Effects Of Semio-chemicals Of Tropical Plant On Diamondback Moth, Plutella Xylostella L.

This study was based on the theory of Pest Population System Control (PPSC). Twenty kinds of extracts of tropical plant were evaluated by the Life Table Method and the Index of Interference of Population Control (IIPC). The main results are as follows:1. The olfactory response to the adult of the diamondback moth on six kinds of plant volatiles was measured in four armed-olfactometer. The influence of olfactory response to the adult of the diamondback moth was evaluated by first choice, last choice, time spend and number of choice. The result showed that these plant volatiles had good deterrent effects on this pest, and that the deterrent effects strengthened with the flow rate of volatiles enhancing. From strong to weak, the deterrent of six kinds of plant volatiles effect on this pest was Artemisia argyi Levl. et Vant., Piper betle L., Artocarpus heterophyllus Lam., Anacardium occidentale L., Eupatorium odoratum L., Mimosa pudica L.. In the flow rate of 100mL/min and 140mL/min, the rate of first choice and last choice of A. argyi, P. betle, A. heterophyllus, and A. occidentale all were 0.2. The result in the test of oviposition deterrent and antifeedant showed that volatiles of P. betle, A. heterophyllus. and E. odoratum had strong effect on diamondback moth. Twelve hours after treating with 2000mg/L, the rate of oviposition deterrent against the adult was 70.52%, 64.84% and 68.86% respectively, the rate of antifeedant against the larva was 60.96%, 53.50% and 52.84% respectively.3. The influencing result on experimental population of diamondback moth showed the volatile of P. betle L. had very strong deterrence against next generation of population in these volatils. Forty chemical compounds were checked out from the volatile of P. betle L. used GC/MS. Among these compounds, the main components were Myristicine and Trans-caryophyllen, their content was 65.222% and 13.894%.4. In concentration of 0.01gDW/mL, all of the twenty alcohol extracts that were conducted in laboratory had effect on the behavior of diamondback moth. The alcohol extracts of A. heterophyllus Lam,, A. occidentale L. and M, pudica L. showed stronger effect oviposition deterrent and antifeedant against experimental population of diamondback moth than others. These three kinds of alcohol extracts showed longer influencing against experimental population of diamondback moth in the test of oviposition deterrent, five days after conducting, these extracts still showed high rates of oviposition deterrent. In the test of influencing the population growing, these extracts showed significant deterrence and interference against the experimental population of diamondback moth. But the alcohol extract of A. heterophyllus Lam. showed the best effect on their population growing, their interference against the experimental population all surpassed 70% in five concentrations.5. The alcohol extracts of A. heterophyllus Lam., A. occidentale L. and M. pudica L. were isolated. The extracts of first isolating were surveyed about the bioassay. The result showed that ethyl acetate extract of the alcohol extracts of A. heterophyllus Lam. had marked effect of oviposition deterrent and antifeedant on this pest. Twenty fractions were obtained using silica gel column from the ethyl acetate extract of the alcohol extracts of A. heterophyllus Lam.. By the bioassay, thefractions of L1 and L13 and L18 and L19 showed strong effect of antifeeding, their rate of antifeeding was 85.71%, 73.33%, 78.57%, 88.87% respectively.6. In the field, the Uniform Design was used to check the Index of Interference of Population Control (IIPC) against diamondback moth by difference concentrations and span of times. Through assaying and returning of (quadratic equation, a model depicting the correlation between IIPC and two factors (A and B) using uniform design is shown thus,Model: Y=0.4628-10.6164 A-0.0212 B+1 17.1290 A2-0.7762ABY-IIPC; A-concentration; B-timesActually, this model equation be used to check IIPC under the nature condition, the result showed that the...