Attacting Effect Of Host Plants Volatiles Of Bemisia Tabaci On Delphastus Catalinae

Delphastus catalinae(Horn), the special feeding predator of whiteflies, is one of the important natural enemies of Bemisia tabaci (Gennadius).In order to obtain good results of using D. catalinae in wihitfly biocontrol, this research studied on the roles of the volatiles of whitefly host plants in D. catalinae habitats searching, including the allurement of whitefly host plants volatiles to D. catalinae, the roles of the antennae of D. catalinae in their host searching, the identification of the plant volatiles and the selectivity action of D.catalinae effected by normative sample of plant volatiles.1.The orientation of D. catalinae to the different treatments for cauliflower, Brassica oleracea var.botrytis L., was investigated using Y-tube olfactory and Petri dish in the lab. The results showed that the volatiles prouduced by cauliflower plants treated with healthy or with mechanical damage, damaged by whitefly eggs or nymph all attracted D. catalinae. Attract action appeared tensity as: herbivore-induced cauliflower plants > artificial-damaged cauliflower plants > healthy cauliflower plants. There was no significant difference between the male and female on the orientation behavior to host plants, but the overall view, female ladybirds on herbivore-induced orientation of cauliflower plants were slightly higher than the male.2. The experiment of D. catalinae with the antennae excised in Y-tube olfactory verified that the antennae played an important role in search of the host plant by detecting the odors from cauliflower plants.3. GC-MS studied on volatiles chemicals of cauliflower plants, SPME, showed that 28 phytochemical volatiles were received from different treatments of cauliflower plants, which had different chemical illustrative plates. Cauliflower plants in different treatments could release alkanes, terpenes, alcohols, aldehydes, esters , phenols and other substances, with higher content in alkanes, alcohols, esters. Volatiles from cauliflower plants by artificial-damaged and herbivore -induced had increased with either the type or the content, and increased more in herbivore-induced plants. Herbivore-induced cauliflower plants released the new volatile substances that were mostly terpenes and alcohols, and with the increasing content of esters, aldehydes and phenols, but with the type not increased. In contrast, the type and content of alkanes were reduced.4. Five kinds of standard samples of volatiles were selected which were new produced or the content increased after herbivore-induced (Docosane, 1-Tridecanol, 1-Tetradecane, 2-Butyl- 1-octanol, Cedrol) and were confected into 5 different con- centration grads of 10^-5-10(^-1) g.ml^-1to test the attractiveness of D. catalinae. The results showed that 5 volatile standard samples all have attractiveness to D. catalinae in the appropriate concentration, and different volatile compounds had different threshold effect and showed a certain regularity. The attractiveness of 2-Butyl-1-octanol and Cedrol increased with standard sample concentration increasing, while the attractiveness of 1-Tridecanol and Docosane increased first and then decreased. The attractiveness of 1-Tetradecane had little change, just slightly decreased with the increase of standard sample concentration.