棉花型和瓜型棉蚜形态和生态适应力的分化

棉蚜由于长期在同种或同类植物上生活，形成了多种寄主专化型。本研究以室内长期用单一寄主培养的棉花型和瓜型棉蚜为材料，采用形态测定、生命表技术、对寄主的选择性试验，以及接触刺激等方法，研究了两寄主型棉蚜的形态分化和生态适应力的差异。结果表明，瓜型棉蚜的一些形态特征值（如体长）极显著地大于棉花型个体，但是头宽、口针和各腿节的长度与体长的比值却极显著的小于棉花型个体。采用7个形态指标与体长的比值，可将瓜型和棉花型棉蚜区分开来。在24℃和26℃下瓜型蚜的净增殖率（R₀）极显著地高于棉花型蚜。27℃和32℃显著缩短了瓜型蚜的平均世代长度，而对棉花型蚜无影响。棉花型蚜对接触刺激的反应比瓜型蚜敏感。两寄主型蚜对寄主的选择能力表现为瓜型蚜显著强于棉花型蚜。因此，两寄主型棉蚜存在明显的形态和生态适应力的分化。

Differentiation in morphometrics and ecological adaptability of cotton and cucumber biotypes of the cotton aphid, Aphis gossypii (Homoptera:Aphididae)

The cotton aphid populations are differentiated in food utility, and the host fidelity has been found all over the world. The morphometric differentiation and ecological adaptabilities of cotton and cucumber biotype aphids were studied used such methods as morphometric analysis, life table, host selection test, and stimulating aphid with a needle. The results showed that the examined morphometric values of the cucumber biotype aphid were significantly higher than that of the cotton biotype aphid, but the ratios of head width, stylet and the femur to body length of the cucumber biotype aphid were significantly lower than that of the cotton biotype aphid. The cucumber and cotton biotype aphids could be distinguished through the discrimination analysis with the indices such as the relative lengths of head, abdomen tube, stylet, femur length of fore-, mid- and hind-leg, and the 3rd segment of antenna to body length. The net reproductive rate of the cucumber biotype aphid reared at 24℃ and 26℃ was significant higher than that of the cotton biotype aphid, but the mean length of a generation was significantly shorter at 27℃ and 32℃. This suggested that the relative lower temperature was more suitable to the cucumber biotype aphid for development and reproduction, and the relative higher temperature was more suitable to the cotton biotype aphid. The response of the cotton biotype aphid to the touch with a little needle was slightly stronger than that of the cucumber biotype aphid. The capacity of the cucumber aphid to orient and select host plant was higher than that of the cotton biotype aphid. The results indicated that the morphometrics and ecological adaptability of the cotton and cucumber biotypes were differentiated