Effects Of Defense Responses In Tomato Plants Induced By Frankliniella Occidentalis On The Behavioural Responses Of Bemisia Tabaci B-biotype And The Parasitoid Encarsia Formosa

Since1980s, the sweetpotato whitefly (Bemisia tabaci) has outbreaked in the United States and other countries. In the past20years, with the trading activities of with poinsettia (Euphorbia pulcherrima) or other flowers, B-type Bemisia tabaci spread in worldwide, outbreaks and has become a worldwide pest, which is known as "super pests". The western flower thrips Frankliniella occidentalism(Pergande) was firstly recorded in China mainland in2003, and has caused serious damages in many regions and resulted in huge economic losses.And the two insects are in a similar niche and they may outbreak at the same time, so our objectives were to reveal the competition and effect between F. occidentalis and B. tabaci. But the plants defenses induced by multiple herbivore species had been rarely studied. In this thesis, we studied the effects of tomato plants defenses induced by F. occidentalis on the behavioural responses of B-biotype B. tabaci and the parasitoid Encarsia formosa to understand ther mechanism of the competition between two pests. The results are as follows:(1) Our study indicates that F. occidentalis interfered the behavioural responses of B-biotype B. tabaci and the parasitoid E. Formosa. Compared with the plants damaged by B. tabaci, the B. tabaci damaged plants interfered by F. occidentalis had great repellent effects upon the host preference and behavioural responses of B. tabaci, and reduced the parasitic rate of E. formosa to B. tabaci. These results imply that the tomato plants infested by F. occidentalis had negative effects on the B-biotype B. tabaci and the parsasitoid of E. Formosa.(2) As the herbivore-induced plant volatiles (HIPVs) is an important indicator evaluating the host plants defenses induced by herbivores, we investigated the differences of the HIPVs content of the different host plants treatments. The results showed that the HIPVs induced by the plants damaged by B. tabaci, F. occidentalis and B. tabaci plus F. occidentalis were significantly different with the undamaged plants. We found that the HIPVs may be the key factor of the host plant reponses induced by western flower thrips, which can affect the behavioural responses of B. tabaci, and the parasitoid E.formosa.