Study On Species, The Occurrence Of Thrips On Alfalfa In Xinjiang And The Influence Of Temperature On The Growth And Development To F.intonsa

In this paper, the thrips species in Xinjiang alfalfa fields and the population dynamics of Odontothrips confuses Priesner and Frankliniella intonsa(Trybom)in alfalfa seed fields were investied. The development and other biology peculiarity of Frankliniella intonsa Trybom under a range of constant temperature were studied. The results are as follows :In alfalfa growing areas of whole Xinjiang Autonomous Region, thrips were collected for 12 species, belonging respectively to three families. The Aeolothripidae(2 species)include Aeolothrips intermedius Bagnall and Aeolothrips xinjiangensis Han. The Thripidae(8 species)include O. confuses, F. intonsa, Frankliniella tenuicornis(Uzel), Thrips tabaci Lindeman, Chirothrips manicatus(Haliday), Scolothrips takahashii Priesner, Thrips atrantus Haliday and Thrips vulgatissimus Haliday. The Phlaeothripidae (2 species)include Haplothrips aculeatus (Fabricius) and Haplothrips tritici (Kurdjumoi). A.intermedius, A. xinjiangensis and C. manicatus are predatory species , and the other nine species of thrips are herbivorous species.The population dynamics of O.confuses and the incidence of reproductive age alfalfa closely related. In late April to May early, O. confuses start to do harm to alfalfa, with the rise of temperature, the numbers started to grow. Alfalfa enter the bud stage by the end of May, and the number of O. confuses rising rapidly. Alfalfa of flower season suffer injuries worst. After mid-July its number dropped noticeably. F. intonsa began rised in late April. Their number has a little climax,later its number fall off for several days,Their number has been on the upward trend to mid-June. In late June after the number rising faster, in late July after their number is gradually declining.5 gathered indicators results showed that the adults of O. confuses, F. intonsa and A.intermedius belong to the aggregation distribution. The reason of O. confuses is the gathering by its own actions or the circumstances; The gathering of F. intonsa and A.intermedius is caused by environmental conditions. Thrips could be atracked by different colours . To O. confuses and F. intonsa, purple is the strongest, obviously stronger than the other colour, followed by dark blue and blue.Each development period of F. intonsa was studied under a range of constant temperature (16, 20, 24, 28, 32, 34℃) in the laborary. Whole generation duration were 37.27, 23.78, 18.10, 13.30, 10.90 and 10.33 days. The development threshold temperature for egg, nymph, prepupa, Pupa, pre-oviposition adult and whole generation were 8.06, 11.49, 12.39, 10.16, 12.94 and 9.56℃. The effective degree-days for the development of each life stage were 82.72 for egg, 71.02 for nymph, 16.21 for prepupa, 41.31 for pupa, 22.03 for pre-oviposition adult and 249.07 for whole generation. F. intonsa can do parthenogenesis.The relationship between F. intonsa's Population trend index (I) and temperature (t) is parabolic trend, fitting equation: I= -0.0371t2+1.8805t-20.486 (R2=0.868)(R2=0.962). At 25.34℃, I has the maximum 3.34.