Host Use Of Cotton-and Cucurbits-Specialized Aphid,Aphis Gossypii Glover And The Effects Of Feeding Experience On Cowpea On The Host Specialization

The capacity of cotton-and cucurbits-specialized aphids Aphis gossypii to use host plants, and the effect of feeding experience on cowpea on the host specialization and acetylcholinesterase activity were studied. The main results were list as followings.The ability of cotton-and cucurbits-specialized aphids to use hibiscus, chrysanthemum, tomato, corn seedlings, radish, pumpkin, potato and cowpea were studied using the host transplantation method. The results showed that the cotton-specialized aphids could use the hibiscus, potato, and cowpea, but could not use the chrysanthemum, tomato, corn seedlings, radish, and pumpkin. The cucurbits-specialized aphids could use pumpkin, potato, and cowpea, but could not use hibiscus, chrysanthemum, tomato, corn seedlings, and radish. The potato and cowpea plants could be used by all or partial of clones of the cotton-and cucurbits-specialized aphids.The capacity of cotton-and cucurbits-specialized aphids to use cowpea and potato plants was studied by successive rearing method. The results showed that both of the cotton-and cucurbits-specialized aphids could establish population on cowpea for more than17generations. The cotton-specialized aphids could produce offspring when they were reared three generations on potato, but the cucurbits-specialized aphids could not. The cucurbits-specialized aphids could not use the potato plant consistently. The cotton-specialized aphids could still use cotton plant, but could not use the cucumber plant even if they were reared on cowpea for17generations. However, the cucurbits-specialized aphids gained the capacity to use cotton plant when they were reared one generation on cowpea, and they still maintained the capacity to use cucumber. Therefore the cowpea plant extended the host range of cucurbits-specialized aphids, and broke the host specialization.The acetylcholinesterase activity of cotton-and cucurbits-specialized aphids on original host plant and cowpea was measured. The results showed that acetylcholinesterase activity of cucurbits-specialized aphids was significantly higher that that of the cotton-specialized aphids on their native host plants. The acetylcholinesterase activity of cotton-specialized aphids increased significantly when they were reared from one to seven generations. But the cucurbits-specialized aphids’were not significant difference among one to seven generations reared on cowpea.The acetylcholinesterase activity of cotton-and cucurbits-specialized aphids reared on cowpea for1-7generations was also measured when they were transferred back onto cotton and cucumber plants. The results showed that the acetylcholinesterase activity of cotton-specialized aphids increased on cotton when they were reared one to five generations on cowpea, but it declined to the cotton-specialized aphid’s level on cotton when they were reared for seven generations on cowpea. The acetylcholinesterase activity of cucurbits-specialized aphids on cotton also increased when they were reared one and five generations on cowpea but it recovered the original level of cotton-specialized aphid on cotton when they were reared seven generations on cowpea. The acetylcholinesterase activity of cucurbits-specialized aphids on cucumber increased as the increase of the generations on cowpea, and it reached the original level of cucurbits-specialized aphid on cucumber after being reared three generations on cowpea. The host range change of cucurbits-specialized aphids accompanied the change of their acetylcholinesterase activity. The acetylcholinesterase activity would be related to the host specialization of Aphis gossypii.