| The serious outbreak of Laodelphax striatellus (Fallen) which transmited rice stripe virus in Jiangsu province resulted in rice yield and economic loss were due to in recent years. In order to research the occurrence and transmission virus regulation of Laodelphax striatellus, fluctuation dynamic of Laodelphax striatellus and effect of different kinds of host plants and temperatures on population of Laodelphax striatellus were studied in this paper. The relationships of transmission virus by Laodelphax striatellus and different stages of rice were researched. The main results were as following:1. The fluctuation dynamic of Laodelphax striatellus was investigated and transfer regulation of Laodelphax striatellus were studied in Yangzhou area. There were 5-6 generations of Laodelphax striatellus in Yangzhou area. The 3 or 4 instar nymph of Laodelphax striatellus overwintered mainly on rice pile, wheat and lawn from November. Adults appeared in middle March. The overwintering adults oviposited in middle April to early May, and then the first generation of nymph appeared and the population started to rise in the field of wheat and the lawn. In middle May, the first generation of adults emerged, and transferred the seedling field of rice and the corn field gradually, resulted in the decrease of population amount of Laodelphax striatellus in the wheat field and the lawn. From late May to early June, the ammount of Laodelphax striatellus was large on the corn field. In middle June, after seeding transplanting, Laodelphax striatellus began to transfer from corn, lawn and weed to rice field. After harvest of rice during the period from middle September to the end of October, they transferred from the field of rice to lawn, weed and wheat field to overwintered in nymph, partely nymph for some on the rice pile. 2. Effect of different host plants on population of Laodelphax striatellus was researched in this paper. The results indicated that Laodelphax striatellus could finish his life history on Fesucaarundinace Schreb and corn. The index of population increase of Laodelphax striatellus on two kinds of rice—Wuxiangjing 14 and Yangjing 9538 were higher than other, which were 40.40 and 22.64 respectivelly. The index of population increase of Laodelphax striatellus on two kinds of the corn—Yangnuo 1 and Zhengdan 958 were lower, which were 13.02 and 9.18 respectively. The index of population increase of Laodelphax striatellus on Fesucaarundinace Schreb was 21.7. The development durations of nymph on the corn (Yangnuo 1, Zhengdan 958) were 16.23d and 16.76d, and on Fesucaarundinace Schreb was 16.25d. The mortality of nymph on corn and Fesucaarundinace Schreb were higher than the rice. The oviposition amount of adult on corn (Yangnuo 1, Zhengdan 958) and Fesucaarundinace Schreb was 45, 22.38 and 39.64 per femal respectively.3. Effect of different temperatures on Laodelphax striatellus was studied. The model was established according to the relationship between temperature and developmental rates. The low-development threshold temperature of each stage and the effective accumulate temperature were figured out by the model of development period and temperature. Ranging from 16 to 31℃, the model of relationship between the temperature and the developmental rates of Laodelphax striatellus was built by wang-lan-ding model. Raging from 16 to 25℃, the every developmental stage of Laodelphax striatellus was decreased with increasing of temperature. The fit temperature rages of Laodelphax striatellus population development were 18.15-30.24℃. The low-development threshold for generation was estimated to be 9.86℃by a linear regression model, and the effective accumulate temperature was 426.42 day degree. At the same time, the life table under different temperatures was established in this paper. The relationship between the temperature (x) and the index of population increase of Laodelphax striatellus (y) could be described by the quadratic curve. The equation was y =-0.4307x2+20.5419x-220.9906(r=0.7490*). Raging from 16 to 31℃, Laodelphax striatellus experimental population tendency index at 25℃was max and was 42.06. At 31℃, the trend index of population was less than 1, and was only 0.8. 4. The relationships between trasmission virus of Laodelphax striatellus and the different satges of rice was researched in this paper. The resule showed tha the syndrome rate of rice stripe virus in the previous stage was higher than in the later one. If inoculated 34 days after seed sowing, the syndrome rate was 27.03%, if rice was inoculated 49 days after seed sowing, the rate decreased to 9.34%. And even to 7.88%, if rice was inoculation was 78 days after sawing. The rice recovered better on its seedling stage than on other stages. The disease would hardly break out if plants were infected by the rice stripe virus in the jointing stage or milk-filling stage.
|
PDF Full Text Request