Studies On Host-adaptation Of Frankliniella Occidentalis

Frankliniella occidentalis is one kind of quarantine pests which damage great many kinds of horticultural plants around the world. It had made a successful biological invasion in China. As a result it had great potential danger to horticultural plants in China. The target of the thesis is to knowing whether host-adaptation has effect on insect'dietary preference or population diversion, so the experiment made a search including the variation of biological characteristics, physiology and biochemistry, molecular biology of Frankliniella occidentalis of different host-populations by the methord of observing pests'growth, detecting its detoxification enzymes's activity, analyzing its genetic differentiation of different host-populations through RAPD-PCR technique.The biological characteristics of Frankliniella occidentalis which were transferred their host from beanpod to green garlic leaf showed a phenomenon at the first several generations after host-changed. It is that the development time lenghthened, survival rate reduced, fecundity dropped, lifespan extended. Along with forced-raised for several generations, the development time got shorter, survival rate increased, fecundity enhanced, but the lifetime unchanged. The biological characteristics of Frankliniella occidentalis which were transferred their host from beanpod to sweet pepper fruit showed a phenomenon at the first several generations after host-changed. It is that development time slightly lenghthened, survival rate greatly reduced, fecundity dropped sharply, lifetime shorted. Along with forced-raised for several generations, the development time got shorter, survival rate increased, fecundity went up a little, but the lifespan was as shorter as before. In the experiment of host-returened experiment, re-changed Frankliniella occidentalis's host from sweet pepper fruit to beanpod, the result showed that development time got no obvious changement, but survival rate of nymph and pupa obviously reduced, fecundity weaken.In the hybridization-experiment of Frankliniella occidentalis's from two different host-population. The two population is Frankliniella occidentalis which fed on beanpod and fed on sweet pepper fruit at 10th generation. It seemed that the biological characteristics of hybridied-decendant was more closer to Frankliniella occidentalis which were fed on sweet pepper fruit. Among the characteristics index, development time unchanged obviously, the survival rate and fecundity got a turbulence, reduced or increase among the generations. In general, the hybridized population adapted to neighter host, and the population showed a decline tendency. In the experiment of host effect Frankliniella occidentalis's detoxification enzymes' activity, detect it in Frankliniella occidentalis from host-population of beanopod, green garlic leaf and sweet pepper fruit. The result indicated a law. At the first generations of host changed from beanpod to green garlic leaf or sweet pepper fruit, the detoxification enzymes'activity increased sharply, especially at the time of host changed 24h later. Then the detoxification enzymes'activity declined along with generations. At the generation 6^th, the the detoxification enzymes'activity got a relative stable stage, but the data of activity was still at obvious higher leval than that from host- population of beanpod.RAPD-PCR technique could point out the differentiation of genetic structure among 5 host-populations. The 5 host populations were Frankliniella occidentalis fed on beanpod, fed on green garlic leaf at 5^th generation, fed on green garlic leaf at 10th generation, fed on sweet pepper fruit at 5^th generation, fed on sweet pepper fruit at 10th generation. The result revealed there was significant differentiation among these host-populations. The population of Frankliniella occidentalis fed on on beanpod showed a richer PPB. On one side, population from same host but at different generations showed more similarity. On the other side, population from different hosts and different generations showed more differentiation. Use UPGMA clustering graph, we can see the relationship among them.Frankliniella occidentalis which were forced to fed on different hosts for several generations got a differentiation in biological characteristics, physiology and genetic structure. We consider this differentiation is a fedding differentiation, a unstable differentiation. However whether this differentiation is reversible is a question. All the experiment supply a fundamental theoretical base for Frankliniella occidentalis controling. In the practice, use different host pull and push Frankliniella occidentalis's distrution, protecting target plants.