棉蚜寄主专化型及其形成的行为机理

通过生活在甜瓜和棉花上的棉蚜Aphisgossypii Glover的行为，研究棉蚜的寄主专化型及其形成的行为机理。生物学观察显示： 两类棉蚜在寄主植物相互交换以后，定居数显著减少，棉花蚜型棉蚜的繁殖系数及若虫存活率显著下降，说明棉蚜存在甜瓜蚜型和棉花蚜型两种寄主专化型。通过刺探电位技术研究棉蚜的取食行为，以探索其寄主专化型形成的行为机理。结果表明： 甜瓜蚜型棉蚜在棉花上的取食行为容易被中断，但其口针定位韧皮部的能力并没有显著削弱；而棉花蚜型棉蚜在甜瓜上的取食行为受到更大的影响，口针无法顺利定位至韧皮部，并在2 h内根本无法在筛管内取食。生物学观察和EPG取食行为分析都显示： 与甜瓜蚜型棉蚜相比，棉花蚜型棉蚜对寄主的要求更严格-寄主专化程度更高，对寄主的利用率更高。

Host-preference biotypes of the cotton aphid, Aphis gossypii Glover and the behavioral mechanism in their formation

The colonization and feeding behavior of the cotton aphid, Aphis gossypii Glover, on melon and cotton plants were studied in order to reveal the behavioral mechanism in formation of different host-preference biotypes. The results of the biological observation showed the number of colonizing aphids decreased significantly when they were transferred to their non-preference plant (melon or cotton). Moreover, both population reproduction coefficient and the nymphal survival rate were also significantly declined when aphids living on cotton were transferred to melon. These data suggested there were two host-preference biotypes in the aphid A. gossypii, the melon biotype and the cotton biotype. Based on the comparisons of feeding behavior between these two host biotypes using electrical penetration graph (EPG), the feeding characteristics of the two host biotypes of cotton aphids on their non-preference host were found as following: (1) The feeding behavior of the melon biotype aphids was interrupted easily on the cotton, but the ability that aphid stylet locating cotton phloem was not affected by frequent interruption in the pathway penetration; (2) The feeding behavior of the cotton biotye aphids was affected so greatly on the melon that the aphids could not locate the melon phloem and feed at the sieve element within 2 hours. The biological observation and EPG feeding behavior record of these two host biotypes both suggested that the cotton biotype aphid had stricter requirement for its host plant and used the host plant more efficiently than melon biotype aphid. These findings may give clues to explain why the aphids living on the cotton and melon respectively could not successfully transfer hostplants mutually.