Interactions Among Cruciferous Vegetables Diamondback Moth(Plutella Xylostella),and Cotesia Plutella

The relationships among cruciferous vegetables, diamondback moth (Plutella xylostell扥, and Cotesia plutella were investigated on the signal communication among the tritrophic levels which includes the allurement of vegetable volatiles to diamondback moth, the allurement of the volatiles from the vegetable and the larvae of diamondback moth to Cotesia plutella, the ultrastructure and the roles of the antennae of diamondback moth and Cotesia plutella in their host searching, and the identification of the vegetable volatiles. In addition, the physiological responses of the vegetable to the feeding of diamondback moth were tested, and the responses were further investigated at the molecular level.I.The orientation of diamondback moth and Cotes!a plutella to the vegetable voiatiles was investigated using Y-tube olfactory in the lab. The results demonstrated that the diamondback moth was attracted by the vegetable volatiles, female adults were attracted more than male adults, and there existed difference of the attraction from different vegetable species. Cotesia plutella was attracted most by the vegetable plants infested by the larvae of diamondback moth, secondly by the artificial damaged plant, thirdly by feces of the larvae, and lastly by the larvae. The experiment of the diamondback moth 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 vegetable.2.The orientation of Cotesiaplutella was tested in a Petri dish in the laboratory. The results indicated that Brassica oleracea L. var. capllala L. and B. Oleracea L. var. bohytis DC. could equally lure Cotesia plutella. Further bioassay was tested using the leaves of Brassica oleracea L. var. capitata L. as experimental material. Leaves infested by larvae of the diamondback moth, enticed Cotesia pluIella more than undamaged and mechanically damaged leaves. Females of Cotesia plutella were more capable of locating the leaves infested by the diamondback moth than the males. Extraction of larval feces of the diamondback moth using different solvent showed different allurements to Cotesia plutella. Methanol extraction had the most allurement to the parasitoid, ethanol extraction also had certain allurement to the parasitoid, and the other solvent extractions showed almost no allurement, including hexane, tetrachloride carbon, ether and water. Learning of Coies~a piutella played an important role in search of the host and its habitat. The parasitoid could increase the capacity of orientation after touching leaves damaged by larvae of the diamondback moth in the previous day, and the times of touching leaves had positive effect on the orientation of the parasitoid. The role of the antennae of Cotesiaplutella to receive chemical cues was testified by the behavior of Cote.cia plutella with the antennae excised.3.There were 9 types of sense organs in the antennae of diamondback moth observed byelectronic scanning microscope, of which the amount of Trichoid Sensillum was the most. There were some differences in the antennae between females and males. Styloconic Sensilla only existed in the antennae of male adult. There were more Squamiform Sensilla in the antennae of males than that in females, and the reverse to Coeloconic Sensilla.4.There were 10 types of sense organs observed in the antennae of Cotesia plutella by using electronic scanning microscopy, of which Trichoid Sensillum and Placoid Sensillum were the main receptors with a large quantity. Differences existed in the antennae between females and males. There were more sense organs in the antennae of females with the unique sense organs of Campanile Sensillum and Ampullaceous Sensillum. The quantity of sensillum in the females was more than that in the males.5.The enzymatic activities of superoxide dismutase (SOD), hydrogen peroxidae (CAT), peroxidase (POD), polyphenol oxidase (PPO), and the content of phenol in the leaves of Chinese cabbage, Brassica campestris L. ssp.