Abstract: Whitefly honeydew is an important kairomone resource for host-searching of parasitoids. Carbohydrate and amino acid composition of honeydew from the whitefly Bemisia tabaci Bbiotype feeding on cabbage and cucumber, and from the greenhouse whitefly, Trialeurodes vaporariorum feeding on cucumber was comparatively analyzed with the ion chromatogram. The results showed that honeydew of the both whiteflies contained abundant carbohydrates and amino acids, however, the total carbohydrates were present at absolutely high levels, as 42.5, 2.6 and 5.4 times as the total amino acids in honeydew of three whitefly/host combinations, respectively. And the principal carbohydrate was oligosaccharide, accounting for 89.3%, 81.7% and 88.2% of the total carbohydrates, respectively in their honeydew. The species of whitefly and host plant significantly affected sugar and amino acid composition of honeydew, especially oligosaccharide composition. Disaccharides trehalulose and turanose were predominant oligosaccharides in honeydew from B. tabaci B-biotype on cabbage, accounting for 52.7% and 35.4% of the total oligosaccharides, respectively. However, the principal oligosaccharides in honeydew from B. tabaci and T. vaporariorum on cucumbers were tetrasaccharide stachyose and trisaccharide melezitose, which accounted for 40.3% and 26.2%, 49.9% and 27.0% of the total oligosaccharides, respectively. The predominant amino acids were alanine in honeydew from B. tabaci on cabbage (accounting for 66.5% of the total amino acids), glycine in honeydew from B. tabaci and T. vaporariorum on cucumbers (accounting for 38.2% and 51.7% of the total amino acids, respectively). A principal volatile Bis (2-ethylhexyl) phthalate was found with GC-MS in honeydew from both B. tabaci on cabbage and T. vaporariorum on cucumber.

Key words: Bemisia tabaci B-biotype, Trialeurodes vaporariorum, honeydew, amino acid, carbohydrate, volatiles, kairomone