diapause termination of Paratlanticus ussuriensis eggs were studied by measuring embryonic development and hatching rates at various conditions of indoor chilling and overwintering temperatures. Diapausing eggs of P. ussuriensis did not hatch at continued incubation at $25^{\circ}C$ and even after chilling for once at either $5^{\circ}C$ or $10^{\circ}C$ for 30, 45 and 60 days. In addition, double chillings at $5^{\circ}C$ with a 90 days interval at $25^{\circ}C$ did not induce hatching of diapausing eggs. However, double chillings at $10^{\circ}C$ induced hatching at 3.6${\sim}$26.7%. When eggs were incubated at $25^{\circ}C$ after chilling for once at $5^{\circ}C$ for various periods, those weights were not changed but those chilled at $10^{\circ}C$ gradually increased to approximately 1.5 times. When 60-days-old eggs were artificially deposited under the soil at three different mountain sites in September 2007, the hatching rates of the first-overwintered eggs were 11.3, 3.5 and 4.1% and those of the second-overwintered eggs were 25.1, 21.6 and 0.4% at Hoepori, Bitanri and Hwasanri, respectively. Most eggs were hatched from mid-March to mid-April but little bit earlier in southern regions. During the hatching period soil temperatures in three tested locations were around 8 to $12^{\circ}C$. In overall, diapausing eggs of P. ussuriensis were greatly influenced by chilling temperature conditions and those repeated cycles, and may required overwintering for one or two times to hatch for the post-embryonic development.