关键词: 二化螟, 寄主, 水稻, 茭白, 光周期反应, 滞育

Abstract:

Photoperiodic responses of diapause induction in the striped stem borers, Chilo suppressalis, collected from both rice field (rice-population) and water-oat field (water-oat-population) were investigated, with the two populations fed on rice and water-oat, respectively. The photoperiodic response curves showed that most of larvae entered diapause regardless of photoperiod length when the rice-population was fed on water-oat or the water-oat-population was fed on rice. This indicated that the two populations have evolved to adapt to their corresponding hosts. Only 5%－6% water-oat-population pupated when larvae fed on rice and larval duration was 15－18 days longer than that fed on water-oat; whereas 30%－40% rice-population fed on water-oat pupated and the larval duration was only 3-8 days shorter than that fed on rice. When the water-oat-population was fed on rice and water-oat, respectively, the weight of larvae (32 days old) fed on rice was equal to 53-1% of the larvae fed on water-oat; whereas when the rice-population was fed on rice and water-oat, respectively, the weight of larvae fed on rice was equal to 79.5% of the larvae fed on water-oat. These results indicated that water-oat-population had little adaptability to rice, whereas the rice-population had some adaptability to water-oat. This suggests that the intra species differentiation has appeared between the two populations and planting of water-oat should be no significant influence on the incidence of striped stem borers in rice field.

Key words: Chilo suppressalis, hostplant, rice, water-oat, photoperiodic response, diapause