Researches On Occurrence Of Major Tobacco Insect Pest In Hunan

The pests caused great loss on tobacco production. Tobacco pests feed on the leaves and stems, which not only affect the quality and quantity of tobacco, but also give rise to the next generation to continue the damage.Combining with the meteorological date, the author recorded the dynamic growth of tobacco and tested four major tobacco pests of Hunan district (Heliothis assulta, Agrotis ypsilon, Prodenia litura and Myzus persicae).By studying the Occurrence regularity of population or theses four tobacco pests, the author also revealed the dynamic occurrence of population, the amount of generation per year and the influence of environment. This research scientifically provides reliable basis for the management of pests in the tobacco field, which laid the foundation for the development of ecology and economy.The results showed that Heliothis assulta is the local major insect damage, whose Adult peak period happened 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 of larva. However, we can predict the occurrence through the number of Agrotis ipsilon moth trapped with sex pheromone and the moth-rainfall coefficient. Both Agrotis ypsilon and Prodenia litura are migrate flight pest, which require similar overwintering environment and migrate climate. Hence, there are some connections between these two pests. Prodenia litura has four to five generations per year, and migration peak occurs at May. So the number of Agrotis ypsilon in April and May can be used to predict the number of immigration of Prodenia litura in May and June. The difference of aphids’ generations per year and the amount in every season are based on the overwintering base number and the climate condition. Generally, the season changing curve is a peak module, and the damage peak occurs mainly in April, May and June. Through collecting specimens and the field investigation in the tobacco base in the Hunan Agricultural University, we confirm that the structure of the arthropod community in the tobacco field contains40arthropod species,which belonged to20families under10orders of Insecta and Arachnoidea. The dominant species of the tobacco pests was Myzus persicae, and 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 period of the tobacco. The stability of the subcommunity of the pests was better than that of the subcommunity of the natural enemies and the neutral insects. The sequence of the index of the dominant concentration was natural enemies, neutral insects and pests. The index that fluctuated most seriously was the subcommunity of the neutral insects.According to the above results, this research provided several suggestions and guides to the prevention and control of tobacco pests of Hunan province.