Influence Of Tomato Varieties On Host-selection Behavior And Detoxification Enzyme Activity Of Bemisia Tabaci

Whitefly Bemisia tabaci (Gennadius)(Homoptera:Aleyrodidae) is one of the major pests in tropical, subtropical, and temperate regions and their adjacent areas. Since invaded China in the late1990s, bio type B has been recorded in many provinces in China, and caused huge losses of agricultural production. Whitefly is one of the main pests of tomato. Many factors may affect the host selection behavior of insect, but it is generally considered that the insect visual and olfactory senses play an important role in host-selection. I compared differences in volatile components among six varieties of tomato, and investigated the response of B-type B. tabaci to the major volatile components. I also studied the activities of esterase and glutathione-S-transferase in whiteflies, which was reared on different tomato varieties. The objective is to explain the reasons why host selectivity of the pest to tomato varieties exist difference. The results are summarized as follows:(1) Thirteen volatile compounds were identified from six tomato varieties, among them, the major components were erpenoids. However, the compositions and contents of the volatile compounds were different among the varieties. The B-type B. tabaci shows the lesser preference for the varieties such as Zheza809and Zheza203, containing more kinds and higher proportion of terpenoids, and the strongest preference for the varieties like Huangtuoyan and Jinfei, containing fewer kinds and lower proportion of terpenoids.(2) The repellent effect of the five individual volatile compounds (1000mg/L) in strong-weak order was:(+)-3-carene and β-caryophyllene>(+)-a-pinene and a-caryophyllene, and (+)-2-carene has no significantly repellent (P>0.05); however,(+)-2-carene (250mg/L) has repellent effect to B-type B. tabaci. While it has no obvious repellent effect at above or below this concentration; There is no difference in olfactory response between the mixture of the three volatiles ((+)-3-carene, P-caryophyllene and (+)-a-pinene) and the single one, but the difference were significantly among the three single volatiles, the order of repellent effect in strong-weak order was:(+)-3-carene> β-caryophyllene>(+)-a-pinene.(3) After transferred onto different tomoto varieties from cotton. the whitefly in F1 and F2generations had significantly difference in the activities of carboxylesterase and glutathione-S-transferase among tomoto varieties. The whitefly in F3generation had significantly difference in the activities of carboxylesterase, but had no significantly difference in the activities of glutathione-S-transferase among tomoto varieties. The protein content of the two enzymes was not significant difference among cultivars, but had significant differences among generations. With the increasing of generations, the carboxylesterase activity decreased gradually, and the activity of glutathione-S-transferase enzyme in F1and F2have no differences, but it is increased in F3.