THE OCCURRENCE OF ALATE TURNIP APHID LIPAPHIS ERVSIMI (HOMOPTERA:APHIDIDAE) AND ITS DEVELOPMENT AND REPRODUCTION

The occurrence of alate turnip aphid ( Lipaphis erysimi) and its development and reproduction were studied in this paper. Alate ratios decreased as the bearing and rearing temperature increased from 15℃ to 20℃ and 25℃. Significantly higher alate ratio (69.2%) was recorded when nymphs were born and reared at 15℃ compared with 11.76% at 25℃. Fewer alate forms developed when the nymphs were born by alate mother than the nymphs were born by wingless mother. A very high alate ratio(93.1±1.2%) was observed when nymphs were born and reared on old leaves, compared to 22.3±2.4% when nymphs were born on old leaves and reared on young leaves. A maternal and nymph wing determination mechanism was suggested. Newly born nymphs took 20.4, 15.8, 9.8 and 8.0 d to develop to alate adults when they were reared on cabbage at 10℃, 15℃, 20℃, 25℃, respectively. Winged adults survived 12.6 d at 15℃ and 17.2～17.7 d at 20～30℃, compared to only 3.7 d on average at 35℃. Higher reproductive rates (37.9 and 39.0 nymphs/female) were found at 20℃ and 25℃, compared to 7.9, 11.9 and 1.3 nymphs/female at 15℃, 30℃ and 35℃ respectively.