The Effect Of Different Celery Cultivars Against Bemisia Tabaci On Cucumber And Study On Its Mechanism

As a host, the whitefly Bemisia tabaci (Gennadius)has been recorded from more than600plant species of74families. It has different preference to different host plants, and its’frefered host plants are cucumber, tomato, cabbage, cotton, tabacco, etc.; nevertheless, there are still many less prefered host plants for it, some of them may have a repellent effect to the whitefly. From2011to2014, basing the former related researches the author selected ninecelerycultivars, used straight tube olfactometer, Y-olfactometer, network rooms in greenhouse, and in open field, studied the choice behavior of the whitefly to the celery cultivars; evaluated the repellent effects of the nine celery cultivars to the whitefly. And for probing the bio-chemical relationship of the celery volatiles between the whiteflies and the celery cultivars, another study was carried out by straight tube olfactometer, Y-tube olfactometer bioassay and HS-SPME-GC\MS. At last, a OBP and two G-protein subunit genes enconding Gaq and Gβ1were cloned from the whitefly.All of the experiments were conducted in Insect Ecological Laboratory of China Agricultural University and at Zhuo Zhou Teaching and Experimental Farm of China Agricultural University. The main results are as follows:(1) The results showed that the celery cultivars Juventus, Ventura and Jinnan had a better repellent effect to the whitefly fromthe following experiment methods:straight tube olfactometer, Y-olfactometer,greenhouse and open field.(2) The results from SPME-GC/MS and headspace adsorption elution GC/MS showed that β-Myrcene, D-Limonene and (E)-β-Ocimene were the dominant repellent volatilesofthe celery cultivars, and the different identification methods have a greate impact on the components of the volatiles of the celery cultivars.(3) The straight tube olfactometer analysis showed that P-Myrcene and D-Limonene has a significant repellent effect to the whitefly, the repellent effect of (E)-β-Ocimene to the whitefly varied with its concentration. To sum up, D-Limonene may be the main repellent active substances, and the repellent effect by P-Myrcene and D-Limonene may be a combination between them.(4) The ORFs of whitefly OBP gene of B. tabaci (B and Q biotype) were cloned by using reverse transcription(RT)-PCR and RACE methods, GenBank accession number is KJ188169.The sequence analysis showed that the acid sequences from the two biotypes of B. tabaciare exactly in the same sequence.(5) The ORFs of G proteinn a subunit(Gaq) and β subunit(Gβ1) of B. tabaci(B and Q biotype) were cloned by using the reverse transcription(RT)-PCR and RACE methods, GenBank accession numbers are JQ922538and KC188671, respectively. The genesfromthe two biotypesof B. tabaciare exactly in the same sequence.Prokaryotic expressionswere done and antiserums were obtained by the two proteins.(6) Quantitative PCR and western blot showed that BtabGaq and BtabGβ1are neither developmental-stage-specific nor tissue-specific. There are significant differences in transcript levels of BtabGaq and BtabGβ1at different developmental stages. The transcription levels of BtabGaq and BtabGβ1in the head were significant higher than thoses in thorax and abdomen.