第四代棉铃虫卵在华北夏玉米田的时空分布

 １９９８～１９９９年在华北夏玉米田对穗期棉铃虫卵在不同播期玉米上时空分布进行了研究．明确了其在玉米田的产卵高峰在８月中、下旬．产卵高峰有多个．虽然在不同播期的玉米田落卵数量不同,但有相同的产卵高峰;产卵部位主要在花丝和雌穗位上的叶片叶鞘上;在早播和中播夏玉米田以散粉期落卵为最多．灌浆期次之．而晚播则以抽雄期落卵最多,散粉期次之;若落卵高峰推后,则不同播期的夏玉米上均以灌浆期落卵最多,散粉期次之;在中、晚播夏玉米田的落卵量明显高于早播,且为害明显比早播重,晚播玉米田又比中播的落卵量大。因此为害则更重。

Spatial-temporal Distributions of Cotton Bollworm Eggs on Summer Corn Seeded at Different Times in North China

The spatial-temporal distributions of cotton bollworm, Helicoverpa armigera (Hubner) eggs on summer corn seeded at early-, middle- and late-times were studied through systematical investiga- tions from 1998 to 1999 in Hengshui, North China. There were several egg peaks during the period from the middle to the late August, and coincided with the pollen-shedding or blister stage of summer corn de- pending on the change of bollworm occurrence. The eggs were mainly deposited on silks of ears, and leaves and sheaths above the ears. The number of eggs laid on middle- and late-seeded summer corn were higher than the early-planted one, caused corresponding the damages to these fields, more heavy on the late-seeded corn.