Researches On Occurrence Of Major Tobacco Insect Pest And Its Forcast And Control In Hunan

The pests caused great loss on tobacco production. Tobacco pests feed on the leaves and stems, not only affect the quality and quantity of tobacco, but also give rise to the next generation to continue the damage.Combined with the meteorological date, the author recorded the dynamic growth of tobacco and testd four major tobacco pests of Hunan district(Heliothis assulta, Agrotis ypsilon, Heliothis assulta and Myzus persicae).By studying the regular pattern of occurrence, it revealed the dynamic occurrence of population, the amount of generation per year and the influence of environment. This provides scientific date to control the pest for the tobacco field.The result showed that, Heliothis assulta which caused damage to the field is originated from local district, their occurance peak showed at the end of May and June, and at the beginning of July. Via utilization the method of effective gather temperature, we can effectively estimate the properties of every originated generation. Agrotis ypsilon is a soil pest, which has four to five generations per year. The damage is closely related to the climate. Usually it causes serious damage at March and May. It is hard to predict the specific time of the occurrence peak oof larva. However, we can predict the occurrence by using number of Agrotis ipsilon moth trapped with sex pheromone and the moth-rainfall coefficient. Agrotis ypsilon and Heliothis assulta are migrate flight pest as well, which require the same wintering environment and migrate climate. Hence, there are some connections between these two pests. Heliothis assulta has four to five genetetions per year, migration peak occurs at May. So the number of Agrotis ypsilon in April and May can be used to predicting the migration of Heliothis assulta on May and June. The aphids’generations per year and the seasons amount are based on the overwintering base number and the climate condition. The season change is one peak module, then the damage peak occurs at April, May and June.Specimens were collected by field investigation at the tobacco base in Hunan agricultural university. The structure of the arthropod community in the tobacco field contains 40 arthropod species,which belonged to 20 families under 10 orders of Insecta and Arachnoidea. The dominant species of the tobacco pests was Myzus persicae; the dominant species of the natural enemies were spider and braconid. The diversity of the subcommunity of the natural enemies was the highest, the second was the subcommunity of the neutral insects, during the growth of the tobacco, The stability of the subcommunity of the pests was better than the subcommunity of the natural enemies and the neutral insects. The sequence of the index of the dominant concentration was natural enemies> neutral insects> pests. And the maximum fluctuation was the subcommunity of the neutral insects.According to the survey, discussion on tobacco pests control was established, which serve for comprehensive prevention and control of tobacco pest.