Overwintering characteristics of the Asian corn borer, Ostrinia furnacalis (Guenée) (Lepidoptera: Crambidae) and prediction of the period of occurrence of overwintering generation adults.

[Objectives] The Asian corn borer Ostrinia furnacalis(Guenee)(Lepidoptera: Crambidae) is an important insect pest of corn in China. Studies of its overwintering characteristics and prediction of the occurrence period of overwintering generation adults are important for improving the control efficiency of this pest. [Methods] The number of overwintering Asian corn borer larvae and the distribution in corn plants were investigated by splitting the stalks and cobs of corn in spring 2007 in Dongchangfu, Qufu, Shanghe, Binchengqu, Jimo and Qixia, Shandong province. Overwintering larvae were placed outdoors to observe pupation. Dates of pupation and survival rates were recorded. [Results] The average number of overwintering larvae in corn stalks and cobs was 41.80 and 19.91 per hundred stalks or cobs, respectively, with larvae in stalks accounting for 67.30% of the total. The ratios of overwintering larvae on the upper, middle and lower parts of corn stalks were 21.18%, 38.80% and 40.02%, respectively. The initial peak, peak, and end peak stage of overwintering generation pupation occurred on May 27, June 5 and June 21, and the initial peak, peak, and end peak stage of overwintering generation eclosion occurred on June 8, June 17 and July 1, respectively. [Conclusion] Because larvae of O. furnacalis mainly overwinter in stalks and cobs, it is important to destroy these as soon as practicable after the harvest. Observations of overwintering generation pupation indicate that the best time to control first generation larvae is from mid to late June and the best time to control second generation larvae is mid-July.