Studies On Diapauses Of Wheat Blossom Midge By RAPD

Wheat blossom midge Sitodiplosis Mosellana (Gehin) is one kind of serious pests of wheat crop in Northern Hemisphere, outbreaking sporadically. They are found in all the wheat-growing regions in China. They occurred many times and seriously reduced the grade of the harvested wheat in history. They still outbreak in some areas, have the enlargement and spread trend, is the potential threat of wheat production in recently years. Owing to it is difficult to raise wheat blossom midges indoors, the records is only seen in the field investigation and observation about the diapause. Being short of the deep research in theory, we still do not see the report about the diapause mechanism. Random amplified polymorphic DNA (RAPD) is simple and operates conveniently as one kind of molecular biology technology, so it is widely applied in the insect taxology, species related relationships, phylogeny, the pest appraisals, the drug resistance diagnosis and ecology etc. In this thesis, we use RAPD technology to research ten kinds of different samples, the main result is as follows:1. The methods of small-size insect's DNA drawing are fairly difficult. After consulting to the methods, we finally choose the method of Collins'(1987) malaria mosquito DNA drawing, because it is good and fairly stable for DNA drawing.2. According to the Marker (DL2000), we make clear that the dimension of wheat midge genomic DNA is about 25kb.3. Improved the existed RAPD system to make it more stable and economical. The total reaction volume is 25μl, including 4.0μl 10×buffer (include Mg2+), 2.0μl dNTPs (each 2.5mM), 1.0μl template DNA, 1.0μl Taq polymerase (1U/μl), 1.0μl random primer, 16.0μl superpure water.4. The genomic DNA of ten samples was amplified with 44 random primers. Only six primers (S1, S50, S81, S83, S1031, S1248) could produce clear fragments and obtained a total number of 81 fragments in ten samples amplified (Fig.1). Among this, S1 amplified 19 fragments, S50 amplified 21 fragments, S81 amplified 9 fragments, S83 amplified 8 fragments, S1031 amplified 13 fragments, and S1248 amplified 11 fragments. Molecular size of the fragments ranges from 200bp-2000bp.5. Through the genetic distance, genetic identity and dendrogram we know that the genetic relationship of the non-cocooned larva is similar but it is complex of the cocooned...