Studies On The Adaptation Of B-biotype And Q-biotype Bemisia Tabaci To Host Plants

Using four host populations of B-biotype Bemisia tabaci and one of Q-biotype B. tabaci, which had been long-term isolatedly cultured on different host plants, we determine the effects of host nutrition and secondary metabolites on'the activities of main digestive enzymes and amino acid metabolism enzyme. We also compared the differences of insect main nutrition, body size and the composition and contents of free amino acid. The results offered the theoretical basis for studing on the adaptation to host plants, Population Division, biotype alternative, comprehensive control of Bemisia tabaci. Our results as follows.Variation of host plant nutrition:The contents and composition of plant nutrition and secondary metabolites were significant different in five host plants. Total sugar contents of poinsettia and cabbage were significantly higher than the other three host plants. Total nitrogen and soluble protein contents of cucumber were highest, followed by cotton and poinsettia, and lowest in cabbage and tomato. Fatty acid content of cabbage was significantly higher than the other four host plants. The water contents of cabbage, cucumber and tomato were significantly higher than those of cotton and poinsettia.Total amino acid and total phenolic content of poinsettia were significantly higher than other four host plants.Variation of main nutrition contents:of whitefly. Results of main nutritions among different host populations of B. tabaci indicated that the contents of total sugars and lipids of cotton population were significantly higher than those of other four host populations. B-biotype cucumber population was the lowest; The total protein and water content in different host populations and different bio types of B. tabaci showed no significant difference.Variation of adult body size of male and female among different host populations: Female body size of B-biotype cucumber, B-biotype tomato and B-biotype cotton populations were significantly larger than B-biotype cabbage and Q-biotype poinsettia populations. Male body size of B-biotype cucumber and cotton populations was significantly larger than B-biotype cabbage, B-biotype tomato and Q-biotype poinsettia populations. Of which male body size of B-biotype cucumber population was the largest, while Q-biotype poinsettia population was the lowest.Digestive enzymes:There were no significant variations in protease, lipase and amylase activity among four B-biotype host populations and Q-biotype poinsettia population. In contrast, significant differences were found in trehalase and invertase activities. Trehalase activity of B-biotype tomato and Q-biotype poinsettia population was significantly higher than B-biotype cotton, B-biotype cucumber and B-biotype cabbage population. In addition, invertase activity of B-type tomato population was significantly higher than other host populations, and the invertase activity of Q-biotype poinsettia population was the lowest.Amino acid metabolism enzymes:GOT activity of B-biotype cotton population was the highest, while Q-biotype poinsettia population was the lowest. GPT activity of B-biotype cotton and Q-biotype poinsettia populations were significantly higher than other three host populations. GS activity of Q-biotype poinsettia population was significantly higher than four B-biotype host populations.Variation of free amino acids:Contents of phosphorylation of serine, ethanolamine phosphate, threonine, tryptophan, glycine, alanine, valine, methionine,β-alanine, tyrosine in Q-biotype were significantly higher than those of B-biotype. In contrast, there were no significant differences in contents of asparagine among four B-biotype host populations and one Q-biotype poinsettia population. There were significant differences in contents of free amino acids among four B-biotype host populations and Q-biotype poinsettia populations. The contents of free amino acids ranked as follows. B-biotype cucumber, B-biotype cabbage, B-biotype tomato, Q-biotype poinsettia and B-biotype cotton populations. However, the citrulline was only detected in B-biotype cucumber population, while Q-carnosine was only detected in Q-biotype poinsettia population. There were significant differences in contents of various amino acids except tryptophan, methionine, cysteine, threonine andβ-alanine in four different B-biotype host populations.According to variations of the composition and contents of free amino acids in five B. tabaci host populations, we used discriminating analysis to distinguish host populations and found that the different host populations were classified into five categories. The results indicated that host plant nutritions had significant effects on composition and content of free amino acid of whitefly.